Haloalkanes

Question 1

Why is the c-x bond polar?

Answer 1

Halogen is more electronegative that c

Question 2

Do haloalkanes react with nucleophiles or electrophiles?

Answer 2

Nucleophiles ( electron pair donors)

Question 3

What mechanism do haloalkanes undergo ?

Answer 3

Nucleophillic substitution

Question 4

How to haloalkanes form alcohols?

Answer 4

They are reacted with water ( slowly) or aq hydroxide ions (quicker) = hydrolysis

Question 5

Give the general equation for the hydrolysis of a haloalkanes using NaOH

Answer 5

RX + NaOH —> ROH + NaX

Question 6

What type of fission happens when the C-X bond breaks in nucleophillic sub?

Answer 6

Heterolytic

Question 7

How to you detect the presence of an alkane ?

Answer 7

AgNO3
White ppt = Cl-
Cream ppt = Br-
Yellow ppt = I- (insoluble in NH4)

Question 8

What is the process for comparing the rates of hydrolysis of haloalkanes ?

Answer 8

• Use haloalkanes with the same chain length but different alkane
• put haloalkane in a test tube and AGNO3 in a test tube
• place in 50° water bath
• at the same time pour AgNO3 test tube into haloalkanes
• record time for precipitate to form
• repeats for other haloalkanes
• rate = 1/time

Question 9

What is the rate of hydrolysis of a haloalkane determined by ?

Answer 9

The strength of the c-x bond
C-Cl has the highest bond enthalpy so slowest reaction time
C-I has lowest so quickest reaction time

Question 10

What were haloalkanes found to do to the environment when used in refrigerants ?

Answer 10

Deplete ozone layer

Question 11

What compound contributes to the depletion of the ozone layer?

Answer 11

CFCl2

Question 12

Shia the radical substitution mechanism for the depletion if the ozone layer

Answer 12

CFCl2 —> Cl* + CF2Cl* (UV)

O3 + Cl* —> O2 + ClO*

ClO* + O —> O2 + Cl*

Overall
O3 + O —> 2O2