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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
Author(s) -
AlAwadi Nouria A.,
Elnagdi Mohamed H.,
AlAwadhi Hanan A.,
ElDusouqui Osman M. E.
Publication year - 1998
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1998)30:7<457::aid-kin1>3.0.co;2-r
Subject(s) - chemistry , pentane , thermal decomposition , arrhenius equation , kinetics , medicinal chemistry , gas phase , diketone , decomposition , stereochemistry , organic chemistry , activation energy , physics , quantum mechanics
Six analogues and derivatives (1–6) of 3‐phenylhydrazonopentane‐2,4‐dione (7) were subjected to gas‐phase thermolysis. The Arrhenius log A (s −1 ) and E a (kJ mol −1 ) of the 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‐( $\underline{\rm{p}}$ ‐nitrophenylhydrazono)‐propanone (2) , 10.68 and 144.9 for 1‐cyano‐1‐( $\underline{\rm{p}}$ ‐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 143.3 kJ mol −1 . The rates of reaction at 600 K are compared with those of 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. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 457–462, 1998