Abstract
The rate of acetic acid catalyzed elimination reaction of 1- (m-nitrophenyl) -2- (2-quinolyl) ethyl acetate [1m] to give trans-2- (m-nitrostyryl) quinoline [2m] is correlated with the electron donability of solvents, ΔνD, rather than with the dilectric constant of solvents, D, because of hydrogen bonding complex between acetic acid and solvent.
Addition of solvents having lone pair of oxygen and/or nitrogen atom (nitrile, carbonyl, ether, alcohol, amide, sulphoxide or amine) caused a decrease in rate for the dichloroacetic acid catalyzed elimination of [1m] in benzene at 40°C. From the drop in rate, the equilibrium constant K of the formation of hydrogen bonding complex between dichloroacetic acid and lone pair of oxygen and/or nitrogen atom in benzene was estimated. A good linear free energy relation was observed between the equilibrium constant K and the electron donability of solvents, SX, which is very important. From the above linear correlation, it is found that the basicity of oxygen atom of alcohols is as strong as that of dioxane (or ethers). A molecule of a strong amine (e.g., triethyl amine) interacted with more than one molecule of dichloroacetic acid in benzene or in toluene at 40°C, which suggests a 1 : 2 complex.
