Alcohols

Question 1

Example of alcohol name with more than one OH:-

Answer 1

Ethan-1,2-diol

Question 2

What is the stability order of alcohols?

Answer 2

3o>2o>1o

Question 3

Primary alcohol:-

Answer 3

Carbon bonded to OH is bonded to one carbon.

Question 4

Secondary alcohol:-

Answer 4

Carbon bonded to OH is bonded to 2 carbons

Question 5

Tertiary alcohol:-

Answer 5

Carbon bonded to OH is bonded to 3 carbons

Question 6

What does O in square brackets represent?

Answer 6

Oxidising agent

Question 7

How do you name an aldehyde?

Answer 7

Use root (e.g meth) with -anal i.e. Methanal

Question 8

What is obtained by alcohol reaction with an oxidising agent?

Answer 8

Aldehyde/ketone and H2O

Question 9

How do you name ketones?

Answer 9

Root -an one

E.g. Propanone

Question 10

Aldehyde functional group:-

Answer 10

C with x bond, double bond to O and single bond to H

Question 11

Ketone functional group:-

Answer 11

C with two single C bonds and a double O bond

Question 12

What can be oxidised to a carboxlylic acid?

Answer 12

Aldehyde

Question 13

Aldehyde/alcohol/ketone test:-

Answer 13

1) Add 1cm depth of each solution to a separate test tube.
2) Add 1cm depth potassium dichromate and 2cm depth of dilute sulfuric acid. Mix thoroughly.
3) Heat each gently in a water bath, pointing away from face.
4) note observations.

Question 14

Test results for tertiary alcohol:-

Answer 14

Not oxidised (stayed orange) + relatively high boiling point.

Question 15

Test results for primary alcohol:-

Answer 15

Oxidised (green) + relatively high boiling point.

Question 16

Test results for ketone:-

Answer 16

Stays orange- can’t be oxidised further as would require breaking C-C bonds

Question 17

Aldehyde test result:-

Answer 17

Oxidised to carboxylic acid (orange to green)

Question 18

Aldehyde and ketone boiling boints relative to alcohols

Answer 18

Relatively lower due to alcohols’ hydrogen bonding.

Question 19

Aldehyde and ketone boiling boints relative to alkanes

Answer 19

Relatively higher due to alkanes’ weak induced dipole-dipole attractions.

Question 20

Why is ethanol a polar molecule?

Answer 20

O is v. electromagnetic so delta neg and consequently the other atom become delta pos. Non-symmetrical dipole distribution and a permanent dipole lead to a polar molecule.

Question 21

Why is ethanol boiling point higher than propane boiling point?

Answer 21

H only has 1 electron and when pulled away acts like a proton. V. delta pos so V. attracted to lone pair of O on other molecule..

Question 22

What gives a carboxylic acid (and water)?

Answer 22

Prolonged oxidation of a primary alcohol with excess oxidising agent.

Question 23

Carboxylic acid functional group:-

Answer 23

C with double bonded O and single OH.

Question 24

Naming alcohols:-

Answer 24

Use alkane root with -an and the number of where the OH is. Number inbetween this and ‘ol’
E.g propan-2-ol

Question 25

Experimental technique using liebig condenser:-

Answer 25

Reflux

Question 26

Refluxing:-

Answer 26

Boiling then condensing repeatedly

Question 27

2 benefits of reflux:-

Answer 27

Prevents loss by evaporation and allows prolonged oxidation

Question 28

What is needed to dehydrate alcohol:-

Answer 28

H atom on carbon adjacent to C-OH

Question 29

Secondary alcohol to ketone conditions:-

Answer 29

Heat w/ aqueous acidic K2Cr2O7

Question 30

Primary alcohol to carboxylic acid:-

Answer 30

Prolonged heating under reflux with aqueous acidic K2Cr2O7 in excess.

Question 31

Primary alcohol to aldehyde:-

Answer 31

Heat with aqueous acidic K2Cr2O7 and distill product off at once to prevent further oxidation.