213
The mixture of liquids contains these three compounds (Fig. 10.7):
Pure fractions of each product can be obtained by careful distillation of the liquid
chlorosilane mixture. Among them, dimethylchlorosilane is the main product (ca.
70–90%) depending on the reaction conditions.
10.3.2 Nucleophilic Substitution of Chlorosilanes
Dialkyldichlorosilane is hydrolyzed to a molecule with two hydroxyl groups due to
the nucleophilic attack by water:
Cl
R
Si
R
Cl H O HO
R
Si
R
OH HCl
− − +
→
− −
+
2
2
2
(10.5)
The product obtained is disilanol. The suffix-ol in silanol is to show that the
molecule contains at least one hydroxyl group bonded to the silicon atom and the
simplest example of dimethyldisilanol (Fig.  10.8) (Shaffer 1957; Andrianov
et al. 1964).
This nomenclature is similar to that of alcohols, the simplest alcohol with two
hydroxyl groups is ethane-1,2-diol or ethylene glycol (Fig. 10.8):
The hydroxyl groups of silanols react spontaneously with each other to give a
siloxane:
10.6
Fig. 10.6 Structure of
diethyldiethoxysilane
Fig. 10.7 Structures of
different
methylchlorosilanes
10 Reactive Silicones as Multifacetic Materials