in diethyl ether byproducts: ClC6H4-p-COOH;

I2; 35percent NH4OH in N,N-dimethyl-formamide; acetone stirring a mixt. of tetraorganotin-compd., iodine and DMF at room temp. for 2 days, addn. of 35percent NH4OH and acetone, stirring overnight, pouring into 1 l of water, stirring for 2 h, pptn.; filtn., drying in air, dissolution in CHCl3, drying over anhyd. CaCl2, filtn., removal of solvent, residue is taked up in MeOH, filtn., concn. yields pure hydroxide, elem. anal.;