Nomenclature and Preparation

Question 1

How are ethers named

Answer 1

Prefix(smaller chain)+oxy+suffix(bigger chain_

Question 2

Bond angle in alcohols

Answer 2

slightly less than 109°28’

Question 3

Why is the bond length in phenols less than that in methanol?

Answer 3

due to
-partial double bond character by the conjugation of the unshared electron pair of oxygen with the aromatic ring.
-sp2 carbon through which oxygen is attached.

Question 4

Bond angle in Ethers

Answer 4

More than angle in tetrahedral structure due to repulsive interaction between the two R groups.

Question 5

Bond length in ethers

Answer 5

almost the same(141pm) as that of alcohols

Question 6

Preparation of Alcohols by alkenes

Answer 6

Addition of water in the presence of acid.

Question 7

Mechanism of preparation of alcohol by alkene

Answer 7

-Protonation to form a carbocation ny electrophilic attack of H3O
-Nucleophilic attack of h2o on carbocation
-Deprotonation to form an alcohol

Question 8

Hydroboration-oxidation

Answer 8

Addition of diborane
addition of same alkene 2 more times to produce trialkyl boranes.
oxidised by hydrogen peroxide(h2o2) to alcohols

Question 9

reduction of aldehydes and ketones

Answer 9

catalyst-plantinum.palladium, nickel
or NaBH4 or LiAlH4.

Question 10

Reduction of carboxylic acid through LiAlH4

Answer 10

reduced to primary alcohols using catalyst LiAlH4

Question 11

Reduction of carboxylic acid(Commercial method)

Answer 11

reduced first to esters and then to alcohols by hydrogen + catalyst.

Question 12

From Grignard reagants

Answer 12

reacts worth R-Mg-X to form an adduct on hydrolysis forms alcohol

Question 13

Other name for phenol

Answer 13

Carbolic acid

Question 14

Preparation from haloarenes(phenol)

Answer 14

chlorobenzene+naoh at 623K and 300 atm to form sodium phenoxide which acidifies to phenol

Question 15

From benzenesulphonic acid

Answer 15

Benzene+oleum then heated (forms benzene with so3h compound) with naoh to form sodium phenoxide which is acidified to phenol.

Question 16

From diazonium salts

Answer 16

Aniline(nh2 on benzene) + nano2 +hcl tp give n2cl on benzene which reacts with warm water to form phenol

Question 17

Cumene

Answer 17

isopropylbenzene

Question 18

From cumene

Answer 18

Cumene is oxidised to form cumene hydroperoxide which reacts with acid to form phenol and acetone(propanone)

Question 19

Properties of alcohols and phenols are due to which group and are modified by which group

Answer 19

due to hydroxyl group and modified by alkyl and aryl groups.

Question 20

Boiling points

Answer 20

Increases with increase in carbon atoms(more vanderwaals force) but decreased with increase in branching as it the van der waals force decrease due to lesser surface area.

Question 21

Why do alcohols have high boiling points?

Answer 21

due to intermolecular hydrogen bonding which is absent in ethers and hydrocarbons.

Question 22

Solubility

Answer 22

decreases with increase in size of alkyl/aryl group as they are hydrophobic.