CHE 275: Organic Chemistry 1 - Study Guide
CHE 275: Organic Chemistry 1 - Study Guide CHE 275
Popular in Organic Chemistry 1
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This 11 page Study Guide was uploaded by an elite notetaker on Monday November 3, 2014. The Study Guide belongs to CHE 275 at Syracuse University taught by Clack in Fall. Since its upload, it has received 187 views. For similar materials see Organic Chemistry 1 in Chemistry at Syracuse University.
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Date Created: 11/03/14
Chapter 6 review for EXAM 2 Addition rezgtion of z mnes I General rxn 0 Hydrogenation of alkenes 0 Addition of H2 to a multiple bond 0 EX 0 Is exothermic 0 Heat of hydrogenation A H O I Can be use to measure relative stability of isomeric alkenes I Highest heat of hydrogenation is the least stable isomer 0 Catalyzed by Pt Pb Rh Ni metals 0 Sterochemical aspects I Syn addition of both H atoms to double bond I Hydrogenation is stereoselective corresponding to addition to less crowed face of double bond 0 A single starting material can give two or more stereoisomeric products but yields one of them in greater amount then the other 0 Heterogeneous reaction I Reaction involving a substance in one phase the solution with a different substance in a second phase Chapter 6 review for EXAM 2 0 Electrophilic addition of Hydrogen halides to alkenes 0 General formula 0 HFltHClltHBrltHI Occur in a variety of solvents pentane benzene dichloromethane chloroform and acetic acid 0 EX 0 Mechanism 39 Overall reaction 39 Step 1 39 Step 2 O Alkyl subunituents increase the reactivity of a double bond toward electrophilic addition 0 Alkyl group are electronreleasing and the more electron rich a double bond the better it can share its 11 bond 0 Marlovnikov s Rule form the most stable product 0 When an unsymmetrically substituted alkene react with a hydrogen halide the hydrogen adds to the carbon that has the greater number of hydrogen and the halogen adds to the carbon having fewer hydrogen 0 EX Addition of H2 S 04 Chapter 6 review for EXAM 2 0 AntiMarlovnikov s Rule 0 Process by free radical chain mechanism 0 For HBr with the addition of peroxide I Addition of HBr to 1Butene O Photochemical addition of HBr I HBr initiated with light with or with not added peroxide I EX I Mechanism for HBr opposite to MarkoVnikoV s rule 0 Initiation step 0 Propagation step 0 Intermolecular reaction 0 Occur in one molecule faster 0 Intramolecular reaction 0 Occur in two molecule slower 0 Acid catalyzed hydration of alkenes 0 Reaction is acid catalyzed typicaly hydration medium is 50 H2504 50 H20 0 Follow MarkoVnikoV s Rule 0 EX Chapter 6 review for EXAM 2 0 Mechanism acid catalyzed hydration of 2methylpropene I The overall reaction I Step 1 protonation of double bond the carboncarbon double bond in the direction that leads to more stable carbocation I Step 2 Capture of carbocation by Water Water acts as a nucleophile to capture tertbutyl cation I Step 3 deprotonation of Oxonium ion tert butyloxonium ion Water acts as a Bronsted base 0 The more stable the carbocation the faster it is formed and the faster the reaction rate 0 Principal of Microscopic reversibility O In equilibrium process the same intermediated and transition states are encountered in the forward direction and the reverse but in the opposite order 0 EX 0 Mechanism 63 and 51 Chapter 6 review for EXAM 2 0 Hydrationdehydration equilibrium 0 How do We control the equilibrium and maximize the yield of the compound We Want 0 For hydration dehydration equilibria the key stress factor is the Water concentration 0 Hydroboration oxidation 0 Convert alkenes to alcohols with a regopchernistry 0 Opposite to markovnikov s rule 0 Hydroboration Is a reaction in which a boron hydride R2 BH adds to carboncarbon II bond form a carbon hydrogen bond and a carbonboron bond result I Reahent Diborane B2 H5 in solvent diglyme O The oxidation stage hydrogen peroxide is the oxidizing agent and the