Fund of Organic Chemistry II
Fund of Organic Chemistry II CHEM 3332
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This 29 page Class Notes was uploaded by Dominic Kling on Saturday September 19, 2015. The Class Notes belongs to CHEM 3332 at University of Houston taught by Thomas Albright in Fall. Since its upload, it has received 63 views. For similar materials see /class/208158/chem-3332-university-of-houston in Chemistry at University of Houston.
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Date Created: 09/19/15
Chapter 20 Carboxylic Acids A Properties 1 AcidicH 0 50 base R 0 lt gt R C BH 3 Q H O 0 Resonancestabilized carboxylale anion 0 O C 39 CHBCHZCHZ 9H 0 H C R R pKa 481 TB Butyric acid gt H8 5 6 ll C H l HSCCHCHZ QH R6 R 5 Cl gtr 2 pKa 406 3Chlorobutyric acid IIHQCHECHQ in gl Ka 452 4Chlorobutyric acid 0 O CHSCHETH in gl pKa 284 2Chlorobutyric acid 2 Addition to carbonyl group o 0 0 base base C H T t C W Hall 0 n7 as n39 SUW quot R 9 L73 R 9 B quotB B H Adianion 3 Protonation two possibilities OH H30 ll H R h Protonation of the RC6H or carbonyl oxygen Always favored why 0 H30 g H R H Protonation of the hydroxyl oxygen 4 Hydrogen bonding Hydrogen bond OIlllllllllH R C C R 5 HIIIHIIIIIO Chapter 20 B Spectroscopic properties 1 IR O H stretch very broad intense 2500 3500 cm391 39 CO stretch intense 1700 cm1 2 1H NMR RCOZH 10 13 ppm broad Disappears upon addition of D20 R OH D20 gt R OD o H II 0 Exchanging protons R C OH D20 gt R C OD 3 13C NMR OC 180 ppm Chapter 20 4 C Nomenclature 1 Common names very prevalent COOH carboXyl group 6 Y acid common name derivation HCOZH formic acid formica Lt ant CH3COZH acetic acid acetum Lt vinegar CH3CH2COZH propionic acid protos pion Gk dairy fat CH3CH22COZH butyric acid butyrum Lt rancid butter CH3CH23COZH valeric acid valerian Lt smelly root CH3CH24COZH caproic acid caper Lt goat oder I I I I 4 4 Br lt 39 3 3 Il OH Ph CHZCHZeHz cli OH wbromoyphenylbutyric acid Chapter 20 5 other COl l ll l lOl l names H II COZH CHs CH COZH CHs C COZH COZH lactic acid pyruwc acId cozH Hozc COZH Hozc CHz COZH phthalic acid oxalic acid malonic acid benzoic acid 2 IUPAC names drop e m alkane name replace With 010 acid Number starting from carboxyl carbon Br Br 0 I I 2 I Iquot I I quot 1 39 nai v 1 u u v I avlu Hsc C CHC OH common name I a5dibromo phenylbutyric acid Ph H cc E4cyclopropyl5methyl3hexenoic acid CH2 OH 0 Chapter 20 3 IUPAC for cycloalkanecarboxylic acids COZH Br trans2bromotrans4methylcyclohexanecarboxyl acid CH3 4 IUPAC for dicarboxylic acids just add diOic acid to end of parent alkane name 3 5 Ho c CHz c CHZCHzc OH 1 2 4 6 CHZCH3 3ethyl3methylhexanedioic acid Chapter 20 7 D Uses not so many derivatives esters amp amides are much more important OZ sugars gt CH3CHZOH gt CH3COZH Vine gar fermentation fermentation HOzc CH24COZH 2 nylon