Chemical properties
It appears as white or light pink crystalline powder with a melting point of 125 ℃, the boiling point of 400 ℃, (98.7kPa) and the relative density of 1.250 (20/4 ℃). It is soluble in boiling ethanol, acetic acid and diluted hydrochloric acid, slightly soluble in ether, slightly soluble in boiling water and slightly soluble in cold water. Its color is darkened under air and light. Analysis reagents are usually benzodine hydrochloride or acetate, which is more soluble, and sulfate is commonly used in the industry. Benzidine acetate is white or nearly white crystals, being soluble in water, acetic acid and hydrochloric acid, as an indicator. Benzidine sulfate is a white crystalline powder or flaky crystal, being soluble in ether, very slightly soluble in water, dilute acid and alcohol.
Uses
Important dye intermediates, benzidine and its derivatives can be used to make direct dyes, acid dyes, vat dyes, ice dyed dyes, sulfur dyes, reactive dyes and organic pigments. More than 250 dyes are made from benzidine, of which the most important is the direct black EW. The benzidine yellow is a widely used organic pigment.
Toxicity
Benzidine is highly toxic, can be absorbed through the respiratory tract, skin and digestive tract, and is highly toxic, belonging to a carcinogen. Both solid and vapor are quickly absorbed through the skin, causing blood damage and causing bladder cancer. Mistakenly eating it can cause nausea, vomiting, liver and kidney damage. Mice oral LD50: 214mg / kg (body weight), rat oral LD50: 309 mg / kg (body weight). Rabbits and dogs have an oral minimum lethal dose of 200mg / kg (weight). The major toxic effect is hemorrhagic cystitis. The effect on the formation of methemoglobin is weak. It has stimulation effect on the skin and mucous membranes, being capable of causing contact dermatitis. It can cause liver cancer in mice and hamsters, causing rat liver, Zymbal gland, breast and colon cancer and cause bladder cancer in dogs. A variety of short-term mutagenicity test has given positive results. The International Agency for Research on Cancer (IARC) classifies it as a human carcinogen (well-documented) with the targets being bladder. The relative risk of bladder cancer in dyes chemical worker is 19 with the incubation period of about 19 years.
Description
Benzidine is a white, greyish-yellow, or slightly reddish crystalline solid or powder. The
major use for benzidine is in the production of dyes, especially azo dyes in the leather, textile,
and paper industries and as a synthetic precursor in the preparation and manufacture
of dyestuffs. It is also used in the manufacture of rubber, as a reagent, and as a stain in
microscopy. It is slightly soluble and slowly changes from a solid to a gas.
Chemical Properties
Benzidine is a white, grayish-yellow, or slightly reddish crystalline solid or powder. The
major use for benzidine is in the production of dyes, especially azo dyes in the leather, textile, and paper industries, as a synthetic precursor in the preparation and manufacture of
dyestuffs. It is also used in the manufacture of dyes and rubber, as a reagent, and as a stain
in microscopy. It is slightly soluble and slowly changes from a solid to a gas.
Chemical Properties
Off-White Solid
Chemical Properties
Benzidine is a white, grayish-yellow crystalline
solid or powder. Turns brownish-red on exposure to air
and light;
Physical properties
Grayish-yellow to pale reddish powder or crystals. Darkens on exposure to air or light. Odorless.
Uses
Benzidine was used extensively in the manu facture of dyes. Because of its cancer-causingeffects in humans, its application in dyes hasbeen curtailed. Other uses of this compoundare in chemical analysis: as a reagent for thedetermination of hydrogen peroxide in milkand in the analysis of nicotine. Its hydrochlo ride is used as a reagent to analyze metalsand sulfate.
Uses
Manufacture of dyestuffs; hardener for
rubber; laboratory reagent
Uses
Potentially mutagenic compound.
Preparation
1-Nitrobenzene restore 1,2-Diphenylhydrazine?turn with acid rearrangement.
Production Methods
Benzidine production is now exclusively for captive consumption and must be carried out in closed systems under stringent workplace controls. Benzidine is used in the synthesisofdyesanddyeintermediates,asahardenerforrubber, and as a laboratory reagent. The ?rst successful synthetic direct dye was Congo Red, a diazo derivative prepared from benzidinebyBoettigerin1884.Nearlyalldirectdyesareazo products. Congo Red is used in humans intravenously for the medical diagnosis of amyloidosis. The basis for its use is an unexplained af?nity for amyloid, which rapidly removes the dye from the blood. It is used medically for the management of profuse capillary hemorrhage such as the one occurring in septicemias and in the terminal phases of leukemia.
Definition
ChEBI: A member of the class of biphenyls that is 1,1'-biphenyl in which the hydrogen at the para-position of each phenyl group has been replaced by an amino group.
