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Orgnic Chm I(Lect)

by: Barton Franecki

Orgnic Chm I(Lect) CHM 201

Marketplace > University of Miami > Chemistry > CHM 201 > Orgnic Chm I Lect
Barton Franecki
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This 90 page Class Notes was uploaded by Barton Franecki on Thursday September 17, 2015. The Class Notes belongs to CHM 201 at University of Miami taught by Staff in Fall. Since its upload, it has received 17 views. For similar materials see /class/205763/chm-201-university-of-miami in Chemistry at University of Miami.

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Date Created: 09/17/15
Chemistry 201 C Alkenes Reactions and Synthesis This presentation was created by Professor Carl H Snyder Chemistry Department University of Miami Coral Gables FL 33124 CSnydermiamiedu Copyright 2004 by Carl H Snyder University of Miami All rights reserved Catalytic Hydrogenation of An Alkene r LN 31 ll r L gt I n nlksuw m z39lkmnt An excellent method for the preparation of alkanes and cycloalkanes Proceeds in excellent yield Also known as catalytic reduction of an a kene Involves a film addition of a molecule of H2 to a 00 double hon Alkenes Reactions quot quot and Synthesis Catalytic Hydrogenation of An Alkene 39 lquotv39 u 1 i W u Il L gt An 31km 01 7 H quotllf39lt39 l TIL I 2 Di inethylcyclolmxnnr vizI 2L1i Incthylcynlohoxn m I39SE39H An excellent method for the preparation of alkanes and cycloalkanes Proceeds in excellent yield Also known as catalytic reduction of an alkene Involves a film addition of a molecule of H2 to a 00 double hnn Syn and Anti Addition X Y N d X Y I C C dgb syn addition X N X C C 2 dag NY anti addition NY In syn addition both adding atoms enter from the same side of the 00 plane In anti addition the adding atoms enter from opposite sides of the 00 plane Commercial Use of Hydrogenation Hill and Entirl torking M n i l Jdt39r DI ecuuric u39id Used to convert liquid vegetable oils into solid or semisolid fats Addition of X2 To CC 11 H 939 r T i ii 39II Iiih I W 1 mm mum in hyh m dicMnridm L w Mm m Anti Addition of X2 The mode of addmon ergtlt2 in 00 is exciusiveiy ant um Mechanism Bromonium Ion Tiu4llwm hlmuumlm um ism imuives the ruhhanuh er a bmmunium iEIri as an intermediate Whi Expiains WWW m WW Mechanism Anti Addition the anti addi Halohydrin Formation An nlimm A hnlnhydrin Halohydnn formanon r The additiun er HOVX m a 00 dunbierbund Haiui vydrins bearxr and 70H uh neighburing Barbuns The Bromonium Ion Again if H20 is iri high Bun tratiun the H20 preempts Er iri anamhg the hhgeamuh The pruduct is a naiDWdrin Bromonium lon Formation Attack By Water Molecule m ii w W ii iim Ni imwiii e i riiiiii 397 Ih l t i l l u tii 2quot iii it w Deprotonation NBS And DMSO ii iii it i eicsaciii K a H ii MM m he martinitimetmmii W MM t new in c it iii t g hm him quothas ii iii Cheth i 39 ii i imi gtlmxin iitiii lih mm Mi i i iimiimiwtir N55 7 Nebrumusucc l lmldE a suurce cit Elrz nmsoe N th i it pularsulvent ii ii 5 L39 v ll 39 Illat39llgill H E Ellinon Alkene Hydration Acid Catalysis Em lune Alkene Hydration Acid Catalyzed Addition of H20 Threecs tep mechanism i Addltl cit H tci tcihh ca Markuvnikuv rEgiDSElE ivit 2 Attack by H20 cih car LEISS cit H frum prutunated aiccihcii rbEIEatlElri therefure fulluvvs v Water adds tn the 00 duuble bend under acidic cuhditiuhs Mechanism of FoldCatalyzed Alkene Hydration ilL 7r 17 Mechanism of FoldCatalyzed Alkene Hydration no u LLI I r 7239 C C il l39 E 231am Ipmwnu Rtzh yield car n elm gu Mechanism of FoldCatalyzed Alkene Hydration Rem oval of a proton 5 EL C Crtquot7ll Hf F i Mechanism of FoldCatalyzed Alkene Hydration HI C g II ELI E ii 1 HC397tquot7t 72139 i A HI I 241ahyL2pmpmmi Oxymercuration Mechanism Alkene Hydration Oxymercuration Idietl1ylcyclopommmi mm lMethytuyctupumeuu HgOAc2 mercuric acetate THF tetrahydrofuran Another 3membered ring Another regioselective Markovnikov reaction No carbocation isformed NaBH4 sodium borohydride LX mm mm mm m m m Oxymercuration Mechanism rm m M Oxymercuration Mechanism Mm minnows vrm Vane smurtnck mi km mm 9 mm M m Oxymercuration Mechanism gawk xxgtlt cm i m aH39 mm 1 My 1 M mm mm mm mm Oxymercuration Mechanism Cyclopropanes via Carbenes ix mime A FMInl rnmhr Aquot mm Addniun are czrhenetu a 00 duuhie band pmduces a cyciupmpane ring Anuther exampie ui rmemheved ungrmmanun Orbital Structure of A Carbene u V r 1 ma k u u w W 4 1m mum r Carhun is 5 hybridized The p urbnai is Empty One 5 urbitai dues nut uveviap WithihE handing urbitai ur anuiher aium m addmuns in 00 Carbene Formation ibree eiedronegatiye Ci s poiarize the CH bonding eiedrons toward the C The H becomes siigbtiyacidic Remoyai oi H by base then toss oi Ct produces CbC dichlorocarbene i ii Cyclopropane Syntheses it I ll ti liid39li errU t t rttt riu iii r i CyclopropaneSyntheses tit it ii 1 i 39i uquot iiii r i it it my UH quotH irriii C t ikl l e lttl iil um A it 39 H i ii iiiit i v i ii i I tigt i i ii yeinbiieiir rim Cyclopropane Hydrocarbon iiiii tii Wit t1v quoti iiiii Itiinriomotbiiiio tioduinoriiyiizine iodide tii tiirbeiiuiit y i gti tiiy 3 moribund NW names nzri ibe iodometby tine a carbene zrnc iodide bebayesyery mucb Cyclopropane Hydrocarbon iii i i W1 Hri i i it Itiinriomotbnno tindumoliiyiizine iodide tit t ui tiuriuiii iyiiinunn irriyiurriniiiyiuunun ibe iodometbybzrnc iodide bebayesyery mucb tie a carbene ThreeMembered Rings in Intermediates and in Products AReyiew and Summary Tbieemembered rings are formed in Haiogenation oi CC Haiobydriniormation Oxymercuration Addtions oi carbenesto CC Hydration via Hydroboration OXIdatIon Borane and leorane In the gaseous state BH3 borane exists as a dimer BZHE diborane In solution in THF BH3 exists as a monomer in a complex with THF Uurunu THF 13H THIquot complex Hydration via l 39 l Oxidation Hydroboration Htwo An orgunubunmu The BH bond adds to CC Normally the remaining BH bonds continue to add to additional alkene molecules producing R33 Hydration via Hydroboration Oxidation Hydroboration of thylene llzt39lL SHE CH t l quot3 MIMI t39ll t39ll lilhylmlr 39l rilltu lm39nnr The three BH bonds of one BH3 usually add to three CC groups The product is a trialkylborane This is not shown in the textbook Hydration via Hydroboration Oxidation Cyclohexene to Cyclohexanol mn Mum r W um Oxidation occurs by a reaction ofthe trialkylborane with alkaline hydrogen p roxide Hydration via Hydroboration Oxidation antiMarkovnikov synAddition Irau 2 mm mum m w ransZMethylcyclopentane must be the product of an antiMarkovnikov synaddition to the CC group Note Here a syn addition produces a trans product Hydroboration A 4Center syn Addition Hydroboration An anti Markovnikov Addition Note that the B adds to the less highly aklylated C and the H adds to the more highly alkylated C Hydroboration Steric Effects Steric crowding especially for RzBH addition leads to antiMarkovnikov regioselectivity Hydroboration Steric Effects 39 1 i 1 u 3 ll Vt argewhen RZB Steric crowding especially for RzBH addition leads to antiMarkovnikov regioselectivity law Hydration of Alkenes A Review and Summary intermediate Markovni o regioselectivity Oxymercuration no carbocation formed Markovnikov regioselectivity Hydroborationoxidation no carbocation antiMarkovnikov synaddition Acidcatalyzed hydration carbocation k v Alkene Hydroxylation r i k I H V II39 V L39 V an 7m 39 7 x N i n i 39 m i imlnwm imimmm Hydroxylation leads to glycol or 12diol formation 0504 is osmium tetroxide NaHSO3 is sodium hydrogen sulfite synAddition 5Membered ring formed as intermediate Polyethylene A Polymer CH2CH2 CH2CH2 gt CH2CH2CH2CH2 CH2CH2CH2CH2 CH2CH2 gt CH2CH2CH2CH2 CHzCHZ Polyethylene A Polymer nCH2CHZ gt CHZCHZ Polymerizations Free radical Termination Types of Polymerizations FreeRadical Polymerization Initiation rurrmrm who r n r n ln theo only one benzoyl peroxlde molecule need undergo rms nomolytlc decomposrnon Propagation Tne polymerlc cnarn grows as me reactorl rs repeated over and over wrrn addltlonal ethylene molecules Freeradical Polymerization n rrr n FreeRadical Polymerization Cationic polymerization Termination W or r l cu f on 1m V vi ruler suing mm Lil cu m m 1 Ii 3H Earl ii 39El rt39llrl39llrl39llr l WWW Ends the polymerlzatlon before all or the alkerle r m nas oeen convened to a polymer unwruvrm lnltlatlon and propagatlon occur by electrophlllc addltlorl to CC double bonds Other Commercial Polymers Pulyprupylene syntnetlcrloers l t u furru E carpetng and nunrclutnlng fabrlcs m a u u Meme A lmwnmuje w run nt Pulystyrerle plastlc rurnlture lrlsulatlrlg cups w my packaglng nuggets More Appripriate Symbolism Polypropylene cn3 l etecnycne Slmllarly ror polystyrene Rubber A Naturally Occurring P mer Rubber ls a polymer or Zrnetnylel 37 butadlene known more commonly as rsoprene CH2OCHCH2 l CH3 Rubber A Naturally Occurring Polymer Natural rubber ls a pulymer or Zmetnylel ae outaulene Tne geumetry urtne cc duuble bunds or natural rubbErls Rubber A Naturally Occurring Polymer Natural mbberls a pulymer or Zmetnylel e outaulene Tne geumetry ortne cc uouole bands or natural rubberls Other Important Polymers Polymer Monomer cellulose glucose glucose terlon c5 3 PVC polyylnyl cnlonoe ongcno End Alkenes Reactions and Synthesis Chermstry 201 c An Overwew ofOrgamc Reaeuons TmspvesemauunWascveatedbv PvuYessquaHH snyeer nm canyeermramr eeu Carmen 2004 12 