Nucleophilic addition reaction

Question 1

to produce a hydroxynitrile from a carbonyl compound, the reagents and conditions are:

Answer 1

-the reagent if hydrogen cyanide and the reaction is carried out in aqueous alkaline solution containing potassium cyanide (KCN)

Question 2

the (simplified) equation for the reaction between propanone and potassium cyanide is:

Answer 2

CH3COCH3 + HCN → CH3C(CN)(OH)CH3

Question 3

the reaction with hydrogen cyanide is a………

………. reaction

Answer 3

addition reaction, nucleophilic

Question 4

name the compound formed when propanal reacts with hydrogen cyanide:

Answer 4

CH3CH2CHO + HCN → CH3CH2CH(OH)CN

2-hydroxybutanenitrile (the extra C from the HCN prolongs the chain, so a propan- chain becomes a butan- chain

Question 5

nucleophilic addition is a ………. step mechanism

Answer 5

2 step

Question 6

the steps for the reaction of a carbonyl compound with hydrogen cyanide are:

Answer 6

1) the nucleophilic attack by a cyanide ion on the carbon atom of the carbonyl group
H H
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O~- = C~+ :CN- → NC - C - O:-
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H H
2)the reaction between the intermediate and a hydrogen cyanide molecule
H H
| |
NC - C - O:- H-CN → NC - C - OH + CN-
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H H

Question 7

if the carbonyl compound then forms a hydroxynitrile with a chiral centre, the chance of either enantiomer forming is

Answer 7

equal, 50% chance for each as the nucleophile can attack from either or below the plane and has a 50% chance of done either

Question 8

the real name for Brady’s reagent is

Answer 8

2,4-dinitrophenylhydrazine

Question 9

brady’s reagent can be used to test for most carbonyl compounds to form

Answer 9

a brightly coloured orange precipitate

Question 10

we can test for individual carbonyl compounds by testing them with…………………and then

Answer 10

do the Brady’s reagent test then filter and dry the orange precipitate formed and test the melting temperature