Phenidone

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

Names
Preferred IUPAC name 1-Phenylpyrazolidin-3-one
Identifiers
CAS Number	92-43-3 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL7660 Y
ChemSpider	6823 Y
ECHA InfoCard	100.001.960
EC Number	202-155-1
PubChem CID	7090
UNII	H0U5612P6K Y
CompTox Dashboard (EPA)	DTXSID1049433
InChI InChI=1S/C9H10N2O/c12-9-6-7-11(10-9)8-4-2-1-3-5-8/h1-5H,6-7H2,(H,10,12) Y Key: CMCWWLVWPDLCRM-UHFFFAOYSA-N Y InChI=1/C9H10N2O/c12-9-6-7-11(10-9)8-4-2-1-3-5-8/h1-5H,6-7H2,(H,10,12) Key: CMCWWLVWPDLCRM-UHFFFAOYAF
SMILES O=C2NN(c1ccccc1)CC2
Properties
Chemical formula	C9H10N2O
Molar mass	162.192 g·mol−1
Appearance	Crystal leaflets or needles
Melting point	121 °C (250 °F; 394 K)
Solubility in water	10 g/100 ml at 100 °C
Solubility in ethanol	10 g/100 ml (hot)
Solubility in diethyl ether	practically insoluble
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Harmful if swallowed
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H411
Precautionary statements	P264, P270, P273, P301+P312, P330, P391, P501
Safety data sheet (SDS)	External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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]

Reaction of phenidone with silver bromide, as occurs in photographic development

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]

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. 2 (1): 1–7. doi:10.1080/03700240.1954.11736538. ISSN 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. 13 (4): 205–209. doi:10.1080/00223638.1965.11737306. ISSN 0022-3638.
4. "Trademark Status & Document Retrieval". tsdr.uspto.gov. Retrieved 2024-11-19.
5. Karlheinz Keller et al. "Photography" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a20_001
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. doi: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: 151. doi:10.2147/BTT.S2542. ISSN 1177-5475. PMC 2727783. PMID 19707438.
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. 874 (1): 15–23. doi:10.1016/S0006-8993(00)02560-9.