Phenidone Explained

Phenidone (1-phenyl-3-pyrazolidinone) is an organic compound that is primarily used as a photographic developer. It has five to ten times the developing power as Metol, capable of achieving the same level of development in both less time and at a lower concentration.^[1] It also has low toxicity and unlike some other developers, does not cause dermatitis upon skin contact.^[2] As a developer, Phenidone is typically used in conjunction with hydroquinone for black and white photography and performs better at lower pH levels.^[3]

Phenidone is Ilford's trademark for this material, which was first filed on Feb. 24, 1953, but has since expired.^[4] Although the compound was first prepared in 1890; it was not until 1940 that J. D. Kendall, in the laboratories of Ilford Limited, discovered the reducing properties of this compound. Large scale production did not become feasible until 1951.^[5]

Phenidone functions as a reducing agent. It converts to the N-phenyl-hydroxypyrazole. It is oxidized in acidic conditions, contributing the electrons it loses to reduce silver halides such as those found in film:^[6]

Phenidone is also a dual cyclooxygenase/lipoxygenase inhibitor, capable of blocking the synthesis of arachidonic acid, which plays a role in causing inflammation in systemic inflammatory response syndrome^[7] and neuronal damage in kainic acid-induced seizures.^[8]

Preparation

Phenidone can be prepared by heating phenyl hydrazine with 3-chloropropanoic acid.^[2]

Notes and References

1. Axford . A.J. . Kendall . J.D. . January 1, 1954 . Phenidone—Part 1; The Mechanism of its Developing Action and its Super-additivity with Hydroquinone * . The Journal of Photographic Science . en . 2 . 1 . 1–7 . 10.1080/03700240.1954.11736538 . 0370-0240.
2. Merck Index of Chemicals and Drugs, 9th ed. monograph 7115
3. Mason . L. F. A. . January 1, 1965 . Role of Phenidone in Modern Processing . The Journal of Photographic Science . en . 13 . 4 . 205–209 . 10.1080/00223638.1965.11737306 . 0022-3638.
4. Web site: Trademark Status & Document Retrieval . 2024-11-19 . tsdr.uspto.gov.
5. Karlheinz Keller et al. "Photography" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim.
6. Spirin . M. G. . Brichkin . S. B. . Razumov . V. F. . 2002 . Phenidone Oxidation during Photoinitiated Chemical Reduction of AgBr Nanocrystals in Water Pools of Reverse Micelles . Colloid Journal . 64 . 3 . 364–368 . 10.1023/A:1015981028758.
7. Schroeder . Torsten . March 2008 . Activity of the lipoxygenase inhibitor 1-phenyl-3-pyrazolidinone (phenidone) and derivatives on the inhibition of adhesion molecule expression on human umbilical vascular endothelial cells . Biologics: Targets & Therapy . en . 151 . 10.2147/BTT.S2542 . 1177-5475 . 2727783 . 19707438 . free.
8. Kim . Hyoung-Chun . Jhoo . Wang-Kee . Bing . Guoying . Shin . Eun-Joo . Wie . Myung-Bok . Kim . Won-Ki . Ko . Kwang Ho . August 18, 2000 . Phenidone prevents kainate-induced neurotoxicity via antioxidant mechanisms . Brain Research . en . 874 . 1 . 15–23 . 10.1016/S0006-8993(00)02560-9.