DETROPYLATIONS OF N,N-DIMETHYLTROPYLAMINE AND N-TROPYLACETAMIDE

Rates have been measured for the decomposition of N-tropylacetamide, 1 , in aqueous acid yielding acetamide and tropylium, and for its format ion from tropylium and acetamide in aqueous solution. Reaction of 1 in dilute hydrochloric acid has k(H)+ = 2.49 x 10(-2) dm(3) mol(-1) s(-1 ) at 25 degrees C, and the equilibrium constant for its formation from tropylium tetrafluoroborate and acetamide is 8.4 x 10(-3) In trichlor oacetic and dichloroacetic acid buffers, rates show dependence on buff er concentration. A mechanism for the transformation is proposed, with N-protonated 1 as a transition state or high energy intermediate, Dec omposition of N,N-dimethyltropylamine in aqueous acid solution at pH < 3.5 shows good first-order behaviour, k = 4.58 x 10(-1) s(-1) at 25 d egrees C, with no dependence on acid concentration or on ionic strengt h.