Alcohols, Alkanoic acids and Esters

Question 1

What is

a primary alcohol?

Answer 1

This is an alcohol that has 1 alkyl group attached to the carbon bearing the -OH group.
It can be represented as: RCH₂OH

Question 2

What is

a secondary alcohol?

Answer 2

This is an alcohol that has 2 alkyl groups attached to the carbon bearing the -OH group.
It can be represented as: RR’CHOH

Question 3

What is

a tertiary alcohol?

Answer 3

This is an alcohol that has 3 alkyl groups attached to the carbon bearing the -OH group.
It can be represented as: RR’R”COH

Question 4

Can tertiary alcohols be oxidised?

Answer 4

No

This can be used as a differentiating test btw primary and secondary alcohols from tertiary alcohols. The 2 turn acidified K₂Cr₂O₇ solution green its original orange to but the latter shows no colour change

Question 5

Why can’t tertiary alcohols be oxidised?

Answer 5

Oxidation is also the removal of hydrogen, in a tertiary alcohol, there is no more hydrogen to be removed

They cannot be oxidised without the breakage of a C-C bond which requires a lot of energy

Question 6

What reactions do alcohols undergo?

Answer 6

1. Oxidation
2. Dehydration (to an alkene)
   3.

Question 7

How are alcohols formed?

Answer 7

1. By hydration of an alkene
2. By the reaction of water or OH^- and a haloalkane
3. By fermentation

Question 8

What kind of reaction

is the hydration of alkenes to form alcohols called?

Answer 8

An electrophilic substitution reaction

Question 9

What kind of reaction

is the formation of alcohols from halogenoalkanes called?

Answer 9

A nucleophilic substitution reaction

Question 10

If the nucleophilic substitution reaction

was said to take on the S_N1 mechanism, what can one expect in the slow step?

Answer 10

The carbocation is formed first before nucleophilic attack occurs

Question 11

If the nucleophilic substitution reaction

was said to take on the S_N2 mechanism, what can one expect in the slow step?

Answer 11

The C-X bond breaks as the carbon froms the bond with the nucleophile

Question 12

What kind of alcohol

can be formed from the nucleophilic substitution of haloalkanes using the S_N2 mechanism?

Answer 12

A primary or secondary alcohol

Question 13

What kind of alcohol

can be formed from the nucleophilic substitution of haloalkanes using the S_N1 mechanism?

Answer 13

A tertiary or secondary alcohol

Question 14

What are the reaction conditions (reagents, catalyst, products)

for the formation of alcohols from halogenoalkanes called?

Answer 14

1. REAGENTS: The halogenoalkane and NaOH/KOH
2. SOLVENT: Water (an aqueous solution)
3. PRODUCT: An alcohol and the sodium halide

the OH^- group is the nucleophile in this case, however, water can also be used as a nucleophile, in that case a hydrogen halide would be formed

Question 15

What happens when an ethanolic solution of NaOH/KOH is used for the reaction with halogenoalkanes?

Answer 15

An elimination reaction occurs and an alkane is formed instead

The carbon bearing the C-X bond looses the Halogen and one of the carbons beside it loses one Hydrogen atom, the C=C bond is formed between these two carbons

Question 16

What does the (Na)OH^- acts as in this case, water is formed from it and the hydrogen taken from one carbon

Answer 16

A base

The OH^- accepts the liberated hydrogen to form water.

Question 17

What is there to note

about the nature of the haloalkane before choosing water or NaOH as your reactant?

Answer 17

Its solubility in water

Question 18

What are the reaction conditions

for the hydration of an alkene?

Answer 18

The reaction is catalysed by a protic acid

E.g.: H₃PO₄ or H₂SO₄

water itself is a weak acid and is unable to duly protonate (provide the H⁺ electrophile needed to attack the double bond). This is provided by the acid instead

Question 19

Does the hydration of an alkene follow Markovnikov’s rule?

where necessary

Answer 19

Yes

Question 20

What is the name of the reverse reaction that forms alkenes from alcohols?

Answer 20

Dehydration

This reaction is catalysed by concentated H₂SO₄

Question 21

What is esterification?

Answer 21

This is the reaction of an alkanol and a carboxylic acid to produce an ester and water

Question 22

What characterises the esterification reaction?

Answer 22

It is a reversible reaction

If nothing is taken out of the reacting system, the backward reaction can occur

Question 23

What catalyses the esterification reaction?

Answer 23

conc. H₂SO₄

Question 24

What is the reverse reaction of esterification called?

Answer 24

Hydrolysis

Question 25

What is a poignant physically-observable characteristic of esters?

Answer 25

They have a sweet smell

Question 26

In an esterification reaction,

what donates the Hydrogen to form the water molecule

Answer 26

The alkanol

contrary to what one would have thought

Question 27

In an esterification reaction,

what donates the -OH group to form the water molecule

Answer 27

The carboxylic acid

contrary to what one would have thought

Question 28

Is esterification the same as neutralisation?

Answer 28

No

Though they have similar products, they are not the same

Question 29

What kind of reaction

is esterification?

Answer 29

A condensation reaction

The small molecule eliminated is water

Question 30

What is

a condensation reaction?

Answer 30

A reaction in which two molecules combine to form a single molecule with the elimination of a small molecule.

Such as water, ethanol or ammonia.

Question 31

What are the reaction conditions

for the oxidation of a primary alcohol to an aldehyde?

Answer 31

Distillation and heating

Question 32

What are the reaction conditions

for the oxidation of a secondary alcohol to a ketone?

Answer 32

Heating

Question 33

What are some uses of esters?

Answer 33

They are used :
1. As food flavourings
2. In saponification reactions
3. In perfume making
4. As plasticsers (in plastic making)

Question 34

From what side do you start naming an ester?

Answer 34

From the side from the alcohol