Abstract:
The work described in this thesis has been dtvided into
six sections .
The first section involves the reaction of
3,5-diphenyl-2-methyl-l,3,4-oxadiazolium perchlorate with acetic
and benzoic anhydrides.
The second section deals with the preparation and
reactions of 1,3,4-thia diazolium salts. Some monomeric
1,3,4-thiadiazoline methine bases have also been prepared by
reacting 1,3,4-thia d iaz ol ium s al t s with concen trated ammonium
hydroxide solution. Variable temperature p.m.r. of
2-(3-acetylacetonylidene)-3,5-diphenyl-A4 -1,3,4-thiadiazoline has
also been described.
The third section deals with prepar a tion and reactions
of some compounds in benzoxazole series.
The fourth section deals with the prep a ration and
reactions of N-alkyl-2-methylbenzothi azolium salts with base , a nd
with some a cetylating and thioacetylating agents. Treatment of
2,3-dimethylbenzothiazolium iodide and of
3-ethyl-2-methylbenzothia zolium iodide with base wa s found to
give the corresponding dimeric methine b a ses and evidence
supporting their structure is also given. Thiol acetic acid was
found to exchange 0 for S in its reactions with 2-acetonylidene-3-methylbenzothiazoline and
2-acetophenonylidene-3-methylbenzothi a zoline.
(ii)
In th e fifth section, the r eactions of
2,3-dimethylbenzselenazolium iodide with a variety of ac e tylating
and thioacetylating agents has been described. The treatment of
2,3-dimethylbenzselenazolium iodide with base was found to give
rise to a dimeric methine base and evidence supporting its
structure is also given. The reactions of this dimeric methine
b a se with benzoic anhydride and phenylisothiocyanate have also
been described.
The sixth section deals with the preparation and
reactions of l-alkyl-2-methylquinolinium salts. Treatment of
1,2-dimethylquinolinium iodide and l-ethyl-2-methylquinolinium
iodide was found to give the corresponding monomeric methine
bases and evidence supporting their structure is also given. The
E-type geometry of the olefinic bond in
2-acetonylidene-l-methylquinoline has been established on the
basis of an N.O.E. experiment.
