Observe the structures of the sodium salts of various carboxylic acids provided in the figure. Which of these salts will yield 2-methylpropane as the major organic product upon heating with a mixture of NaOH and CaO ?

Step-by-step solution

Heating a sodium salt of a carboxylic acid with soda lime ( NaOH and CaO ) results in decarboxylation, yielding an alkane with one carbon atom less than the original salt. The general reaction is: R-COONa NaOH + CaO, R-H + Na₂CO₃ We need the product to be 2-methylpropane, which has the structure CH₃-CH(CH₃)-CH₃ or (CH₃)₃CH . Let us analyze the decarboxylation products of the given salts: For I: CH₃-CH₂-CH(CH₃)-COONa CH₃-CH₂-CH₂-CH₃ (n-butane) For II: (CH₃)₃C-COONa (CH₃)₃CH (2-methylpropane) For III: CH₃-CH(CH₃)-CH₂