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Org. Synth. 1958, 38, 32
DOI: 10.15227/orgsyn.038.0032
5-FORMYL-4-PHENANTHROIC ACID
[4-Phenanthrenecarboxylic acid, 5-formyl-]
Submitted by R. E. Dessy and M. S. Newman1.
Checked by J. D. Roberts and D. I. Schuster.
1. Procedure

Caution! Ozone is extremely toxic and can react explosively with certain oxidizable substances. Ozone also reacts with some compounds to form explosive and shock-sensitive products. Ozone should only be handled by individuals trained in its proper and safe use and all operations should be carried out in a well-ventilated fume hood behind a protective safety shield. [Note added September 2009].

A solution of 25 g. (0.125 mole) of pyrene (Note 1) in 100 ml. of dimethylformamide (Note 2) and (Note 3) is treated with a 50% excess of ozone (Note 4). The solution of the ozonide is added at a moderate rate, with stirring, to 500 ml. of 1% aqueous acetic acid. The suspension is allowed to stand overnight (Note 5), and the resulting solid is collected by filtration and washed with water.
The moist solid is suspended in 200 ml. of 10% aqueous potassium hydroxide solution, and the suspension is boiled for 5 minutes. The hot solution is filtered, and the remaining solid is again extracted, using 100 ml. of potassium hydroxide solution.
To the dark-brown combined filtrates is added 100 ml. of potassium hypochlorite solution (Note 6), and the resulting solution is permitted to stand overnight. The mixture is then heated on a steam bath for 4 hours. The resulting orange solution is filtered while hot, and 100 ml. of 35% sodium hydroxide solution is added. The solution is cooled to 5°, the resulting solid is collected by filtration and washed with a small amount of saturated sodium chloride solution.
The moist sodium salt is digested with 50 ml. of cold 6N hydrochloric acid, and after several hours the mixture is filtered and the resulting solid acid dried.
The crude acid is dissolved in 100 ml. of boiling dimethylformamide, and 100 ml. of hot glacial acetic acid is added. Water is added to the hot solution until it becomes cloudy, and then just enough dimethylformamide is added to render the solution clear again. It is cooled to 5°, and the resulting acid collected by filtration and washed with glacial acetic acid. Upon drying, 10–11.5 g. (32–38%) of 5-formyl-4-phenanthroic acid (Note 7), melting at 272–276° (Note 8), is obtained.
2. Notes
1. Technical pyrene, Reilly Tar and Chemical Corp., was employed. Purification did not improve the over-all yield, and purer pyrene is not sufficiently soluble in dimethylformamide.
2. Freshly distilled dimethylformamide should be employed. The yields with the technical grade solvent were very erratic.
3. Complete solution is attained by heating the mixture for 5 minutes on a steam bath.
4. An ozonizer similar to that described by Henne and Perilstein2 was employed. At an oxygen flow rate of 30 l./hr. it produced about 30 millimoles of O3 per hour (3% conversion). Under these conditions the ozonization of 25 g. of pyrene requires about 6 hours.
5. Filtration of the hydrolyzate immediately after decomposition is difficult because of the fine nature of the solid. Upon standing, coagulation takes place to yield a granular brown solid.
6. The potassium hypochlorite solution was prepared3 from the calcium hypochlorite sold by Mathieson Chemical Corporation under the trade name HTH. If the HTH reagent used is not fresh, it is found that subsequent heating of the filtrate with the potassium hypochlorite solution does not result in an orange solution. The solution remains dark brown, and the product is distinctly brown. The yield is not affected.
7. Unpublished experiments indicate that 5-formyl-4-phenanthroic acid exists mainly in the cyclic hydroxylactone form.
8. The checkers found that the melting point depends on the rate of heating. A reproducible melting point was obtained if the sample was placed in the bath at 270° and the temperature raised at the rate of two degrees per minute.
3. Discussion
The only reported method of preparation of 5-formyl-4-phenanthroic acid is by the reaction described here.4

References and Notes
  1. Ohio State University, Columbus, Ohio.
  2. Henne and Perilstein, J. Am. Chem. Soc., 65, 2183 (1943).
  3. Org. Syntheses Coll. Vol. 2, 429 (1943).
  4. Vollmann, Becker, Corell, and Streeck, Ann., 531, 65 (1937).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

hydrochloric acid (7647-01-0)

acetic acid (64-19-7)

sodium hydroxide (1310-73-2)

sodium chloride (7647-14-5)

oxygen (7782-44-7)

potassium hydroxide (1310-58-3)

potassium hypochlorite

ozone (10028-15-6)

calcium hypochlorite (7778-54-3)

pyrene (129-00-0)

dimethylformamide (68-12-2)

5-Formyl-4-phenanthroic acid,
4-Phenanthrenecarboxylic acid, 5-formyl- (5684-15-1)