Alkali Metal Salts of Alkylphosphonic Acids IIF-IIH

General procedure To a solution of [-(substituted phenoxyacetoxy)alkylphos-phonic acid M9 (5.5 mmol) in methanol (20 mL) was added lithium hydroxide monohydrate (5 mmol), the mixture was stirred at room temperature 1-2 h and monitored by TLC analysis. The solution was evaporated at reduced pressure. The residual solid was recrystallized from acetonitrile to afford the pure product as a white solid, i.e., monolithium salt of [-(substituted phenoxyacetoxy)alkylphos-phonic acid IIP. 

Monosodium salts of [-(substituted phenoxyacetoxy)alkylphosphonic acids IIG and monopotassium salts of [-(substituted phenoxyacetoxy)alkylphosphonic acids IIH could be synthesized using sodium hydroxide and potassium carbonate as bases, respectively, with the similar methods mentioned above [23, 24]. 

The structures, physicochemical data, and yields of IIF-IIH are listed in Tables 9.19, 9.20 and 9.21, respectively. 

General procedure An appropriate dimethyl 1-(substituted phenoxyacetoxy) alkylphosphonate (0.0025 mol) was added to 2-methylpropan-2-amine (5 mL). The resultant mixture was stirred at room temperamre for 20-36 h or refluxed at 46 °C for 6-8 h. Then the excess 2-methylpropan-2-amine was removed under reduced pressure and washed with acetone to afford crude products as white solids or colorless oil. Further, recrystallization from acetonitrile or flash column chromatography on silica gel using a mixture of petroleum ether/ethanol (v/v 3/1) afforded corresponding lU as a white solid or colorless oil. A series of IIJ could be obtained by this procedure [26, 27]. 

---

Scheme 9.12 Synthesis of alkali metal salts of alkylphosphonic acids IIF-IIH...

---