Carbonyl Compounds

Question 0

The carbonyl group is present in…

Answer 0

Aldehydes and ketones

Question 1

What is the carbonyl group

Answer 1

C=O

Question 2

What is the functional group for esters

Answer 2

COO

Question 3

Esters can be made from what. How are they named

Answer 3

An alcohol and a carboxylic acid

They are named with 2 parts. The first part comes from the alcohol and the second from the carboxylic acid

Question 4

Uses for esters

Answer 4

Esters are polar liquids, so polar organic compounds will dissolve in them. Also have low boiling points so they evaporate easily from mixtures, making them good solvents in glues and printing inks.

Used in plasticisers, added to plastics during polymerisation to make plastic more flexible. Over time the plasticiser molecules escape, plastic becomes brittle and stiff

Question 5

Esters are easily hydrolysed to form… What are the 2 types of hydrolysis of esters and what is formed

Answer 5

Alcohols

Acid hydrolysis and base hydrolysis, with both you get an alcohol but the second product is different

Question 6

Explain acid hydrolysis of esters

Answer 6

Splits the ester into an acid and an alcohol, have to reflux the ester with a dilute acid such as HCl or H2SO4. Is a reversible reaction so need to add plenty of water to move the equilibrium to the right

Question 7

Explain base hydrolysis of esters

Answer 7

Reflux ester with dilute alkali such as NaOH, get a carboxylate ion and alcohol

Question 8

Fats and oils are esters of…

Answer 8

Fatty acids and glycerol

Question 9

Fatty acids are…

Answer 9

Long chain carboxylic acids, they combine with glycerol to make fats and oils. Fatty acids can be saturated or unsaturated.

Question 10

Most of a fat or oil is made from….properties?

Answer 10

Fatty acid chains

Fats- mainly saturated hydrocarbon chains, fit neatly together, increasing vdw forces between them. Means higher temps needed to melt them, solid at room temp.

Oils- unsaturated hydrocarbon chains, double bonds mean chains are bent and don’t pack together well, decreasing effect of vdw forces. Easier to melt, liquids at room temp.

Question 11

Biodiesel is a mixture of…

Answer 11

Methyl esters of fatty acids

Question 12

How is biodiesel made

Answer 12

React oils with methanol using potassium hydroxide as a catalyst

Question 13

Why is biodiesel not carbon neutral

Answer 13

Energy is used to make the fertiliser to grow the crops, used in planting, harvesting and converting the oil. This energy could come from fossil fuels

Question 14

Oils and fats can be hydrolysed to…

Answer 14

Glycerol, soap and fatty acids

Question 15

Aldehydes info

Answer 15

Have their carbonyl group at the end of the carbon chain. Their names end in -al

Question 16

Ketones info

Answer 16

Have their carbonyl group in the middle of the carbon chain. Their names end in -one, often have a number to show which carbon the carbonyl group is on

Question 17

What happens with Fehlings solutions and Benedicts solution

Answer 17

They are used as oxidising agents. They are both a deep blue Cu2+ complexes, which recuse to brick red Cu2O when warmed with an aldehyde, remain blue with ketone (as ketones aren’t easily oxidised)

Question 18

What happens with Tollens reagent

Answer 18

Ammonical silver nitrate, (Ag(NH3)2)+ reduced to silver when warmed with an aldehyde, but not with ketone. Goes from colourless to metallic silver, which will cost the inside of the apparatus to form a silver mirror

Question 19

You can reduce aldehydes and ketones back to….

Answer 19

Alcohols
NaBH4 dissolved in water with methanol is usually the rescuing agent used. But in equations (H) is often used to indicate a hydrogen from a reducing agent.

Question 20

What oxidising agent turns alcohols to aldehydes and ketones

Answer 20

Acidified potassium dichromate which goes from Orange to green

Question 21

Hydrogen cyanide will react with carbonyls by what mechanism…

Answer 21

Nucleophilic addition.
HCN reacts with carbonyl compounds to produce hydroxynitriles.

HCN=weak acid, partially dissolves in water to form H+ ions and CN- ions. The CN- group Attucks partially positive carbon atom and donates a pair of electrons. Both electrons from double bond transfer to the oxygen. H+ (from either HCN or water) bonds to the oxygen to form the hydroxyl group (OH)

Question 22

A carboxyl group contains which groups

Answer 22

Carbonyl group and a hydroxyl group

Question 23

Carboxylic acids contain which functional group

Answer 23

Carboxyl -COOH always on end of chain and is more important than other functional groups so all the other functional groups in the molecule are numbered starting from this carbon
To name them you find the longest alkane chain take off the ‘e’ and add ‘oic acid’

Question 24

Carboxylic acids are ..... acids

Answer 24

Weak, in water they partially dissolve into a carboxylate ion and an H+ ion

Question 25

Carboxylic acids react with carbonates to form....

Answer 25

Carbon dioxide, a salt, water. CO2 fizzes out of the solution

Question 26

Carboxylic acids react with alcohols to form...

Answer 26

Esters If you heat a carboxylic acid with an alcohol in presence of a strong acid catalyst=ester. Called an esterification reaction, also a condensation reaction as water is released. Conc sulfuric acid usually used as acid catalyst

Question 27

Acyl chlorides have the functional group.... What is their general formula

Answer 27

-COCl CnH2n-1OCl

Question 28

Acyl chlorides react with...

Answer 28

Water Alcohols Ammonia Amines Each time chlorine is substituted by an oxygen or nitrogen group and misty fumes of hydrogen chloride are given off

Question 29

An acid anhydride is made from...

Answer 29

2 identical carboxylic acid molecules

Question 30

Acyl chloride reactions are....

Answer 30

Nucleophilic addition elimination In acyl chlorides both the Cl and O2 atoms draw electrons towards themselves, so carbon has slightest is positive charge so can be attacked by nucleophiles

Question 31

Why is ethanoic anhydride used in industry instead of ethanol chloride

Answer 31

Cheaper than ethanoyl chloride Safer to use than ethanoyl chloride as it's less corrosive, reacts more slowly with water and doesn't produce dangerous hydrogen chloride fumes

Question 32

What is the formula for glycerol

Answer 32

1,2,3-propanetriol

Question 33

Suggest how the rate of reaction of propanone with HCN would compare with the rate of reaction of propanal with HCN when a nucleophile is involved in both reactions

Answer 33

Propanal is a faster reaction as it is easier to attack at the end of the chain. Propanone is slower as the alkyl group is less exposed in the middle of the chain