Oligomeric Hydroxyaryloxycyclotriphosphazenes with Decreased Functionality Based on Resorcinol
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Oligomeric Hydroxyaryloxycyclotriphosphazenes with Decreased Functionality Based on Resorcinol Yu. V. Bilichenkoa, Duong Thien Nguyena, V. V. Kireeva,*, R. S. Borisovb,c, I. S. Sirotina, and S. N. Filatova a b Topchiev
Mendeleev University of Chemical Technology of Russia, Moscow, 125047 Russia Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, 119991 Russia c Peoples’ Friendship University of Russia, Moscow, 117198 Russia *е-mail: [email protected] Received January 22, 2020; revised March 3, 2020; accepted March 19, 2020
Abstract—Oligomeric hydroxyaryloxycyclotriphosphazenes P3N3Cln(OC6H5)x(OC6H4OH)y are obtained by the polycondensation of phenoxychlorocyclotriphosphazenes with the general formula P3N3Cl(6−x)(OC6H5)x (x = 3.1, 4.5) with an excess of resorcinol under homogeneous (pyridine) and heterogeneous (K2CO3) acceptance of HCl in a yield of 60–85%. Full substitution of the chlorine atoms in the specified oligomers (n = 0) under homogenous acceptance of HCl by pyridine is reached only at a molar ratio of phenoxychlorocyclophosphazene : resorcinol = 1 : 12; the formed oligomers contain up to 3% Cl at a ratio of 1 : 6. The structure of the compounds present in the composition of oligohydroxyaryloxycyclotriphosphazenes and their relative concentration are determined by 31P NMR spectroscopy and MALDI-TOF mass spectrometry. DOI: 10.1134/S1560090420040028
The products of polycondensation of chlorocyclophosphazenes (CCPs) with diatomic phenols, hydroxyaryloxycyclotriphosphazenes (HAPs), are of interest for both the synthesis of various types of phosphazene-containing polymers (polyethers, phenol formaldehyde and epoxide resins) and modification of common organic polymers for the purpose of improving their physical and mechanical characteristics and thermal and fire resistance [1]. The high functionality of CCPs, which is equal to six even in the case of the lowest homolog hexachlorocyclotriphosphazene (HCP) can be designated as a characteristic feature of the processes of synthesis of HAPs. To exclude gelation upon the interaction of HCP with diphenols, it is necessary to use at least a 15-fold excess of diphenol in accordance with the Flory gelation theory [2]. However, subsequent removal of the excess of diphenol is a multistage laborintensive process. The use of monophenolates of diphenols for the reaction with CCPs makes it possible to decrease their excess but, owing to the presence of an equilibrium amount of a diphenolate in the monophenolate, the HAPs being formed contain oligomers in their composition, the molecules of which are built from two or more partially or fully substituted phosphazene cycles connected by dioxyaromatic radicals [3].
Another characteristic feature of the reaction of diphenols with CCPs is the need for the full substitution of the chlorine atoms in the cycles. This is particularly relevant for HCP, in which full substitution is achieved either under harsher conditions (high temperature and duration) or, again, at a large excess of diphenol [4]. It turned
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