Experimental evidence to support viscosity dependence of rates of Diels-Alder reactions in solvent media

This note is aimed at ascertaining whether rates of Diels-Alder reactions depend on the viscosity of solvent media in which the reactions are performed. On the basis of the data collected from the literature and in this laboratory, it is seen in general that the rates increase in the solvents with their viscosities ranging up to similar to1.2 cP. In solvents possessing viscosities above 1.2 cP, a drop in the reaction rates is observed in all cases. The effect of temperature on the above phenomena is also examined.