Halogenoalkanes

Question 1

electronegativity of carbon and halogens

Answer 1

carbon is δ+

halogen is δ-

Question 2

nucleophile

Answer 2

electron pair donor

Question 3

:NH3

Answer 3

no charge

Question 4

:OH- reaction

nucleophilic substitution

Answer 4

produce alcohol

warm aqueous potassium or sodium hydroxide

Question 5

:CN- reaction

nucleophilic substitution

Answer 5

heat with ethanolic potassium cyanide under reflux

Question 6

:NH3 reaction

nucleophilic substitution

Answer 6

ethanolic ammonia + excess amonnia

heat under pressure

C-Br
C-NH3
C-NH2

Question 7

nucleophilic substitution

Answer 7

Nu to C

C-X to X

Question 8

strengths of bonds

Answer 8

C-F strongest, least reactive, highest bond enthalpy

Question 9

Hydrolysis

Answer 9

CH3CH2X + H2O -> CH3CH2OH + X- + H+

Water is a poor nucleophile but it can react slowly with halogenoalkanes in a substitution reaction

Question 10

Aqueous silver nitrate

Answer 10

added to a halogenoalkane. The halide leaving group combines with a silver ion to form a silver halide precipitate.
The precipitate only forms when the halide ion has left the halogenoalkane and so the rate of formation of the precipitate can be used to compare the reactivity of the different halogenoalkanes.

The quicker the precipitate is formed, the faster the substitution reaction and the more reactive the halogenoalkane.

Question 11

AgI

Answer 11

yellow ppt forms fastest

Question 12

AgBr

Answer 12

cream ppt

Question 13

AgCl

Answer 13

white ppt forms slowest

Question 14

elimination

Answer 14

halogenoalkane -> alkene

Reagents: Base, OH-
Potassium (or sodium) hydroxide

Conditions: In ethanol ; heat

Question 15

elimination mechanism

Answer 15

:OH- to H
H-C to C-C
C-Br to Br

Question 16

ozone reaction

Answer 16

Cl. + O3 -> ClO. +O2

ClO. + O3 -> 2O2 + Cl.