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• Hydrazine derivative

  Phenylhydrazine is also known as the hydrazinobenzene. It was first successfully synthesized by the German organic chemist Hermann-Emil-Fischer in 1875 and is the first synthesized hydrazine derivatives. At room temperature, it is a pale yellow crystalline or oily liquid while at low temperature it appears as monoclinic prismatic crystals. It can be easily subject to oxidization in the air and exhibit dark brown or dark red.
  
  Phenylhydrazine is one of the hydrazine derivatives and is often abbreviated as PhNHNH2. It is slightly soluble in water and alkali solution and can be dissolved in dilute acid. It is miscible with ethanol, ethyl ether, chloroform and benzene. Common method of its preparation is through the reaction between aniline and sodium nitrite under the action of hydrochloric acid for generation of diazonium salt which is then reduced by sulfite/sodium reduction for obtaining it. Acid precipitation can generate phenylhydrazine hydrochloride with neutralization generating phenylhydrazine.
  Phenylhydrazine can be applied to making dyes, drugs, and being used as developer. It is also an important reagent for identification of carbonyl group and can be used for identifying aldehydes, ketones and carbohydrates. It can react with benzaldehyde to generate phenylhydrazine. We can use the hydrazone generated through phenylhydrazine or 2, 4-dinitrophenylhydrazine to identify aldehydes and ketones, It can trigger Fischer indole synthesis upon reaction with aldehydes and ketones (first found by the Emil Hermann Fischer in 1883, the reaction is using phenylhydrazine and aldehyde, ketone for heating and rearrangement under acid-catalysis for the elimination of one molecule of ammonia to give 2-or 3-substituted indole.) to give indole ring-class compound.;

• Hermann Emil Fischer

  Phenylhydrazine (Hydrazinobenzene) is the chemical compound characterized by Hermann Emil Fischer in 1895. Fischer is a German organic chemist. He used phenylhydrazine to react with carbohydrate and generate hydrazone and osazone and form a crystalline compound which is easy for purification. Then it is decomposed into pure sugar. This is a powerful means for studying carbohydrate structures and synthesis of a variety of sugars and enables the theoretic clarification of the structure of glucose and summarizing of the general stereoisomerism phenomenon of saccharides and further using of Fischer projection for describing it. He has also demonstrated that the caffeine, theophylline, uric acid all belongs to purine derivatives and also had successfully synthesized purine. He also had opened up the study of proteins and had demonstrated that amino acids forms polypeptide via peptide bond and successfully synthesized polypeptides. In 1902, Fischer, because of the synthesis of purine and carbohydrate, was awarded for the Nobel Prize in Chemistry.
  The above information is edited by the Chemicalbook of Dai Xiongfeng. ;

• Phenylhydrazine: preparation and application

  Phenylhydrazine is the first synthetic hydrazine derivatives which can often be used as intermediates of organic dyes, pharmaceuticals and pesticide. It can also be used as organic intermediates for synthesis of pyrazoline, triazole, and indole; It can also be used as dye intermediates like disazo dye intermediates such as 1-phenyl-3-methyl-5-pyrazolone and so on; It can also be used as pharmaceutical intermediates for preparation of antipyretic, analgesic, anti-inflammatory drugs such as antipyrine and aminopyrine, etc; it can also be used as photography drugs (photosensitive dye); phenylhydrazine is also the raw material for the production of pesticides "imputed phosphorus"; phenylhydrazine is also an important kind of carbonyl group identification reagents used for identifying aldehydes, ketones and carbohydrates.
  Phenylhydrazine is toxic. After inhalation, due to hemolysis, it can cause anemia and headache and can even cause jaundice in severe cases. It can also have stimulating effect on the eyes such as causing corneal disorders. Rat-oral LD50:188 mg/kg. Workplace: maximum allowable concentration: 0.44mg/m3.
  Lab often uses aniline as raw materials for reaction with sodium nitrite in hydrochloric acid for generating diazonium salt and then reacted with sulfur dioxide and sulfurous acid for reduction to produce phenylhydrazine sodium sulfonate and further salting via hydrochloric acid to form phenylhydrazine hydrochloride. After neutralization and deacidification, we can obtain phenylhydrazine.
  
