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Question: Which of the following reactions are used in the preparation of alcohols? (A) \( {{C}_{2}}{{H}_{5}...

Which of the following reactions are used in the preparation of alcohols?
(A) C2H5Br+KOH(aq)→{{C}_{2}}{{H}_{5}}Br+KO{{H}_{(aq)}}\xrightarrow{{}}
(B) (CH3)2C−O→LiAlH4{{\left( C{{H}_{3}} \right)}_{2}}C-O\xrightarrow{LiAl{{H}_{4}}}
(C) H3C−C(=O)−OCH3→Ni/H2{{H}_{3}}C-C(=O)-OC{{H}_{3}}\xrightarrow{Ni/{{H}_{2}}}
(D) CH2CH2−Cl→H2OC{{H}_{2}}C{{H}_{2}}-Cl\xrightarrow{{{H}_{2}}O}

Explanation

Solution

Hint : We know that to identify the type of substrate such as primary, secondary or tertiary alcohol. Identify which substrate needs a catalyst. The alkyl halides then undergo hydrolysis to produce alcohols. Another way is to heat the alkyl halides with moist silver oxide.

Complete Step By Step Answer:
To prepare alkyl halide, you react with an alcohol with hydrogen chloride. In this reaction, you replace the chlorine atom hydroxyl group. In this reaction, tertiary alcohols are much more reactive than primary or secondary alcohols. If you start with tertiary alcohol, you do not need a catalyst. Thus, when you mix a tertiary alcohol with hydrogen chloride, you will get tertiary alcohol as the product. If you start with primary and secondary alcohol, you need a catalyst.
The most common catalyst is anhydrous zinc chloride. Thus, when you mix a primary or secondary with hydrogen chloride, you will not get primary or secondary alcohol as the product. But, when you mix a primary or secondary with hydrogen chloride in presence of anhydrous zinc chloride catalyst, you will get primary or secondary alcohol as the product.
Here option C i.e. H3C−C(=O)−OCH3→Ni/H2{{H}_{3}}C-C(=O)-OC{{H}_{3}}\xrightarrow{Ni/{{H}_{2}}} satisfies the reactions are used in the preparation of alcohols and the following reaction is carried out as given below;
H3C−C(=O)−OCH3→Ni/H2[H3C−CH2−OH]+[CH3−OH].{{H}_{3}}C-C(=O)-OC{{H}_{3}}\xrightarrow{Ni/{{H}_{2}}}\left[ {{H}_{3}}C-CH_{2}^{{}}-OH \right]+\left[ CH_{3}^{{}}-OH \right].

Note :
Remember that in primary alcohol, the carbon atom bearing hydroxyl group is attached to only one other carbon atom. In secondary alcohol, the carbon atom bearing hydroxyl group is attached to two other carbon atoms. In tertiary alcohol, the carbon atom bearing hydroxyl group is attached to three other carbon atoms.