Abstract: Silanes of the general formula ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 in the molecule are the same or different and represent aliphatic hydrocarbon groups,R.sup.4 is a divalent hydrocarbon group with 3 to 14 carbon atoms,R.sup.5 is a group having the formula --O(CH.sub.2).sub.b -- or a polyether group having the formula --(OC.sub.n H.sub.2n).sub.c --, whereinb has a value of 1 to 6,n has an average value of 2 to 2.5c has a value of 1 to 10, anda is 0 or 1, which fulfill the condition that they lower the surface tension of a 1% by weight aqueous solution to a value of .ltoreq.25 mN/m at 25.degree. C., measured with a Du Nooy tensiometer. The silanes are biologically degradable, resistant to hydrolysis and have pronounced surface active properties.