Synthesis and study of some new tricyclocphosphazene containing organo- sulfur and -selenium compounds as fire retardants

Abstract A new series of hexaarylthiocyclophosphazenes and hexaarylselenocyclophosphazenes ( i.e . N 3 P 3 (E-C 6 H 4 -R) 6 , where E= S, R= H( 1 ); E= S,R= OCH 3 ( 2 ); E= S, R= CH 3 ( 3 ); E= Se, R= H( 4 ); E= Se, R= OCH 3 ( 5 ) and E= Se, R= CH 3 ( 6 )) were prepared in good yields by reaction of the corresponding arylthiolate and arylselenolate anions with hexachlorocyclophosphazene under argon atmosphere. The thermal properties of compounds 1 - 6 were studied by TGA. All prepared compounds showed a good thermal stability. Char yields were between 37-68% at750 o C for compounds 1 - 6 . All compounds were characterized by elemental analysis, FT-IR, 1 H, 13 Cand 31 PNMR and thermal gravimetric techniques. Keywords : Hexachlorocyclophosphazene, Arylthiolate,Arylselenolate, Fire retardants Introduction Phosphazenes, compounds having –P=N– group in their molecules, constitute one of the important class of compounds in thechemistry of phosphorus and nitrogen [1]. The highly reactive P-Cl bonds in hexachlorocyclophosphazenecan are easily replaced by reaction with alcohols, amines and organometallic reagents. The halogen replacement reactions are the most important ways to increase the diversity of cyclophosphazenes [1-4].Chlorocyclophosphazenes have been widely studied because they have excellent flame retardancy and environmental safety. It is worth noting that hexaaryloxyphosphazene and perfluoroaryloxyphosphazene exhibit excellent thermal and chemical stability which can be used to fireproof materials, high temperature lubricants, vacuum pump oils and hard disk surface lubricants [5-7]. Research about the functionality of polyphosphazene is very active andincludes flame retardant, special rubber, biomedicine, liquid crystal, photoelectricity materials, and many other uses [8-11]. The aim of this work is to prepare a new series of cyclotriphosphazenes containing organosulfur and organoselenium moieties in hope to use them as fire retardants. To the best of our knowledge, no such compounds have been prepared in the literature.