Functional Group Chemistry 3

Question 1

Describe alcohols

Answer 1

Unsaturated or saturated
O = sp3
Act as Nu-
Reactivity controlled by e- rich O

Question 2

What happens to alcohol boiling point as homologous sequence increases?

Answer 2

Increases

Question 3

Why do alcohols have unusually high boiling points?

Answer 3

H bonding

Question 4

What happens to solubility of alcohols as size of alkyl group increases?

Answer 4

Decreases

Question 5

What is the pKa range of alcohols?

Answer 5

15.5-18.0

Question 6

What happens to acidity of alcohols as alkyl group increases?

Answer 6

Decreases

Question 7

What do halogens do to alcohols?

Answer 7

Increase acidity = e- withdrawal

Question 8

What is the preparation of alcohols?

Answer 8

CO + 2H2 —-> CH3OH
400 degrees
ZnO/CrO3

Question 9

What are the 3 main ways more complex alcohols are formed?

Answer 9

Hydration of alkenes
Hydrolysis of alkyl halides
Reduction of aldehydes/ketones/esters

Question 10

What can the aldehyde be reduced to?

Answer 10

Primary alcohol

Question 11

What can a carboxylic ester be reduced to?

Answer 11

Primary alcohol

Question 12

What can a carboxylic acid be reduced to?

Answer 12

Primary alcohol

Question 13

What is a ketone reduced to?

Answer 13

Secondary alcohol

Question 14

What are aldehydes and ketones reduced by?

Answer 14

Sodium borohydride = NaBH4
OR
Lithium aluminium hydride = LiAlH4

Question 15

What can acids + esters only be reduced by?

Answer 15

LiAlH4

Question 16

How can alkoxides be formed?

Answer 16

React ethanol with sodium metal (redox reaction)
OR
Cleavage of haloalkanes by hydroxide
Conversion to haloalkanes

Question 17

Describe addition of H-X to alcohols

Answer 17

HCl, HBr or HI
Displaces hydroxyl with halogen
Form haloalkane

Question 18

How is an ester formed from an alcohol?

Answer 18

Acid + alcohol ⇆ ester + H2O

H+ catalyst = H2SO4

Question 19

What is the equation for acid dehydration?

Answer 19

Acid + alcohol ⇆ ester + H2O

Question 20

What is the equation for acid hydrolysis?

Answer 20

Ester + H2O ⇆ acid + alcohol

Question 21

What are alcohols oxidised to?

Answer 21

Aldehydes —-> carboxylic acids

Ketones

Question 22

What is needed for alcohol oxidation?

Answer 22

Metal salts

Question 23

Describe phenols

Answer 23

Planar
C-O bond distance shorter
Unusual H bonding

Question 24

What does the hydroxyl group of phenols allow?

Answer 24

H bonding to other phenol molecules in H2O

Question 25

What does the H bonding in phenols do?

Answer 25

Raises melting point | Increases solubility in H2O

Question 26

What is phenoxide stabilised by?

Answer 26

Resonance

Question 27

What do phenols have compared to alcohols?

Answer 27

Higher acidity

Question 28

Describe haloalkanes

Answer 28

Act as E+ Reactivity controlled by e- poor C C can be attacked by Nu- Halogen can leave with e- pair

Question 29

What does it mean that the C-halogen bond is polar?

Answer 29

Bonded C has partial positive charge

Question 30

What does a haloalkane have compared to alkane?

Answer 30

Higher boiling point | = greater polarizability of C-X bond

Question 31

What is the density of liquid haloalkanes compared to hydrocarbons?

Answer 31

Higher

Question 32

How are haloalkanes prepared?

Answer 32

Free radical substitution of alkanes Electrophilic addition to alkenes Halogenation of alcohols Halogenation of alkenes/alkynes

Question 33

Describe nucleophilic substitution of haloalkanes

Answer 33

Alkyl halides polarised at C-X bond = C electrophilic | Nu- replaces halide in C-X bond