Kinetic studies with a 20-fold or greater excess of nitric acid over mesitylene in carbon tetrachloride show that nitration to the mono-substituted product is of the sixth order in nitric acid and of zeroth order in mesitylene. The nitration reaction has a negative temperature coefficient and the order in both reactants remains unchanged down to –23°, the lowest temperature studied.

I.r. examination of solutions of nitric acid in the solvent at 25°, 0°, and –8° failed to produce evidence for polymeric forms at the concentrations used.

The addition of trifluoroacetic acid increases the rate of nitration and kinetic analysis shows that the order in trifluoroacetic acid is about unity while that in nitric acid decreases to approximately four.

A transition complex highly solvated by nitric acid is indicated by these results.