Diazepines. Part VIII. Equilibria and entropy changes in condensation reactions leading to 2,3-dihydro-1,4-diazepines. Ultraviolet and infrared spectra of products

Abstract

Preparations of a series of 2,3-dihydro-1,4-diazepines by condensation of 1,2-diamines with 1,3-dicarbonyl compounds are reported, and the formation of alternative products is discussed. Equilibrium constants for the formation of a series of 2,3-dihydro-1,4-diazepines in aqueous solution, and the ultraviolet and infrared spectra of these compounds, are related to the disposition of substituent methyl groups. An empirical equation is used to calculate values for entropies of reaction. Such values, and other estimated values, are used in an analysis of the reaction sequence to account for the measured entropies of reaction of two of the equilibria.