Reaction of Alkanes (Electrophilic addition)

Question 1

Four reactions that are under electrophilic addition?

Answer 1

1. Addition of Hydrogen Halides
2. Addition of Halogens
3. Formation of Halohydrin
4. Hydration (addition of water)

Question 2

Describe the process of addition of hydrogen halides

Answer 2

(R): conc. HX/ HX(g) in CCl4 solvent

• gaseous HCl and HBr are generated in situs by reacting with NaCl(s) or NaBr(s) with conc. H2SO4
• double bond is broken, add in H and X

Question 3

Describe the process of addition of halogens

Answer 3

(R): X2 in CCl4 (X=Cl/Br)
(C): r.t.p, in dark (preventing free radical sub.)

-double bond is broken, add in X and X

Question 4

Describe the process of formation of halohydrin (haloaocohol)

Answer 4

(R): aq. X2
(C) r.t.p

• 2 steps-> water act as Nu: to attack the carbocation formed in the slow step
• double bond breaks, add in X and OH (water)
• major+minor

Question 5

Describe the process of hydration

1. Industrial
2. Lab

Answer 5

1. Industrial
   (R): H2O (steam), H3PO4, catalyst
   (C): heat, high pressure
2. Lab
   (R&C): cold conc. H2SO4
   -double bond breaks, add in X and X

(R&C): H20, Heat