Advices For Studying Organic Chemistry

temperature and 1 atm pressure.

2) Ethyl bromide (bp 38 °C) and ethyl iodide (bp 72 °C) are both liquids, but ethyl

chloride (bp 13 °C) is a gas.

3) The propyl chlorides, propyl bromides, and propyl iodides are all liquids.

4) In general, higher alkyl chlorides, bromides, and iodides are all liquids and tend

to have boiling points near those of alkanes of similar molecular weights.

5) Polyfluoroalkanes tend to have unusually low boiling points.

i) Hexafluoroethane boils at –79 °C, even though its molecular weight (MW =

138) is near that of decane (MW = 144; bp 174 °C).

6.3 NUCLEOPHILIC SUBSTITUTION REACTIONS

1. Nucleophilic Substitution Reactions:

Nu − + R XXR Nu + −

Nucleophile Alkyl halide

(substrate)

Product Halide ion

Examples:

HO − + CH 3 Cl CH 3 OH + Cl −

CH 3 O − ++CH 3 CH 2 Br CH 3 CH 2 OCH 3 Br −

I − + CH 3 CH 2 CH 2 Cl CH 3 CH 2 CH 2 I + Cl −

2. A nucleophile, a species with an unshared electron pair (lone-pair electrons),
   reacts with an alkyl halide (substrate) by replacing the halogen substituent
   (leaving group).


3. In nucleophilic substitution reactions, the C–X bond of the substrate undergoes
   heterolysis, and the lone-pair electrons of the nucleophile is used to form a new