iodine in benzene byproducts: dibutyliodophosphine, CH2CH2; under protective gas addn. of (n-Bu)3Sn(CH2)2P(n-Bu)2 in benzene at 0-5°C in drops with stirring to I2 in benzene; evapn., vac. distn.;

bromine in not given byproducts: CH2CH2, P(n-Bu)2Br; in nonpolar solvents;