Secondary and tertiary alcohols always give `E_(1)` reaction in dehydration. Primary alcohols whose `beta-` carbon is `3^(@)`or `4^(@)` also give `E_(1)` reaction. However, the primary alcohols whose `beta-`carbon is `1^(@)` or `2^(@)` give `E_(2)` reaction. Dehydrating agents like conc. `H_(2)SO_(4), Al_(2)O_(3)`, anhydrous `ZnCl_(2)` are used.
The reactivity of alcohols for elimination reaction lies in following sequence `:`
Tertiary alcohol `gt` secondary alcohol `gt` primary alcohol
Electron attracting group present in alcohols increase the reactivity for dehydration. Greater is the `-I` effect of the group present in alcohol, more will be its reactivity. Both `E_(1)` and `E_(2)` mechanism give the product according to Satzeff's rule, i.e., major product is the most substituted alkene.
`underset("3-Methylbutan-2-ol")(CH_(3)-underset(CH_(3))underset(|)(C)H-overset(OH)overset(|)(C)H-CH_(3)underset("above 413K")overset("conc." H_(2)SO_(4))(rarr))`
`underset("2-Methylbut-2-ene(major product)")(CH_(3)-underset(CH_(3))underset(|)(C)=CH-CH_(3))+underset("3-Methylbut-1-ene(minor product)")(CH_(3)-underset(CH_(3))underset(|)(C)H-CH=CH_(2))`
Arrange the reactivity of given four alcohols in decreasing order for dehydration .

Options

A. A gtBgtCgtD
B. DgtCgtBgtA
C. CgtBgtDgtA
D. BgtCgtAgtD

Answer

C

Explanation

[Hint]
Nearer is the -I the group to the alcoholic group, greater is its reactivity for dehydration.