GAS-PHASE THERMOLYSIS OF DIALLYL(4-FLUOROPHENYL) AND ALLYL(T-BUTYLAMINO)PHENYL PHOSPHINES

Dially(4-fluorophenyl)phosphine and allyl(t-butyl-amino)phenylphosphin e were pyrolyzed in at stirred-flow reactor at 340-420 degrees C/9-19 Torr, using toluene as carrier gas. The primary reaction products were propene, 1-(4-fluorophenyl)-1-phosphabutadiene, and 1-phenyl-2-t-buty liminophosphine. The phosphorus-containing products gave rise to [4+2] and [2+2] cylcoaddition products, respectively. The consumption of th ese phosphines showed first-order kinetics, with the rate coefficients following the Arrhenius equations: Dially(4-fluorophenyl)phosphine: k (s(-1))=10(9.00+/-0.32) exp (-122+/-4 kJ/mol RT) Allyl(t-bulylamino)ph enylphosphine: k(s(-1))=10(9.04+/-0.25) exp (-113+/-3 kJ/mol RT) The r esults support a six-center transition-state unimolecular elimination reaction mechanism for both reactants. (C) 1997 John Wiley & Sons, Inc .