The correct order for the rate of thermal decarboxylation of the following compounds is

Concept:

→ The rate of thermal decarboxylation of organic carboxylic acids depends on several factors, including the stability of the carboxylate ion, the strength of the carbon-oxygen bond, and the electronic properties of the substituents on the aromatic ring.

Explanation:

→ Benzoic acid does not have an electron-withdrawing group attached to the aromatic ring, and the carbon-oxygen bond in the carboxylate group is relatively strong, making it more difficult to break. Therefore, the decarboxylation of A is expected to be the slowest among the three compounds.

→ Picolinic acid also has an electron-withdrawing group (-COOH) attached to the aromatic ring, but it is less stable than the carboxylate ion in C because the nitrogen atom in the pyridine ring can donate electron density to the carboxylate group.

However, the carbon-oxygen bond in the carboxylate group is still relatively weak, making it easier to break than in A. Therefore, the decarboxylation of B is expected to be faster than A but slower than C.

→ (2-(pyridin-2-yl)acetic acid) has an electron-withdrawing group (-COOH) attached to the aromatic ring, which makes the carboxylate ion more stable.

Additionally, the carbon-oxygen bond in the carboxylate group is relatively weak, making it easier to break. Therefore, the decarboxylation of C is expected to be faster than the other two compounds

Conclusion:
In summary, the correct order for the rate of thermal decarboxylation of the given compounds is C > B > A, with C being the fastest and A being the slowest.