Dissociation contants of cyanoacetic acid in aqueous solution have been measured a t 5' intervals between 5" and 45", with an accuracy in In K of the order of 0.005%. Fifteen interpolation equations have been tested by statistical methods, and three of these have been found to be capable of expressing the dependence of In K upon temperature within experimental error.These three equations, and graphical interpolation, show that the heat-capacity loss accompanying the ionisation of cyanoacetic acid passes through a minimum at 20-30". This is very likely to be due to the effects of temperature upon the structure of water, the hydration of molecules, and the hydration of ions. Present knowledge of these topics is reviewed. The strength of cyanoacetic acid is shown to depend on an entropy effect, as well as on the normally accepted influence of a polar substituent. The results are discussed in relation to recent data on the halogenoacetic acids.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.