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Title: Organic gas generators
Author: Stephen, Karen M. A.
ISNI:       0000 0001 3480 0987
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1989
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Three heterocyclic systems were prepared along with derivatives. The thermal decompositions of these heterocycles was examined and their suitability as gas generators assessed, with respect to, melting point, decomposition temperature, volume and type of gases evolved, ease of hydrolysis, and ease of preparation. The preparation of 2-azido-5-phenyl-1,3,4-oxadiazole by a variety of routes is described. It was stable above its melting point and at higher temperatures decomposition was violent, evolving nitrogen, along with the formation of benzoyl cyanide. 1,2,4-Oxadiazolidine-3,5-dione melted at 103-105oC and decomposed at ca 155oC with gas evolution. 2,2'-Adipoyldi-1,2,4-oxadiazolidine-3,5-dione and the corresponding succinyl derivatives were prepared in good yield and decomposed on melting. The oxalyl and malonyl derivatives were more difficult to prepare due to their ease of hydrolysis. The oxalyl derivative decomposed ca 20o above its melting point. Parabanic acid (2,4,5-triketoimidazolidine) was easily prepared in high yield and decomposed on melting. N,N'-Diacetyl- and N,N'-dibenzoyl-parabanic acids were prepared, via the disodium salt of parabanic acid, and decomposed on melting. Monoacetyl parabanic acid decomposed 20-30o above its melting point. Hydrolysis of the acetyl derivatives was studied by 1H nmr spectroscopy. In the presence of adventitious water in the solvent diacetylparabanic acid gives, initially, the monoacetyl derivative and acetic acid, followed by ring opening to N-acetyloxaluric acid. This ease of hydrolysis reduces its attractiveness as a potential gas generator. An X-ray crystallographic determination was carried out on diacetylparabanic acid and the significance of the bond lengths in the hydrolysis process is discussed. N,N'-Adipoyldi-parabanic acid was prepared in low yield and decomposed ca 20o above its melting point.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic chemistry