Hexamethyl-disilazane prodn. from trimethyl chlorosilane - and ammonia, using preformed prod. as solvent and low temp. distillative recovery

摘要

Prodn. of hexamethyldisilazane (I) comprises reacting (CH3)3SiCl (II) with gaseous NH3 using pre-formed (I) as solvent. (I) is recovered from the NH4Cl formed by distillation pref. at 75 degrees C under reduced press. Pref. first is not 50, esp. 10-30 wt. % of the total amt. of (II) is reacted, and then the rest of the (II) is introduced with at least a stoichiometric amount of NH3. The distillation is pref. in a column at 30-100 mm Hg and an NH3 excess press. of 150-200 mm is maintained in the reactor. (I) is recovered without fractional distillation; the distillation temp. is so low that NH4Cl sublimation is not a problem; and volume yields are improved.