Wurtz makes symmetrical alkanes by coupling. Corey-House is best for unsymmetrical alkanes using Gilman reagent. Decarboxylation shortens the carbon chain using soda lime. Focus on product prediction and limitations.
Frequently Asked Questions
Why is Wurtz reaction not suitable for preparing unsymmetrical alkanes?▾
The Wurtz reaction, when performed with two different alkyl halides (R-X and R'-X), leads to a mixture of three products: R-R, R'-R', and R-R'. Since these alkanes often have similar boiling points, their separation becomes extremely difficult and inefficient.
What is soda lime and its role in decarboxylation?▾
Soda lime is a mixture of solid sodium hydroxide (NaOH) and calcium oxide (CaO). In decarboxylation, NaOH acts as the primary reactant to remove the carboxyl group as CO₂ (which then forms Na₂CO₃), while CaO prevents the fusion of glass apparatus and makes NaOH less deliquescent.
How does Corey-House synthesis overcome the limitations of Wurtz reaction?▾
Corey-House synthesis uses a Gilman reagent (lithium dialkylcuprate) which selectively reacts with a primary alkyl halide to form the desired unsymmetrical alkane. This method avoids the formation of a complex mixture of products, making it superior to Wurtz reaction for synthesizing unsymmetrical alkanes.
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