Advices For Studying Organic Chemistry

2) Phosphorous tribromide (PBr 3 ):

+ PBr 3 −10 to 0

oC

3 (CH 3 ) 2 CHCH 2 OH 4 h 3 (CH( (^3) 55-60%) 2 CHCH) 2 Br + H 3 PO 3
3) Thionyl chloride (SOCl 2 ):

• SOCl (^2) (an orpyrid neganic base) +HCl
  (91%)
  (forms a salt
  with pyridine)
  H 3 CO CH 2 OH H 3 CO CH 2 Cl
  +SO 2

1.13 ALKYL HALIDES FROM THE REACTION OF ALCOHOLS WITH

1. When alcohols react with a HX, a substitution takes place producing an RX and

i

1

HYDROGEN HALIDES

H 2 O:

R OH + HX R X + H 2 O

1) The order of reactivity of the HX is: HI > HBr > HCl (HF is generally

2) reactivity of alcohols is: 3° > 2° > 1° < methyl.

2. The reaction is acid catalyzed.
   ROH + NaX

unreactive).

The order of

H 2 SO (^4) RX + NaHSO 4 + H 2 O

11.13A MECHANISMS OF THE REACTIONS OF ALCOHOLS WITH HX

1. 2°, 3°, allylic, and benzylic alcohols appear to react by an SN1 mechanism.
   
   
   1. The porotonated alcohol acts as the substrate.