Abstract:
The work described in this thesis has been divided into seven
sections. The first section involves the preparation of N'-acyl-N'-arylN-
benzothiohydrazides by the acylation of N'-aryl-N-benzothiohydrazides
and is followed by a brief discussion of their possible conformation in
solution.
The second section deals with the preparation of 1,3,4-thiadiazolium
salts by the action of perchloric acid/acetic anhydride on N'-acylN'-
aryl-N-benzothiohydrazides and also by the reaction of N'-arylN-
benzothiohydrazides with nitriles in an acidic medium. The preparation
of 2-methylthio-I,3,4-thiadiazolium methosulfate by methylating the
corresponding thione is also described.
The third section deals with the reaction of 2-phenyl- and
2-methyl-I,3,4-thiadiazolium salts with alcohols in the presence of base.
The stability and spectra of these compounds are discussed. Treatment
of the 2-methyl-I,3,4-thiadiazolium salt with base was found to give
rise to a dimeric anhydrobase and evidence supporting its structure is
given. The anhydrobase could be trapped by a variety of acylating and
thioacylating agents before dimerization occurred.
In the fourth section, the reaction of N'-acyl-N'-aryl-N-benzothiohydrazides
with a variety of acid anhydrides is described. These
compounds were found to be identical with those obtained by acylating
the anhydrobase. The mass spectral fragmentation of these compounds is
described and the anomolous product obtained upon thiobenzoylation of
3-methyl-l-phenyl-pyrazal-5-one is also discussed.
The fifth section deals with thioacyl derivatives of the anhydrobase
which were prepared by the action of phosphorus pentasulfide upon the
oxygen analogues and also obtained as the major product of the reaction
of thioacetic acid with compounds related to N'-aryl-N-benzothiohydrazides.
The mass spectra and p.m.r. spectra of these compounds are discussed.
In the sixth section, the reaction of the 2-methylthio-l,3,4-
thiadiazolium salt with active methylene compounds to give acyl and
diacyl derivatives of the anhydrobase is described. Some aspects of
these compounds are discussed.
The seventh section describes the synthesis of ncyanine~' type dyes
incorporating the l,3,4-thiadiazole ring and their spectra are briefly
discussed.
