Dictionary of Chemistry [6th Ed.]

63 benzoylation

b

benzilic acid rearrangement An
organic rearrangement reaction in
which benzil(1,2-diphenylethan-1,2-
dione) is treated with hydroxide and
then acid to give benzilic acid (2-hy-
droxy-2,2-diphenylethanoic acid):

C 6 H 5 .CO.CO.C 6 H 5 →

(C 6 H 5 ) 2 C(OH).COOH

In the reaction a phenyl group
(C 6 H 5 –) migrates from one carbon
atom to another. The reaction was
discovered in 1828 by Justus von
*Liebig; it was theÜrst rearrange-
ment reaction to be described.

benzoateSee benzenecarboxylate.

benzodiazepines A group of re-
lated psychotic drugs that affect the
central nervous system. They are
used medically in the treatment of
anxiety, insomnia, convulsions, and
alcohol withdrawal. All are addictive
and available only as prescription
drugs in the UK. Common examples
are diazepam (Valium) and Ûuni-
trazepam (Rohypnol).

benzoic acidSee benzenecar-
boxylic acid.

benzoinA colourless crystalline
compound, C 6 H 5 CHOHCOC 6 H 5 ; m.p.

137 °C. It is a condensation product of

*benzenecarbaldehyde (benzalde-

hyde), made by the action of sodium

cyanide on benzenecarbaldehyde in

alcoholic solution. It also occurs natu-

rally as the resin of a tropical tree. It

is both a secondary alcohol and a ke-

tone, and gives reactions characteris-

tic of both types of compound.

benzopyrene A crystalline aro-

matic hydrocarbon, C 20 H 12 ; m.p.

179 °C. It is found in coal tar and is

highly carcinogenic.

1

2 3

4

5

6

9 8 7

10

11

12

2a

5a

8a 7a

12a

Benzopyrene





Benzilic acid rearrangement

Benzfuran isomers

benzoquinoneSee cyclohexadi-

ene-1,4-dione.

benzoylationA chemical reaction

in which a benzoyl group (benzene-

carbonyl group, C 6 H 5 CO) is intro-

duced into a molecule. See acylation.