- A need exists for the development of new synthetic polymers that have special chemical, electrical, or mechanical properties. As a part of this effort, the work described in this thesis deals with several synthetic, mechanistic, and structural aspects of cyclic and high polymeric phosphazenes that contain alkyl or aryl side groups attached to the skeleton through P-C bonds.
An understanding has been obtained of the complex mechanisms that are followed when alkyl or aryl Grignard reagents react with hexachlorocyclotriphosphazene in the tetrahydrofuran. The main products are monoalkylcyclotriphosphazenes, N(,3)P(,3)Cl(,5)R, and bi- (cyclotriphosphazenes), N(,3)P(,3)Cl(,4)R (,2). The reaction pathways that lead to both products involve participation by metallophosphazene intermediates. These results provide clues to what might be expected when high polymeric (NPCl(,2))(,n) reacts with Grignard reagents.
The structure of the bi(cyclotriphosphazene), N(,3)P(,3)Cl(,4)CH(,3) (,2), has been determined by X-ray analysis. The structural features of the molecule can be understood in terms of steric interactions and (pi)-bonding hypotheses.
The reactions between Grignard reagents and aminophospha- zenes have been investigated. Alkyl Grignard reagents with N(,3)P(,3)Cl(,3)- N(CH(,3))(,2) (,3) to yield N(,3)P(,3)R(,3) N(CH(,3))(,2) (,3). Deamination was achieved by subsequent reaction with hydrogen chloride to yield N(,3)P(,3)Cl(,3)R(,3). Compounds of formula N(,3)P(,3)Cl(,4)R(,2) were prepared in a similar manner.
Cyclotriphosphazenes that bear both dimethylamino and chlorine side groups react with aluminum alkyls to replace only the chlorine atoms that are geminal to dimethylamino groups. Substitutive chlo- rine replacement also occurs when aluminum alkyls react with tetrameric derivatives. Preliminary evidence indicates that chlorine replacement is accompanied by skeletal bond cleavage when high polymeric phosphazene substrates are employed.
Finally, the ring-opening polymerizations of alkylchlorocyclo- phosphazenes have been studied. At elevated temperatures, these reactions yield moisture-sensitive high polymers and cyclic oligo- mers. Subsequent chlorine replacement by sodium trifluoroethoxide generates stable, organophosphazene derivatives. The experimental evidence is consistent with competitive polymerization and depolymerization mechanisms.
- Dissertation Note:
- Ph.D. The Pennsylvania State University 1986.
- Source: Dissertation Abstracts International, Volume: 47-11, Section: B, page: 4542.
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