GB709634A - Improvements in organic silicon compounds and their preparation - Google Patents

Abstract

The invention comprises organic nitrogen base silicates of the general formula: <FORM:0709634/IV (b)/1> wherein R1 and R2 are independent substituent groups selected from hydrogen and alkyl, hydroxyalkyl, aminoalkyl, amidino, cycloalkyl, aralkyl and aryl groups, R3 being an independent substituent group selected from hydrogen and the aforesaid groups and R4 being an independent substituent group selected from the aforesaid groups other than alkyl or R3 and R4 being both -CH2- groups forming part of a heterocyclic ring structure which includes the nitrogen atom, X is a number varying from 0.5 to 4 and Y is a number varying from 0 to 15, and a process for preparing organic nitrogen base silicates by dissolving a silica which is soluble in aqueous alkalis in a solution containing at least 0.1 per cent of an organic nitrogen base, which base has a dissociation constant of at least 10-5 and recovering the resultant organic nitrogen base silicate. Organic nitrogen base silicates may also be prepared by contacting a sodium silicate solution with a synthetic resin base exchange compound which has previously been contacted with an organic nitrogen base, in the resulting base exchange; the sodium ion in solution is replaced by the organic ammonium ion to form a solution of the corresponding organic nitrogen base silicate. The preferred organic nitrogen base silicates are the tetra-b -ethanol ammonium silicates, phenyltrimethylammonium silicates and guanidine silicates which have respectively the formul : <FORM:0709634/IV (b)/2> <FORM:0709634/IV (b)/3> and <FORM:0709634/IV (b)/4> where X and Y have the significance indicated above. Any organic nitrogen base of the following types may be used to form the organic nitrogen base silicates: primary, secondary and tertiary alkyl amines, alkyl quaternary ammonium bases in which at least one of the alkyl groups is substituted by a hydroxyl or amino group, primary, secondary and tertiary aryl amines, aryl quaternary ammonium bases, heterocyclic amines; amidino amines, cycloalkyl amines and aralkyl amines. The organic nitrogen base silicates may be prepared in water or in an organic solvent, e.g. methyl, ethyl or butyl alcohol or acetone. The silica used in the process may be hydrated, or may be in the form of a silica sol or a silica gel which may be finely divided. Dehydrated amorphous silicas such as diatomaceous earths and dried gels, vitreous silica, and crystalline forms of silica such as quartz, cristobalite or tridymite may also be used. If saturated solutions of the nitrogen bases are used for reaction with the silica, the desired base silicates may be recovered by cooling, or by concentrating the resulting solution before cooling. Precipitation of the base silicates may also be brought about by the addition of a small amount of acid or an organic water miscible solvent, e.g. alcohol or acetone. In the examples, organic nitrogen base silicates are formed by the reaction of a silica with each of the following organic nitrogen bases: phenyltrimethylammonium hydroxide and butoxide, tetra-b -ethanolammonium, benzyltrimethylammonium and dibenzyldimethylammonium hydroxides, guanidine, morpholine, cyclo- and dicyclo-hexylamine, ethylene and diethylene diamine, triethylene tetramine, tetraethylene pentamine and mono-, di- and triethanolamine.