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Tetraphenyldiphosphine, from the initial preparation, was added to 25 ml of toluene containing sufficient sulfur for complete reaction.The mixture was heated to with stirring, under an inert atmosphere for 6 hr. The hot toluene solution was then filtered and evaporated. This reaction resulted in essentially 100% conversion based on the initial quantity of tetraphenyldiphosphine.The white crystals obtained from this reaction were recrystallized from chloroform-methanol and vacuum dried. The infrared spec-trum83 was identical with that reported for tetraphenyldiphosphine disulfide. The mass spectrum was consistent, exhibiting a peak at 434, attributable to the parent ion [(C6H5)2P(S)P(S)(C6H5)2, mol wt 434], Diphenylphosphinic Anhydride, (CGH5)2P(0)0P(0)(CeH:)2. Tetraphenyldiphosphine, 0.22 g (0.6 mmol) from the initial preparation, was added to 15 ml of toluene containing a small amount of diphenylchlorophosphine (0.05 g). Dry oxygen in excess was introduced into the solution at room temperature, and the reaction continued until oxygen take-up ceased. The toluene solution was then filtered through decolorizing charcoal, concentrated by evaporation under vacuum, and allowed to stand at room temperature.The crystals which formed on standing were washed repeatedly with dry, cold heptane or ether and dried under vacuum at room temperature. The material was then recrystallized several times from toluene. In this preparation as in those above, the presence of moisture led to the formation of diphenylphosphinic acid, which was removed by washing with 1 % aqueous potassium hydroxide as described previously.Diphenylphosphinic anhydride melted at 144-145°, lit.10 142-143°. Its infrared spectrum contained a band at 1236 cm-1 assigned to the P=Ozl stretching frequency and a band at 960 cm-1 assigned to the P-O-P22 linkage.Mass spectral data showed a parent ion peak corresponding to a mass of 418 [(C6H6)2P(0)0P(0)(CeH6)2; mol wt 418], and a fragmentation pattern consistent with that of diphenylphosphinic anhydride.

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Recent investigations in this laboratory concerning structure-physical property relationships of nitroaliphatic and fluoronitroaliphatic compounds generated a need for the bistrinitroethyl and bisfluorodinitroethyl esters of a homologous series of dibasic acids. Furthermore, we desired to obtain certain of these esters in rather large quantities for testing of explosive properties.A study of the literature available to us revealed several approaches which have been used to effect esterifications with 2,2,2-trinitroethanol (1) and 2fluoro-2,2-dimtroethanol (2). The low basicity of these alcohols requires the use of a strong condensing ageflt or a reactive carboxylic acid derivative to effect esterification. The esterification methods generally used are: (1) transesterification of the methyl ester of the desired acid and the alcohol in fuming sulfuric acid,1.(2) the acid and alcohol in fuming sulfuric acid solvent,1 2 (3) the acid and alcohol in polyphosphoric acid solvent,8 (4) the aluminum chloride catalyzed reaction of the acid chloride and the alcohol in an inert solvent,4 5and (5) the neat acid chloride and the alcohol.6 The first

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