Question

Why is trans-cinnamic acid soluble in acetone but insoluble in NaOH?

Answer 1

Ans. Trans-cinnamic acid is an organic compound. It has a non-polar benzene ring, to which the hydrophobic alkene (C3) with a terminal –COOH group is linked.

Since the molecule has non-polar region, it does not solvate in aqueous solutions under normal conditions. Acetone, being an organic solvent, can solvate trans-cinnamic acid.

# The –COOH group on trans-cinnamic acid can react with NaOH to form respective carboxylate sale as follow-

                        C8H7COOH + NaOH -----90⁰C----> C8H7COO^-Na⁺ + H2O

If the reaction happens, the resultant product sodium cinnamate becomes soluble in water due to presence of net negative charge on it. The equilibrium also shift to the right and larger amount of the compound can be solvated in aqueous solution of NaOH.

However, the reaction occurs only at 90⁰-95⁰. So, trans-cinnamate becomes soluble in aqueous solution at round 90⁰C. But at room temperature, it’s sparingly soluble in aqueous solutions.