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 57b

Chapter 10, Problem 57b

Show how this 1° alcohol can be made from the following:

(b) formaldehyde

Verified step by step guidance

Step 1: Recognize that the target molecule is a primary alcohol (1° alcohol) with a hydroxyl group (-OH) attached to a carbon that is bonded to only one other carbon atom.

Step 2: Formaldehyde (HCHO) can act as a starting material for the synthesis of primary alcohols through nucleophilic addition reactions. Identify the need for a Grignard reagent to introduce the desired carbon chain.

Step 3: Prepare the Grignard reagent by reacting an alkyl halide (e.g., cyclobutyl bromide or cyclopentyl bromide) with magnesium in dry ether to form cyclobutyl magnesium bromide or cyclopentyl magnesium bromide.

Step 4: React the Grignard reagent with formaldehyde in an anhydrous environment. The nucleophilic carbon of the Grignard reagent attacks the electrophilic carbonyl carbon of formaldehyde, forming a new C-C bond and resulting in an alkoxide intermediate.

Step 5: Perform an acid workup (e.g., using dilute HCl or H2O) to protonate the alkoxide intermediate, yielding the desired primary alcohol.

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Key Concepts

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

1° Alcohols

Primary (1°) alcohols are organic compounds where the hydroxyl (-OH) group is attached to a carbon atom that is connected to only one other carbon atom. This structure influences their reactivity and properties, making them more susceptible to oxidation compared to secondary or tertiary alcohols.

Formaldehyde as a Reactant

Formaldehyde (HCHO) is a simple aldehyde that can be used in organic synthesis to produce alcohols. In the presence of a suitable reducing agent, formaldehyde can react with Grignard reagents or organolithium compounds to yield primary alcohols, making it a key starting material in alcohol synthesis.

Nucleophilic Addition Reactions

Nucleophilic addition reactions are fundamental in organic chemistry, where a nucleophile attacks an electrophilic carbon atom, leading to the formation of new bonds. In the context of synthesizing alcohols from aldehydes, the nucleophile (like a Grignard reagent) adds to the carbonyl carbon of formaldehyde, resulting in the formation of a primary alcohol after subsequent protonation.

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Related Practice

Textbook Question

Show how this 1° alcohol can be made from the following:

(d) a carboxylic acid

854

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Textbook Question

Often, compounds can be synthesized by more than one method. Show how this 3° alcohol can be made from the following:

692

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Textbook Question

For each synthesis, start with bromocyclohexane and predict the products. Assume that an excess of each reactant is added so that all possible reactions that can happen will happen.

(a)

1630

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Textbook Question

Show how this 1° alcohol can be made from the following:

(a) a 1° alkyl bromide

827

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Textbook Question

Often, compounds can be synthesized by more than one method. Show how this 3° alcohol can be made from the following:

(d) a 3° alkyl bromide

602