Alcohols

Question 1

What is formed on the dissociation of ethanol?

Answer 1

Ethoxide and hydroxonium ion

Question 2

Reaction with Na

Answer 2

Hydrogen is replaced by Na
CH3CH2ONa

Question 3

Dehydration of alcohols

Answer 3

Reagents: Al2O3/concentrated H2SO4 catalyst
Conditions: heat
Alkene is produced

Question 4

Substitution of OH with a halogen

Answer 4

Reagents and conditions: HX or KBr with H2SO4/H3PO4 or PCl3 heat or PCl5 or SOCl2 or NaI with H3PO4
Halogenoalkane is produced

Question 5

Oxidation of primary alcohols

Answer 5

Reagents: KmnO4 OR K2Cr2O7(aq)/H+
Conditions: distillation - aldehyde/reflux - c. acid

Question 6

Oxidation of secondary alcohols

Answer 6

A ketone is produced

Question 7

Condensation with acid

Answer 7

Reagent: c. acid
Conditions: c. H2SO4 or H3PO4 (catalyst)
A ester is produced

Question 8

Tri-iodomethane reaction

Answer 8

Reagents: I2(aq), NaOH(aq)
Type of reaction: Oxidation
Tri-iodomethane is formed (a yellow ppt)

Question 9

What is the tri-iodomethane reaction used to detect? (3)

Answer 9

1) Methylalcohol
2) Methyl ketone group
3) Ethanal
The methyl group is converted to CHI3

Question 10

Reactions that produce alcohols (6)

Answer 10

1) Nucleophilic substitution of halogenoalkane
2) Alkene + steam
3) Oxidation of alkenes
4) Reduction of aldehyde/ketone
5) Reduction of c. acid
6) Hydrolysis of acid

Question 11

Compare the acidity of alcohols with water

Answer 11

Alcohols are less acidic than alcohols. The ethoxide ion formed upon dissociation of the alcohol is destabilised by the presence of the alkyl group which is electron pushing. The reaction lies more to the left