CHZCOZH adipic acid HocozH citric acid COZH l t CHZCOZH G 2 9 yes ers COZH phthalic acid 0 T i Hici GHQrCHS 390 0 1110 Lauricacid 1 KQHHno n 12 Myristic acid Hicig CH2CH3 quotgt 3 n 14 Paimitic acid 0 2 H30 H20 HQ CH2n CH3 n 16 Siearic acid k Fatty acid r1 18 Arachidic acid H f CHEWCHS H Afat Chapter 20 8 lye hydrophillic region hydrophobic region m039 M 0 0 C Xr base 5 00 M Q HQJKWQWCHG 39W TQJKmHerHg I 63 I 0 0 7 A fatty acid A soap iquot 3 L 2 2 em 93 MCa0ng soap SClll l l Alongchain hydrocarbon Nil Na R H detergents 0 Chapter 20 Chapter 20 10 m m E Synthesis of carboxylic acids 1 Oxidation of primary alcohols o o Na2Cr207 RCHz OH RlH RlOH Chpt 11 2 H2304 2 Oxidation of alkynes With permanganate KMnO4 o o 910 0 heat OH39 0 3 Oxidation of alkynes With ozone 1 03 O O gt 93910 2 H20 OH HO Chapter 20 11 4 Benzylic oxidation n COZH KMnO4 H20 gt or Na2C r207 H2304 Chpt 17 14 5 Carboxylation of Grignard reagents a overall rxn 1C02 R MgX gt R COZH 2 H30 b mechanism A R MgX i gt 0 Chapter 20 c examples Mg 1co2 CH2CHBr gtcH2CHMgBr gtCH2CH 002H Et20 2 H30 Br 1 MgEt zo COZH gt 2 co2 3 H30 CH3 CH3 6 Synthesis and hydrolysis of nitriles NaCN Rx R CN gt R COZH SNZ Hl H20 or39OH H20 0 We39ll see the mechanism later F Nucleophilic acyl substitution 1 overall general reaction 0 H e R c x Nuc gt R C Nuc X e x OH OR39 NH2 OCOR Nuc39 0 We shall see that many of these reactions are reversible 0 2 Fischer esterification a overall reaction acid catalyzed O u 0 l H g R H An ester H replaces H Chapter 20 14 b mechanism 0 OH b39H OH H g gt 239 I A gtROH R c o I u H u H 39 R OH R OH ROH R OH I u OH R Acxd D B H29R 3le R Cf QR QH A H u H IJR cnm IDR IJR c u gt c lt c lt gt c lt H c R R g R QH RQH R QH Ester E gH H30 H20 C Chapter 20 395H 5H 0 26H g gt ll C I RQH R I o 39I H 39 H 7 39 39 R gH R QH R9H R QH R Acid 9H n B H2QR EH RQH l R IE OR OH A Q H H OR R ulna lea of c lt c lt gt c lt gt C lt R c o R Q R QH RQH R 9H 0H Estjr E H30 H239039 C c To get a reasonable yield of ester we need to 0 use excess alcohol I 0 distill ester off as soon as it is formed Chapter 20 d formation of lactones must be 5 0r 6 membered rings 0 ll 7039 C 6H HCI C f 0 quot H o cQH 2 0 H H H H Alactone G Synthesis and uses of acid chlo des 39 1 synthesis 39 39 a SOCl2 and PCl5 Chapter 20 17 0 soma 4 100 CC 0 II c gl gt90 6 6H 6 Cu C PCIE 100 c N02 N02 93 002 Recall from Chapter 16 R7 H gt H ilz Oxaly chloride 0 CICC39C39l Phosgene 0 II b oxalyl chloride and phosgene If C 02 co HCl 01 Cl c I 002 HCl 18 R 01 2 uses of acid chlorides a general reactions 0 HOH p c39 Esters R QR O NH3 ll A 39d 0 U ITquot as H R NH2 0 E3 0 H2b g C b r d ar oxylc acu s R QH 1LIAIH4 R CHAOH Alcohols 21420 quot Chapter 20 19 o R b general mechanism e 0 39 o IJ II N gt R IZ Cl gt R C N N R C Cl Another example 9 H C addition C I 39 elimination w quot F CR g lt43 