Cyclohexanol is converted to cyclohexane-1,2-diol via a two-step synthesis that proceeds via intermediate Q.
Which row identifies the type of reaction in step 1 and in step 2?
| Step 1 | Step 2 | |
|---|---|---|
| A | dehydration | oxidation |
| B | dehydration | nucleophilic substitution |
| C | reduction | oxidation |
| D | reduction | nucleophilic substitution |
Correct Answer: \( \boxed{\mathrm{A}} \)
In step 1, cyclohexanol is converted into cyclohexene by eliminating a molecule of water. This is a dehydration reaction.
In step 2, the alkene is converted into cyclohexane-1,2-diol by oxidation with an oxidising agent such as cold, dilute acidified \(\mathrm{KMnO_4}\).
Two hydroxyl groups are added across the carbon-carbon double bond to form the vicinal diol.
Therefore, the correct answer is (A).
The diagram shows the structure of compound X.
X undergoes hydrolysis to form product Y in which all of the bromine atoms are replaced by hydroxyl groups.
Product Z is formed by oxidation of Y.
Two suggestions are listed.
1 Y is a secondary alcohol.
2 Z is a ketone.
Which suggestions are correct?
Correct Answer: \( \boxed{\mathrm{A}} \)
Hydrolysis replaces each bromine atom with a hydroxyl group. In the cyclohexane ring, each carbon bearing a hydroxyl group is bonded to two other carbon atoms, so every \(\mathrm{-OH}\) group is on a secondary carbon.
On oxidation, secondary alcohols are oxidised to ketones.
Therefore, product Y is a secondary alcohol and product Z contains ketone groups.
Hence, both suggestions are correct and the correct answer is (A).
Which reaction mixture produces a primary alcohol as the major product?
Correct Answer: \( \boxed{\mathrm{C}} \)
Lithium aluminium hydride reduces carboxylic acids to primary alcohols.
The reaction is:
\(\mathrm{CH_3CH_2CH_2COOH \xrightarrow{LiAlH_4} CH_3CH_2CH_2CH_2OH}\)
Option (A) produces a secondary alcohol, option (B) produces a secondary alcohol by Markovnikov addition, and option (D) oxidises ethene rather than producing an alcohol.
Therefore, the correct answer is (C).