General Description
A grayish-yellow to grayish-red, crystalline solid. Toxic by ingestion, inhalation, and skin absorption. Combustion produces toxic oxides of nitrogen. Used to make other chemicals and in chemical and biological analysis.
Air & Water Reactions
Darkens on exposure to air and light. Soluble in hot water.
Reactivity Profile
Benzidine forms insoluble salts with sulfuric acid. Can be diazotized, acetylated and alkylated. Is hypergolic with red fuming nitric acid . Neutralizes acids in exothermic reactions to form salts plus water. May be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen may be generated in combination with strong reducing agents, such as hydrides.
Hazard
Highly toxic by ingestion, inhalation, and
skin absorption. Confirmed carcinogen.
Health Hazard
Exposure to benzidine causes irritation to the eyes. Laboratory animals exposed to benzidine at as low as 0.01% to 0.08% in food showed adverse health effects, such as organ
weight decrease in the liver, kidney, and body weight, and an increase in spleen weight,
swelling of the liver, and blood in the urine. Exposure may cause an increase in urination, blood in the urine, and urinary tract tumors. Benzidine is considered acutely toxic
to humans by ingestion, with an estimated oral lethal dose of between 50 and 500 mg/kg.
The symptoms of acute ingestion exposure include cyanosis, headache, mental confusion,
nausea, and vertigo. Dermal exposure may cause skin rashes and irritation. Prolonged
exposure to benzidine causes bladder injury in humans
Health Hazard
Benzidine is a known carcinogen, causingbladder cancer in humans. Numerous reportsin the literature document its carcinogenicityin animals and humans. Oral or subcutaneousapplication of this compound in experimentalanimals produced tumors in liver, blood,lungs, and skin. The routes of entry intohuman body are primarily the inhalation of its dusts and absorption through skin. Whilehumans and dogs develop bladder cancerfrom benzidine, rodents primarily developliver cancer.Relatively little information is availableon the noncancer health hazard from ben zidine. The acute oral toxicity in animalswas moderate. Ingestion can produce nausea,vomiting, kidney, and liver damage. The oralLD50 values in test animals were in the range150–300 mg/kg.The mechanism of carcinogenicity of ben zidine is thought to involve its metabolictransformations forming reactive intermedi ates binding to DNA. Such DNA adductshave been identified in rodent liver. It testedpositive in most genotoxic tests. Its car cinogenicity may possibly be related to theslow rate of liver detoxification by acetyla tion allowing activation of benzidine or itsmetabolites in urine (Whysner et al. 1996)..
Health Hazard
Poisonous if inhaled, swallowed or absorbed through skin. May cause contact dermatitis, irritation or sensitization. Ingestion may cause nausea and vomiting.
Safety Profile
Confirmed human
carcinogen producing bladder tumors.
Experimental carcinogenic and tumorigenic
data. Poison by ingestion and intraperitoneal
routes. Human mutation data reported. Can
cause damage to blood, including hemolysis
and bone marrow depression. On ingestion
causes nausea and vomiting, which may be
followed by liver and kidney damage. Any
exposure is considered extremely hazardous.
When heated to decomposition it emits
highly toxic fumes of NOx. See also
AROMATIC AMINES.
Potential Exposure
Benzidine is used primarily in the
manufacture of azo dyestuffs; there are over 250 of these
produced. Other uses, including some which may have
been discontinued, are in the rubber industry as a hardener;
in the manufacture of plastic films; for detection of
occult blood in feces, urine, and body fluids; in the detection
of H2O2 in milk; in the production of security paper;
and as a laboratory reagent in determining HCN, sulfate,
nicotine, and certain sugars. No substitute has been found
for its use in dyes. Free benzidine is present in the
benzidine-derived azo dyes. According to industry, quality
control specifications require that the level not exceed
20 ppm and in practice the level is usually below 10 ppm.
Regulations in the USA concerning this chemical define
strict procedures to avoid worker contact: mixture containing
0.1% or more must be maintained in isolated or closed
systems; employees must observe special personal hygiene
rules, and certain procedures must be followed in case of
emergencies. Some p-phenylenediamine compounds have
been used as rubber components, and DFG warns of danger
of skin sensitization. Benzidine and dyes metabolized to
benzidine: The following three benzidine-based dyes have
been tested and found to cause cancer in rodents after oral
exposure for 13 weeks (NCI 1978, IARC 1982): C.I. direct
black 38 (CAS 1937-37-7) caused liver cancer in rats and
mice, mammary-gland cancer in mice, and colon and
urinary-bladder cancer in rats. C.I. direct Blue 6 (CAS
2602-46-2) caused liver cancer in rats. C.I. direct brown 95
(CAS 16071-86-6) caused hepatocellular adenoma in the
liver and one malignant liver tumor in rats.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Use gastric lavage if ingested followed bysaline catharsis. Medical observation is recommended for24-48 h after breathing overexposure, as pulmonary edemamay be delayed. As first aid for pulmonary edema, a doctoror authorized paramedic may consider administering a corticosteroid spray.
