| Names | |
|---|---|
|  Preferred IUPAC name  1-Phenylpyrazolidin-3-one  | |
| Identifiers | |
3D model (JSmol)  | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.001.960 | 
| EC Number | 
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 PubChem CID  | |
| UNII | |
 CompTox Dashboard (EPA)  | |
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| Properties | |
| C9H10N2O | |
| Molar mass | 162.192 g·mol−1 | 
| Appearance | Crystal leaflets or needles | 
| Melting point | 121 °C (250 °F; 394 K) | 
| 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: | |
|   | |
| Warning | |
| H302, H411 | |
| 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).  | |
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]
Phenidone can be prepared by heating phenyl hydrazine with 3-chloropropanoic acid. [2]