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Kinetics and Mechanism of Dehydrochlorination of 3‐Chloro‐1,5‐diarylformazans and Their Mass Spectra
Author(s) -
Shawali Ahmad S.,
Abdelkhalek Ahmad A.,
Sayed Abdelwahed R.
Publication year - 2001
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200100099
Subject(s) - chemistry , triethylamine , substituent , kinetics , mass spectrum , reaction rate constant , aryl , ion , fragmentation (computing) , ionic strength , aqueous solution , mass spectrometry , medicinal chemistry , photochemistry , organic chemistry , alkyl , physics , chromatography , quantum mechanics , computer science , operating system
In aqueous dioxane containing triethylamine the title 3‐chloroformazans 1 are converted into the corresponding 1,4‐bis(arylazo)‐3,6‐diaryl‐1,2,4,5‐tetrazines 3 via head‐to‐tail dimerization of the intitially formed 1,3‐dipolar ions 2. The kinetics of triethylamine‐catalyzed dehydrochlorination of 1 in 70% dioxane at 27°C and ionic strength of 0.1 were studied. The rate data were linearly correlated with enhanced Hammett substituent constants σ x − and an overall ρ value of 0.2 was determined for the variation of the N‐aryl substituent. These results were interpreted in terms of a two‐step mechanism. Also, the mechanisms of the unimolecular fragmentation of 1 and 3 in the mass spectrometer are discussed.