Preparation of di-tert-butyl phosphate potassium salt_industrial additives

Background and overview^[1]

Di-tert-butyl phosphate potassium salt is an ester derivative and can be used as a pharmaceutical synthesis intermediate.

Preparation^[1]

Method 1: Preparation of potassium di-tert-butyl phosphate: Potassium di-tert-butyl phosphate (261 kg, 1.00 molar equivalent), tetra-n-butyl ammonium hydrogen sulfate (18.5 kg, 0.05 molar equivalent) and sodium bicarbonate (kg, 4.50 molar equivalents) To a mixture of water (1150 kg) was added isopropyl acetate (1275 kg). The mixture was warmed to approximately 35°C and chloromethyl chlorosulfate (313 kg, 1.80 molar equivalents) was then added over approximately 4 hours. The mixture was stirred for a further approximately 45 minutes, cooled to approximately 25°C and the layers were then separated. The organic phase was cooled to approximately 10° C. and washed twice with a 2% w/v aqueous potassium bicarbonate diluent solution (2 x 800 kg) and subsequently with a mixture of 2% w/v potassium bicarbonate and 20 % w/v aqueous potassium bicarbonate solution (640 kg) for washing. The resulting organic solution was then distilled to half volume at <100 mbar, keeping the temperature below 45°C. The resulting mixture was filtered and the filter washed with isopropyl acetate (115 kg) to obtain the title compound di-tert-butyl phosphate potassium salt as a solution with a typical solution strength of about 25% w/v and a yield of about 90% .

Method 2: Combine di-tert-butyl phosphite (40.36mmol) and potassium bicarbonate (24.22mmol) in 35ml of water. The solution was stirred in an ice bath and potassium permanganate (28.25 mmole) was added in three equal portions over one hour. The reaction was then allowed to continue at room temperature for another half hour.

Decolorizing carbon (600 mg) was then incorporated as the reaction was heated to 60 °C for 15 min. The reaction was then vacuum filtered to remove solid magnesium dioxide. The solid was washed several times with water. The filtrate was then combined with one gram of decolorizing carbon and heated at 60°C for a further twenty minutes. The solution was filtered again to obtain a colorless solution, which was then evaporated in vacuo to obtain crude di-tert-butyl phosphate potassium salt.