organoborane is converted to an alcohol 0 Lead to the overall hydration of an alkene 0 Features I Hydration of alkenes I Regioselectivity opposite to markovnikov r rule I No rearrangement I Stereospecific syn addition Chapter 6 review for EXAM 2 0 Oxidation of an organoborane Synaddition Organoborane intermediate Step 1 hydrogen peroxide is converted to its anion in basic solution Step 2 anion of hydrogen peroxide acts as a nucleophile attacking boron and forming an oxygenboron bond Step 3 carbon migrates from boron to oxygen displacing hydroxide ion Carbon migrates with the pair of electron in the carbon boron bond these become the electrons in the carbon oxygen bond Step 4 hydrolysis cleaves the boronoxygen bond yielding the alcohol Chapter 6 review for EXAM 2 O H and OH become attached to same face of double bond 0 B adds to less substituted carbon 0 EX 0 Addition of halogens to alkenes 0 General feature 0 Product is called Vicinal dihalides two substituents are Vicinal is they are attached to adjacent carbons O Rearrangement do not really occur 0 Stereochemistry I Reaction of chlorine and bronmine anti addition id observed add to opposite face of the double bond 0 Limited to C12 Br2 I F2 is explosive and I2 is endothermic 0 Mechanism is electrophilic addition I B1quot 2 is not polar but it is polarizable I 2 Steps 0 Step 1 Formation of bromonium ion 0 Step 2 nucleophilic attack on bromonium ion by bromide Chapter 6 review for EXAM 2 0 Conversion of alkenes to vicinal halohydrins 0 General formular 0 Anti addition occur 0 Formation of a bromohydrin 0 FreeRadical Addition of Hydrogen Bromide to Alkenes O Sometime follow the Markovnikov s rule sometimes doesn39t O Peroxide effect I Occur of peroxide will form the primary haloalkene I Anti Markovinkov s Rule 0 The order of free radical I TertiarygtSecondarygtprimary 0 Addition of a Br ion to C1 gives a secondary alkyl radical 0 Addition of a Br ion to C2 gives a primary alkyl radical 0 Free radical addition of hydrogen bromide to 1 butene I The overall reaction 0 Initiation 0 Step 1 homolytic dissociation of a peroxide into two alkoxy radicals 0 Step 2 hayrogen atom abstraction form hydrogen bromide by an alkoxy radical 0 Chain propagation Chapter 6 review for EXAM 2 0 Step 3 addition of a bromine atom to the alkene 0 Step 4 abstraction of a hydrogen atom form hydrogen bromide by the free radical formed in step 3 I Regioselectly favor the more stable carbocation Epoxidation of alkene 0 Three member ring that contain oxygen are called epoxides 0 Naming O Epoxyalkene 0 Epoxidation process 0 Commonly use peroxy acid is peroxyacetic acid CH3 C02 OH Ozonolysis of alkene 0 Ozone 0 Can be represent as a hybrid of its two most stable Lewis structure 0 Powerful electrophile O Undergo reaction With CC bouble bond and form ozonide I Ozoide structure 0 Ozoides undergo hydrolysis in Water giving carbonyl compound Chapter 6 review for EXAM 2 O Mechanism Ozonolysis 0 General equation 0 Provide a method for the preparation of aldehydes and ketones 0 EX 0 EX Polvmerization Reaction of alkenes with alkenes In more concentrated solution of sulfuric acid For a mixture of two product 0 EX 2 same monomer form two different dimer Cationic polymerization O Acid catalyzed dimerization of 2methylpropene I Step 1 protonation of the C C double bond in the direction that leads to more stable carbocation I Step 2 the carbocation acts as an electrophile toward the alkene A C C bond is formed resulting in a new carbocation I Step 3 loss of a proton form this carbocation can produce either 244trimethyllpentene or 244trimethyl2pentene Chapter 6 review for EXAM 2 0 Freeradical polymerization O Freeradical polymerization mechanism 0 Step 1 hemolytic dissociation of a peroxide products alkoxy radicals that serve as freeradical initiators 0 Step 2 an alkoxy radical adds to the CC double bond 0 Step 3 The radical produced in Step 2 adds to a second molecule of ethylene
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