Advices For Studying Organic Chemistry

A Mechanism for the Reduction Reaction

The Dissolving Metal Reduction of an Alkyne

CC CC

R

R

Li + R R CC

R

R

H

− H

NHEt

Radical anion Vinylic radical

A lithium atom donates an electron to

the π bond of the alkyne. An electron

pair shifts to one carbon as the

hybridization states change to sp^2.

The radical anion acts as

a base and removes a

proton from a molecule

of the ethylamine.

−

CC

R

R H H H

Li CC

R

R

CC

R

R

H NHEt H

Vinylic radical trans-Vinylic anion trans-Alkene

A second lithium atom

donates an electron to

the vinylic radical.

The anion acts as a base and

removes a proton from a second

molecule of ethylamine.

(^)

7.16 MOLECULAR FORMULAS OF HYDROCARBONS:

THE INDEX OF HYDROGEN DEFICIENCY

1. 1-Hexene and cyclohexane have the same molecular formula (C 6 H 12 ):

CH 2 =CHCH 2 CH 2 CH 2 CH 3

1-Hexene Cyclohexane

1) Cyclohexane and 1-hexene are constitutional isomers.

2. Alkynes and alkenes with two double bonds (alkadienes) have the general formula
   CnH2n–2.

1. Hydrocarbons with one triple bond and one double bond (alkenynes) and alkenes