Carl H Snyder UnrvereronWramr Alngms reserved An Ovcrviuwof nganlcneamans Energy cnanges m cnernrear Reaetrons HrTAS AG sthe cnanee rmne cuhhsnee enemy ansrs ne energy ernerence betweenme reauame and n2 preeuus WAG rs neganyeme reamen rs Xergoma m rereases enerey m me res1 enneunnerse HA rsposrnyemereaeuenrs endergoma m absuvbs enerey quotUm me resmnneunryerse Energy cnanges m cnernrear Reaeuons Hr TAS AH sthe change mtneenlhzlny Tms sthe neatunne reamun uHhe dmevence between the me gene shenmns uHhe veactamsand We 2 WAH rs negenyeme veacuun rs swat197mm m rereases hea n AH rsposrnyeme veacuun rs endomerm Nabsuvbsheat Energy cnanges m cnernrear Reaetrons AG AHr AS AS rsme enan e m me mlrnw ans rs me molecular dreamer e1 me veacuun enne ernerence m merecmar ere r e eemnereauamsane preeuus HAS rs negenyer ersmeereeereases as a resuu enne reauren HAS rsposrnye ersmeer rnereases asa resunennereacnen Energy cnanges m cnernrea Reaeuons Hr TAS AH sthe eemrnannenn mWE meat mammv e1 ereanrc reaurens Bond Dissociation Energies USIng Bond UlSSOCIalIOn tnergles um lVlm l n n C Furthe reactan u l u CHN l gt CH3quot quot4 u l o n as n l 253 r 2 a E l nn ter in cn n or out quot939 Endothermlcby57 r an kJmol Enthalpy of the Chlorination up Mud ammoquot mm Iur an urban almand at u would Ta lmixum t mg w tmm r wuld wl mam m u mm m m neviw rudllm m L39Mwluvnmuer um t W mm mm nnnrrmlawmleulmmnmd uth m u mulch li wVJtLrnm uy mm 4021 an r m min Enthalpy ofthe Chlorination Hrl39l r 1utul n TuL D t l mu mzmuuat munth ln tlmul The Enthalpy Calculation The enthalpy calculatlon does not glye us the entropy c ange Therefore tne enthalpy calculatlon does not glye usthe cnange ln GlbbS Free nergy The cnange ln GlbbS Free Energy does not tell us What tne rate or tne reactlon 5 l All these calculatlons rerer to molecules ln tne gas onase most organlc reactlons occur ln tne liquid phase Nonetheless The Enthalpy Calculation Enthalpy calulatlons are good general gul Enthalpy calculatlons are useful ror cornoanng reactlons or Slmllartypesy lnyolylng Slmllar rnolecu e5 The loolnatlon or rnetnane l5 endnlhermlc The chlorlnatlon or rnetnane l5 exotnermlc End An Overview of Organic Reactions Chemistry 201 C Organic Compounds Alkanes and Cycloalkanes This presentation was created by p University of Miami Coral Gables FL 33124 CSnydermiamiedu Copyright 2004 by Carl H Snyder 39versgy of Miami All rights ts xxx r Y 0 Organic Compounds Alkanes and Cycloalkanes nu Lewis Structures 0 E Lewis structures of The Lewis Structure of Methane H o H the hydrogen atom u and Hquot C H H C H the carbon atom 0 Lewis structures show u the elemental symbol V and the valence 1 1 quotI electrons Methane consists of4 hydrogens covalently bonded to one central carbon atom Methane The Molecular Model Methane A Covalent I Hydrocarbon quot g 1 Methanein 3dimensional lil perspective H H H J H H C TquotI CH1 H A Methane in a 2dimensional 0 1 4 representation H H unhnm in The Methyl Radical o o o o o H2C1H gt HiC H o o o t H methyl radical H Loss ofa hydrogen atom from methane produces the methyl radical also known as the methyl free radica Note that loss of any one of methane s four hydrogens produces the same methyl radical A Radical In chemistry a radical is any species bearing an unpaired electron Ethane From Two Methyl adicals H H n The combination of H 1 o 39 H two methyl radicals I if forms ethane Ethane can form in many other ways as well Ethane Expanded Structure Condensed Structure And Molecular Formula H H H I I H Expanded structure I H H Condensed structure Molecular formula C2H6 Ethane The Molecular Model Ethane in 3dimensional perspective E H H Ethane in a 2dimensional L L H representation i i ll lithium r39rn The Ethyl Radical CH gt H 39H H the ethyl radical Loss ofa hydrogen atom 39om ethane produces the ethyl radical also known as the ethyl free radical Notice that loss of any one of ethane s six hydrogens produces the same ethyl radical HI Propane From An Ethyl Radical And A Methyl Radical H H u H 11 391 up gtjm lizqz qzttl H H H H H 11 The combination of an ethyl radical and a methyl radical produces propane Propane can form in many other ways as well Prgpane Excpanded Structure ondense Structure And Molecular Formula H H H Expanded structure I H H H Condensed structure Molecular formula C3H8 Propane The Molecular Model PropaneIn 3dlmenslonal I V a perspective Propane a 2dimensional l representation Prnjmlw CJ39IIH Alkanes and Alkyl Groups Methane ethane and propane are members of a group of hydrocarbons known as the alkanes Removing a hydrogen atom from an alkane produces an alkyl group CH is the methyl group as in methyl chloride CHsCl CHsCHZ is the ethyl group as in ethyl chloride CHsCHZCl Alkyl groups are indicated generically by the symbol R as in RCl The First Members of The Alkane Series Condensed Molecular Name Structure Formula Methane CH 4 CH4 Ethane CH 3 CH3 C2146 Propane CH CH CH3 C3H8 Butane C4H10 All compounds whose molecular formulas fit the general formula CnH2n2 are alkanes Some Terms to Remember Hydrocarbon A compound composed exclusively of hydrogen and carbon Saturated hydrocarbon A compound of general formula CnHQM containing the maximum possible number of hydro gens per carbon Alkane The family of compounds with the general formula CnHQM the saturated hydrocarbons Aliphatic hydrocarbons An older term for the alkane family derived from a Greek word for quotfatquot or quotfatty substancequot Classes of Carbo ns Primary 1 and Secondary 2 Carbons A Ianmy 1 u carbon is bonded to exactly one other carbon A secondary 2 carbon is bonded to exactly two other carbons Classes of Hydrogens Hydrogens always take the same class as the carbons to which they are bonded All hydrogens on a primary carbon are primary hydrogens All hydrogens on a secondary carbon are secondary hydrogens 1 And 2 Hydrogens ln Propane 1 1 carbon 1 1a carbon l CH3 CH2 CH3 Propane containstwo 1 carbons and 1 And 2 Hydrogens ln Propane 1 1 carbon 1 1 carbon CH3 CH2 CH3 3 1 hydrogens 3 1 hydrogens Propane contains two 1 carbons and six 1 hydrogens and 1 And 2 Hydrogens ln Propane 1 1a carbon 1 1a carbon 1 2 carbon l CH3 CH2 CH3 3 1anydrogens 3 1 7hydrogens Propane contains two 1 carbons and six 1 hydrogens and one 2 carbon and 1 And 2 Hydrogens ln Propane 1 1 carbon 1 1 carbon 1 2 carbon l 2 2a hydrogen 3 1anydrogens 3 1 7hydrogens Propane contains two 1 carbons and six 1 hydrogens and one 2 carbon and two 2 hydrogens Two Different Propyl Radicals H2992ng a Hzgzgzg H H H H H H H primary propyl radical Removing a 1 H produces a 1 propyl radical Two Different Propyl Radicals H H H H H H H H H H H H primary propyl radical Hzgzgzng a H H H H H H secondary propyl radical Removing a 1 H produces a 1 propyl radical Removing a 2 H produces a 2 propyl radical The Propyl Radical and the Isopropyl Radical 1 3 i i gt I Iquot Imaginary quot V 7 quot l i fr nintuffigi gtiaiiii IL I 3 mm til It39lll lIl l i l rupiuw rL39I39 lilivi n39n pyl Two Different Butanes CH3CH2 CH239 CH3 4 ClIg 3112 01110143 straight chain The addition of a methyl group to the 1 carbon of a propyl radical produces a straightchain C4H1O39 Two Different Butanes CH3CH2 CHZ CH3 3 CHg CH CHEC1413 straight chain CH3 C143 CIIg llIL CH3 CH CH 3 39 3 branched chain The addition of a methyl group to the 1 carbon of a propyl radical produces a straightchain C4H10 The addition of a methyl group to the 2 carbon of an isopropyl radical produces a branchedchain 4 1039 lsomers Different compounds that share the same molecular formula are known as isomers The straightchain structure and the branched chain structure represent the two isomers of butane C4H10 143 CH2 CH2 CH3 CH3 9H CH 3 CH3 straightchain branchedchat The Two Isomers of Butane Aitnougn eacn structure represents one or tne rsorners or butane cm the strargntcnarn structure is known as butane and tne branchedechain structure rs known as The Tertiary Carbon And The Tertiary Hydrogen Of Isobutane A tertramsa carbon H is bonded to exactiy 1 three other carbons 8 a m 2 a U 3 or tertiary hydrogen The Tertiary Carbon And The Tertiary Hydrogen Of Isobutane A tertra as carbon 3 mm tertiary hydrogen The Tertiary Carbon And The Tertiary Hydrogen Of Isobutane A tert ary 3a carbon is bonded to exactiy three other car orrs ema carbon is a tertiary hydrogen They re All Butane C4Hm Ln Intron Izminnxrnurvu nnrm Jzu ml m lt11 nu cu FHJDTIKXCHE cummmu cu Eacn or tnese structures represents butane tne Straightechairr unbrancneo rsorner As iong as you can basstrorn one end ortne chain to tne otner end Without encountering a branch it s butane The Three Isomers of Pentane C5H12 pentane isopentane neopentane The Quaternary Carbon of Neopentane A quacernary4 oon caroon rs ded co exacuy four other carbons varences are consumed rn oonorng Names no straignx 03m Alknnus to other carbons a WWW quacemarycarbon czrhnn cannocbebondedcoa u n hydrogen H H Oualernary hydrogens donocexrsc quot a n r n u Number n The F1rst 10 Alkanes cnrhuns meuln quot1 Name t M We are concemed wick cke names ofcke rsc 10 alkanes Those wick ve or more carbons begin wick cerms denved from Latin or Greek words They end wim m co specify in we are dealing wim alkcmes 3 mn 4 Bulunu 5 Vrhl39 r r 9 N01 t to nuxuw 1 er Alkyl Groups The Two 03 Alkyl Groups 6 MUHLH lHKIUH n 4 HKH CHTCHTCHTO rs propyl chloride CHae HeO ca rs isopropyl chloride or W n mm Ukrrlzmiir li M m