Synthesis and Hydrolysis of Hexakis(imidazolyl)cyclotriphosphazene

Harry R. Allcock, T. J. FuUer

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

The reaction of imidazole with hexachlorocyclotriphosphazene (I) has yielded hexakis(imidazolyl)cyclotriphosphazene (II). Compound II has been studied as a model for the analogous linear high polymer which is a prospective biodegradable carrier macromolecule. Compound II is hydrolytically unstable and decomposes to hydroxyphosphazenes, imidazole, and phosphate in aqueous media. A kinetic analysis of the removal of the first imidazolyl group from II in unbuffered 20% aqueous tetrahydrofuran within the pH range of 6.5-7.8 has shown that the hydrolysis is autocatalyzed by the free imidazole liberated in this step. Initially, the displacement of imidazole is a first-order process with respect to [II], but the release of imidazole gives rise to faster, second-order reaction in which the rate depends on the first powers of [II] and [imidazole]. The evidence favors the influence of free imidazole as a general-base catalyst and not via the formation of hydroxide ion. TV-Methylimidazole reacts with I to form an unusual series of highly reactive yellow salts of the general formula [N3P3Cl6-x(C4H6N2)x]x+xCl (VII). The chemistry of II and VII is discussed in terms of its relationship to the synthesis and reactions of the analogous linear high polymeric phosphazenes.

Original languageEnglish (US)
Pages (from-to)2250-2256
Number of pages7
JournalJournal of the American Chemical Society
Volume103
Issue number9
DOIs
StatePublished - Jan 1 1981

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Macromolecules
Hydrolysis
Phosphates
Salts
Catalysts
Kinetics
Ions
Polymers
imidazole
Linear Models

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

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abstract = "The reaction of imidazole with hexachlorocyclotriphosphazene (I) has yielded hexakis(imidazolyl)cyclotriphosphazene (II). Compound II has been studied as a model for the analogous linear high polymer which is a prospective biodegradable carrier macromolecule. Compound II is hydrolytically unstable and decomposes to hydroxyphosphazenes, imidazole, and phosphate in aqueous media. A kinetic analysis of the removal of the first imidazolyl group from II in unbuffered 20{\%} aqueous tetrahydrofuran within the pH range of 6.5-7.8 has shown that the hydrolysis is autocatalyzed by the free imidazole liberated in this step. Initially, the displacement of imidazole is a first-order process with respect to [II], but the release of imidazole gives rise to faster, second-order reaction in which the rate depends on the first powers of [II] and [imidazole]. The evidence favors the influence of free imidazole as a general-base catalyst and not via the formation of hydroxide ion. TV-Methylimidazole reacts with I to form an unusual series of highly reactive yellow salts of the general formula [N3P3Cl6-x(C4H6N2)x]x+xCl (VII). The chemistry of II and VII is discussed in terms of its relationship to the synthesis and reactions of the analogous linear high polymeric phosphazenes.",
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Synthesis and Hydrolysis of Hexakis(imidazolyl)cyclotriphosphazene. / Allcock, Harry R.; FuUer, T. J.

In: Journal of the American Chemical Society, Vol. 103, No. 9, 01.01.1981, p. 2250-2256.

Research output: Contribution to journalArticle

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AB - The reaction of imidazole with hexachlorocyclotriphosphazene (I) has yielded hexakis(imidazolyl)cyclotriphosphazene (II). Compound II has been studied as a model for the analogous linear high polymer which is a prospective biodegradable carrier macromolecule. Compound II is hydrolytically unstable and decomposes to hydroxyphosphazenes, imidazole, and phosphate in aqueous media. A kinetic analysis of the removal of the first imidazolyl group from II in unbuffered 20% aqueous tetrahydrofuran within the pH range of 6.5-7.8 has shown that the hydrolysis is autocatalyzed by the free imidazole liberated in this step. Initially, the displacement of imidazole is a first-order process with respect to [II], but the release of imidazole gives rise to faster, second-order reaction in which the rate depends on the first powers of [II] and [imidazole]. The evidence favors the influence of free imidazole as a general-base catalyst and not via the formation of hydroxide ion. TV-Methylimidazole reacts with I to form an unusual series of highly reactive yellow salts of the general formula [N3P3Cl6-x(C4H6N2)x]x+xCl (VII). The chemistry of II and VII is discussed in terms of its relationship to the synthesis and reactions of the analogous linear high polymeric phosphazenes.

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