Properties, uses and production technology of o-phenylenediamine

　　Phenylenediamine is the simplest aromatic diamine.There are three kinds of isomers,namely o-phenylenediamine,m-phenylenediamine,p-phenylenediamine.P-phenylenediamine,also known as Usol,is a colorless crystal that quickly oxidizes to black in air.Boiling point 267℃.Soluble in water,ethanol and ether.Used as raw materials or intermediates for dyes,vulcanization accelerators for rubber,developers in the photographic industry,fur dyes and hair dyes.Those with more contacts are hair dyers,hairdressers and those who often dye hair.It can enter the human body through the skin.Oxidized intermediates have various degrees of sensitization.It can cause eczema-like or moss-like dermatitis,which often occurs in skin folds on the face,neck and forearm.Damaged.Inhaling its dust can cause bronchial asthma.The symptoms of oral poisoning are similar to aniline poisoning.Mainly take symptomatic treatment.O-phenylenediamine is also known as 1,2-diaminobenzene and 1,2-phenylenediamine.Those precipitated from water are white to pale yellow leaf crystals,and those precipitated from chloroform are prismatic crystals.It is easy to change color when exposed to air,from white to yellow,to chemicalbook brown,to purple,and finally to black.The relative density is 1.2698.Melting point 103～104℃.Boiling point 256~258℃.Slightly soluble in cold water(4.15 at 35℃),easily soluble in hot water(733 at 81℃),ethanol,ether,chloroform and benzene.It reacts with inorganic acids to form water-soluble salts;the aqueous solution reacts with carbon disulfide to form 2-mercaptobenzimidazole;it reacts with carbon dioxide under pressure to form benzimidazolone.This product is toxic.After inhalation,it can cause visual impairment,contact with the skin,cause inflammation,enter the eyes,and cause inflammation.Rat oral LD501070mg/kg.M-Phenylenediamine is a rhombic crystal,which quickly oxidizes to yellow-brown in the air.The proportion is 1.139.Melting point is 62.8℃,boiling point is 284℃.Soluble in water,alcohol,ketone,etc.Used in the dye chemical industry,and as a curing agent for plastics.Can enter the human body from the respiratory tract,skin and gastrointestinal tract.Acute poisoning can cause methemoglobinemia,and can cause liver damage and hemolytic anemia.