carbonyl compound reactions

Question 1

describe the carbonyl group structure

Answer 1

C = O
- C is partially positive
- O is partially negative
- making it very polar
- small aldehydes and ketones are completely miscible (dissolve) with water

Question 2

what is an aldehyde group?

Answer 2

C=O on the end

Question 3

what is a ketone?

Answer 3

C=O in the chain

Question 4

describe benzaldehyde

Answer 4

• simplest aromatic aldehyde
• benzene with H-C=O

Question 5

describe phenylethanone

Answer 5

• simplest aromatic ketone
• benzene with H-C=O(CH3)

Question 6

primary alcohols are oxidised to …. by ….

Answer 6

aldehydes
heating and distilling

Question 7

secondary alcohols are oxidised to… by ….

Answer 7

ketones
heating under reflux

Question 8

aldehydes are oxidised to …. by ….

Answer 8

carboxylic acids
heating under reflux

Question 9

what is the reagent for alcohol oxidation?

Answer 9

acidified potassium dichromate

Question 10

what colour does potassium dichromate turn during oxidation?

Answer 10

orange to green

Question 11

aldehydes and ketones are reduced to …

Answer 11

their respective alcohols

Question 12

what is the reducing agent used to reduce aldehydes and ketones?

Answer 12

NaBH4

Question 13

what are the reagents and conditions for reducing aldehydes and ketones?

Answer 13

• NaBH4
• warm using water or ethanol as a solvent
• represented by [H]

Question 14

how does NaBH4 act as a nucleophile?

Answer 14

1) hydride attacks delta positive carbon on the carbonyl and forms a bond
- arrow from H 2 e- to the C and then from double bond to the delta negative O

2) an intermediate forms and then reacts with a water molecule
- arrow from O 2 e- to the H of water and then from bond to O of water

3) organic product is an alcohol
- other product = the hydroxide ion

Question 15

which bonds make up a double bond?

Answer 15

pi and sigma

Question 16

what is the difference between a pi and sigma bond?

Answer 16

pi = p orbitals overlap above and below the planes of adjacent carbon atoms

sigma = p / s orbitals overlap on the same plane of adjacent carbon atoms

Question 17

what property do carbonyl double bonds have, that alkenes don’t? what does this mean?

Answer 17

they are polar
- attract negative charged species
- act as nucleophiles

Question 18

what reaction do carbonyls undergo?

Answer 18

nucleophilic substitution

Question 19

what does an aldehyde reduce to?

Answer 19

primary alcohol

Question 20

what does a ketone reduce to?

Answer 20

secondary alcohol

Question 21

what is the first step in a reduction mechanism?

Answer 21

protonation

Question 22

why are the electrons on H- ion attracted to the carbonyl?

Answer 22

• dipole on carbonyl attracts a pair of electrons on the hydride ion
• the electron pair in the pi bond are repelled onto the oxygen

Question 23

the hydroxide ion is only in the…. not the ….

Answer 23

mechanism
equation

Question 24

what is the role of the H- ion?

Answer 24

nucleophile