Aldehydes and Ketones

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Synthesis of Aldehydes

Oxidation
Reduction	or or	or

Synthesis of Ketones

Ozonolysis			+
Oxidation
Friedel-Crafts Acylations		+
Coupling	R'₂CuLi	+
Addition to Alkynes	R-CºC-R' + H₂O

Nucleophilic Addition

Nucleophilic addition reactions generally follow one of two possible mechanisms. The first is direct attack of the carbonyl carbon (d⁺) by a nucleophile. This is the predominant mechanism for strong nucleophiles.

The second mechanism predominates in strongly acidic environments. In this mechanism, the carbonyl oxygen is protonated, generating a positively charged compound. This intermediate can be drawn as two resonance structures, where the positive charge is localized on either the oxygen or the carbonyl carbon. In the second step, the carbonyl carbon (which carries a partial positive charge) is attacked by a nucleophile. Since the intermediate is already positively charged, the attacking nucleophile does not have to be particularly strong for this reaction to proceed.

Specific Examples

Addition of Water				(gem-diol)
Addition of Hydrides
Addition of Alcohols	or		(hemiacetal)		(acetal)
Addition of Amines		+	(1° amine)		(imine)
Wolff-Kishner Reduction
(Formation of ylide)					(ylide)
Wittig Reaction		+	(ylide)
Reformatsky Reaction		+	(a-bromoester)		(b-hydroxyester)
(Dehydration of hydroxyester)					(a,b-unsaturated ester)
Oxidation				(carboxylic acid)