15: Haloalkanes

Question 1

how does one compare the rates of reaction of different C-X bonds?

Answer 1

compare using hydrolysis of haloalkanes with water (nucleophile) and ethanol (to speed up reaction) and presence of AgNO3 (to identify halogen)

Question 2

what is the method for rate of hydrolysis of haloalkanes?

Answer 2

1. add 3 drops of haloalkane to 1cm^3 of ethanol in a test tube
2. Add 0.1moldm^-3 AgNO3 to a test tube
3. let test tubes stand in a water bath at 60 degrees C and wait till they reach a constant temp
4. add 1cm^3 of silver nitrate to each test tube and start stopwatch
5. observe for 5 mins
6. note times when precipitate forms, the colour of precipitate and solubility in ammonia (identification)

Question 3

define nucleophile

Answer 3

electron pair donor

Question 4

what is trend of rate of reaction for C-X bonds?

Answer 4

going down group C-X bond has a weaker bond enthalpy
breaks more easily
rate of reaction increases
(C-I reacts faster, C-Cl reacts slowest)