Haloalkanes

Question 1

Test for X via hydrolysis

Answer 1

Neutralise solution with nitric acid + AgNO₃. Ag should become AgX

Question 2

Key features

Answer 2

Polar, covalent C-X

↑size = ↓C-X bond strength, therefore ↓activation energy

Question 3

Primary haloalkane reaction

Answer 3

Nucleophilic substitution:

Nucleophile e.g OH- approaches δ+ C opposite δ-X and forms dative bond

C-X bond is simultsneously broken, releasing halide ion

Question 4

C-X →OH

Answer 4

React with warm NaOH to produce OHs via nuc sub. Mechanism = hydrolysis

Question 5

HX →nitriles, RCN

Answer 5

HX+ potassium cyanide via ethanol, nuc sub occurs

CN- ion is nucleophile, so C skeleton extends +1

Nitrile can by hydrolysed to make COOH

Question 6

HX + NH₃

Answer 6

HX →primary amines, RNH₂ via nuc sub

As N has lone pair, excess NH₃ can = more substitution →R₂NH, R₃N, R₄N+X-

Question 7

HX →C=C

Answer 7

HX + KOH via OH

Elimination reaction
•OH- is base, an H is lost from C bearing X. Result = 2 isomeric alkenes