Ch.10 - Structure and Synthesis of Alcohols

Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook

Wade 9th Edition

Ch.10 - Structure and Synthesis of Alcohols

Problem 41f

Chapter 10, Problem 41f

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

Verified step by step guidance

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.

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.

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.

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.

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.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

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.

Recommended video:

Guided course

04:25

Name the longest carbon chain

Related Practice

Textbook Question

Complete the following acid–base reactions. In each case, indicate whether the equilibrium favors the reactants or the products, and explain your reasoning.

(e) (CH₃)₃C–O^– + CH₃CH₂OH ⇌

views

Textbook Question

Complete the following acid–base reactions. In each case, indicate whether the equilibrium favors the reactants or the products, and explain your reasoning.

(f) (CH₃)₃C–O^– + H₂O ⇌

views

Textbook Question

Show how you would synthesize the following:

c. cyclohexylmethanol from an alkyl halide using an S_N2 reaction

Textbook Question

Complete the following acid–base reactions. In each case, indicate whether the equilibrium favors the reactants or the products, and explain your reasoning.

(d)

views

Textbook Question

Show how you would synthesize the following:

e. cis-pent-2-en-1-thiol from a suitable alkenyl halide

views

Textbook Question

Show how you would synthesize the following:

a. 2-phenylethanol by the addition of formaldehyde to a suitable Grignard reagent

views