Organic Chemistry

Section 20.1 Reduction Reactions 845

3-D Molecules:

Styrene;

Ethyl benzene

Murray Raney (1885–1966)was

born in Kentucky. He received a B.A.

from the University of Kentucky in

1909, and in 1951 the university

awarded him an honorary Doctor

of Science. He worked at the Gilman

Paint and Varnish Co. in

Chattanooga, Tennessee, were he

patented several chemical and

metallurgical processes. In 1963,

the company was sold and renamed

W. R. Grace & Co., Raney Catalyst

Division.

Catalytic hydrogenation can also be used to reduce carbon–nitrogen double and triple

bonds. The reaction products are amines.

The carbonyl group of ketones and aldehydes can be reduced by catalytic hydro-

genation, with Raney nickel as the metal catalyst. (Raney nickel is finely dispersed

nickel with adsorbed hydrogen, so an external source of is not needed.) Aldehydes

are reduced to primary alcohols, and ketones are reduced to secondary alcohols.

The reduction of an acyl chloride can be stopped at an aldehyde if a partially deac-

tivated catalyst is used. This reaction is known as the Rosenmund reduction. The cat-

alyst for the Rosenmund reduction is similar to the partially deactivated palladium

catalyst used to stop the reduction of an alkyne at a cis alkene (Section 6.8).

The carbonyl groups of carboxylic acids, esters, and amides are less reactive, so

they are harder to reduce than the carbonyl groups of aldehydes and ketones

(Section 18.5). They cannot be reduced by catalytic hydrogenation (except under ex-

treme conditions). They can, however, be reduced by a method we will discuss later in

this section.

C

O

C

O

a carboxylic acid

no reaction

H 2

Raney Ni

no reaction

H 2

Raney Ni

H (^2) no reaction
Raney Ni
an ester
an amide
CH 3 CH 2 OH
C
O
CH 3 CH 2 OCH 3
CH 3 CH 2 NHCH 3
C
O
an acyl chloride an aldehyde
H 2
partially
deactivated
Pd
CH 3 CH 2 Cl
C
CH 3 CH 2 H
O
OH
CH 3 CH 2 CHCH 3
H 2
Raney Ni
H 2
Raney Ni
a secondary alcohol
a ketone
CH 3 CH 2 CH 2 CH 2 OH
a primary alcohol
an aldehyde
C
CH 3 CH 2 CH 3
O
C
CH 3 CH 2 CH 2 H
O
H 2
CH 3 CH 2 CH NCH 3 + H 2 CH 3 CH 2 CH 2 NHCH 3
Pd/C
Pd/C
CH 3 CH 2 CH 2 CN
methylpropylamine
butylamine

• 2 H 2 CH 3 CH 2 CH 2 CH 2 NH 2
  CH CH 2
  H 2
  Pd/C CH^2 CH^3
  Karl W. Rosenmund (1884–1964)
  was born in Berlin. He was a
  professor of chemistry at the
  University of Kiel.
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