Methyl Methylphosphinate Mil

In order to avoid the reaction of dichloro(methyl)phosphine MIO with the water in the air, we carried out the reaction under N2 atmosphere. Moreover, MIO reacts exothermically with alcohol, so MIO must be dropped slowly into the solution of alcohol. Be cautious MIO is very toxic and corrosive. 

General procediure O-Methyl methylphosphinate Mil (0.02 mol) and an appropriate aldehyde (0.024 mol) were stirred at room temperature for 10 min. To this mixture cooled in an ice-water bath triethylamine (0.01 mol) was slowly added 

The structures, physicochemical data, and yields of M12 are listed in Table 9.23. 

General procedure A solution of an appropriate substituted phenoxyacetic chloride M5 (0.022 mol) in trichloromethane (10 mL) was added to a stirred mixture of corresponding 0-methyl (l-hydroxyalkyl)methylphosphinate (0.02 mol) and triethylamine (0.022 mol) in trichloromethane (25 mL) at 2-4 °C. The resultant mixture was stirred at ambient temperature for 3-5 h, and then at 40 °C for 1-2 h. The mixture was washed with 0.1 M hydrochloric acid, saturated sodium hydrogen carbonate solution and brine, dried and evaporated. The residue was purified by column chromatography on silica gel and eluted with petroleum ether/acetone (6/1, v/v) to give the corresponding title compound as a yellow liquid or white solid. IIIA-IIIG could be obtained by this procedure in 58-89 % yields [7, 28-30]. 

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O-methyl [1-(substituted phenoxyacetoxy)alkyl]methylphosphinates IIIA-IIIG were easily synthesized by the reaction of O-methyl (l-hydroxyalkyl)meth-ylphosphinates with substituted phenoxyacetyl chlorides. The synthetic route of IIIA-IIIG is shown in Scheme 4.6. O-Methyl methylphosphinate Mil was prepared in a two-step sequence starting from phosphorus trichloride, methyl iodide, and aluminium trichloride. O-Methyl (l-hydroxyalkyl)methylphosphinates M12 were prepared by the addition of Mil and several kinds of aldehydes using tri-ethylamine as the catalyst. Substituted phenoxyacetic acids M4 and substituted phenoxyacetyl chlorides MS were prepared using the method which has been introduced in Chap. 2. IIIA-IIIG were obtained by the condensation of M12 with different substituted phenoxyacetyl chlorides MS. 

Methyl (1-hydroxyalkyl)methylphosphinates M12 could be prepared by the nucleophilic addition of 0-methyl methylphosphinate Mil with several kinds of aldehydes (Scheme 4.9). 

Methyl methylphosphinate Mil could be prepared from the corresponding dichloro(methyl)phosphine MIO by reacting with methanol under anhydrous condition. MIO was very sensitive to water and easily oxidized, therefore, this reaction was protected from the atmosphere under anhydrous condition. 

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