Ethanol → 5-(tert-Butyl)oxazole-2-carboxylic acid

Reaction equation

[OH-:1].[Na+].[C:3]([C:7]1[O:11][CH:10]=[N:9][CH:8]=1)([CH3:6])([CH3:5])[CH3:4].[CH2:12]([OH:14])C>O>[C:3]([C:7]1[O:11][C:10]([C:12]([OH:14])=[O:1])=[N:9][CH:8]=1)([CH3:6])([CH3:5])[CH3:4]

Participants

Procedure

A solution of sodium hydroxide (0.96 g, 24 mmol) in water (25 ml) is added to a stirred solution of 5-tert-butyl-oxazole .2-carboxylic acid ethyl ester (3.94 g, 20 mmol) In ethanol (35 ml), and the mixture is warmed to 60° C. and stirred for 1 h. The ethanol is then removed by distillation and the aqueous residue is washed with diethyl ether and acidified with 5 N hydrochloric acid. The resulting precipitate is collected by filtration and dried to give 5-tert-butyl-oxazole-2-carboxylic acid (2.30 g, 68%) as beige crystals. This material is used immediately without further purification since, on prolonged storage, it undergoes spontaneous decarboxylation to 5-tert-butyl-oxazole.