Tetrahedral intermediaie Chapter 20 R CI6 0 Q o Anhydride F z 20 H Este fication With diazomethane o 1 overall reaction RlOH CH2N2 gt R C OCH3 2 mechanism 0 5 2 39 a R R 0 0 II 5N2 ll C HeC K Na CCH3 N2 R R 9 A methyl ester 3 example 5C H 6C CH3 E N2 No2 No2 100 HCH27NEN A diazonium ion 21 1 Direct condensation of carboxylic acids With amines 1 general reaction 39 10 Kquot A A C H NHZR quot C n NHSR gt C H20 R R R NHR Acid Base An ammonium salt An amide Notice loss of waterithis is adehydration reaction We can make this a much better reaction by 2 DCC dicyclohexylcarbodiimide Nci 1 CHQKIHZ z H3C H30 22 Amide Mechanism is basically 6 H 0 R c H gt CN lt gt o c lt HN N RicO o H a ivyH Overall change sN note leavmg group change N 0 N39 0 N j I 4 Q1 c 0 C Fl C 0 C R C O add39rticn N deprotcnation R NH2 NH H N 0 2 9 0 F NH N l R V 23 Good eavmg Amwde group J Preparation of anhydrides If If Ii 3 C C H C H26 R QH Hg R R H Two acids Anhydride Water xi Ki 396 K 2C cquot c M Cquot D enmination CuC 6 R g 9 R R Q c R R 9 R quot J Tetrahedral Anhydride intermediate 00 a better procedure uses DCC or 13205 to react With the water formed 0 O 0 R C OH or R C O C R P205 Chapter 20 O K Reduction of carboxylic acids 1 general reaction 0 CH3 1LiAiH4 RCH 6H gt R 2 H20 2 quot A specific example 25 HOOC CH28 COOH w HOCHg CHZyE CHQOH 2 97 2 mechanism AIH 0 5 2 0 UAIHquot H i ABH UAIHquot R 051 3 L39 75AM 2 gt 7 e I gt I R 9 L14 3 I R H 2 H Aldehyde cannot survive inLiAlH 0 5 ll LiAIH4 H95 C gt R C H RCH2OH H0 H l H 3 alternatives we can stop at the aldehyde stage by using bulky aluminum hydrides 0 II R c c LiHAIOCCH33 gt RCH L Alkylation of carboxylic acids 1 general reaction The general case 0 K Recall ll H 12RLl C no 39 R bi 2H201 R R X 2 LI gt R L l A specific example 0 1 2 CH3SCLE pentane 25 quotC I C H gt c 67 Chapter 20 26 2 mechanism 0 O 6 L 3 H R RH Lg addltion R L 01 R g W H7 If I I R Li R 7 Adianion U 6H 0 R Cl2 L m R C 6H H20 g I I u H20 u R R R R Hydrate Ketone LI 0 If 0 139 quot H Li R 0 C r H R g Li H 3Q quotGquot RCR 9 H HLi RiiiL gt LT b R R 27 H This reaction ls fine as long as L is a good leaving group M Summary l Nomenclature common amp lUPAC 2 Spectroscopy 339Synthesis of39carboxylic acids reVieW39 a oxidation of alcohols b oxidation of alkynes c benzylic oxidation 4Carboxylation of Grignard Reagents 5 Hydrolysis of nitriles 6 Fisher esterification mech 7 Syntheisi of acid chlorides 4 ways 839Synthetic uses of acid chlorides a preparation of esters b preparation of amides 0 preparation of anhydrides d reduction to alcohols and aldehydes 39 Chapter 20 2839 9 Esterification with diazomethane mech lt 10 Condensation of acids With amines use of DCC 11 Reduction of carboxylic acids mech 12 Alkylation of carboxylic acids inech Chapter 20 29
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