NaBH4 reacts with carboxylic acids via H2 evolution but not with alcohols

Steps:

• Tartaric acid is HO2CCH(OH)CH(OH)CO2H, a dicarboxylic acid.
• Excess LiAlH4 reduces both COOH groups to CH2OH, forming J as HOCH2CH(OH)CH(OH)CH2OH (a tetraol).
• NaBH4(aq) with tartaric acid: acidic COOH protons decompose NaBH4, evolving H2 gas (reaction occurs).
• NaBH4(aq) with J: neutral alcohol groups do not decompose NaBH4 (no reaction).

Why B is correct:

• Tartaric acid's COOH groups protonate BH4-, causing decomposition and H2 evolution, per NaBH4's sensitivity to strong acids.

Why the others are wrong:

• A: J lacks COOH, so no reaction with NaBH4.
• C: Tartaric acid reacts due to acidity, unlike J.
• D: Tartaric acid does react, producing H2.

Final answer: B