Losing CO₂: Decarboxylation, Kolbe Electrolysis and Reduction

Key points

• Soda lime (NaOH + CaO), heat: RCOONa → R–H + Na₂CO₃, an alkane with one carbon less (CH₃COONa → CH₄).
• Simple arrow picture: the O⁻ lone pair forms C=O, the C–C pair moves onto the alkyl carbon, CO₂ leaves; the carbanion takes an H.
• Kolbe electrolysis: at the anode RCOO⁻ → R· + CO₂; 2R· → R–R (CH₃COONa → ethane).
• LiAlH₄ or B₂H₆, then H₃O⁺: RCOOH → RCH₂OH; NaBH₄ does not reduce –COOH.

Three ways the COOH changes

Kolbe electrolysis at the anode

• CH₃COO⁻ − e⁻ → CH₃COO·
• CH₃COO· → CH₃· + CO₂
• CH₃· + ·CH₃ → CH₃–CH₃

Quick quiz

5 questions. Choose an answer for each, then submit to see your score and the explanations.