CHTCHTCHTCHTO 5 butyl chloride CHTZr cyi LCc c3 5 Secbmyl chloride The Four C4 Alkyl Groups CHTCHVCHZVCi is isobutyl chloride iCHl CHTK LCi is tenbutyl chloride CH3 The IUPAC International Union of Pure and Applied Chemistry System I39i39t UViPJi K nxi uf x IUPAC IUPAC IUPAC IUPAC sun Ide Ilmmlwrmmuh WW I ugtmmHhm m WWW H A m mm Im A Hm u V 4 1 NH H H m M u u IUPAC 1 Wh mrnL mu mm m Ain qu m m uunncnmmasmw Lvnumhrr In mm r rmm mm u an arm mm IUPAC munmmiimmmmmhypmmm mammoth nlkylgmnpmmnMalphmlgpnmmnlm ilmninmlm mm Whalintmldmllmnfmmm39fhwg mm and Mud m laud Ahlh n difa y mnln xquot Ind whirl ml Mt nn edundtlrb IUPACExampe1 EHQCHS CH30H20H2 H UH3 IUPACExampe1 IUPACExampe1 IUPACExampe1 UPACExampe2 H3 39 CmCHCHCH20H20H3 I 1ch3 IUPAC Example 2 IUPAC Example 2 IUPAC Example 2 lll ll7lllillll ll i ll 1 1 quota 2 3 a 52 39 I l2 ll a if Mi 3 l IUPAC Example 3 CH3 lug CH3 CHCH39 CHECH3 CHECHECH3 IUPAC Example 3 rl39lll IUPAC Example 3 lUPAC Example 3 l wxxx fl llllllmxll lUPAC Example 4 CH3 CH30H2quotC GH20HOH3 JHQ Hg la lUPAC Example 4 lUPAC Example 4 lUPAC Example 4 a l I ll lil39ll l39 l quotl l 4 39l quotll l swanllwaamp lUPAC Example 5 JHmIH2 1H3 01420143 CH3 IUPAC Example 5 lM H l e 439lllfll i Elyljll HLJHLHi IUPAC Example 5 H l fijlEi 1 5 Ir 4 lquot l C I 1 1 l i h m l l IUPAC Example 5 C Ellfl l li s 4 quot39l l ll El pupil l 5 ll l l lsl 393 a may 397 llfrlLlaitHIiIi Cycloalkanes HULL Naming Cycloalkanes Find the parent TLqu 1313 IlLllll l JL l39 cl tarlHJn mourns in law ring mil ll39IIie PHI39I39II Hrr 3H NH lamest subszlilursm rImin I4 tho number nitl turban 512 7311 11111 39 um 4110 II I39 than he l lm39ullul in llu MlhrI iLuIJI39l It L Iln39l39u rllm l Naming Cycloalkanes 339 l39 quotin IIIquotIN In till 39i l II392 I Hm 1 1 i l I39 Jazm 139 n uIL39 s 39r r 39Iquot l lu39nl quot 39 illlillfquot15 quot1quot uhquotll 39 39 39 up ur l Iilquot I Inil I ul lilquot i l I n39 Naming Cycloalkanes i I 39quotl1II 39 39 T L12quot mgrT az39l39il jf rfL ri llifs gr 1 law 1 l1 rllu li39illlnllll l39l39lLifllIlil j J39a39I3939 Elnaquot lsllcglv IIEEEIl 39a 5 Has 3mm Illl 11 I Ill7 Ln illpln quotui3i39i quot31 I3939nquot39 quot all l39w ilquotiul I 39HIlrsqquot II Ii IIquot EJSHI39IFLLEW71114 Ii39jl l39IIlllI Iignn Naming Cycloalkanes if Ir E IFIV EFl l39iquotra MW ran 39E39j39lllu 1 Vii Lin72 I39u 39lj39 IE a lay 39i3939vn a u u w E39li Bali39s l 31 Ig lli Fl JI39lI Ifjl 39ll 1 I i739lu jgIng39s l39jlzilnl Li lji Cycloalkanes Example 1 HI EIIa IIz CHE Cycloalkanes Example 1 Cycloalkanes Example 1 39 r l 2 as l l 393 3 39739 9I Ii quot39 L a I g Cycloalkanes Example 1 E w a rZ39Ei lj ni LE39i139s39Lh393u Eggr I Ii39iTEI F5 2 Ln CycloalkanesExampe2 CH3 CHUHg Hg CycloalkanesExampe2 CycloalkanesExampe2 Jquot u lllun ugclcuhumm CycloalkanesExample3 Cl 0H3 CHQCHE CycloalkanesExample3 CycloalkanesExample3 Cycloalkanes Example 3 Kinds of lsomerism Constitutional isomers show different sequences in the connections oftheir atoms butane and isobutane are constitutionsisomers Stereoiso ers show the same sequences of connections but differ in the 3dimensional spacial orientation oftheir atoms uiiimimm ll ll ill H m w All new The Rigid Ring of Cyclopropane The rigid ring of cyclopropane xes substituents on each side of the ring allowing the kind of stereoisomerism known as geometric or cisltrans isomerism cis12Dimethylcyclopropane vagi h if mi2iiinmhyicytinpmpanc The two CH groups of cis12 dimethylcycfopropane lie on the same side of the rin Moving one ofthe CH3 groups to the otherside ofthe rin would require breaking covalen bonds w ich is a highenergy process trans12 Dimethvlcvclopropane Hi ii ll i 39Il ntmilnimiii lr cloprupanu The two CH groups of trans12 dimethylcycfopropane lie on opposite sides of the rin Moving one ofthe CH3 groups to the other side of the rin would require breaking covalent bonds w ich is a highenergy process Configurational lsomers If interconverting isomers as in the e of stereoisomers requires the breaking and reforming of covalent bonds the isomers are known as con gurational isomers End Organic Compounds Alkanes and Cycloalkanes 017 Chemistry 201 Section C Structure Determination Nuclear Magnetic Resonance Spectroscopy This presentation was created by r CSnydermiami edu Copyright 2004 by Cari H Snyder Universgv of Miami All rights reserve Structure Determination Nuclear Ma net c Resonance Spectroscopy Nuclei in a Magnetic Field Nuclear spin gives nuclei of some elements the properties of bar magnets In a magnetic eld a small majorit l of these bar magnets line up parallelto the el A minority are antiparallel disorganized iii mam d rn ll naralll exist at higher energy levels than with Nuclear Magnetic Resonance When the energy of an applied radio 39equency equals the energy difference between parallel and antiparallel nuclei lowenergy parallelnuclei absorb the radio energ and undergo spinflip to a higher energy antiparallel state AE v Energyabsorbing nuclei are said to be in resonance Shielding Molecular structural factors affect electron densities near different kinds of rotons Different kinds of protons lie in different electrical High electron densities tend to shield protons 39om the Jl effects ofan applied magnetic eld Local shielding can decrease the full effects of an applied magnetic eld A local magnetic eld can reduce the external eld ap lied b the magnet producing a smaller e ective ocal el Different kinds of protons in different local magnetic environments resonate at different radio 39equencies Beffective Bapplied 39 Blucal 8 Delta The Chemical Shift were shielded to the very same extent all Id experience the same magnetic eld strength and all protons would spin ip with the same energy and therefore at the very same radio frequency r ons experiencing different shielding absorb energy at different radio frequencies The absorption 39equency is measured as the chemical shift a delta Delta is measured with reference to TMS tetramethylsilane CH3Si a convenient standard reference If all protons prot ns wou Definition of 8 Observed chemical shift separation from TMS in Hz Spectrometer frequency in viR The 1H NMR Region TMS de nes 6 0 m Upfield and high eld lie to the right toward lower values of 6 Down eld and lowfield lie to the left toward higher values of 6 1H NMR or PMR Proton Magnetic Resonance 1 Number of absorption regions How many chemically different kinds of hydrogen are presen 2 Chemical shifts Chemical environments of the hydrogens present 3 Relative peak areas Relative numbers of each kind of hydrogen 4 Spinspin splitting patterns Numbers of 3 hydrogens present Number of Absorption Regions um Only one kind ofH 12 allylic in 23dimethyl2butene NMR absorption in only one region about 17 ppm Number of Absorption Regions Two different hydrogens of methyl acetate r d p o uce absorptions in two different NMR regions Chem39ca39 Sh39 s Chemical Shifts Chemical Shifts Chemical Shifts rimrriii min a i Mi AHyhc H s absorb at about i 7 ppm Chemical Shifts gem39ca39 Sh39 s 39 quot The CH3 hydrogens ot the iertbutyi group absorb at The CH3 adiaceht to the co methyi ketorie i 2 ppm absorbs at 2 i ppm As in methyi acetate the CH3 hydrogens of the methyi The CH3 bohoeoto the o absorbs at 3 7 ppm 9 0 bowed 0 We 0 81350 813 6 D m not shown in rabie The stepped trace gives reiahve peak areas Relative Peak Areas r I I 39 39 F 1 Every individual H absorbs with the same intensity as every other H Relative peak areas are given by the heights of the steps Peak area ratios equal ratios of numbers of HS producing the peaks in this case 26 13 39 SpinSpin Splitting Steps ratio is about 345 This equals the 23 ratio of the HS associated with each peak The inserted mullplots reveal spinspin splitting SpinSpin Splitting Origin Br fl Br CCCI l H H parallel Tiantiparallel Ho l Ho l SpinSpin Splitting Orrgrn r l3l BrCCCl H H H parallel Tlantiparallel 50 of the H s on the 0 bearing the two Br39s are subjected to an enhanced magnetic field 50 are subjected to a diminished magnetic field The result is two absorptions a doublet The same holds true for the H on the 0 bearing the H T H l two Cl39s SpinSpin Splitting Origin Br 3951 l r Br B U UI The peaks appear as Iii 395 two doublets II 39 rm LIME A an Ilfmr Millsl He II lIK c quot sex at the H s on the r bearing the two r39e are id39 sub39retztocl to an unharmed magnetite flew cans are subjected he a dimlntehed magnetic eld The mth is H H two absorptions a doublet The same holds true for Ali the H on the Cl banning the H H w tum Eli39s SpinSpin Splitting Ei39r Ltl l l Bra Gl I II HH He Effect Uri magnetic I I I39ield s trenntlt Hatiu AL The peels appear as a triplet and a doublet fl ll 1 ll gr gr no dimintehed effect enhanced l 2 1 39 Br C Ho SpinSpin Splitting H 139 H The De I a quartet and a doublet strongly weakly e an enhan aks appear as lTT UT TTT TLT iTL iii TTl Til mys39 lgly dimin dimin nh SpinSpin Splitting The n1 Rule Asageneml nlle lulled then 1 rule prawns thathavenequivalem n 1 peaks in theirN39M39R spectrum neighbvnngnnmms mm It refers to the number of mutually equivalent protons on the neighboring carbons quartet signature ofan ethyl SpinS pin Splitting Multiplicity An unsplit peak is the signature of hydr gens on a carbon that face no neighboring protons A tripletquartet 34 is the signature of an ethyl group A doubletheptet 27 is the signature of an isopropyl group Summary of Multiplicities lsopropyl