CarbonylChemistry study guide for Midterm II

CarbonylChemistry study guide for Midterm II - Carbonyl...

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Carbonyl Chemistry
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(5) FORMAL REACTION WITH NUCLEOPHILIC HYDRIDE ANION - REDUCTION TO ALCOHOLS : CH 3 C H O CH 3 C CH 3 O O O O - C CH 3 CH 3 H H - H 2 O D OH H OD OH C CH 3 CH 3 H OH C CH 3 H H (i) NaBH 4 or LiAlH 4 "H - " Hydride anion (ii) H 2 O 1 alcohol 2 alcohol However the actual mechnism is more complicated and does n o t actually involve free hydride anion. (i) NaBD 4 (ii) H 2 O (i) NaBH 4 (ii) D 2 O Reduction by sodium borohydride, NaBH 4 or lithium aluminium hydride, LiAlH 4 , is conveniently regarded as nucleophilic attack by hydride anion on the electrophilic carbonyl carbon atom: In the alcohol reduction product the hydrogen attached to the carbonyl carbon arises from BH 4 Š or AlH 4 Š and that attached to oxygen from water employed in the work-up:
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(6) OTHER REDUCTION REACTIONS OF ALDEHYDES AND KETONES (i) CATALYTIC HYDROGENATION O H OH H 2 [Pt] Addition of hydrogen across C-O double bond (ii) REDUCTION WITH DEOXYGENATION (a) Basic conditions - Wolff-Kischner reduction O H H N 2 H 4 , NaOH ROH, Heat (b) Acidic conditions - Clemmensen reduction O H H Zn/Hg HCl, Heat Zinc amalgam (a liquid zinc-mercury alloy) increases the reactivity of zinc as a reducing agent. The Clemmensen and Wolff-Kischner reactions are complementary - one is suitable for acid-sensitive compounds, the other for base sensitive materials.
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(7) OXIDATION OF ALDEHYDES AND KETONES Aldehydes: CH 3 C O H [O] CH 3 C O OH Aldehyde Carboxylic acid
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This note was uploaded on 12/16/2008 for the course CHEM 140B taught by Professor Nefzi during the Spring '06 term at UCSD.

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CarbonylChemistry study guide for Midterm II - Carbonyl...

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