Sol-gel process, a most usefully and effectively process, has a lot of advantage for preparation of a variety of advanced materials in various structures and sizes, via polymerization of metal and semiconductor hydroxides or via hydrolysis and condensation of their alkoxides, since in nucleophilic substitution (SN) reaction and nucleophilic addition (AN) reaction, the substituent with thelargest partial negative charge,is the nucleophile, and in SN reactions the substituent with the largest positive charge, + , is theleaving group or nucleofugal.
