carbamatoorganosilanes are produced in exceptionally high yield with a high degree of purity , by reacting an aminoorganosilane with a dialkylcarbonate in the presence of a basic catalyst , wherein a first reaction period proceeds at a temperature in the range of 35 - 65 ° c ., followed by a later reaction period at a temperature at least 10 ° c . higher . a low level of catalyst allows its removal by simple exit filtration , without a separate filtration step .