Home › CBSE Class 12 › Chemistry › Alcohols, Phenols and Ethers › Ethanol reacts with $\mathrm{PCl_5}$ to give whi…
Ethanol reacts with $\mathrm{PCl_5}$ to give which set of products?
A$\mathrm{CH_3CH_2Cl} + \mathrm{POCl_3} + \mathrm{HCl}$
B$\mathrm{CH_3CH_3} + \mathrm{H_2O}$
C$\mathrm{CH_3CH_2OH \cdot HCl}$ (complex salt)
D$\mathrm{CH_3CHO} + \mathrm{H_2}$
Answer & Solution
Correct answer: A. $\mathrm{CH_3CH_2Cl} + \mathrm{POCl_3} + \mathrm{HCl}$
1. NCERT §7.4 (Reactions of alcohols — halogenation): $\mathrm{PCl_5}$ is a strong chlorinating agent that converts alcohols to alkyl chlorides.
2. Generic equation: $\mathrm{R{-}OH} + \mathrm{PCl_5} \to \mathrm{R{-}Cl} + \mathrm{POCl_3} + \mathrm{HCl}$.
3. For ethanol: $\mathrm{CH_3CH_2OH} + \mathrm{PCl_5} \to \mathrm{CH_3CH_2Cl} + \mathrm{POCl_3} + \mathrm{HCl}$.
4. All three by-products are formed: ethyl chloride (the substitution product), phosphoryl chloride (from $\mathrm{PCl_5}$ losing $\mathrm{Cl}$ and gaining $\mathrm{O}$), and HCl gas.
5. Option B describes a different reaction. Option C is a salt that doesn't form. Option D is dehydrogenation, not happening here.
_Source: NCERT Class 12 Chemistry Part 2, Ch 7, §7.4 (Conversion of alcohols to alkyl halides — $\mathrm{PCl_5}$, $\mathrm{PCl_3}$, $\mathrm{SOCl_2}$), p. 12–13._
Related questions
With which two hydrogen halides is the peroxide effect not observed?Addition anti to Markovnikov rule is known as the peroxide or:Who framed the rule for adding HBr to unsymmetrical alkenes, in 1869?An intermediate conformation between eclipsed and staggered is called:Eclipsed and staggered conformations are represented by Newman and:Across all conformations, what stays the same?How many conformations can an alkane have by rotation about single bonds?Spatial arrangements interconverted by rotation about a single bond are called: