4.3 Alcohols and Phenols

Question 1

Nucleophile

Answer 1

Electron pair doner (attracted to +)

Question 2

Electrophile

Answer 2

Electron pair acceptor (attracted to -)

Question 3

How are primary alcohols synthesised?

Answer 3

in nucleophilic substitution with Primary aliphatic halogenoalkanes or reduction of carbonyls

Question 4

What are the mechanism steps for nucleophilic substitution of halogenoalkanes?

Answer 4

1. OH- attracted to C
2. Cl- and Na+ join

Question 5

What are the characteristics of oxidation?

Answer 5

*Loss of electrons
*Adding oxygen
*Removing hydrogen

Question 6

What are the characteristics of reduction?

Answer 6

*Gaining of electrons
*Addition of Hydrogen

Question 7

What is the catalyst to reduce a carboxylic acid to an alcohol?

Answer 7

Lithium Aluminium Tetrahydride (LiAlH4) (dry ether)

Question 8

What is the catalyst to reduce an aldehyde to an alcohol?

Answer 8

Sodium Boron Tetrahydride (NaBH4) (aq)

Question 9

Why can primary and secondary alcohols be oxidised but not tertiary?

Answer 9

As 3* alcohols do not have hydrogens on a delta positive carbon

Question 10

What is the observation in the oxidation of alcohols?

Answer 10

organge to green

Question 11

What is the oxidising agent used for alcohols?

Answer 11

Acidified potassium dichromate (H+/K2Cr2O7)

Question 12

List the stages of oxidation for primary alcohols:

Answer 12

1* alcohol —> Aldehyde —> Carboxylic acid

Question 13

List the stages of oxidation for secondary alcohols:

Answer 13

2* alcohol —> Ketone

Question 14

What catalyst is used when HCl and an alcohol react?

Answer 14

Zinc chloride (ZnCl2) (Anhydrous conditions)

Question 15

What catalyst is used when HBr and an alcohol react?

Answer 15

Sodium bromide (NaBr) followed by conc. sulfuric acid (H2SO4)

Question 16

What are the products when hydrogen halides and alcohols react?

Answer 16

Halogenoalkane + Water

Question 17

What are the characteristics of Ethanoyl chloride?

Answer 17

*Strong electrophile
*reacts like a carboxylic acid

Question 18

What are the benefits of using ethanoyl chloride over a carboxylic acid in esterification?

Answer 18

• Forms fewer products in mixture, so is more easily extracted
  *No catalyst is required

Question 19

Why is phenol an acid?

Answer 19

Lone pairs on oxygen move into delocalised ring releasing the Hydrogen

Question 20

Why is phenol a weak acid?

Answer 20

Hydrogens only partially dissociate

Question 21

What is the test and observations for phenol?

Answer 21

A purple solution in Iron (III) chloride (Fe(III)Cl3)

Question 22

How does Phenol bond with halogens?

Answer 22

High electron density induces polarity ( no catalyst needed)