Show how you would synthesize the following:
f. 2,5-dimethylhexane from a four-carbon alkyl halide

Verified step by step guidance

1. Step 1: Begin by identifying the target molecule, 2,5-dimethylhexane, and its structural features. It has a six-carbon chain with methyl groups attached at the 2nd and 5th positions. This suggests that the synthesis will involve chain elongation and branching.
2. Step 2: Choose a suitable four-carbon alkyl halide as the starting material. For example, 1-bromobutane (CH₃CH₂CH₂CH₂Br) can serve as the base structure for chain elongation.
3. Step 3: Perform a reaction to introduce branching. Use a Grignard reagent, such as methylmagnesium bromide (CH₃MgBr), to add a methyl group to the chain. This reaction will require a carbonyl intermediate, such as butanone (CH₃CH₂COCH₃), which can be synthesized from the alkyl halide.
4. Step 4: Repeat the process to introduce the second methyl group at the desired position. This can be achieved by converting the intermediate into another carbonyl compound and reacting it with methylmagnesium bromide again.
5. Step 5: Finally, ensure the product is fully reduced to form the desired alkane, 2,5-dimethylhexane. Use hydrogenation (H₂ with a metal catalyst like Pd/C) to reduce any remaining unsaturated bonds or intermediates to the final alkane structure.

Key Concepts

Alkyl Halides

Alkyl halides are organic compounds containing a carbon chain bonded to a halogen atom (F, Cl, Br, I). They serve as important intermediates in organic synthesis, allowing for the introduction of functional groups through nucleophilic substitution or elimination reactions. Understanding their reactivity is crucial for designing synthetic pathways.

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group (like a halogen) by a nucleophile. These reactions can occur via two main mechanisms: SN1 (unimolecular) and SN2 (bimolecular). The choice of mechanism affects the stereochemistry and rate of the reaction, which is essential for synthesizing specific products like 2,5-dimethylhexane.

Carbon Chain Elongation

Carbon chain elongation is a synthetic strategy used to increase the length of a carbon chain in organic molecules. This can be achieved through various methods, including coupling reactions or the use of alkyl halides in nucleophilic substitution. In the context of synthesizing 2,5-dimethylhexane, understanding how to effectively elongate a four-carbon alkyl halide is key to achieving the desired product.