Ionization constants of alkyl-substituted cyclopropanecarboxylic acids

Abstract

1. From a comparison of the constants of cyclopropanecarboxylic acids containing trialkylsilyl and trialkylgermyl substituents it follows that the interaction between the silicon or germanium atom and the carboxy group is not transmitted through the cyclopropane ring irrespective of whether the silicon atom is in theα- orβ-position relative to the carbon atom of the three-membered ring. 2. Replacement of an aliphatic chain by a cyclopropane ring in a carboxylic acid leads to diminution in the strength of the caid. 3. Increase in the number of alkyl substituents on the carbon atoms forming the cyclopropane ring leads to diminution in the strength of the cyclopropanecarboxylic acid. 4. Branching of the alkyl substituents leads to diminution of the strength of the cyclopropanecarboxylic acid when there is a secondary or tertiary carbon atom in the substituent in theα-position relative to the carbon atom of the three-membered ring.