alcohols, phenols and ethers

Question 1

Preparing phenol from benzene sulphonic acid

Answer 1

1. Oleum
2. Heat with molten NaOH
3. Acidification of sodium salt

Question 2

Preparing phenol from haloarene (Dow’s process)

Answer 2

1. NaOH
2. HCl

Question 3

Phenol preparation from cumene?

Byproduct of this method?

Answer 3

1. Oxidize (—–> Cumene hydroperoxide)
2. Dilute acid

Acetone is byproduct

Question 4

BP of alcohols and phenols compared to hydrocarbons?

Answer 4

high coz of intermolecular H bonding

Question 5

BP order: Aldehyde, Alcohol, Alkane, ether?

Answer 5

Alcohol > Aldehyde > Ether > Alkane

Question 6

Reaction of alcohols and phenols with metals

Answer 6

Product: Alkoxides/Phenoxides

Question 7

Acidity of alcohols and phenols compared to water

Answer 7

Alcohols are less acidic than water due to electron donating
- R group

Phenols are more acidic than alcohols and water

Phenol>Alcohol>Water

Question 8

Why phenols are more acidic than alcohols?

Answer 8

Phenols on release of H, form phenoxide ion which is more stable than the alkoxide ion

The C to which OH is attached in phenol is sp2 hybridized and so is more EN. This increases the polarity of O-H bond and results in an increase in ionization of phenols than that of alcohols.

In alkoxide ion, the negative charge is localized on oxygen while in phenoxide ion, the charge is delocalized.
The delocalization of negative charge makes phenoxide ion more stable.

Even in phenol the charge is delocalized, but in phenol the resonance structures have charge separation because of which phenol is less stable than phenoxide ion.

Question 9

Esterification

Answer 9

Alcohols and phenols react with carboxylic acids, acid chlorides and acid anhydrides to form esters.