Sodium Acetate → 1-(Methoxydimethylsilyl)methanol 1-acetate

Participants

Reaction Conditions

Reaction Steps

A mixture of 61.1 kg of Hydroseal G 400 H and 50 kg (609.4 mol) of sodium acetate was dried by heating at 150° C./2 mbar for 1.5 h. After cooling down to below 120° C., the vacuum was broken with nitrogen, 3.76 kg (11.1 mol) of tetrabutylphosphonium bromide were added and the temperature was adjusted to 120° C. Then, under agitation, 73.2 kg (528 mol) of (chloromethyl)methoxydimethylsilane were metered in over 2.5 h. The mixture was subsequently stirred at the same temperature for a further 4 h. The product was then distilled out through a column at 20 mbar (head), 46-55° C. (head) and 73-145° C. (pot), while a further 36.7 kg of Hydroseal G 400 H were metered in during the distillation to ensure stirrability. The product (acetoxymethyl)methoxydimethylsilane (80.4 kg, 495.5 mol, 94% of theory; purity 99.4% (GC area %)) was obtained as a colorless liquid. The solvent, sodium chloride, excess sodium acetate and the phase transfer catalyst in the form of the chloride, bromide and acetate salt of tetrabutylphosphonium remained in the residue. The residue was worked up by filtration using an inverting filter centrifuge to give 93 kg of filtrate (Hydroseal) and 41 kg of solid material (NaCl, NaOAc, Bu4PBr; anions and cations exchanged in part). The filter cake was washed with xylene (isomer mixture, 2×20 L) and filtered once more by the same method. The filtrate contained the xylene-soluble phase transfer catalyst in the form of the chloride, bromide and acetate salt of tetrabutylphosphonium, the filter cake contained above all the sodium salts of the chloride, in part also of the acetate and of the bromide. The solvent thus recovered and the recovered catalyst can be reused, in which case the xylene can optionally be distilled off or co-used.

Provenance & Evidence