Bromide s commaquot Spin Mutt lt DIatmulllDlrl ubwn39nd le t mm lntensltles N adlitenquot melons n 4 n Area ratio 1165 16 Mult39Pl39ci39tY 39 72 For a pentet the ratio of intensities is Absorptions In 2 NMR regions 15101051 13C NMR SPeCtFOH etW Methyl Acetate 1H And 139 thR 7 riie 7 l a 0P l 77M ii W7 I I ll I H til Protons on chemically different CHa s have different values of 5 C at bottom Chemically different l3C s have different values of 5 l m m u m m m 9 mm Spinspin splitting patterns are oflittle use in C NMR spectrometry Area ratios are also of little use Chemical shifts are of some value The number of different C atoms is re ected by the number of absorption regions End Structure Determination Nuclear Magnetic Resonance Chemistry 201 C Alkyl Halides This presentation was created by Professor Carl H Snyder Chemistry Department University of Miami Coral Gables FL 33124 CSnydermiamiedu Copyright 2004 by Carl H Snyder University of Miami All rights reserved Alkyl Halides Naming Alkyl Halides Sup 1 Find the Inn Lz39iplu SI LP 1 Number the nearer the chain lll ld name it as the parent Ii39 thumbing nr 111 the 3121mm v inin must mutain its n39L39 1t chain beginningr m the em is ulkyl or rm m the whens of the pm suimtituont wagmIiess of whether 7391 quotillll lll39llclti kl number t ti39l diilpf to in 14 v H Ii Er g1 C39Ei 39fgil39ilit 3HTHJ ZH it I39i Mi ruthluuuzJ him m mphnu lir ilnvzl tutu H a I Ir pmm Naming Alkyl Halides a Ifmore than one ufthe same kind trfhalogen is present number each and use one of the pre xes 117 311 tetm and so on For example 22lvllichlvmLn i Ili39lj Malnutrit b If di 39erent halogens are present number all and list them in alpha betical order when writing the name For example 1 IEI39U 1521 Lisa am it ii l39il Ltrrmmlnr Mus1 l rl39t Ll39 poulqu Naming Alkyl Halides 39i39rb39i 39vquotlm39 I39nul Inf i4 hrl39 i llrg l fur Naming Alkyl Halides i39H Ill CHE39IL quotC lalumum mm L39 lodnmtquot h Iquotrl u i u Alkyl Halides From CC ditions By anti addition or x2 3 Markovnikov addition or rici HBr or Halogenation of Alkanes Free Radical Chlorination of CH4 39 I tetrasniurnrnetnane lquot 7 ii I Vi i iii ii Free radical chlorination or rnethane gives chioromethane methyl chlnride dichloromethane methylene chlnride trichioromethane churufurrn 3 Chlorination of Methane A Free Radical Reaction ll li 7 7il lirii g i17 7iitiii Ii 1 human L39lxlurim Chlnmmclhmw The mechanism is initiated byfree radicals and proceeds With the creation and reaction of free radicals lnitiation iii n iiiiiiii ii i Light as a reaction condition can be represented as hv Where h represents Planck s constant and v represents the radiation frequency sim Propagation up Mimi snip id is n inni q u Viii siiii ii iti kcuunl w m mi iiii mei39 iutmcr Termination ii i iiiiii i ii I Free Radical l of Halo enation of Alkanes with Alkanes Mechanism Multip e Classes of Hydrogens iahnimm Y 7 M Rate iEmw Conc x probability factor iillliiliiiili ii 7 mimniin HH HL H39I p39l w i in ii mm i I w limiiw t v WWW W mutummmxn m i will WWWMW iimi39u l i til x ii i c 7 i ii n Relative Rates of Chlorination Radical Stabilities A Function of Radical Stabilities ll 1 It i i i High lliC II 39 ll R It of Stabilities of alkyl free radicals is the arne as he order of Stabilities of Carbocations i The order 5 Free Radical Bromination Allylic Bromination With m i H i NBromosuccinimide NBS more selective in mi 4 i u than chlorination T 5 i5 more like i m e free rad m L mummyMW product w T s Stabili re ectg freg NrBrornosuccinirnide NBS effects brornination radical stability exclusively in the allyi0 position NBS Bromination Free Radical Mechanism 83 produces a low concentration of Ear2 The result l5 5 free radical bromination at the A Complete Set of Radical Stabilities allylic carbon Alcohol to Alkyl Halide HX n 39i n 7 n m mun it y lulmwm mm 39ll I ll r lll H mm Alcohol to Alkyl Halide PBr3 uu mil u quotwquot Zlkrumalmlmv m i iwi ttt lit ll Alcohol to Alkyl Halide SOCI2 a mum mm ridmm mum The Grignard Reagent Reaction of an alkyl halide RVX magnes RMgX mm ngieldaaGrign Wim ard reagent Alkyl Halide to Alkane via Gngnard Reagent Hi39illili llj ILi39IL v Lini iiri iiAHIiiiCH i iiimumvmm Mu ruining new nutth iumriiwmm w mm quotMm m W Mg gtRMggtlt RMgX H20 9 RH Mg omx The H at H20 repiaces the W at RM x Use at D20 yieids RD 3 deuteruaikane CHJCHZMgEr D20 gt CHJCH2D MgOHgtlt CC Bond Formation Via The The Gilman Reagent man Rea em than at RX With Li yieids an alkyllithi minimum rvm um Aikyiiithium and Cui pruduce RZCuLi the Gilman reagent mu v i i u WW Uudnmur w i ri mm m iwiiynyiu It I umiim ihil iilivium 24 Hi i i mm iim mummipo in Mmvi mm m n 00 Bond Formation Via The Gilman R nt cuminMm Oxidation n Organic Chemistry mm u H i i WW 04mm m i ii n in e v w l niuiiim linrun mm mm Oxidation In Organic Chemistry mm ix i a Oxidation n Organic Chemistry Uhiihivii Mummimiimink unwind um um u 1 u u y M i immimr i i ii mm m mm H H Mum WWW mum rammwmm Reduction n Organic Chemistry Reduction n Organic hemistry m mum mimiiim t i39 i i H i mm M 39 mix mm 1mm H i i minim n Reduction n Organic Chemistry i inquot m mu m xi it W End Aikyi Haiides Chemistry 201 C r I 7 7 Alkynes An Introduction to W l 39 Organic SyntheSIS r v This presentation was created by 9 r rof ssor Carl H Snyder 9 hemistry Department E l r Alkynes An Introduction 51 CSnydermiamiedu to Organic Synthe 5 Copyright 2004 by Carl H Snyder University of Miami All rights Structure of Acetylene sp Hybridization 2 unhybridized p orbitals 2 sp orbitals sp hybridized carbons a linear molecu Alkyl Alkenyl and Alkynyl Groups Naming Alkynes mum1i J39llv on my 1397 l v i l u mm m um um l ramm Terminal And Internal Alkynes i arid 02 e A hydrogen i5 bonded to an 5 carbon Internal alkyne e Botn 5p carbons are bonded to carbon atomS Re VR Terminal alkyne e Contains a tribie bond between or R 3ch Creation of Triple Bond Eiirnination ottwo Hgtlt trorn Viti ai oinaiioe Additions To Alkynes Addition of HX Markuvnikuv orientation can occur eitner once ortWice J u Addition of HX i N ll M tquot t e r39 i H A Vinyiic carbocation is an intermediate Stereochemistry of Addition L iit iit lt11 m on Aooition ot Hgtlt to an internai aikyrie proooces a trans proooct Addition of X2 i liiiit Aooition otgtlt2 can occur eitner once DrMiEE Produces a trans proooct Aldeh des and Ketones Addition of H20 H and Hg y Catalyzed c r 7 a v u l carbonyl I IaN v J v A II group m R C H Acidcatalyzed as in acidcatalyzed aldehyde hydration of a kenes Also requires Hg catalysis I Involves eno intermediate CH3 C H acetaldehyde Aldehydes and Ketones KetoEnol Tautomerism O il ll 39339 339 carbonyl 3pm iquot group CH C nn tautamt H1314 Lulamot R C H R C R Ilan fire yml Ij39n39n nn39mt thwartI aldehyde ketone Ketone R20O O Enol HO resides on sp2 carbon of 00 I H Tautomerism Rapid interconversion of constitutional CH3 C I I CH3 C CH3 Isomers acetaldehyde acetone Ketoenol tautomerism usualy favors the keto form Terminal vs Internal Terminal vs Internal l39 G I 39quot quot E 11 Iij R39 A l I I 11M 39 7 quot A 39 I F unw I39 I quot quot H I I quot HV 1 Li 1a 1 in I m 1 quot39 quot H 39iHl39 RUE gt 3quotquot in il I39IIErrmj ulJ csno 39 IiLu An iI39I1I I39r39I39I allum Mirdun I39 II I I li 397 t quotll Vii ms I 39 L39quot x Hquot quot EEZ2 1 nrmina39l a39llkym A thgrl kEEq39suui39 Internal alkyne gives a mixture of two ketones Internal alkyne gives a mixture Of tWO ketones Because of Markovnikov orientation a terminal alkyne gives predominantly a methyl ketone A Choice of Products from A Addition of H20 Choice of Reagents Hydrobor tionOxidation H Terminal Alkynes K39H i niniiui Mum iii ii 1 Vi m nnimmu V ii ii iiimi r ii iii iiuii mu Terminai aikynes pruduce uniy aidenydes en Emsg ngfmm a terminai aikvnei use H2 HydruburatiDnDxidatiun 9 4i 2 Fur an aidenyde frum a terminai a kynei use hydruburatiunDxidatiun Addition of H20 Addition of H2 HydroborationOXIdation Catalytic Reduction Ketonesfrom Internal Alkynes emu uumuitiiuu wiw Mam imuitu Mmt b ililwlimlm irunill vpntdnlllunlklumil i i r Wm mixermiuiynwu ueusmimmii iin m new meiuuumuiiw mum u i ii i ruld in Mm m m m m miueuit mi qiumlmc mummumuii mmqu uiimmn mmmul nzdilmuwylxu swim Elurwmgxm mime prvdun ween uwmi ti u L5 f f HydruburatiDnDxidatiun at an unsymmetricai aikyriE a mm 1mm R VCECVR X gives a mixture at We different ketunes rushum Addition of H2 Lithium And Ammonia mum mm w iiitiuiwu This metnud gives a trans aikene mmth anii i i m m m H Q additiun at H Fur 3 Dis aikerie mmth syn additiun use the H i w i H m i i Lindlar catalyst Fur an a We use H2 and WC The ufterminai aikynes is mere aeiuieman any utherhydrugen uf aikanes aikenes uraikynes Stability of the Acetylide Anion The greater the 5 character of the orbruai the closerto the nucleus it lies andthe lower its energy Alkylation of The Acetylide Anion 9 m m g s g a a a a L39 x S at a g the acetyli e anion Here the anion l5 methylated Mechanism of The Alkylation s i Z r m e e v llmCrYKr rm Mquot WM rrm memmv m l l l u e r r i l u l hcnmC comm mud quotWWW mi irrt ir rear K mil mi N m and ol m Nivdmn r Alkylation Generality ii iii m r 7 m uumniuurm m ii m r rrr r MW 1 rim rm mi idlmu Alkylation Limitation Organic Synthesis Challenge tllk llillri ll lt2 vnrw39ui LULCMJ39H we mm Organic Synthesis Strategy imrricdiutc p u quot ll llrut product For cxnmplv rl thr linnl prorluit is nn yy r m m