A new interpretation of the Acidic and Basic structures in Carbons. I. Lactone groups of the ordinary and fluorescein types in carbons

Methylation of a sugar carbon or carbon black with diazomethane produces a methoxyl group which is readily hydrolysed by dilute acid but which is not due to the presence of a simple carboxylic ester, since the titration curves of the carbons are those of much weaker acids. It most probably arises from the methylation of a lactone which is present in conjunction with a phenol, such as occurs in the fluorescein and phthalein dyestuffs. This, however, accounts for only part of the acidity of the carbons, some of which is due to a group which reacts with alkali but not with diazomethane and is probably a normal lactone group. The remainder of the acidity of the carbons is due to phenolic hydroxyl groups. Infra-red spectroscopic evidence is presented in support of these views. The effects of temperature and of oxidation on the concentration of these various groups have also been studied.