A process for the prepn. of silicon and aluminum N,N-dialkylcarbamates, Si(O2CNR2)4 (R = Et, CHMe2) and Al[O2CN(CHMe2)2]3 resp., comprises treatment of SiCl4 or AlBr3 with secondary amine and CO2 in anhyd. toluene. Hydrolyzing the N,N-dialkylcarbamate was achieved by adding H2O at temp. of from 15 to 40 in an org. solvent, i.e., THF. For example, stirring SiCl4 and HN(CHMe2)2 in PhMe under CO2 at atm. pressure for 12 h, filtration of insol. HN(CHMe2)2.HCl, and evapn. gave Si[O2CN(CHMe2)2]4. Hydrolysis of this in aq. THF gave a solid with Si content 8.8% (81% yield vs. SiCl4), which upon thermogravimetric anal. showed most wt. loss substantially below 100, being complete at 600 in air. The resulting SiO2-contg. product had surface area 700 m2/g.
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