The correct order of decreasing reactivity to | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) The dehydration of alcohols in the presence of $H_3PO_4$ proceeds via the formation of a carbocation intermediate. The rate of reaction depends on

Vedclass · Accepted Answer

$II > III > I$

Vedclass · Answer

(A) The dehydration of alcohols in the presence of $H_3PO_4$ proceeds via the formation of a carbocation intermediate. The rate of reaction depends on the stability of the carbocation formed.$I$: Phenol (or cyclohexadienol derivative) forms a highly stable aromatic carbocation (benzene ring system).$II$: Cyclohexadienol forms a conjugated diene system upon dehydration.$III$: Cyclohexenol forms a simple alkene.Comparing the stability of the carbocations formed:$1$. Compound $II$ (cyclohexa$-1,4-$dien$-1-$ol) leads to the formation of benzene,which is highly stable due to aromaticity.$2$. Compound $III$ (cyclohex$-2-$en$-1-$ol) leads to the formation of cyclohexadiene.$3$. Compound $I$ (phenol) is not an alcohol in the aliphatic sense and does not undergo dehydration to an alkene under these conditions; however,based on the provided structures,$II$ is the most reactive due to the formation of aromatic benzene,followed by $III$,and $I$ is the least reactive.Thus,the correct order of reactivity is $II > III > I$.

The correct order of decreasing reactivity towards $H_3PO_4$ for the following compounds is:

Similar Questions

Which of the following is a primary alcohol?

The correct order of boiling point for primary $(1^{\circ})$,secondary $(2^{\circ})$ and tertiary $(3^{\circ})$ alcohols is

Which bond in ethyl alcohol undergoes cleavage during its reaction with sodalime?

Which of the following is a secondary allylic alcohol?

In the following sequence of reaction,$Z$ $\xrightarrow{PCl_5} X$ $\xrightarrow[\Delta]{\text{Alc. KOH}} Y$ $\xrightarrow{H_2O/H^{+}} Z$ (Major),$Z$ is:

Vedclass Test Series

Exam Paper Generator

Online Exam Module