Unit 6

Question 1

What is an aldehyde?

Answer 1

Has a c=o at the end of a molecule

Question 2

What is a ketone?

Answer 2

Has a c=o in the middle of the molecule

Question 3

What are some properties of aldehydes and ketones?

Answer 3

Polar
miscible with water
volatile

Question 4

What is the suffix for an aldehyde?

Answer 4

Al

Question 5

What is the suffix for a ketone?

Answer 5

one

Question 6

How can you make an aldehyde from a primary alcohol?

Answer 6

By adding PCC (weal oxidising agent)

Question 7

How can you make a ketone from a secondary alcohol?

Answer 7

potassium dichromate and sulphuric acid. (K2cr207 & h2so4) acidic conditions are best can just put (H+)

Question 8

What can ozonolysis be used for?

Answer 8

To find the position of a double bond

Question 9

What is ozonolysis?

Answer 9

Splitting of a double bond and inserting oxygens creating two carbonyl derivatives. Two molecules with c=o will be formed

Question 10

What is PCC

Answer 10

A weak oxidising agent that is selective so can be used to oxidise a primary alcohol to an aldehyde

Question 11

How can you produce benzaldehyde? (using chlorine)

Answer 11

React methylbenzene and chlorine in UV (form free radical) light then reflux to get benzaldehyde

Question 12

How can you reduce benzoyl Chloride to get benzaldehyde? (aromatic)

Answer 12

Reduce benzoyl chloride using hydrogen and palladium catalyst mixed with barium sulfate

Question 13

Why do addition reactions take place on aldehydes and ketones?

Answer 13

the c=o is polar as o is very electronegative. This slight positive charge on the C allows for nucleophilic attack which breaks the double bond (pi) and means H+ can be attached to the o (OH) as its down in acidic conditions

Question 14

How do aldehydes and ketones react with water?

Answer 14

to form diols/hydrates but they arent very stable

Question 15

What happens when you react an aldehyde with a alcohol?

Answer 15

Form an ether it can be used to protect ketone groups from further reaction

Question 16

What colour does Na2Cr207 turn in the presence of an aldehyde

Answer 16

Goes from orange to green

Question 17

Ketones are very hard to oxidise true or false?

Answer 17

True

Question 18

Why is there difference in reactivity between aldehydes and ketones

Answer 18

Aldehyde is more reactive. as its less sterically hindered

less inductive groups (e- donating trying to stabilise) so the carbon centre is more + than in a ketone

Question 19

Test for the carbonyl group? (aldehyde or ketone)

Answer 19

2-4 dinitrophenylhydrazine. If theres aldehydes or ketones present there will be an orange precipitate formed

Question 20

Test for aldehydes?

Answer 20

Tollens reagent. Clear solution will turn like a silver mirror.
Can also use Fehlings solution which will turn from blue to orange

Question 21

What happens if you condensate two aldehydes?

Answer 21

you make an aldol (2 functional groups)

Question 22

What do alcohols contain?

Answer 22

OH hydroxyl group

Question 23

what are primary secondary and tertiary alcohols

Answer 23

Primary- Carbon with the OH is bonded to 1 other C
Secondary- Carbon with the OH is bonded to 2 other Cs
Tertiary- Carbon with the OH is bonded to 3 other Cs
Phenol- bonded to benzene

Question 24

What numbers correspond to Ortho?

Answer 24

1,2

Question 25

What numbers correspond to Meta?

Answer 25

1,3

Question 26

What numbers correspond to para

Answer 26

1,4

Question 27

How do you get from an alkene to an alcohol?

Answer 27

An acid catalyst and water

Question 28

How do you get from a carboxylic acid to a alcohol?

Answer 28

Lithium aluminium hydride in acidic conditions

Question 29

How do you get from a halogen alkane to an alcohol?

Answer 29

Sodium hydroxide

Question 30

Why do alcohols have high boiling points?

Answer 30

Hydrogen bonding and permanent dipole to dipole attractions

Question 31

Small alcohols are miscible in water but this decreases with the size of the alkyl group

Answer 31

Alkyl group is non polar. The polar hydrogen bonds between OH is what makes it miscible so if you increase non polar bit you decrease solubility

Question 32

Alkyl group decreases acidity in alcohols, why?

Answer 32

more Ch3 bonds push electrons to the O

Question 33

Halogens increase acidity in alcohols, why?

Answer 33

They pull electrons towards themselves making H+ even more positive

Question 34

Why is phenol more acidic than another alcohol?

Answer 34

Phenol is much more stable as the delocalized electrons can distribute the charge. Because it is stable it doesn't mind losing the H as much. Also the H gets even more positive

Question 35

Reduction of aldehydes and ketones using sodium borohydride gives what?

Answer 35

Alcohols

Question 36

How can you get and alcohol from aldehydes and ketones?

Answer 36

Reduce them using sodium borohydride

Question 37

Reacting an alcohol with sulfuric acid gives?

Answer 37

An alkene

Question 38

Reacting an alcohol with sodium dichromate and sulfuric acid gives what?

Answer 38

Carboxylic acid

Question 39

Reaction of an alcohol with PCC gives?

Answer 39

An aldehyde