Journal of the Serbian Chemical Society 2000 Volume 65, Issue 12, Pages: 839-846
https://doi.org/10.2298/JSC0012839N
Full text ( 86 KB)
Reactivity of cyclohex-1-enylcarboxylic and 2-methylcyclohex-1-enylcarboxylic acids with diazodiphenylmethane in aprotic solvents
Nikolić Jasmina B. (Faculty of Technology and Metallurgy, Department of Organic Chemistry, Belgrade)
Ušćumlić Gordana S. (Faculty of Technology and Metallurgy, Department of Organic Chemistry, Belgrade)
Krstić Vera V. (Faculty of Technology and Metallurgy, Department of Organic Chemistry, Belgrade)
Rate constants for the reaction of diazodiphenylmethane with
cyclohex-1-enylcarboxylic acid and 2-methylcyclohex-1-enylcarboxylic acid
were determined in nine aprotic solvents, as well as in seven protic
solvents, at 30°C using the appropriate UV-spectroscopic method. In protic
solvents the unsubsituted acid displayed higher reaction rates than the
methyl-substituted one. The results in aprotic solvents showed quite the
opposite, and the reaction rates were considerably lower. In order to
explain the obtained results through solvent effects, reaction rate
constants (k) of the examined acids were correlated using the total
solvatochromic equation of the form: log k=logk0+sπ*+aα+bβ, where π* is the
measure of the solvent polarity, a represents the scale of the solvent
hydrogen bond donor acidities (HBD) and b represents the scale of the
solvent hydrogen bond acceptor basicities (HBA). The correlation of the
kinetic data were carried out by means of multiple linear regression
analysis and the opposite effects of aprotic solvents, as well as the
difference in the influence of protic and aprotic solvents on the reaction
of the two examined acids with DDM were discussed. The results presented in
this paper for cyclohex-1-enylcarboxylic and
2-methylcyclohex-1-enylcarboxylic acids were compared with the kinetic data
for benzoic acid obtained in the same chemical reaction, under the same
experimental conditions.
Keywords: cyclohex-1-enylcarboxylic acid, 2-methylcyclohex-1-enylcarboxylic acid, diazodiphenyulmethane, kinetic measurements, protic and aprotic solvents