Carcinogenicity
Benzidine is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans.
Source
Benzidine can enter the environment by transport, use, and disposal, or by dyes and
pigments containing the compound. A photodegradation product of 3,3′-dichlorobenzidine.
Based on laboratory analysis of 7 coal tar samples, benzidine was ND (EPRI, 1990).
Environmental Fate
Biological. In activated sludge, <0.1% mineralized to carbon dioxide after 5 d (Freitag et al.,
1985). Kincannon and Lin (1985) reported a half-life of 76 d when benzidine in sludge was
applied to a sandy loam soil.
Soil. Benzidine was added to different soils and incubated in the dark at 23 °C under a carbon
dioxide-free atmosphere. After 1 yr, 8.3 to 11.6% of the added benzidine degraded to carbon
dioxide primarily by microbial metabolism and partially by hydrolysis (Graveel et al., 1986).
Tentatively identified biooxidation compounds using GC/MS include hydroxybenzidine, 3-
hydroxybenzidine, 4-amino-4′-nitrobiphenyl, N,N′-dihydroxybenzidine, 3,3′-dihydroxybenzidine
and 4,4′-dinitrobiphenyl (Baird et al., 1977). Under aerobic conditions, the half-life was estimated
to be 2 to 8 d (Lu et al., 1977).
Chemical/Physical. Benzidine is not subject to hydrolysis (Kollig, 1993). Reacts with HCl
forming a salt (C12H12N2?2HCl) that is very soluble in water (61.7 mg/L at 25 °C) (Bowman et al.,
1976).
storage
Benzidine should be kept stored in a cool, well-ventilated area, in closed, sealed containers
and out of sunlight and away from heat.
Shipping
UN1885 Benzidine, Hazard Class: 6.1; Labels:
6.1—Poisonous materials. PGII.
Properties and Applications
white or pink micro crystalline powder. Melting point 125 ℃, boiling point 400 ℃, relative density 1.250 (20 ℃). Soluble in ethanol, rare hydrochloric acid and acetic acid boiling, slightly soluble in ethyl ether, slightly soluble in water, very slightly soluble in cold water. In the air and light color line darker. This product is the dye and organic pigments intermediate.
Purification Methods
Its solution in *benzene is decolorized by percolating through two 2-cm columns of activated alumina, then concentrated until benzidine crystallises on cooling. Recrystallise alternately from EtOH and *benzene to constant absorption spectrum [Carlin et al. J Am Chem Soc 73 1002 1951]. It has also been crystallised from hot water (charcoal) and from diethyl ether. Dry it under vacuum in an Abderhalden pistol. Store it in the dark in a stoppered container. CARCINOGENIC. [Beilstein 13 IV 364.]
Toxicity evaluation
Industries release benzidine into the environment in the form
of liquid waste and sludges. Benzidine may also be released
into the environment due to spillage during transport. In air,
benzidine is found bound to suspended particles or as a vapor,
which may be brought back to the earth’s surface by rain or
gravity.
Incompatibilities
Dust may form explosive mixture with
air. Incompatible with oxidizers (chlorates, nitrates, peroxides,
permanganates, perchlorates, chlorine, bromine, fluorine,
etc.); contact may cause fires or explosions. On
contact with strong reducing agents, such as hydrides may
form flammable gases. Keep away from alkaline materials,
strong bases, strong acids, oxoacids, epoxides. Contact with
red fuming nitric acid may cause fire. Oxidizes in air.
Neutralizes acids in exothermic reactions to form salts plus
water. May be incompatible with isocyanates, halogenated
organics, peroxides, phenols (acidic), epoxides, anhydrides,
and acid halides.
Waste Disposal
Incineration; oxides of nitrogen
are removed from the effluent gas by scrubber, catalytic
or thermal device. Package spill residues and
sorbent media in 17 hour epoxy-lined drums and move to
an EPA-approved disposal site. Treatment may include
destruction by potassium permanganate oxidation, hightemperature
incineration, or microwave plasma methods.
398 Benzidine
Encapsulation by organic polyester resin or silicate fixation.
These disposal procedures should be confirmed with
responsible environmental engineering and regulatory
officials.
Precautions
At high temperatures, benzidine breaks down and releases highly poisonous fumes.
During use and handling, workers should wear butyl rubber gloves, goggles, and full
body plastic coveralls and ensure that no skin is exposed.