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• Chemical Properties

  Phenylhydrazine is pale yellow oily liquid with the melting point being 19.8 ℃ and boiling point being 173.5 ℃/13.33kPa, n20D being 1.608 and the relative density being 1.0978 (20 ℃). It is slightly soluble in water and petroleum ether and soluble in alcohol, ether, chloroform and benzene. It can be evaporated together with steam. It is also easily to get dark in the air. Phenylhydrazine hydrochloride [59-88-1] is solid with the m.p. being 250~254 ℃ (decomposition). ;

• Uses

  In the field of pesticide production, phenylhydrazine can be used for synthesizing the intermediate 1-phenyl-semicarbazide of the organophosphorus pesticides, triazophos as well as the intermediate 1-phenyl-3, 6-hydroxy pyridazine of pyridaphenthione. It is also the intermediates of the novel bactericidal varieties, famoxadone and fenamidone. In addition, hydrazine benzene, as a raw material for organic synthesis, can also be used as the intermediates of dye and pharmaceutical industry as well as being used as an analytical reagent.
  The product is the intermediate of dye, pharmaceuticals and pesticides. It can be used for the production of Naphthol AS-G, drugs such as antipyrine and so on. Dissolving the phenylhydrazine in 95% ethanol and following by addition of benzaldehyde and reflux for 1 h can obtain the phenylhydrazone. Phenylhydrazone can also be used as the intermediate of organic synthesis. Phenylhydrazine is also used as an analytical reagent.
  As a weak base, it can be used to precipitate lead, chromium and other trivalent, tetravalent element in the form of hydroxide. It can also be used for photometric determination of aluminum, chromium, copper, molybdenum, titanium, and zirconium. It can also be used for verification of gold, iridium, molybdenum, palladium, platinum, and silver. It can be used as the reducing agent for colorimetric assay of phosphorus acid. It can also react with aldehydes, ketones and sugars to get phenylhydrazone with different melting points according which we will be able to identify these substances. ;

• Production method

  It can be produced from aniline which undergoes diazotization, reduction, acid precipitation to obtain phenylhydrazine hydrochloride and then further neutralization to obtain phenylhydrazine.
  The preparation method is based on aniline which successively undergoes diazotization, reduction, acid precipitation, and neutralization to derive it.
  Diazotization: add a certain amount of water, 30% hydrochloric acid and aniline to the reaction pot, cooled to 2 ℃, control the temperature at around 0~5 ℃ and add drop wise of solution of sodium nitrite to until the starch iodide test solution turns blue, stir for 30 mins for completion of the reaction and obtain the diazonium solution.
  Reduction: add water, sodium bisulfite and 30% alkaline solution to the reduction kettle, heated to 80 ℃, maintain the temperature in 80~85 ℃ and pH = 6.2~6.7, within 20min trickle add the above diazo solution, stirring was continued for 1.5 h, then add zinc powder, diatomaceous earth, stirred filtrate with the filtrate suck into the acid precipitation tank.
  Acid precipitation: to the above filtrate add 30% hydrochloric for acid precipitation at 70 ℃, the temperature is maintained in 85~90 ℃, stir for 10min and cool to below 20 ℃, suck, filtration to yield phenylhydrazine hydrochloride.
  Neutralization: add the alkaline solution to the reaction pot, stir and simultaneously add the above phenylhydrazine hydrochloride and an appropriate amount of water, heated to 50 ℃, stirred at 50~60 ℃ for 1 h, allowed to stand for more than 8h, separate out the lower aqueous solution, It was the top oil that was phenylhydrazine with the content of about 80% and the total yield of 83.5%. ;

• Mutagenicity and Toxicity of Carcinogenic

  Phenylhydrazine is toxic by single exposure via the oral route (LD50 80–188 mg/kg body weight) and is expected to be toxic by the inhalation and dermal routes (data from these routes of exposure are less clear). Phenylhydrazine has potential for skin and eye irritation,and there is evidence that it has skin-sensitizing properties in humans. Exposure to phenylhydrazine may cause damage to red blood cells, potentially resulting in anaemia and consequential secondary involvement of other tissues, such as the spleen and liver. Phenylhydrazine is mutagenic in vitro, and there is some evidence to indicate that it may express genotoxic activity in vivo. The substance is clearly carcinogenic in mice following oral dosing, inducing tumours of the vascular system. The mechanism for tumour formation is unclear, but a genotoxic component cannot be excluded. Hence, it is not considered possible to reliably identify a level of exposure at which there will be no risk of carcinogenic or genotoxic effects.;

• environmental effects

  Phenylhydrazine is degraded photochemically and autoxidizes in water. It is readily biodegradable, and this is expected to be the major route of breakdown in the environment. There is minimal sorption to particulates.
  Phenylhydrazine is toxic to aquatic organisms, with the lowest reported no-observed-effect concentration (NOEC) in standard acute fish tests at 0.01 mg/litre; fish are generally more sensitive than either daphnids or bacteria. A NOEC of 0.49 :g/litre has been reported for embryo-larval stages of the zebra fish (Brachydanio rerio).;

• Flammable and hazard characteristics

  it is combustible upon fire with heating emitting toxic nitrogen compound gas ;

• Storage characteristics

  Treasury: ventilation, low-temperature and dry; store it separately from oxidants, acids and food additives ;

• Extinguishing agent

  water, spray, foam, CO2, sand ;

• Professional Standards

  TLV-TWA 0.1 PPM; TWA 5 PPM (22 mg/cubic meter); STEL 2 mg/m3 ;

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