134221-75-3Relevant academic research and scientific papers
Synthesis and Hydrolysis of Substituted Tetrahydropyrimidinium Salts. Behaviour of the Degradation Products on Varying pH.
Reverdito, Ana M.,Orelli, Liliana,Dalmaso, Monica,Perillo, Isabel,Fernandez, Beatriz M.
, p. 273 - 281 (2007/10/02)
Reaction of 1,2-diaryl-3-methyl-1,4,5,6-tetrahydropyrimidinium iodides 1a-i with alkaline solutions afforded N-aroyl-N-aryl-N'-methyltrimethylenediamines 2a-i.Compounds 2 are stable under acid conditions but in neutral or alkaline media spontaneously rearrange giving N-aroyl-N'-aryl-N-methyltrimethylenediamines 3a-i.Treating compound 3 with concentrated acids reverse reaction takes place. Kinetic studies were performed on this intramolecular N->N' aroyl transfer over the H0-pH range -0.9 to 2.30.Compounds 3 undergo acyl transfer to give 2 by a mechanism which involves a change in the rate determining step from formation to acid-c atalysed decomposition of a six-membered heterocyclic intermediate on going from H0 to pH values.The existence of maxima in the pH rate profile allow to determine apparent pKa values of the hexahydropyrimidine intermediates which gave good correlation with the Swain F substituent constants.Stability of these heterocycles was also predicted by determination of thermodynamic parameters.Comparisons are made with the behaviour of five-membered heterocyclic intermediates (imidazolidine derivatives) which were studied in an earlier paper.
