ketones and aldehydes

Question 1

formation of hemiacetals

Answer 1

addition of a molecule of alcohol to the carbonyl group

Question 2

roles of acid catalyst

Answer 2

makes the carbon susceptible to nucleophilic attack

Question 3

addition of an amine

Answer 3

results in the formation of imines

1) reaction with a nucleophile to form a new bond
2) conversion of OH to H20c (a better leaving group)
3) Removal of proton from N forms the double bond

Question 4

alpha halogenation

Answer 4

Reaction occurs via the enol tautometer

Question 5

oxidation of aldehydes

Answer 5

Aldehydes are easily oxidised by common oxidising agents to carboxylic acids

Question 6

oxidation of ketones

Answer 6

Not easily oxidised

oxidised via the enol form at high temperatures by strong agents

Question 7

reduction

Answer 7

a Carbonyl group is reduced to OH in the presence of hydrogen and a transition metal catalyst

Question 8

Reduction with metal hydrides

Answer 8

Carbonyl group is reduced to OH
Nucleophillic attack, Hydirde ion acts as the nucleophile forming a tetrahedral carbonly intermediate (O- BH3+)
- proton transfer from water forms hydroxi group

Question 9

Grinard Reagents

Answer 9

Acts as strong bases by donation electrons in the C-MG bond