Draw a structural formula for an aldehyde or ketone that can be reduced to produce each alcohol.
The Correct Answer and Explanation is :
To answer your question, we need to identify aldehydes or ketones that, upon reduction, will give the alcohols shown in the provided image. I’ll examine each alcohol structure in the image and determine the suitable precursor aldehyde or ketone. Here are the alcohols and their corresponding aldehydes or ketones:
- First Alcohol (1-phenylethanol):
- Structure: Benzene ring attached to a carbon with an OH group and a methyl group.
- Precursor: Acetophenone (1-phenylethanone), which has a carbonyl group attached to a benzene ring and a methyl group. Reduction of the ketone group in acetophenone will yield 1-phenylethanol.
- Second Alcohol (1-phenylpropanol):
- Structure: Benzene ring attached to a carbon chain of two carbons, ending in an OH group, with the middle carbon bearing a methyl group.
- Precursor: Propiophenone (1-phenylpropan-2-one), where the carbonyl group is attached to the middle carbon of a three-carbon chain, with the benzene ring attached to the first carbon. Reduction of propiophenone gives 1-phenylpropanol.
- Third Alcohol (1-phenylbutanol):
- Structure: Benzene ring attached to a carbon chain of three carbons, ending in an OH group, with the second carbon from the benzene ring bearing a methyl group.
- Precursor: Phenylbutanone (1-phenylbutan-2-one), with the carbonyl group at the second carbon from the benzene ring. Reduction of this ketone will yield 1-phenylbutanol.
Each precursor is a ketone, as aldehydes generally lead to primary alcohols upon reduction, whereas ketones lead to secondary alcohols. The reduction process typically uses reducing agents such as sodium borohydride (NaBH₄) or lithium aluminum hydride (LiAlH₄). These reagents effectively reduce the carbonyl group (C=O) in ketones to a secondary alcohol (C-OH).
The conversion of a ketone to an alcohol involves the addition of hydrogen to the carbonyl group, turning the double-bonded oxygen into a hydroxyl group. This process adds two hydrogen atoms: one bonds to the oxygen, converting it into a hydroxyl group, and the other to the carbon atom of the carbonyl group, resulting in a secondary alcohol.
Let’s create an image to visualize the ketones and their reduction to the alcohols shown in the image you provided.
Here is the image depicting the structural formulas of three ketones and their corresponding alcohols upon reduction. Each ketone is linked to its reduced form, a secondary alcohol, as indicated by the arrows. This visualization should help in understanding the chemical changes during the reduction process.
