Silicon halides phosphorus

A148. C. T. Mortimer, Reaction Heats and Bond Strengths. Pergamon, Oxford, 1962. 201 pp. Metal-carbon and metal-halide bonds are considered in Chapter 8, and bond strengths in silicon, phosphorus, and sulfur compounds in Chapter 10. 

Phosphorus has been determined40 in phosphosilico organic compounds (POSi bonds) by dissolving the sample in water, leaving for 4-5 h to hydrolyse (or for 30-40 min at 80°) and titrating the alkylphosphinic acid so produced with 0.1 M-alkali to the thymolphthalein end-point. A method has been described41 for the simultaneous determination of free phosphorus, combined phosphorus and silicon in the reaction products of tetraalkoxysilanes with phosphorus halides. 

Samples containing heavy metal additives, lead alkyls, etc., may interfere with the test method. Elements such as silicon, phosphorus, calcium, potassium, and halides interfere if present in concentrations of more than a few hundred milligrams per kilogram. Consult instrument manufacturers instructions for specific interference data. Materials used in the study to determine precision contained up to 250 mg/kg vanadium, 50 mg/kg nickel, and 15 mg/kg iron with no detectable bias introduced. 

A. Nucleophilic Reactions of the P=0 Group.—Tris(trifluoromethyl)-phosphine oxide (33) reacts with hexamethyldisiloxane to give a phos-phorane, whose n.m.r. spectrum at — 140 °C shows non-equivalent trifluoromethyl groups. Although this unusual reaction clearly involves nucleophilic attack of the phosphoryl oxygen on silicon at some stage of the reaction, a full study of the mechanism has not been published. Tertiary phosphine oxides can be converted cleanly into dichlorophos-phoranes (34) by treatment with two moles of phosphorus pentachloride. Alkylation of the sodium salt of tetraphenylmethylenediphosphine dioxide (35) with alkyl halides, in dimethyl sulphoxide, has been reported to... 

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