it gt will llXi Having lirunrl rn irqutrlrult Jt tul u l uqu inch slap til it trims unit you not b 39 i gt r Organic Synthesis Solution Octane What reaction converts an alkyne to an alkane What alkyne would you start with to obtain octane Organic Synthesis Solution Octane How would you convert 1pentyne to lodyne Organic Synthesis Solution L39llJ Jllglfllli39 Cl W 39EM39HQCHQF t ll 39lr r lrl ontynn elemtyne rleuiu Vlith these steps you have converted 1pentyne to octane Problem 1 memoir ainlay marrqu on rur x i0 i 1mm Mia B H lull citworm Convert a Scarbon terminal alkyne into a Ocarbon cis 2alkene What s the nal step Problem 1 Solution Eligillyt lla Flt Ellyll39llyfjllyl 39Cll v lihyul ll ritEIlexene Problem 1 Solution Problem 1 Solution murmur wunumc i u mnemonic u mummcm i H mncnpux c ru v u m m rm39u I39u tut mwuuv mu V v autumn Ecll v 39 a u H mm l i Problem 2 Problem 2 Solution Dir H0770 v Ex 47 4 mmmmcn mu my man mum m n Cunven a Zrcavbun alkyne min a Srcavbun 2 l W mm w v m mm cum twaiiclpuicny Problem 2 Solution Problem 2 Solution mum m N W iii if m lr mm v l 1hL ll H m II myquot Problem 2 Solution Problem 3 ll rquot III IiL39II I 539 t39Zf iii HCECH RX gt CH3 HZCHZCHZCH20H20H itcrnty39l Hit a 5139 3 Acetylene Alkyl 1Hexano halide mnmnmnu cu L umum m r um Convert a 2carbon alkyne into a terminal i39ilIi39lltfltjtTir EllJ Iiquot 6carbon unbranched alcohol l THE 1 1 1 I quotH Hm in rum trill in it Problem 3 Solution Problem 3 Solution 31131lagtfllli liit an v mmgrixr39iigtncii urn iJILl ZYJtTlt1llitIJl BEL 1quot a ifiii tI55111inintriguiigni tillttjllntjll39 lltill LfiL mum riiriii iiiflattiigiuigrui I U Hullllli Problem 3 Solution End lit L7H iL quott if r 39 13913 1 Itl quot13 till mienr1i tiLr m r a Lilxiiilllgliquotii ll tin rut1511LrjiJi1iiitu mt 139 u mm MW t I w IiiIIgtsiu39rlil mistr C Stereochemistry of Alkanes and Cycl nes Tnis presentation was created by Snydermiami edu Copyrigm 2004 by Cari H Snyder Uniyereiiy of Miami Aiirigms Stereozhemistry of Ailtanes andCydoalkane Conformational Isomers Different structures at a muiecuie that resuitfrum rotation about sigma bondsare knuvvri as conformational isom ers ur conformers rifurrnatiuriai iseirners er etnane appear Conformational Isomers and Configurational Isomers Conformational isomers conformers interconvert through rotation about sigma ondsi a iowreriergy process Con gurational isomers interconvert inrougn the breaking arid reforming of coyaierit bonds a highreriergy process The Newman Projection o The sawhorse Sta gereoi and Eclipsed Con ormations of Ethane Staggeredr Hydrugeris are farthestfrum eaen utner tne iuvvest energy enrirurrnatiuri Eclipsedr Hydrugeris are iuses ttu eaen utheri tne highest energy curifurrnatiuri Tne We eenrermatiens differ in energy by 3 X 4 El KJmui i2 El kJmui Conformational Analysis of Ethane x it n g m Conformational Analysis of Ethane n Conformational Analysis of Ethane m l r l 1 Ll mu l r i ANA J Conformations of Propane Tne snape ufthe energy ys rutatiun curve fur prupane is the sarne asfur Ethane buttne truugnetuepeak energy difference is greaterfur prupaneydue m eclipsed methylenydrugen nteractiun Conformations of Butane n n n T u n Net n n in mm t r m at vwn the CH3 gruups asfar apart as pussibley the ann cunfurmatiun nastne luvvest energy cauehe is intermediate m margy origCH3 Eclipsing pruduces the highesteenergy furmatiun Conformational Analysis of Butane M I mag es of G a u Che B uta ne 339quot 7 m ix 15 In 39 fl In Il39n I 1 l5 I l39l39l 517 15539 L157 JI quotJI I ll 39 I39ll W J 1H k J u H quot hr 1 quot quot39 quot 391 A 53 a I a l N I E u A a As A we Han A E erg 39eSBOftTWO EC39 39 psed E nergy Costs for I nte ractions U anes in Alkane Conformations H I M Two CH3H if 39 39 39 M HH Tallyinc 41 Energy nits rcizr lntcriIIrtfnns39 in AIFIEEIJ39iE39 Cn n F l39Im l39E I I g I eclipslngs are quot 39 M A I less energetic EMF nubquot rs55 a than 39 Irn39ll39 arra39rrsoiq rJ 13211 Inquot rHr I39I39IEa j39 a ulnar3913 39 IainDi J J E E e quot39I39igcal39i 41623 Fl iv39 LELI C ITi39l b39 Clat 61 L Elf5 knth TI55 II i jIfl 7 E one ijT39Ti L113 2 EGLLE I TE 533 124 1 I 3939 and two eclipsings The Bayer Strain Theory The Bayer Strain Theory 1885 Summary As ring angles required by plane geometry deviate round from the tetrahedral angle they introduce strain into a cycloalkane This is true The bond angles Of the As rings grow larger and smaller than cyclopentane tetrahedral sp3 carbon they should show increasing angular strain and are about 1095o increasing strain energy But only if the rings are Any phenomenon that planar39 d Note that the Baeyer Strain Theory leads to incorrect ten 8 to 39ncfease or predictions of ring energies decrease this value adds strain to the m o I e c u I e a n d i n c re a s e s 39 39 a j 2 39 39 its e n e rg y 39 Ha M t t h vlffj39arl uzzlr1u1gu 33elaaylaamlisu urnu L39 Inli1rr1n I1 1 Baeyer Strain Theory Predictions What s the ii itemai angie of cyciohexane By Whatyaiue does this differ from the tetrahedrai angie What s the ii itemai angie of ai i ii ifii iiteiy iarge cycioaikane The Baeyer Strain Theory Experimental Observations r 7 s n iuuv thzw The Baeyer Strain Theory Today One of Two Chair Conformations of Cyclohexane Axial and Equatorial Hydrogens in Chair Cyclohexane Chair Cyclohexane A Newman Projection Red hydrogens are axial Blue hydrogens are H H H equatorial H Two equatorial hydrogens are not shown in the H H Newman projection H H H of cyclohexane lnterconversion of The Two Chair Conformers of Cyclohexane The aXIal su bsituents of one chair conformation become equ 39 atorial 3 F in the other chair conformation 7 39 T 39 chair conformation ll mar become aXIal in the 39 other chair conformation lnterconversion of The Two Chair Conformers of Cyclohexane 99 3 391 is 39Ofga is in Hip The axial subsituents of one chair conformation become equatorial in the other chair conformation The equatorial substituents ofone chair conformation become aXIal in the other chair conformation Newman Projections of the ChairChair lnterconversion HHH HHH H H gtH H H H H H HHH HHH Axial and equatorial substituents interchange as one chair conformation flips to the other chair conformation Alkylcyclohexanes V a l 2 v 7 if j k 9 l 3 V 1 quot3 l Ii f3 1 Ringflip allows the alkyl group to occupy either an axial or an equatorial position Steric interference occurs between an axial alkyl group and aXIal hydrogens Molecular energy is lowest with the alkyl group in the WH Both Chair Conformers of Methylcyclohexane HHCH3 HHH H H H CH3 gt H H H H HHH HHH The conformer bearing the equatorial CH3 is lower in energy than the conformer bearing the axial CH3 group The equil brium favors the isomer with the equatorial CH3 group Conformers of cis12 Dimethylcyclohexane CisIn 5 quot 39 each conformer one CH3 is axial one I is equatorial lli 539quot Conformers of trans12 Dimethylcyclohexane Trans Both CH3 groups are axial in one conformer equatorial in the other V Conformers of trans12 Dimethylcyclohexane Since both CH3 groups 39ll can be 39 equatorial in the trans geometric isomer the Elm 5 trans is the lower E i energy 39 IE t geometric isomer cis and trans12 Dimethylcyclohexane H H CH3 H H CH3 H OH H CH3 18 2 H H H H H H H H H H 11 H CH3 H H H H H HCH3 Ha trans gt H H CH3 H H H Because both CH3 groups can occupy equatorial positions in the trans configuration the trans configuration contains less strain energy than the cis cis and trans13 Dimethylcyclohexane CH3H CH3 H H H H H CH3 CH3 15 T H H H H H H H H H H gt H H CH3 H H H H H CH3 trans 1H3 H H H H H H GH3H H Here because both CH3 groups can occupy equatorial positions in the cis configuration the cis configuration contains less strain energy than the trans cis and trans14 Dimethylcyclohexane For 12dimethylcyclohexane the trans geometric isomer has the lesser amount of strain energy For 13dimethylcyclohexane the cis geometric isomer has the lesser amount of strain energy For 14dimethylcyclohexane Boat Cyclohexane Polycyclic Molecules Decalin A polycyclic molecule contains two or more rings Fused rings share one or more sides Bridgehead atoms are incorporated into two or more rings A highenergy conformation of cyclohexane Will not consider in detail H I 4 sets of HH eclipsing C iii ma a Jim 3 39 CiS39 and transDecalin More Complex FusedRing Compounds Testosterone A Steroid A Sex Hormone transDecalin Bridgehead H s are trans to each other lower energy isomer cisDecalin Bridgehead H s are cis to each other higher energy isomer Less crowding of H s in the trans isomer 39li39st Dsk rnquot Ill ti l39nid End Stereochemistry of Alkanes and Cycloalkanes Chemxsh39y nydzxmmm1 ed a n mam auth an WK All quot5 2 mm g 0 Smtlure and Bonding What s Orgmic About Organic Chemist 7 7 mam xera n pmd by lwmgthmgswexe camudasman duTwulHaxmhmm yand mum mm m 177mm cam m meanchzmxcals anwdfrom vmg argumsms The Wm Fame Theory of Orgamc Chemxstry L 1 mamxywm Cenmnzsr MW chemistsbehzved m Mm farcequot mm presume pmpenyaf um um was meded funk rammmr axgamc campu This thzmy 1 mm absenceafdus m farcequot af 1Mquot mm m axganlc campmmds cmddbe mm m Chevreul s Soap 1816 r Mlchzlchzvn anchchzmls Emma mp mm M mm m mm 5 We 1 Emma an mm mmqu mm mm mm gamma wmmmmm a m m m Wohla s Synthesxs ofUrea In 1223 Fmdthomumgm charms Wulrllu39s awaysz AAmam mm mm dad Ammade m 3914 my ram hmym39mgmm Emmy Organic Chemistry The Chenlistry of Carbon