GAS-PHASE KINETICS OF ELIMINATION-REACTIONS OF PENTANE-2,4-DIONE DERIVATIVES - PART II[1] - THERMOLYSIS OF DERIVATIVES AND ANALOGS OF 3-PHENYLHYDRAZONOPENTANE-2,4-DIONE
Na. Alawadi et al., GAS-PHASE KINETICS OF ELIMINATION-REACTIONS OF PENTANE-2,4-DIONE DERIVATIVES - PART II[1] - THERMOLYSIS OF DERIVATIVES AND ANALOGS OF 3-PHENYLHYDRAZONOPENTANE-2,4-DIONE, International journal of chemical kinetics, 30(7), 1998, pp. 457-462
Six analogues and derivatives (1-6) of 3-phenylhydrazonopentane-2.4-di
one (7) were subjected to gas-phase thermolysis. The Arrhenius log A (
s(-1)) and Ea (kJ mol(-1)) of the analogues (1-5) are, respectively: 1
0.42 and 140.8 for 1-cyano-1-phenyl-hydrazonopropanone (1), 11.19 and
135.4 for 1-cyano-1-(p-nitrophenylhydrazono)-propanone (2), 10.68 and
144.9 for l-cyano-1-(p-methoxyphenylhydrazono)propanone (3), 11.76 and
137.8 for 1-cyano-3-phenyl-1-phenylhydrazonopropanone (4), and 11.29
and 145.9 for 1-cyano-1-phenylhydrazonobutanone (5). The corresponding
values for ethyl 3-oxo-2-phenylhydrazonobutanoate (6) are 11.90 s(-1)
and 141.3 kJ mol(-1). The rates of reaction at 600 K are compared wit
h those of the title diketone (7) and of pentane-2,4-dione (8) and rat
ionalized in terms of a plausible elimination pathway involving a semi
concerted six-membered transition state. (C) 1998 John Wiley & Sons, I
nc.