Question

Rate of decarboxylation of carboxylic acid is highest in

Answer 1

Answer:

The rate of decarboxylation of picolinic acid 1 is greater than isonicotinic acid 2. Zwitterion 4 has been proposed as the intermediate. Note that the electron pair is in the sigma framework. An electrostatic stabilization is proposed that requires that the charges be proximate. A competitive reaction in base (no zwitterion) demonstrated that 1 decarboxylated >100 times faster than 2 which was recovered after 20 days. Since nicotinic acid 3 is inexpensive and wasn't studied by the researchers, I suspect that it is stable also.