No abstract

A novel and convenient method has been developed for the preparation of tris(hydroxymethyl) phosphine oxide (THPO) from tetrakis(hydroxymethy1) phosphonium chloride (THPC). The method consists essentially of oxidative deformylation of THPC with lead carbonate in n-propyl alcohol. The reaction is facilitated by azeotropic distillation of di-npropylformal and n-propyl alcohol.The reaction of THPC with lead carbonate as well as with lead oxide has been studied in detail in aqueous solution and in n-propyl alcohol. The reaction proceeds via the initial formation of tetrakis(hydroxymethy1) phosphonium hydroxide (THPOH) followed by deformylation to tris(hydroxymethy1) phosphine (THP). T H P then undergoes oxidation by air as well as by lead carbonate or oxide to THPO. If air is bubbled through the mixture a t elevated temperatures, atmospheric oxidation predominates with little or no oxidation by the lead compound.Depending upon the reaction conditions, a phosphonium hydroxide, a phosphine, or a phosphine oxide are products of the reaction of tetrakis(hydoxymethy1) phosphonium chloride with lead carbonate or oxide.For several years this laboratory has been engaged in the synthesis of phosphoruscontaining polymers in order to provide flame resistant and thermally stable end products. One of the starting materials for the introduction of phosphorus into the polymeric molecules was tetrakis(hydroxymethy1) phosphonium chloride, referred to as THPC.Although several polymers derived from T H P C have been reported (5, 6), we have found that in many instances phosphorus was not incorporated into the polymeric chains which are primarily formed by polycondensation reaetions of formaldehyde resulting from the degradation of THPC. These polymers, insufficiently characterized, possessed poor hydrolytic stability and fracture strength. By use of tris(hydroxymethy1) phosphine oxide (THPO) and its monobenzoylated derivative we were able to obtain polymers containing phosphorus in the polymeric chain which possessed markedly improved hydrolytic stability, fracture strength, flame resistance, etc. (3).A key problem which arose in the initial stages of work with THPO-derived polymers was the conversion of commercially available T H P C t o THPO. Methods previously described for this conversion required a number of tedious operations to isolate the product. In attempting to devise a better method for the synthesis of THPO from T H P C some interesting chemistry was uncovered involving not only the preparation of THPO but also the formation of tetrakis(hydroxymethy1) phosphonium hydroxide (THPOH) and tris(hydroxymethy1) phosphine (THP). This paper is concerned with a new synthesis of THPO from T H P C and with the properties and reactions of some of the intermediates.T H P C was reported (1,2) to react with aqueous sodium hydroxide a t room temperature or upon gentle heating below SO0 C to yield THPO with the evolution of one molecule of I hydrogen. On boiling, a second molecule of hydrogen is given off with the formation of the...

from light. The solution was cooled to 20°. Upon adjusting to pH 3 with concentrated hydrochloric acid, pteroic acid separated as a bright yellow solid. This was centrifuged at 3000 rpm and washed thoroughly by suspension and centrifugation with three to five 10-ml portions of water. The moist solid was freezedried to give 263 mg of pteroic acid (84%). The nmr spectrum in deuterated trifluoroacetic acid showed a singlet at 4.90 (2 H, bridge CH2), doublet at 7.49 (2 H, / = 9 cps, benzene CH), doublet at 7.85 (2 H, J = 9 cps, benzene CH), and a singlet at 8.54 (1 H, pteridine CH).

The character of the residues from pyrolytic decomposition of organo‐phosphorus polymers has suggested the use of such materials in ablative materials required for heat shields in reentry vehicles, rocket nozzles, etc. Phosphorus‐containing phenolic resol and novolak resins were prepared by condensing di(p‐hydroxyphenyl)‐phenyl‐(phosphine oxide) with aldehydes. The mechanical properties of the basic phosphorus‐phenolics were improved by internal plasticization through chemical reaction of the resin in the early stages of polycondensation with acrylonitrile‐butadiene copolymers (NBR) and with silences and slicone resins. To improve the compatibility of the phosphorus phenolics with NBR copolymers, the phosphorus‐containing phenolics were initially etherified by “butanolization” in order to decrease their polarity. The preparation of coatings and molded discs from some modified and unmodified phosphorus‐containing phenolic‐resin formulations is described. Preliminary observations relating to the properties of the trial products are reported.

Tris‐hydroxymethylphosphine oxide (THPO) derived from commercially available tetrakishydroxy‐methylphosphonium chloride (THPC), was studied for its flame retardant properties in reactions with carboxylic acids, anhydrides, diisocyanates, urea, phenol, acyl and aroyl halides. Then the monobenzylated derivative of THPO referred to as BHPO was studied, which is more stable and more reactive with difunctional molecules.