Alkyl substituted benzoic acids. Part III. Isopropylbenzoic acids

Abstract

Isopropylation of bromo- or iodo-benzene gives a mixture of mono-, di-, and tri-isopropyl halogenobenzenes. When these are separated by fractionation and carbonated to give the corresponding benzoic acids, the large differences in acid strengths between the individual acids facilitate their separation from solutions of their salts by fractional precipitation with mineral acid. Benzoic acids with the following substituents were thus obtained pure 2-isopropyl, 4-isopropyl, 2,4-di-isopropyl, 2,6-di-isopropyl, 2,4,5-tri-isopropyl, and 2,4,6-tri-isopropyl, all, except possibly 4-isopropylbenzoic acid, more readily than by methods previously described.