Compounds Because almost all chemical compounds found in living systems contain carbon today we recognize organic chemistry as the chemistry ofcarbml c m 01m One vital compound common to all living things contains no carbon at all Which compoundis that Carbon s s and p orbitals amnion pnrhlml ti J1 tannin Only s andp orbitals are available on a carbon atom The Isolated Carbon Atom s Three 17 Atomic Orbitals havean incur m tii Note that the s orbital is not shown in this illustration Carbon sp3 Hybridization One and three p orbitals a total of4 orbitals containing 4 electrons hybridize to four ergetically equivalent 5p orbitals again a total of4 orbitals containing 4 electrons The Lewis Structure of Methane lll39 Lewis structures show all valence electrons The Molecular Structure of Methane CH4 K ll Overlap ofeach ofthe sp3 orbitals ofthe carbon with an s orbital ofa hydrogen produces methane CH4 a tetrahedral hydrocarbon containing fourspiscovaen on Methane A Tetrahedral Hydrocarbon ownan Ethane CZH H H i l r I in A39HCII H Samarax In lionwmlbun Lewis strucmrc Vaicncc bund strucmre c undensed strucmre eOr ita an Moecuar Structure ofEthane C2H r Tnc cunanc mulemle Bantams Six spin CrH bundsand nnc spay crc bund The Hybridization of Carbon sp3 r The carbons of alkanes s 2 r The carbons ofthe double bond of aikcncs which wc will consider later in CHM 201 c sp rThe carbons ofthe mpic bond of aikyncs which wc will considerlater m CHM 201C End Structure and Bonding Chemistrx201 C Reactions of Ikyl Halides Nucleophilic Substitutions and Eliminations Tnis presentation was created by Professor Cari H Snyder onernistry Depart e t Uniyersity OfMiami Corai oaoies FL 33m CSnydermiami eou CopyngntzooA by Cari H Sn der Univelsgy orMiarni Airign s reserye Reatlions of Alkyl Halides Nucleophilic Substitutions an Eliminatiu 5 Nucleophilic Substitution and Elimination Reactions siiimiiiniiii Ari Eiectrunrricb reagent Nu repiaces a ieaying group x in a nucieopniiic substitution Ari Eiectrunrricb reagent Nu bands to an H as Hgtlt is rernoyeu in a eiinination readion Nucleophilic Substitution Tne repiacernent ofone oftne groups oon e to a car ori by a nucieopbiie such as 39orH 39 tteirii i3 xi i v Tne ieaving gvuup The Rate OfA Nucleophilic Substitution For PM H039 anion x7 Reaction rate Rate of disappearance of PM Typicai rate equation rate k x Remy HO39 R my a constant at any giyen ternperature PM concentration of PM nor concentration of H039 or otner nucieopniie Rate Order Tne rate aideis tne sum ofthe exponen s ofthe concentration terms Rate w Remy HO39 represents a second orderrate equation Rate k x PM represents a filsiordel rate equation Rate k x PM x no3 represents a fifth order rate equation We Wiii examine rirst oroerano second order reac ions Molecularity the number of chemical particles covalent change in the transition state We will examine unimolecular and bimolecular nucleophilic substitution reactions The molecularity of a mechanism refers to ions andor molecules that undergo SM and Sn2 Sn1 refers to a nucleophilic n substitution S reaction that follows a unimolecular 1 mechanism Sn2 refers to a nucleophilic n substitution S reaction that follows a bimolecular 2 mechanism Sn2 A typical Sn2 reaction 5 I 39L39 39 i 239 l aa 39in I CHs39 39 Ext mg Leaving group Br Kinetics are second order Nucleophile lift391 elicit ma iLF39I uz lll rifz HO The Sn2 Mechanism Sn2 Stereochemistry Sn2 substitution occurs With I 7 Walden V hi I inversion a 7 39 1 complete inversion in the i stereochemistry s ofthe reacting a J carbon Walden Inversion A Walden inversion occurs when there is an inversion of configuration at a chiral center An inversion in the sign of rotation may or may not accompany the Walden inversion An inversion in the RS assignment may or may not accompany the Walden inversion U Walden Inversion w Sn2 Substrate Steric Effects M 4amp9 Asthe bu k crthe substrate mcreases the apprcach crthe huctecphrte became rhcre hmdered Sn2 Substrate Steric Effects m Nuctecphrhc attack m an shz reactrch stews wrth rhcreasrhg afkyf substrtutreh an the reactmg ca h CHTX rs rhcst reactwe ct mack rs teast reactwe thrce thathuctecphrtescah be afHEInS cr erecthcahy heutrat bases e g NH3 Sn2 Effect Of The Nucleophile Nuctecphrhcrty parauets basrcrty chty rrthe attackrhg aterh rerhams uhc ahged Nuctecphrhcrty usuaHy mcreases as We mDVE Wh a ccmrhh uf the Perrcmcrabte Sn2 Leaving Group th geherar Eunvefsmn uf a strong base tc a weak base cr Eunvefsmn uf a stron huctecphrte tc a weak huctecphrte tsavured m cherhrcat reactrchs Leavmg gruups that pruduce weak bases cr weak huctecphrtes react fastest m the shz precess Sn2 Leaving Group ml w ml l ltllll 2 39ll Tne Weakest bases make me best leavlng gruups n r e slV39 Sn2 Protic and Aprotic Solvents Protic solvent 7 A solvent contalnlng protons bonded to o orN alorns Examples HOVH CHarOrH crlaeer2 Dipolar aprotic solvent 7 A solvent wrtn a large dlpole but wrtnout protons onde o or a orns xamples acetol lltrlle dlmethylformamlde DMF dlmethyl sulfoxlde DMSO hexamethylphosphoramlde HMPA lift H a or mm mm Sn2 Solvatlon Solvatlon the UN assuclatlun Elf a nucleuphlle Wlth sulverlt l mulecules luWErs Energy at a nucleupnlle and reduces lts capacltytu act as a nucleupnlle ll Ull Tnls assuclatlun ls OR Famcularly lrnpunant lr lt rurrns tnruugn nydrogen Dondlng Sn2 Effect of Solvent 39Hrllmlr llr39r e Anomaler snz reactluns are raster ln dlpular aprutl sulvents Suhwlnlk Summary Sn2 Substrate m L 1 n rrrr lrll ml rm r Summary Sn2 Nucleophile n lulllhll m ml r l r r hlr l l lllv nl rm n new Summary Sn2 Leaving Group I lrquot rt irrgl grim innitli tm inr fifr urrlp39 rirrwl39ut39 Ill this it ticn Hutu lhua rlrcrtctzainrz liti Hl lll lllf l39itr39thir rg liar r39rurilirm rgatn liliill tl Slnlilr si39r39rir u39mi hymn titli Summary Sn2 Stereochemistry Complete Walden inversion Observed as complete inversion of con guration Summary Sn2 Solvent biolqu Pruiic solvents saltalc tin rirrtleupl iilm lllrfr rjitt39 imitating ir gzjrnuru39tslntt energy ir rrenjngr M7 tutti clccrrueinp tho i39rfttirilirltt tart Polar nprntir 17 vents rLlIl r quirl lhig trucnunprtnylity retinn rut Itr rl ll rri uutillltlpltilitt Trlriur39r t39l39rtfrr it39 ringing the J rrnm39rrlr tsltr39 finerm c39rl39llu turtleiphiln lttt39zr39r tiuirtg it 1an inrrvusirzg the reaction ruruj Sn1 CH3 CH3 l l CH3tfBr H20 gt CH3ICOH HBr CH3 CH3 Atypical Sn1 reaction Nucleophile H20 Substrate tertbutyl group Leaving group Br Kinetics are first order ReactionrateRateofdjsappeannueofalkylhalide kxRX The Sn1 Mechanism its in GHarlzBr Nu39 0H3tlzNu Br CH3 0H3 The overall reaction The Sn1 Mechanism H3 0H3 CHarlaBr Nu GH3l3Nu Br CH3 CH3 CH3 slow GH3 GH3cBr Z GH3t3 Br CH3 CH3 The overall reaction Step 1 ionization of RX to produce a carbocation The Snl Mechanism CH3 CH 3 l CHBlIJBr Nu GH3iI3Nu Br 0H3 CH3 CH3 slow CH 3 GHarlnBr Z 0H3t3 Br CH3 CH3 I3H3 fast EH3 GHaiH Nu39 lt CHBlIJNu CH3 CH 3 The overall reaction Step 1 ionization of RX to produce a carbocation Step 2 reaction of the carbocation with a nucleophile The Snl Mechanism hrornideion l n prudtlL L up H int r2 0 on Rate Determining Step The slow step in any multi step mechanism is known as the ratedetermining step rds The ratedetermining step is the step that determines the overall rate of the overall reaction Snl Reaction Coordinate Diagram J l t39 Iii 39rrr39r3939r iu39r illii l l39r39lt t l39iflif liIrrtim ctrraring quot slow formation a of carbocation hi Ir lizr rLrerrrlzurr ll mrrrnrrrlinrr r STEP 1 HEutL Ll Zd gnrurre Snl Reaction Coordinate Diagram z u u quot m 39 quot slow formation oi carbocation 39l i I 39s39 l3rrlearlrcr Stir l39r r 39r l39 l eilir39lll STEP 1 Step 1 is the ratedetermining step lierrliiir gll39rljlfi39 Sn1 Reaction Coordinate Diagram msheadbnof carbocation with nudeothe tprfp hint 7rrlrIL39tui STEP 2 inrrirrn rI39En H IlIll39liin Lll39li395 3i Sn1 Substrate Effect of substrate is exactly opposite that found in Sn2 3 faster than 2 2 faster than 1 1 faster than CH3 H 3r illquot 39 H lIJll a lquotgtr H H ill I Lilly I I r 11 t n fir t in 39iirr m iiyg rj rn Sn1 Substrate Carbocations ll II H II i r n lift lII39 viiIquot 39 l i i 1 1 ll t I ll I 15 I y J In Sn1 substrate reactivity parallels carbocation stability Sn1 Leaving Group Illquot if 131quot 13hquot 39 l l39nanifl Leaving group effects are identical with those of the Sn2 reaction Snl Nucleophile Because the nucelophile enters into the SM mechanism only after the rate determining step has been completed the nucleophile does not play a role in determining the rate of the reaction Sn1 rate kx R X Nucleophile is not part of the rate equa on Sn1 H20 As A Leaving Group V4 5 H lll l ill I39 I i Hwy I file It I39l If 13 Imam r39a w vlm W quot7 f Ilv I ll nil 15 PL I39I till Iquot MI In 12mm rh39x ml JMI 39T39 r I J up a la r l fur pl Ivl l l Sn1 Solvent 1 mm Because the solvent helps to separate and stabilize the individual ions generated in the rds solvents of high dielectric constant facilitate the ionization and therefore increase the speed of the Sn1 reaction quotquot11quot Sn1 Mixed Solvent 1 mil 39rhi y mnl Dielectric constant of water 804 Dielectric constant of ethanol 243 Increasing the concentration of water in a waterethanol solvent mixture increases the rate of an Sn1 reaction Sn1 Stereochemistry lu ugh 40 retention and 60 inversion results in an observed 