Ethers

Question 1

2 taught methods to prepare ether?

Answer 1

From Haloalkane and Alcohol

Question 2

Solubility

Answer 2

Lower members are soluble: H bonding
Higher member: Less soluble

Question 3

Boiling point

Answer 3

Lower than isomeric alcohols (H-bond)

Question 4

Reaction with cold and conc. mineral acids?

Answer 4

Oxonium salts.
(Diethyloxonium chloride, diethyloxonium bisulphate)

Question 5

Reaction with HX?

Answer 5

Alcohol and haloalkane
Eg, R-O-R + HX ——> R-OH + R-X
Larger alkyl group forms alcohol and smaller goes to form haloalkane.

Question 6

Product when reaction between anisole and hydrogen iodide takes place? Why?

Answer 6

Phenol and iodomethane.
iodine cannot break the partial double bond of C—O group in anisole due to resonance.

Question 7

Reaction with sulphuric acid?
ROR + H2SO4 ——> ?

Answer 7

ROR + H2SO4 ——> R- OH + R—HSO4
Alcohol and alkyl hydrogen sulphate

Question 8

Reaction with PCl5?
ROR + PCl5 ——> ?

Answer 8

ROR + PCl5 ——> R—Cl + POCl3

Chloroalkane + POCl3

Question 9

Action of light and air?

Answer 9

Formation of hydrogen peroxide.

Peroxide of ether decomposes violently at height temperature.

Question 10

Why iron wire is kept in bottles containing impure ether?

Answer 10

Prevents formation of explosive and thermally unstable ether peroxide.
Iron has higher affinity towards oxygen.
Fe + O2 ——> FeO
FeO + ether peroxide —> ether + Fe2O3

Question 11

How do you get ether from alcohol?
2 ways.

Answer 11

1)
Heat up to 140 degrees in presence of conc. H2SO4
2)
Heat up to 250 degrees in presence of Al2O3

Question 12

Uses of ethers:
(Any 4)
Hint: GRASs

Answer 12

1) preparation of Grignard’s Reagent
2) as a Refrigerant
3) general Anesthetic in surgery
4) industrial Solvents for gum, resin, oils.

Question 13

Reaction with chlorine in the dark?
Excess chlorine in light?

CH3—CH2—O—CH2—CH3 + Cl2 —> ?

Answer 13

A-A’ dichloro diethyl ether
CH3—CH ( Cl )—O—CH ( Cl )—CH3

Per chloro diethyl ether
CCl3—CCl2—O—CCl2—CCl3