Preparation and some reactions of 3,9‐dichloro‐2,4,8,10‐tetraoxa‐3,9‐diphosphaspiro[5.5] undecane‐3,9‐disulfide

Abstract

3, 9‐Dichloro‐2, 4, 8, 10‐tetraoxa‐3, 9‐diphosphaspiro[5. 5]undecane‐3,9‐disulfide (I), has been synthesized by treating a dimethylacetamide solution of 2, 4, 8, 10‐tetraoxa‐3,9‐diphosphaspiro[5. 5]undecane‐3, 9‐disulfide (III) with carbon tetrachloride. A number of other known methods for converting dialkyl phosphorothioites to thiophosphorochloridates were also applied to III, but all failed to produce I. Chlorination of either I or III gave an acyclic product, 4, 4‐bis(chloromethyl)‐1, 1, 7, 7‐tetrachloro‐2, 6‐dioxa‐1, 7‐di‐phosphaheptane‐1, 7‐dioxide (IV), in nearly quantitative yield. The same compound was also obtained by the previously known method of chlorinating 3, 9‐dichloro‐2,4,8,10‐tetraoxa‐3, 9‐diphosphaspiro[5.5]undecane (II). The treatment of pentaerythritol with phosphorus pentachloride gave IV in minor amount along with a 25% yield of 4,4‐bis‐(chloromethyl)‐1‐chloro‐2, 6‐dioxa‐1‐phosphacyclohexane‐1‐oxide (VII). The hydrolysis of I in heated aqueous sodium carbonate gave, after acidification, 3,9‐dihydroxy‐2,4,8,10‐tetraoxa‐3, 9‐diphosphaspiro[5. 5]undecane‐3, 9‐disulfide (VIII). A number of derivatives were prepared by reaction of I with phenoxides and amines. The corresponding thio‐phosphorofluoridate XI was prepared by treatment of I with potassium fluoride in dioxane.

Structural Basis for Intumescence—Part II: Synthesis and Characterization of Intumescent Polymers Containing Spirophosphorus Moiety in the Backbone

“…The spiro compound (Scheme 1) was synthesized [17,[19][20][21][22][23] as detailed below. Pentaerythritol (2 mol, 272.3 g) and phosphorus oxychloride (4.3 mol, 660 g) were placed in a 3 L round bottom flask under reflux, protected from atmospheric air.…”