A study of the relative acidities of a series of methoxy substituted coumarilic and thianaphthene-2-carboxylic acids in aqueous alcohol and infrared studies of the corresponding methyl esters

This work Is an extension of the study on the coumarone (I) and thianaphthene (II) systems previously investigated by Hanson and Ruchelman, (1), (2). The objectives of this research are: (1) to Investigate the aromatic properties of the coumarone and thianaphthene systems; (2) to Investigate the effects produced at a carboxyl group In the 2-posltlon of the heterocyclic ring by a substituent located In the benzene ring portion of the molecule; (3) to investigate the transmission of electronic effects through the oxygen and sulfur heteroatoms and compare their abilities to transmit these effects with the vinyl group, -CH=CH-, of completely carbocyclic systems; and (4) to develop and Improve the techniques of synthesis of the coumarones and thianaphthenes which were previously difficult to synthesize. The ionization constants of the methoxy substituted coumarllic acids and thianaphthene-2-carboxyllo acids were determined as well as the carbonyl stretching frequencies of the methyl esters of the acids. The data obtained was used in an attempt to provide answers to the objectives stated previously.