Aldehydes, Ketones and Carboxylic Acids name reactions

Making aldehydes and ketones

Rosenmund reduction

$\displaystyle \text{RCOCl} + \text{H}_2 \xrightarrow{\text{Pd-BaSO}_4} \text{RCHO} + \text{HCl}$

Stephen reaction

$\displaystyle \text{RCN} \xrightarrow[\text{then H}_3\text{O}^+]{\text{SnCl}_2/\text{HCl}} \text{RCHO}$

Etard reaction

$\displaystyle \text{C}_6\text{H}_5\text{CH}_3 \xrightarrow[\text{then H}_3\text{O}^+]{\text{CrO}_2\text{Cl}_2} \text{C}_6\text{H}_5\text{CHO}$

Gatterman-Koch reaction

$\displaystyle \text{C}_6\text{H}_6 + \text{CO} + \text{HCl} \xrightarrow{\text{anhyd. AlCl}_3/\text{CuCl}} \text{C}_6\text{H}_5\text{CHO}$

Reactions of the carbonyl group

Clemmensen reduction

$\displaystyle \text{>C=O} \xrightarrow{\text{Zn-Hg, conc. HCl}} \text{>CH}_2$

Wolff-Kishner reduction

$\displaystyle \text{>C=O} \xrightarrow[\text{KOH, glycol, heat}]{\text{NH}_2\text{NH}_2} \text{>CH}_2$

Aldol condensation

$\displaystyle 2\text{CH}_3\text{CHO} \xrightarrow{\text{dil. NaOH}} \text{CH}_3\text{CH(OH)CH}_2\text{CHO}$

Needs an α-hydrogen. Heating gives the α,β-unsaturated product.

Cannizzaro reaction

$\displaystyle 2\text{HCHO} \xrightarrow{\text{conc. KOH}} \text{CH}_3\text{OH} + \text{HCOOK}$

For aldehydes with no α-hydrogen.

Carboxylic acids

Hell-Volhard-Zelinsky reaction

$\displaystyle \text{RCH}_2\text{COOH} \xrightarrow[\text{then H}_2\text{O}]{\text{X}_2,\ \text{red P}} \text{RCHXCOOH}$

Decarboxylation

$\displaystyle \text{RCOONa} \xrightarrow{\text{NaOH, CaO, heat}} \text{R-H} + \text{Na}_2\text{CO}_3$

Tests

• Tollens' reagent gives a silver mirror with aldehydes, and doesn't react with ketones.
• Fehling's solution gives a red-brown precipitate with aliphatic aldehydes, but not aromatic ones.
• The iodoform test (yellow precipitate) is positive for methyl ketones, ethanal and ethanol.