80 racemization and 20 inversion Sn1 reactions occur with a combinaton of racemization and inversion Sn1 Racemization I L35 l i J A quotr am im l mmm r m tr Iui i xumliml Racemization results from equal probability of attack on both sides of a planar carbocation Inversion results from a shielding effect of the departing leaving group The incoming nucleophile has Sn1 Inversion a higher probability of approach from the unshielded side of the carbocation m mm i Summary Sn1 Substrate n Suhsi rulL39 Summary Sn1 Leaving Group Summary Sn1 Nucleophile u mtlttininit trim mm mm smut ens cw mums quotminimum mniiiiiimi rum mm tit mm m mrr i muttwants Wk Mu Summary Sn1 Solvent Summary Sn 1 Stereochemistry A Combination of inversion and retention ith a smaii excess of inversion over ten i0 Observed as a Combination of inversion and racemization Sn1 Characteristics The best substrates yieid the most stabie carbocatioris a and aiiy ic react rastest carbocatiori formatiori thus increasing the reaction rate The best solvent are po rsoivents iike water that stabiiize the carbocatiori by soiyatiori thus increasing the reaction Elimination vs Substitution ir eirmrrratrerr arr uncur eirmrrratrerr aiways culminates with substitutiun Sumetimes eirmrrratrerr predominates semetrmes substitutiuri predominates The Direction of Elimination Zaltzev s Rule Which H will be eliminated along with X Zaitzev s rule gives the answer um um menMu tn E2 vs E1 E2 Elimination bimolecular Rate k X RX X base E1 Elimination unimolecular Rate k X RX E2 Mechanism m dwnhh huml V 5mm in E2 vs Sn2 The E2 mechanism competes with the Sn2 Both have the same rate equation Both have the same reaction coordinate diagram Both operate under the same experimental conditions E2 Syn and Anti Periplanar E2 Anti Periplanar Transition State E2 Stereochemistry mesJZSVDibrornobutane BVZVBrOWOVZVbutene E2 Cyclohexane And The Anti Periplanar Requirement mummnmnc n ma arvnm mm quotmmW u u L H u AtntA H w For E2 elimination from a c clohexane ring the ring must adopt a conforma Ion that places the H and the X in an anti periplanar relationship E2 Elimination From Menthyl and Neomenthyl Chloride this The bulky a kyl groups occupy equatorial positions Therefore the H and the Cl are largely axial anti periplanarto each other only in neomenthyl chloride Anti periplanar elimination from neomenthyl chloride produces 3menthene exclusively E2 Elimination From Menthyl and Neomenthyl Chloride 394 mm Anti periplanar elimination from menthyl chloride requires ring ip to less stable conformation Product is 2menthene The E1 Mechanism E1 VS 33911 3 1 if Fla 74v N H cuzvtlwou uuf 5 mt an an aunt nurm H 2 M quotIn llmimJ ID f 7 C4 Br 2 u an r g EMF qu gt mfr an an l c H a r39 mum WWW n 5 4 w DHEAJLQ quot2 gt canq quot30 CH3 K 392 E2 Anti Periplanar vs E1 Zaitzev Summary 1 Aky Halides Elimination From Menthyl Chloride a pm m MM u i um ii 39 WM i Luninuimw rmwmbnxrmm iH iiCli u N L i i V React by SM up when sirurig bases are used i w i by E2 meebamsms Summary 2O Alkyl Halides summary 39 20 Alkyl Halides numb ui 1b iiuii lewi riliimv mmumm in HimOiwnI ilmvmIninmvnmymi m HM 7 mum mm m mirimphili g quotmi in new 4 x Wm WM WW I um Ii mum m L L mi my i i I y ML u m Ample 24mm 39 i CH W x humid mu Mum39ivvl39 ii blimmnpmlmmv i i mmm enmz my in uyi Mimiquot rm m x mm by our 0 React by E2 iii the presence uf strung bases Summary 3 Alkyl Halides any ii i i ii i u Summary 3 Alkyl Halides 77 im mi y 3 im Ha 7 pn r mmim wnmrnrmmmmmp uhmluimu Jud El Minnimiliiquot 9 Ln mm W EZfavured iri generai 5m Summary Sn1 Sn2 r WWW WWW mumM u 51 mm mm H 2 u u w m w Juw m vum m Summary E1 E2 qran R Lom n mm 5ch Summary Overall End React ons okay Hahdes Nuc eophmc Subsmut ons and EhmmaUOHS Chemistry 201 C Alkenes Structure and Reactivity This presentation was created by Professor Carl H Snyder Chemistry Department University of Miami Coral Gables FL 33124 CSnydermiamiedu Copyright 2004 by Carl H Snyder University of Miami All rights reserved Aiken as Structure and Reactivity Unsatu ration ri I l ll It EHlqutLt 39139Hu tin1 hy i39ngvns ma rartn rci39l P1h lumenca L39 H ftawur tryLlrrjuxcna mrsmquotrunri An alkane CnH2n2 is fully saturated with hydrogens A molecule is unsaturated when it contains fewer hydrogens andor halogens and oxygens than an alkane of corresponding carbon content The degree of unsaturation or index of hydrogen de ciency equals the number of H2 molecules it would take to saturate the molecule Jm Degree of Unsaturation Index of Hydrogen Deficiency 06 4HethylL3pentadiene C e BicycleIL01hmm LbiethylZ pentyne two double bonds tune ring one two rings one trilile band double bond CsHm What is the index of hydrogen deficiency of each IUPAC Rules STEP 1 Name Lhu parent JIFEHTQCRI an Find the the dn uhle bnnrl and name the compound all Cl LC Tr H VIZquot l39 CH rH fir E N01quot in hexane since the d 393 39an i Nzlri39nrrl 11 I t t mill cwnlaiim H1 t rilquot nx Illl nlll drain quottartan chain containing STEP 2 IUPAC Rules Number the carbon atoms in the chain Begin at Lin crul mu t39 uublc hand or if llzu 11ml hum equidistant from the awn and quot is ru39lr unwrua that ll ule hond cm39buns L39IJL Leivu Lhu Emit3 pl f IIIIIP nm rfhm s CH L E3f L3fTTI1Cll quot ENC 3311 32it 339ll 3939TIt39liiJQEii IUPAC Rules mm the nth mm Xumbuiiewhsldticm aiwvdm m 1 iiaii mi iili rimm n nhrhrixml Imlimlc tn hirbtmdin unknown once minim nnminmn mimmuhen innntanmic umunud n mom Hm itmhun artmin and m we ni Vim whim m where in min cw it mo mi i 9i gii0lliglii mi cmm timing 0 t owing n cnetlu hm n viliiniih n m cirimik ubu i mom Cycloalkenes WWW Special Names for Special it M An all mm The term methylene aiso appiieS to the VCHT group in aikahes cycioaikahes cycioaikehes and other organic moiecuies mm 51 Eolmimn Names otsmnmhan lampnund Sy l cu iv 1 u m illil Fllrrlir HL II HL H tn Common Names of Some Alkenes note error in title oflable st name common mm L in mm i it Lunn it humme Sp2 Hybridization Two of the three p orbitais combine With the Singie 5 orbitai to tohn three so orbitais ieaving one D onotai unhybridized Tnetnree so orbitais point to the apexea of an equiiaterai tnahgie The unhybridized p orbitai i5 perpendicuiar to the piahe of the thahgie Iu nirium Ap tmmtu form a orbond tohn a h pi bond Lomoination of Two 3 Carbons to Form a nBond 2 so orbitais onefrom each carbon overiap to 2 p orbitais onefrom each carbon overiap to ohm t nunquot mnn 140ml Ethene or Ethylene m ytmdum a Ethylene No Rotation About The nBond Rotation about the doublebond requires breaking 39 the nbond 39 Bre kingthe n lt 39 ond requires about 268 kJmol The rotational barrier in ethane is on y kJmole Geometric lsomerIsm In 2Butene exists as 2Butene two geometric lsomers cis2butene with both methyl H J opposite sides of Pa F the double bond 7 H imnmmww aentlca ana Nonlaentlca Alkenes m Ivli iltlkdl tux limb mm The top two structures are mutually identical The bottom two structures differ 39om one another If either sp2 carbon bears two identica substituents geometric isomerism is not possible Identify These Geometric lsomers H BF Cl Br CC CC C1 H H H Are these two geometric isomers Which is cis which is trans Chemistry Reaches A Higher Plane F Br Cl Br CC C C1 1 F I Are these two geometric isomers Which is cis which is trans The Easy EZSystem A general system of geometric designation Substituents on each sp2 carbon are ranked by atomic number Zisomer Substituents ofsimilar rank are on the same side ofthe CC double bond zusammen Eisomer Substituents of similar rank are on opposite sides ofthe CC double bond entgegen z flnulvli Emu mmnw mm CahnlngoldPrelog Sequence Rules CahnlngoldPrelog Sequence Rules CahnlngoldPrelog Sequence Rules Kin4 Mulliplvlmrlvh39d vlunu m masz m Hm mututh i Hm m l im in Is This An E Or A Z lsomer H3CH2C CH2C1 CH3 CHZOH Chemistry Reaches A Higher Plane F Br Cl Br CC C C1 1 F I Are these two geometric isomers Which is E which is Z Stability ofAlkenes Thmudymic slab ilin 7 Refers m m mexgy content of an um 1r alkmeAxslhzmudynmicdly more mm exgy um sum E Kinen39c Sammy Mus m m charmed mummy of an sum 1r alkemAxskine callymme mm um 51km E um um A 15 1255 Inker m react an sum E or lesshkelym xenctmpnily m Thermodynamic Stabilities of Alkenes 2 heats of combusuan z heats of hydragznahon Equilibxia Tums mm C ombusdon Heatnlused on cambusuan magnum andmzmrlrbulem s m mu DH 2 kmm faundthxwugm and czhlyud mm m mm mm dumdymmm ymnxe able by cdmhtnd vahle am mm Catalytic Hydrogenation of An Alkene Addman m mm an a kene pmduces an 5mg 5m bmn samevsmzhmene pmduue the me 3 km hmane anv dmevence n mm mm mm dmevenue ntne enmgvrmmems anneti Eeamemmsumevs mmmm h 2 um um Heals of Hydrogenation r mVW m 7 wzamene mses 2n mm va2 franszrbmeneasesan v w m franszr mene must mm a mmm 25 than does crszrhmene Energy Differencei 4 kJmOIG Origin of The Energy Difference cis Z butene trans Z butene 39 120 kJmol I quot 116 kJmol x I butane L Everm Ionr h39url 927m IquotIl transZButene is more stable than cis 2 butene The energy differenceoxiginates in the CH CH by 4 kJmol crowding present in the cis isomer but not in the trans Heats of Hydrogenation A Generalization lam 6quot Meals in In general alkyl group subsitution on the carbons of a CC doublebond stabilizes the alkene lowers its energy Substitution Aiken fi1 ilvlilJVMI Tur uubmlulul Electrophilic Additions of HX To CC A Reaction Mechanism v