Novel Approach for the Synthesis of Chlorophosphazene Cycles with a Defined Size via Controlled Cyclization of Linear Oligodichlorophosphazenes [Cl(PCl2=N)n–PCl3]+[PCl6]−

Autor: Mikhail Gorlov, Nikolay Bredov, Andrey Esin, Igor Sirotin, Mikhail Soldatov, Volodymyr Oberemok, Vyacheslav V. Kireev
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: International Journal of Molecular Sciences, Vol 22, Iss 11, p 5958 (2021)
Druh dokumentu: article
ISSN: 1422-0067
1661-6596
DOI: 10.3390/ijms22115958
Popis: Despite a significant number of investigations in the field of phosphazene chemistry, the formation mechanism of this class of cyclic compounds is still poorly studied. At the same time, a thorough understanding of this process is necessary, both for the direct production of phosphazene rings of a given size and for the controlled cyclization reaction when it is secondary and undesirable. We synthesized a series of short linear phosphazene oligomers with the general formula Cl[PCl2=N]n–PCl3+PCl6– and studied their tendency to form cyclic structures under the influence of elevated temperatures or in the presence of nitrogen-containing agents, such as hexamethyldisilazane (HMDS) or ammonium chloride. It was established that linear oligophosphazenes are inert when heated in the absence of the mentioned cyclization agents, and the formation of cyclic products occurs only when these agents are involved in the process. The ability to obtain the desired size phosphazene cycle from corresponding linear chains is shown for the first time. Known obstacles, such as side interaction with the PCl6– counterion and a tendency of longer chains to undergo crosslinking elongation instead of cyclization are still relevant, and ways to overcome them are being discussed.
Databáze: Directory of Open Access Journals
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