Single Choice

Which of the following alcohols will give the most stable carbocation during dehydration?

A2-Methyl -1- propanol
B2-Methyl -2- propanol
Correct Answer
C1-Butanol
D2-Butanol

Solution

Alcohol $$+ H_2SO_4 \rightarrow$$ Alkene
The dehydration reaction is an elimination reaction that goes via carbocation formation as shown in the figure.
Tertiary carbocations are most stable due to + Inductive effect of alkyl groups, then is secondary and least stable is primary. Therefore the reactivity and stability of carbocation follow the order as
Tertiary alcohol>secondary alcohol>primary alcohol
2-Methyl-1-propanol forms secondary carbocation as: $$(CH_3)_2CHCH_{2}^+$$
2-Methyl-2-propanol forms tertiary carbocation as: $$(CH_3)_3C^+$$
1-Butanol forms primary carbocation as: $$CH_3CH_2CH_2CH_2^+$$
and 2-Butanol forms secondary carbocation as: $$CH_3CH^+CH_2CH_3$$
Thus most stable carbocation is formed by 2-Methyl -2- propanol during its dehydration.

SIMILAR QUESTIONS

Alcohols, Phenols and Ethers

Dehydration of alcohols can be done by using:

Alcohols, Phenols and Ethers

State how the following conversions can be carried out. Ethyl alcohol to Ethene.

Alcohols, Phenols and Ethers

In the following sequence of reactions, $$CH_3Br\overset{KCN}{\rightarrow}A\overset{H_3O^+}{\rightarrow}B\overset{LiAlH_4}{\rightarrow}C$$ The end product C is:

Alcohols, Phenols and Ethers

Explain mechanism of acid catalyses dehydration of ethyl alcohol?

Alcohols, Phenols and Ethers

The major product of the above reaction is :

Alcohols, Phenols and Ethers

Acid catalysed dehydration of t-butanol is faster than that of n-butanol because:

Alcohols, Phenols and Ethers

Choose the correct answer among the alternatives given: In the following reactions, (i)$$CH_3-\overset{CH_3}{\overset{|}C}H-\underset{OH}{\underset{|}C}H-CH_3\xrightarrow{H^+/heat}\underset{[Major\ product]}A +\underset{[Minor\ product]} B$$ (ii)$$A\xrightarrow[in\,absence\,of \,peroxide]{HBr,dark}\underset{Major\ product}C+\underset{Minor\ product}D$$ The major products $$A$$ and $$C$$ are respectively?

Alcohols, Phenols and Ethers

Name the reagents used in the following reaction: Dehydration of propan-2-ol to propene.

Alcohols, Phenols and Ethers

Which is the best reagent to convert cyclohexanol into cyclohexene?

Alcohols, Phenols and Ethers

In the following dehydration of diol with $$\displaystyle { H }_{ 3 }{ PO }_{ 4 }$$, following product is:

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