Acetylacetone (pK_a = 9.0) reacts with carbonate ion: CH3COCH2COCH3 + CO3^2- CH3COCHCOCH3^- + HCO3-. Given pK_a(HCO3-) = 10.3, calculate log_10K for this reaction. Give the answer to one decimal place.

JEE Main levelNumerical answerDifficulty 2 of 3g2125

Acetylacetone ( $p K_{a} = 9.0$ ) reacts with carbonate ion: $CH X_{3} COCH X_{2} COCH X_{3} + CO X_{3} X^{2 -} CH X_{3} COCHCOCH X_{3} X^{-} + HCO X_{3} X^{-}$ . Given $p K_{a} (HCO X_{3} X^{-}) = 10.3$ , calculate $lo g_{10} K$ for this reaction. Give the answer to one decimal place.

Numerical answer type, tolerance 0.05.

lo g K = p K_{a} (HCO X_{3} X^{-}) - p K_{a} (acetylacetone) = 10.3 - 9.0 = 1.3

. So

K \approx 20

and the enolate is formed to a large extent.