Dimethylphosphinic acid

Dimethylphenylthiourea, 46, 70 Dimethylphosphine, 46, 103 Dimethylphosphinic acid, 46, 103 Dimethylphosphinyl chloride, 46, 103 N,N-Dimethyl-l,3-propanediamine, reaction with ethyl isocyanate, 48, S3... 

A)iV-Dimethylphosphinic acid, see Glvphosate Dimethyl phosphoric acid, see Mevinphos, Oxvdemeton-methvl... 

K.G. Tokhadze et al., First example of the ABC v(OH) absorption structure for both gaseous and crystalline phase Infrared studies of dimethylphosphinic acid. J. Mol. Struct. 404, 55-62 (1997)... 

The mass spectra are also reported for the thiophosphates (192), derivatives of dimethylphosphinic acid (193), and the phosphadiazoles... 

Reaction of white phosphorus with sodium hydroxide or sodium eth-oxide in ethanol generates a dark red solution of an uncharacterized metastable phosphorus compound (9) which possesses nucleophilic properties (10). The red product decomposes slowly even at 0 to hydrogen, phosphine, and sodium hypophosphite (9). But addition of methyl iodide to the freshly prepared solution is reported to give methylphos-phine, methylphosphonic acid, dimethylphosphinic acid, and trimethyl-phosphine oxide (10). Analogous products were reported from reaction with isoamyl iodide, where isoamylphosphonic acid was obtained in 59% yield based on the iodide. 

Compared with formic acid (pX = 3.77 in water, 5.75 in 95% aqueous ethanol), acetic acid (pKa = 4.76 in water), and benzoic acid (pK = 4.17 in water, 7.07 in 95% aqueous ethanol), simple symmetrical dialkylphosphinic acids (1) are moderately strong acids. Thus, for dimethylphosphinic acid (R = Me), pK = 3.08 (in water) and 6.64 in 95% aqueous ethanol, figures which rise to 3.56 for R = Pr and 4.24 for R = Bu for solutions in water for R = Ph, pK = 5.80 in 95% aqueous ethanol. These values can also be compared with those for the dialkyl phosphoric acids for dimethyl hydrogenphosphate, pK = 0.47 in water and 1.88 in 80% aqueous ethanol. Obviously the phosphorus-oxygen bonded acids are rather stronger, with the simple phosphinic acids closer to the carboxylic acids in their acidity. 

Dimethylphosphine, (CH3)2PHA—This occurs as described under methylphosphme, p. 4. It is a colourless liquid, B.pt. 25° C., lighter than w ater and insoluble in it. When dissolved in hydrochloric acid it may be oxidised to dimethylphosphinic acid by means of fuming nitric acid. It is easily oxidised and inflames m air. It readily combines with acids, all the salts being easily soluble. The hydrochloride fields a crystalline platinichloride. The phosphine unites with sulphur and carbon disulphide. 

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