3,3-Dimethyl-2-butanol cannot be prepared by:
(A) Reaction of the given aldehyde with MeMgBr followed by H3O+
(B) Acid-catalysed hydration of the given alkene
(C) Ozonolysis followed by reduction using NaBH4/MeOH
(D) Reduction using LiAlH4/H3O+
(E) Acid-catalysed hydration of the given alkyne using Hg2+/H+
Choose the correct answer from the options given below:

Question

How many molecules are secondary alcohol?

Answer 1

To determine which reactions cannot prepare 3,3-dimethyl-2-butanol, we'll analyze each option.

Option A: Reaction of the given aldehyde with MeMgBr followed by H₃O⁺.
This involves the Grignard reaction. The given aldehyde, when reacted with methyl magnesium bromide, forms the tertiary alcohol 3,3-dimethyl-2-butanol upon acid workup. This reaction is correct for preparing the alcohol.
Option B: Acid-catalysed hydration of the given alkene.
The given alkene is 2,3-dimethyl-2-butene. Acid-catalyzed hydration typically forms Markovnikov addition products. The resultant product from this reaction would be a secondary alcohol, not the desired tertiary alcohol. Thus, this does not yield 3,3-dimethyl-2-butanol.
Option C: Ozonolysis followed by reduction using NaBH₄/MeOH.
Ozonolysis of an alkene generally leads to the formation of aldehydes or ketones. In the presence of a strong reducing agent like NaBH₄, they can be reduced to primary or secondary alcohols. The compound given and the subsequent reactions do not match the formation of the desired alcohol.
Option D: Reduction using LiAlH₄/H₃O⁺.
This method is typically used to reduce ketones and aldehydes to alcohols. The ketone shown can be reduced by LiAlH₄ to 3,3-dimethyl-2-butanol. This method is valid for the preparation of the alcohol.
Option E: Acid-catalysed hydration of the given alkyne using Hg²⁺/H⁺.
Such hydration of alkynes usually leads to ketones through enol intermediates, rather than tertiary alcohols. The resulting structure does not match 3,3-dimethyl-2-butanol.

Therefore, options B and E are unable to produce 3,3-dimethyl-2-butanol.

The correct answer is: B and E only.

Answer 2

To determine which reactions cannot prepare 3,3-dimethyl-2-butanol, we'll analyze each option.

Option A: Reaction of the given aldehyde with MeMgBr followed by H₃O⁺.
This involves the Grignard reaction. The given aldehyde, when reacted with methyl magnesium bromide, forms the tertiary alcohol 3,3-dimethyl-2-butanol upon acid workup. This reaction is correct for preparing the alcohol.
Option B: Acid-catalysed hydration of the given alkene.
The given alkene is 2,3-dimethyl-2-butene. Acid-catalyzed hydration typically forms Markovnikov addition products. The resultant product from this reaction would be a secondary alcohol, not the desired tertiary alcohol. Thus, this does not yield 3,3-dimethyl-2-butanol.
Option C: Ozonolysis followed by reduction using NaBH₄/MeOH.
Ozonolysis of an alkene generally leads to the formation of aldehydes or ketones. In the presence of a strong reducing agent like NaBH₄, they can be reduced to primary or secondary alcohols. The compound given and the subsequent reactions do not match the formation of the desired alcohol.
Option D: Reduction using LiAlH₄/H₃O⁺.
This method is typically used to reduce ketones and aldehydes to alcohols. The ketone shown can be reduced by LiAlH₄ to 3,3-dimethyl-2-butanol. This method is valid for the preparation of the alcohol.
Option E: Acid-catalysed hydration of the given alkyne using Hg²⁺/H⁺.
Such hydration of alkynes usually leads to ketones through enol intermediates, rather than tertiary alcohols. The resulting structure does not match 3,3-dimethyl-2-butanol.

Therefore, options B and E are unable to produce 3,3-dimethyl-2-butanol.

The correct answer is: B and E only.

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