Organic Reactions Volume 4 - Sciencemadness Dot Org

SYNTHESIS OF BENZOQUINONES BY OXIDATION 353
silver oxide to give such varied types as ^-camphor-10-sulfonylquinone
330 (30-80% yield), 2,5-dibenzoylquinone 331 (70% crude yield), and
carbomethoxyquinone 332 (60% yield). Carbomethoxyquinone is so
sensitive that it can be prepared with no other oxidizing agent.
Only two benzoquinones with a free carboxyl group attached directly
to the quinone nucleus have been obtained. Durylic acid quinone, 95 ' 333
results in quantitative yield from oxidation of 2,4,5-trimethyl-3,6-diaminobenzoic
acid with ferric chloride. Triphenylquinonecarboxylic
acid 238a is obtained by oxidation of the corresponding hydroquinone
with ferric chloride. The instability of such acids is probably due in
NH2
H3CV^iCO2H
H1Oi^JcH,
NH2
PeCl,
~r
H3(V -^X -J]CO2H
H3d
O
v-x
Y
O
JcH3
part to the 0~keto acid grouping. 333 " Attempted preparations of quinone
acids and esters have been published. 95 ' 332
A variety of dialkylaminoquinonedisulfonates has been prepared by
oxidizing a mixture of hydroquinone, the appropriate amine, and sulfur
dioxide with air in the presence of cupric hydroxide. 334 " 338 No yields
are reported.
O
f^S + CV NH 4- SO ^U CH3HN^SSO2OH-CH3NH2
kj + CH3NH2 + s ° 2 5^i£ CH3NH2.HOO2SIJNHCH3
T
Dimetliylammonium 2,5-dimethylaminoquinone-3,6-disulfonate
Chromic acid-sulfuric acid mixture has been useful for preparing a
number of rather sensitive quinones. Oxidation of benzoylhydroquinone
gives benzoylquinone in 77% yield, 339 and dibenzoylhydroquinone gives
330 Hunter and Kvalnes, J. Am. Chem. Soc, 54, 2880 (1932).
331 Pummerer and Buchta, Ber., 69, 1021 (1936).
832 Brunner, Monatsh., 34, 913 (1913).
333 Smith and Denyes, J. Am. Chem. Soc, 56, 475 (1934).
333a Loewy, Ber., 19, 2387 (1886).
334 Garreau, Compt. rend., 202, 1186 (1936).
335 Garreau, Compt. rend., 203, 1073 (1936).
336 Garreau, Compt. rend., 204, 692 (1937).
337 Garreau, Compt. rend., 204, 1570 (1937).
338 Garreau, Ann. chim., 10, 485 (1938).
3,9 Bogert and Howells, J. Am. Chem. Soc, 52, 844 (1930).