Question

Alkyl halide is converted to alkane:

• A. Wurtz Reaction
• B. Birch reaction
• C. Sabatier-Senderens reaction
• D. Grignard reaction

Hint:

Wurtz Reaction = Alkyl halide + Na (dry ether) → Alkane. Useful for synthesizing symmetrical alkanes in organic chemistry.

Answer 1

The Correct Option is A

- The Wurtz reaction involves the coupling of two alkyl halides using sodium metal in dry ether, producing a higher alkane.
- General reaction: \[ 2R-X + 2Na \xrightarrow{\text{dry ether}} R-R + 2NaX \] where \( R \) is an alkyl group and \( X \) is a halide.
- It is mainly used for the synthesis of symmetric alkane from primary alkyl halides.
- The Birch reaction is a type of reduction reaction of aromatic rings using sodium and alcohol in liquid ammonia.
- The Sabatier-Senderens reaction is a hydrogenation of alkenes/alkynes using nickel catalysts.
- The Grignard reaction involves formation of C–C bonds using Grignard reagents, not direct conversion of alkyl halides to alkanes.
- Therefore, the correct reaction for converting alkyl halides to alkanes is the Wurtz Reaction.

Answer 2

The question asks which named reaction converts an alkyl halide directly into an alkane. Let's look at what each of these four reactions actually does to its starting material.

1. Wurtz Reaction: Two molecules of an alkyl halide are treated with sodium metal in dry ether. Each carbon-halogen bond breaks, sodium removes the halogen atoms as sodium halide, and the two alkyl fragments join to form a single, longer alkane chain.
2. Birch reaction: This reaction adds hydrogen atoms across an aromatic ring using sodium or lithium in liquid ammonia with an alcohol, converting benzene derivatives into partially reduced dienes. It starts from an aromatic ring, not an alkyl halide, so it does not fit here.
3. Sabatier-Senderens reaction: This is catalytic hydrogenation of an alkene or alkyne over a nickel catalyst, adding hydrogen across a carbon-carbon multiple bond to give an alkane. The starting material here is an unsaturated hydrocarbon, not an alkyl halide.
4. Grignard reaction: An alkyl halide is first converted into a Grignard reagent using magnesium, which is then reacted with a carbonyl compound to build a new carbon-carbon bond and form an alcohol after workup. The end product is an alcohol, not an alkane, so this does not match either.

Only the Wurtz reaction takes an alkyl halide as the starting material and delivers an alkane as the product, by coupling two alkyl fragments with sodium.

So the correct answer is Wurtz Reaction.