organic_chemistry_R-_and_H-

organic_chemistry_R-_and_H- - alcohol to an alkyl halide: R...

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organic chemistry: R - and H - overview of reactions for R - and H - attack carbonyls or epoxides attack carbonyls or epoxides attack carbonyls or epoxides attack carbonyls as nucleophiles Å Å Å Å R MgBr R Li LiAl H 4 NaB H 4 Na H as bases (faster) Æ Æ Æ Æ deprotonate O H , N H , or S H Another name for “expoxides” is “oxacyclopropanes”. acid-base reactions for R - and H - reactions: Na H + RO H Æ H— H + NaOR R MgX + RO H Æ R— H + ROMgX Similar deprotonation reactions with other O- H , N- H , or S- H groups. mechanisms: synthetic utility: Na H deprotonates alcohols, turning a poor nucleophile/base (neutral O, only good enough for S N 1/E1) into a good nucleophile/base (O - , good enough for S N 2/E2). To replace a functional group with a H : R MgX + H 3 O + Æ R H + H 2 O + + MgX Or, to replace a functional group with a D : R MgX + D 3 O + Æ R D + D 2 O + + MgX some other useful reactions to convert a 1 ° or 2 ° alcohol to an alkyl bromide: R OH + PBr 3 Æ R Br to convert a 1 ° or 2 ° alcohol to an alkyl chloride: R OH + SOCl 2 Æ R Cl to convert a 3
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Unformatted text preview: alcohol to an alkyl halide: R OH + HX R X + H 2 O (S N 1) ( X = Cl , Br , or I ) to synthesize a Grignard reagent: RX + Mg R MgX , X = Cl , Br , or I to synthesize an alkyl lithium: RX + 2 Li RLi + LiX to synthesize an organocuprate: 2 RLi + CuI R 2 CuLi + LiI Organocuprates can act as nucleophiles in an S N 2 reaction: R 2 CuLi + RX R-R Grignards and alkyl lithiums, in contrast, cannot act as S N 2 nucleophiles. Synthetic utility: Defunctionalizes, adds carbon-carbon sigma bonds. Some courses may not cover organocuprates. 1 www.freelance-teacher.com organic chemistry: R-and H-using R-to attack carbonyls and epoxides reactions: synthetic utility: Form carbon-carbon bonds. RMgX + carbonyl forms a new C-C bond, with an O-on the C that was attacked. RMgX + epoxide forms a new C-C bond, with an O-on the C next to the C that was attacked. 2 www.freelance-teacher.com...
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This note was uploaded on 07/16/2011 for the course CHEM 310M taught by Professor Bocknack during the Spring '09 term at University of Texas at Austin.

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organic_chemistry_R-_and_H- - alcohol to an alkyl halide: R...

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