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Ball-and-stick model of phenylhydrazine Space-filling model of phenylhydrazine
CAS number 100-63-0 YesY
PubChem 7516
ChemSpider 7235 YesY
KEGG C02304 YesY
ChEBI CHEBI:27924 YesY
Jmol-3D images Image 1
Molecular formula C6H8N2
Molar mass 108.14 g/mol
Density 1.0978 g/cm3
Melting point 19.5 °C
24 °C for hemihydrate
Boiling point 243.5 °C (decomposition)
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g., fluorine Special hazards (white): no codeNFPA 704 four-colored diamond
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Phenylhydrazine is the chemical compound with the formula C6H5NHNH2. Organic chemists abbreviate the compound as PhNHNH2.

Chemical properties[edit]

Phenylhydrazine forms monoclinic prisms that melt to an oil around room temperature which may turn yellow to dark red upon exposure to air.[1] Phenylhydrazine is miscible with ethanol, diethyl ether, chloroform, and benzene. It is sparingly soluble in water.


Phenylhydrazine is prepared by reducing aniline with sodium nitrite in the presence of hydrogen chloride to form the diazonium salt, which is subsequently reduced using sodium sulfite in the presence of sodium hydroxide to form the final product.[3]


Phenylhydrazine was the first hydrazine derivative characterized, reported by Emil Fischer in 1875.[4] He prepared it by reduction of a phenyl diazonium salt using sulfite salts. Fischer used phenylhydrazine to characterize sugars via formation of hydrazones with the sugar aldehyde. He also demonstrated in this first paper many of the key properties recognized for hydrazines.


Phenylhydrazine is used to prepare indoles via the Fischer Indole Synthesis, which are intermediates in the synthesis of various dyes and pharmaceuticals.

Phenylhydrazine is used to form phenylhydrazones of natural mixtures of simple sugars in order to render the differing sugars easily separable from each other.[5]

The compound is also used to induce acute hemolytic anemia in studies examining the hematopoietic system.


Exposure to phenylhydrazine may cause contact dermatitis, hemolytic anemia, and liver and kidney injury.[1]

See also[edit]


  1. ^ a b c Merck Index, 11th Edition, 7264.
  2. ^ Pure component properties
  3. ^ Merck Index of Chemicals and Drugs, 9th ed. monograph 7098
  4. ^ Fischer, E. (1875) "Ueber aromatische Hydrazinverbindungen," Berichte der deutschen chemischen Gesellschaft, 8: 589-594.
  5. ^ Streitweiser, Andrew Jr.; Heathcock, Clayton H. (1976). Introduction to Organic Chemistry. Macmillan. ISBN 0-02-418010-6. 

External links[edit]