nrr39rn n a re H action mechnnimA mlmniam deaf b HI dulaSl Hardy wan um Us plum III with name a a rlwmjta traluSomntjan I39Mehbnmlu am 39ln lken J L J Li t t A n I Iwrhyiovloiuww Mummimuilulurluhumn W M L k l mu trawl lit w mum rmmu mu Lillianm The CC bond of alkenes and cycloalkenes readily undergoes electrophilic addition Electrophile and Nucleophile Tbe reagenttnat seeks Shamans 5 an electrophile runrncn centertnat S subjetttu attack We and that S a nucle n by an enacter seeks a center uf pusmve charge phile o Nucleophilic nElectrons of 00 F39be ectruns uftne typma 00 dumb band are are subjecttu attack by an Ehattruph e W are tbemsetves mare nucleopmrctnan Stgmae ectruns uf a typma crc smgte band The 2Step Mechanism urs t Enamer uf farm as an mtermemate The 2Step Mechanism carbocation A r an m w farm as a earbbeatmn mtermemate Carburetmma su sbz nybr u zed Sp Carbon and Carbocation Step 1 mm Mmubm Mm 32 52 Hybnmzed arbun Origg nngfnw my r cytmiquot myt 39 F Sim 4 cmmm bmzatmn uf HErtu H and Er Cunversmn uf QC 7 Ehe runs tn CVH U E Emruns Furmatmn uf a 3 earbbeatmn A Review of The Two Steps The 2step mechanism of the electrophilic minimum additon of HX intemtsiisto CC double bond as applied to H Br an d isobutylene Reaction ofthe Br anion a nucleophile with the carbocation an electrophile to form tert butyl bromide A Reaction Coordinate Diagram Energy vs reaction Transnlon State coor Inate Lranstion states Think ofthe The transition state represents the r of OVI lm t V 0 l 1 highestenergy 3333i the atomic l sm39cmre inv lved iquot and mo ecular each step fa I structures as they u 1 reaction It is unstable t 39 iv 7 t exist at each given tnl to out and c b l m isolated n e m n it to Carbocation Formation Transition State For In the rst step Carbocation Formation iSObUtylene and 6 represents a partial H quotH HBr read to form positive charge The the t39bUtYl 8 single partial charge of u carbocation H the H is now I t The transition state distributed between forthe rst i theH andtheC 39 resembles a C Lquot Dashed or dotted lines 39 it 4v structure represent covalent t d t bonds being formed 11632 la 6 and being broken isobutylene an d the carbocation Product Formation In the second step the carbocation reacts with a m bromide ion to form tbutyl bromide The transition state for the second step quotE is intermeidate l between the carbocation and 39i the product Transition State For Product Formation The Br s negative 8 charge and the BI carbocation s positive 39 H charge are in the I process of being neutralized CH3 C CH2 The dashed or dotted line represents a bond 3 being formed sp3sp2 The C receiving the H is sp2 in the alkene intermediate between sp2 and sp3 in the transition state and sp3 in the carbocation intermediate Electrophilic Addition to Alkenes Can Be Regiospeclflc dh39i iitl 39rrri39li391I39 i 39 13 411 39 III HJ ti TEL r V i F quot Pillquot 4 IfillgafiTEfliiti iiiI39E tjlfjl Still CH 2 Ectlayilbl39nparuw EIlllhim39LIilinuliljylurummu HaltrtEmr1hyljmrmr Muir rl39w39uzl39r arri lquot quotI39iquotiquot l rru 39iI Regiospecific Addition of XY to a 00 double bond occurs with only one of two poss ble orientations Regioselective Addition of XY to a 00 double bond occurs predominantly but not exclusively with one orientation Activation Energy The activation energy of each l f step represents the energy required to l l convert the y 1 M o o reactants to the l l actlvatlon tranSItIon state energy There is an inverse l I relationship between the size of the activation energy and the rate of the reaction Markovnikov s Rule I l I 1 limlnial39mnl ul v ln 2 null 5 n y K 1 Int 3quot wait 1i lifi m iia39 it 9lrquot39 w Illv r rmls K quot A r z r iy I 5 m r itrl quotlilr rrn It HI armquot I min i m h m n I n ill5 Jl HH l lquot fri u I I 3 t I ll 5 r i39 IaEillEunajrra ll I 39 l w Markovnikov s Rule Does Not Operate When 39 340111 mum um m i the 21unl nicui39u Ur wnli litlzr lrlmvm mumn result2 i u H ll 7 lllli ll t39lli llt39lllll mt i lll39lll39li lNv39lunnprnuliu 3Iz mmwu The Basis of Markovnikov s Rule The Basis of Markovnikov s Rule Stability of The lntermediate Carbocation l H ner 5 lil i iv H H il MNIU39I l rimmzv I J Sccondnry 13 p rcriimy t3 1 htsigh j 539 More mum The basis of Markovn kov s Rule lies in the stability of the intermediate carbocation Stability of carbocations 3 gt 2 gt 1 gt CH3 The more stable the carbocation the lowerthe activation energy for its formation and the faster it is formed Q Wh Should The Ene y of The In ermediate Affect e Rate of The Reaction A Hammond s Postulate m i H Hammond s Postulate In an endergonic reaction one in which energy flows into the system the transition state looks like the products In an exergonic reaction one in which energy flows out of the system the transition state looks like the reactants ammond s Postulate in Formation of the intermediate ACtlon is endergonic The TS resembles the 3 carbcation is minr more stable than 1 carbocation TS forformation m m of 3 is more 39 Imjlm 39 stable and forms 7 gum i W er An Unexpected Product l H H 3 in i r n u a l MlvliI lImluxw 2139luruXmoIhlhula tappnn lr rl Formation of 2chloro3methy butane is the expected product of electrophilic addition of HCI to 3methyl1 butene Formation of 2chloro2methy butane is ne e Carbocation Rearrangement Hydride Shift m u i rm u m um lu r L r r rtt c 1 r h F ii in l u J mun t Wm uwmnmwmmm Mrmlnvimlhnmm A shi of a H39 converts a less stable 2 to a more stable 3 carbocation Carbocation Rearrangement Methyl Shift or n moi Ahk 139s w r u u m lhnwllv39l x lmum r mm illuminant mm WWW A shi of a CH3 converts a less stable 2 to a more stable 3 carbocation End Alkenes Structure and Reactivity Cepyngm 2004 by Carl H Snyder University Ufiiiami All rights reserve nuiugated oienes a Ultraviolet Spectu oscopy Chemistry 201 C i Conjugated Dienes and Ultraviolet quot A T Spectroscopy Thisp tationWaS reate by Professor Cari H Snyder Chemistry Department Universi Conjugation A eonyugatee system unsists er aiternating singie and duubie bunds With atieasttwu duubie bunds separated by a singie b d Fur a uruugated nydrucarbun the minimai requirement is ccrcc All carbons of conjugated system in a olyene are spz hybrldlzed Heats of Hydrogenation mm 114 x Nnaisui y mgenalion InisommAikenasard menus out a Ltucill i 739 mm c Lih new Huh cxbc zcwminti Thermodynamic Stabilization um tit iliiii u u unmet w eats er nydmgenatiun demunstrate tnermudynami stabiiizanun tnmugn uruugatiun AH 070 reiative te re met r The increased s characteruftnese bun spLsp3 bunds is paniyresp he mudynami Stabiiity er a e CC Bonds ofA Conjugated S m singie bunds er a uruugated system are esplsp1 e e s nsibie mugated 5me Hi my w mm IL The Conjugated System All Barbe hybndlze The 02703 bend Elf CH2CHVCHCH2has duublerbund character 3 er CchHrCHZVCH H2 is sp3 hybrldlled it interrupts the umugated system ris er a uruugated system are sp2 n crude r Linenlzmene z nnncnnlunzled rcec 137hulzdlen2 z cnnluuzled mene Delocalization Of rr Electrons 7K eieetrens er 1 Brbutadiene left are spread nut amung the A arbuns ufthe 7K system These electruns are delocallzed 7K eieetrens er 1 Arperitadierie right an uncumugated system are localized between or land 02 and between 073 and 074 Cifit39it r Linenlzdleney z nnncnnluumm 1Lhulzdime z cnnluumed mene Delocalization of 7 Electrons The deiocaiization on electrons is a stabilizing factor in conjugated systems Bondingand Antibonding c rbitals in H2 at m i7 Tim M uem i witty Bonding and Antibonding 7r Orbitals in Ethylene The 7 and n Orbitals of Ethylene n a a an lb ndl l Dvbltal a bundinm uvbltal l eieetren de The nude er the n39 Drbltal l5 a regluri ufzeru rislty The 7 and n Orbitals of ene 13Butadi 12 And 14Addition In A Conj ugated System 12 And 14Addition The 2El Allylic Carbocation Rubber and Gutta Percha Namva vubbev s the Zepmymev n We conjugated men bmamene Guna pevcha s Guna pevcha s namva vubbev 11 A 1mm e rsoprene ZrmemyM 37 heErpmymevuhsupvene heme and move bnme than be H k lt JL mm mm 5 Neoprene Neoprene sthe Zepmymev uHhe conjugated mene choroprene zremumrw ibuamene mmencaH mpunamsymheu vubbev 49 ran m me my MW m Ultraviol et Spectroscopy m WM mmmm The Ultraviolet Region Absurptiun or Energy in the ultraviulet region leads to electronic excitation Eieetronre Excitatiun is particularly efficient in Electronic Excitation Occurs Witn promotion of an electron from a bonding molecular oribital to a nonbonding orantibonding molecular orbital Known as a we 16 transition Generally rrorn the Highest Occupied Molecular Orbital HOMO to the Lowest Unoccupied Molecular Orbital LUMO The energy difference between HOMO and LUMO determines the frequency or the UV energytnat s absorbed nv Electronic Excitation in 13 Butadiene MolarAbsorbtivity m and quotmm u w Innln mm s W m null main mmum r dl ntd by h Nlullm mm mm t phynml mum lnmrlaer a my pn lmhl mum Imgtb1vMilndL nlumnnmw ru w panlmluu h m with mm muemailuqmlmurmuunnmlrrulu i mo mm m mm mm man my m m mam he s an ii Imile 4quot nrwiu TM are amiin um i uliullv m imnb mi w m ii urqu um m rt n quotnoquot 7 mm 0 mama u quota my mud n VII in la mm Molar Absorbtivity UV range 200400 nrn Molar absorbtwityeori0000 orgreater l5 good evidence ofa coniugated The UV Spectrum of 13 Butadiene ia mim39 kw M lrli an m m m m ninnninnnn At am an nrn em Zl EIEIEI


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