Gas-phase kinetics of elimination reactions of pentane-2,4-dione derivatives. Part ii [1]. Thermolysis of derivatives and analogues of 3-phenylhydrazonopentane-2,4-dione

✍ Scribed by Nouria A. Al-Awadi; Mohamed H. Elnagdi; Hanan A. Al-Awadhi; Osman M. E. El-Dusouqui

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 135 KB
• Volume: 30
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/(sici)1097-4601(1998)30:7<457::aid-kin1>3.0.co;2-r

✦ Synopsis

Six analogues and derivatives (1-6) of 3-phenylhydrazonopentane-2,4-dione (7) were subjected to gas-phase thermolysis. The Arrhenius log A and Ea (kJ ) of the Ϫ1 Ϫ1

(s ) mol analogues (1-5) are, respectively: 10.42 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 1-cyano-1-(p-methoxyphenylhydrazono)propanone (3), 11.76 and 137.8 for 1-cyano-3phenyl-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 and 143.3 kJ The rates of reaction at are compared with those of Ϫ1 Ϫ1 s mol . 600 K the title diketone (7) and of pentane-2,4-dione (8) and rationalized in terms of a plausible elimination pathway involving a semiconcerted six-membered transition state.