Decreasing order of dehydration of the following alcohols is
- $a>d>b>c$
- $d > b > c > a$
- $b > a > d > c$
- $b>d>c>a$
The Correct Option is D
Approach Solution - 1
The correct option is (D): b > d > c > a.
The order of dehydration of alcohols depends on the stability of the carbocation intermediate formed during the reaction. The more stable the carbocation intermediate, the easier it is for the alcohol to undergo dehydration. Therefore, we analyze the structures of the alcohols to determine the stability of the carbocation intermediates:
- a > d > b > c: This order suggests that alcohol a is the most easily dehydrated, followed by alcohol d, then alcohol b, and finally alcohol c. This implies:
- Alcohol a: Tertiary
- Alcohol d: Secondary
- Alcohol b: Primary
- Alcohol c: Primary
- d > b > c > a: This order suggests that alcohol d is the most easily dehydrated, followed by alcohol b, then alcohol c, and finally alcohol a. This implies:
- Alcohol d: Tertiary
- Alcohol b: Secondary
- Alcohol c: Primary
- Alcohol a: Primary
- b > a > d > c: This order suggests that alcohol b is the most easily dehydrated, followed by alcohol a, then alcohol d, and finally alcohol c. This implies:
- Alcohol b: Tertiary
- Alcohol a: Secondary
- Alcohol d: Primary
- Alcohol c: Primary
- b > d > c > a: This order suggests that alcohol b is the most easily dehydrated, followed by alcohol d, then alcohol c, and finally alcohol a. This implies:
- Alcohol b: Tertiary
- Alcohol d: Secondary
- Alcohol c: Primary
- Alcohol a: Primary
Summary: Based on the given orders of dehydration, we conclude that alcohol b is the most easily dehydrated in all cases, as it is tertiary. The order of the remaining alcohols varies depending on the specific order given.
Approach Solution -2
Dehydration of Alcohols and Carbocation Stability:
The dehydration of alcohols follows the stability of the carbocations formed during the reaction. The stability of the carbocation depends on the degree of substitution:
- Alcohol b: Forms a tertiary carbocation, which is the most stable due to maximum alkyl group stabilization.
- Alcohol d: Forms a secondary carbocation, which is moderately stable.
- Alcohol c: Forms another secondary carbocation, similar to d, but slightly less stable due to fewer substituents.
- Alcohol a: Forms a primary carbocation, which is the least stable.
Conclusion: The order of dehydration follows the carbocation stability: b > d > c > a.
Top Questions on Alcohols, Phenols and Ethers
From the following, how many compounds contain at least one secondary alcohol?
- JEE Main - 2026
- Chemistry
- Alcohols, Phenols and Ethers
- How methanol is prepared industrially? Write the chemical equation.
- KBPE - 2026
- Chemistry
- Alcohols, Phenols and Ethers
Name the products formed when phenol is treated with the following reagents:
(i) Bromine water
(ii) Zinc dust
(iii) Conc. HNO_3- KBPE - 2026
- Chemistry
- Alcohols, Phenols and Ethers
(i) Predict the products A and B in the hydroboration-oxidation reaction.
(ii) Explain the preparation of phenol from cumene.- KBPE - 2026
- Chemistry
- Alcohols, Phenols and Ethers
- Why is Phenol more acidic than alcohols?
- NBSE Class XII - 2026
- Chemistry
- Alcohols, Phenols and Ethers
Questions Asked in JEE Main exam
MX is a sparingly soluble salt that follows the given solubility equilibrium at 298 K.
MX(s) $\rightleftharpoons M^{+(aq) }+ X^{-}(aq)$; $K_{sp} = 10^{-10}$
If the standard reduction potential for $M^{+}(aq) + e^{-} \rightarrow M(s)$ is $(E^{\circ}_{M^{+}/M}) = 0.79$ V, then the value of the standard reduction potential for the metal/metal insoluble salt electrode $E^{\circ}_{X^{-}/MX(s)/M}$ is ____________ mV. (nearest integer)
[Given : $\frac{2.303 RT}{F} = 0.059$ V]- JEE Main - 2026
- Electrochemistry
An infinitely long straight wire carrying current $I$ is bent in a planar shape as shown in the diagram. The radius of the circular part is $r$. The magnetic field at the centre $O$ of the circular loop is :
- JEE Main - 2026
- Current electricity
- For two identical cells each having emf \(E\) and internal resistance \(r\), the current through an external resistor of \(6\,\Omega\) is the same when the cells are connected in series as well as in parallel. The value of the internal resistance \(r\) is ________ \(\Omega\).
- JEE Main - 2026
- Current electricity
- The half-life of $^{65}$Zn is 245 days. After $x$ days, 75% of the original activity remained. The value of $x$ in days is __________ (Nearest integer).}
(Given: $\log 3 = 0.4771$ and $\log 2 = 0.3010$)- JEE Main - 2026
- Surface Chemistry
- The hydrogen spectrum consists of several spectral lines in Lyman series (L$_1$, L$_2$, L$_3$ ...; L$_1$ has lowest energy among Lyman series). Similarly, it consists of several spectral lines in Balmer series (B$_1$, B$_2$, B$_3$ ...; B$_1$ has lowest energy among Balmer lines). The energy of L$_1$ is $x$ times the energy of B$_1$. The value of $x$ is ___ $\times 10^{-1}$. (Nearest integer)
- JEE Main - 2026
- Atomic Structure
Concepts Used:
Alcohols, Phenols, and Ethers
Alcohol is formed when a saturated carbon atom bonds to a hydroxyl (-OH) group. It is an organic compound that contains a hydroxyl functional group attached to a carbon atom.
Phenol is formed when the -OH group replaces the hydrogen atom in benzene. It is an organic compound in which a hydroxyl group directly attaches to an aromatic hydrocarbon.
Ether is formed when oxygen atom bonds to two alkyl or aryl groups. It is an organic compound that has an oxygen atom that is connected to two aryl and alkyl groups.
Read More: Alcohol, Phenol, and Ethers