92-87-5 Usage
Description
Benzidine is a white, greyish-yellow, or slightly reddish crystalline solid or powder that is primarily used in the production of dyes, especially azo dyes in the leather, textile, and paper industries. It is also used as a synthetic precursor in the preparation and manufacture of dyestuffs, in the manufacture of rubber, as a reagent, and as a stain in microscopy. Benzidine is slightly soluble and slowly changes from a solid to a gas.
Uses
Used in Dyestuff Production:
Benzidine is used as an important dye intermediate for the production of direct dyes, acid dyes, vat dyes, ice dyed dyes, sulfur dyes, reactive dyes, and organic pigments. More than 250 dyes are made from benzidine, with the most important being direct black EW and benzidine yellow, a widely used organic pigment.
Used in Rubber Industry:
Benzidine is used as a hardener for rubber, enhancing the strength and durability of rubber products.
Used in Chemical Analysis:
Benzidine is used as a reagent for the determination of hydrogen peroxide in milk and in the analysis of nicotine. Its hydrochloride is also used as a reagent to analyze metals and sulfate.
Used in Laboratory Research:
Benzidine is used as a laboratory reagent for various chemical reactions and analyses.
Used in Microscopy:
Benzidine is used as a stain in microscopy, aiding in the visualization of cellular structures and components.
Note: Benzidine was extensively used in the manufacture of dyes, but due to its cancer-causing effects in humans, its application in dyes has been curtailed. It is also considered a potentially mutagenic compound.
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.
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.
Synthesis Reference(s)
The Journal of Organic Chemistry, 41, p. 2661, 1976 DOI: 10.1021/jo00877a041Synthesis, p. 40, 1976 DOI: 10.1055/s-1976-23952
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
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.
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
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.
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.
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.
Check Digit Verification of cas no
The CAS Registry Mumber 92-87-5 includes 5 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 2 digits, 9 and 2 respectively; the second part has 2 digits, 8 and 7 respectively.
Calculate Digit Verification of CAS Registry Number 92-87:
(4*9)+(3*2)+(2*8)+(1*7)=65
65 % 10 = 5
So 92-87-5 is a valid CAS Registry Number.
InChI:InChI=1/C12H12N2/c13-11-5-1-9(2-6-11)10-3-7-12(14)8-4-10/h1-8H,13-14H2
92-87-5Relevant articles and documents
-
Hammick,Mason
, p. 638 (1946)
-
-
Robinson
, p. 220 (1941)
-
Surface Silylation of Hybrid Benzidinium Lead Perovskite and its Influence on the Photocatalytic Activity
Peng, Yong,Albero, Josep,García, Hermenegildo
, p. 6384 - 6390 (2019)
Surface coating of benzidinium lead iodide perovskite has been successfully accomplished by silanization with three different silylating agents, obtaining samples with average thickness from 2 to 6 nm as revealed by transmission electron microscopy. The obtained (organo)silica-coated hybrid perovskites exhibit enhanced hydrophobic character and, therefore, increased stability against moisture. However, its photocatalytic activity towards the cis-to-trans isomerization of stilbene diminishes as a function of the coating thickness, although a notable activity for this photocatalytic reaction is still observed.
-
Snyder
, p. 340 (1962)
-
Ligand and Base Free Synthesis of Biaryls from Aryl Halides in Aqueous Media with Recyclable Ti0.97Pd0.03O1.97 Catalyst
Prasanna,Bhat, Shrikanth K.,Usha,Hegde
, p. 3313 - 3322 (2021/03/04)
Abstract: Facile protocol for the synthesis of biaryls from aryl halides in presence of magnesium metal without prior formation of organometallic intermediate has been exploited. Irrespective of aqueous medium, Ti0.97Pd0.03O1.97 catalyst supports C–C bond formation reaction in presence of metals rather than dehalogenation without any additives. Homocoupling of 16 different aryl halides furnished corresponding biphenyls in good yield with better functional group tolerance. The recovery of the catalyst was carried out by employing catalyst coated cordierite monolith up to 7th cycle with high yields. A new approach for the cross-coupling reaction is also attempted. Graphic Abstract: [Figure not available: see fulltext.]
Azo bond formation on metal surfaces
Meng, Xiangzhi,Klaasen, Henning,Viergutz, Lena,Schulze Lammers, Bertram,Witteler, Melanie C.,M?nig, Harry,Amirjalayer, Saeed,Liu, Lacheng,Neugebauer, Johannes,Gao, Hong-Ying,Studer, Armido,Fuchs, Harald
supporting information, p. 1458 - 1464 (2020/12/14)
The formation of azo compounds via redox cross-coupling of nitroarenes and arylamines, challenging in solution phase chemistry, is achieved by on-surface chemistry. Reaction products are analyzed with a cryogenic scanning tunneling microscope (STM) and X-ray photoelectron spectroscopy (XPS). By using well-designed precursors containing both an amino and a nitro functionality, azo polymers are prepared on surface via highly efficient nitro-amino cross-coupling. Experiments conducted on other substrates and surface orientations reveal that the metal surface has a significant effect on the reaction efficiency. The reaction was further found to proceed from partially oxidized/reduced precursors in dimerization reactions, shedding light on the mechanism that was studied by DFT calculations.
Cu/CuxS-Embedded N,S-Doped Porous Carbon Derived in Situ from a MOF Designed for Efficient Catalysis
Wang, Dongsheng,Fan, Mingyue,He, Tingyu,Zeng, Fanming,Hu, Xiaoli,Li, Chun,Su, Zhongmin
supporting information, p. 11468 - 11476 (2021/06/14)
The reasonable design of the precursor of a carbon-based nanocatalyst is an important pathway to improve catalytic performance. In this study, a simple solvothermal method was used to synthesize [Cu(TPT)(2,5-tdc)] ? 2H2O (Cu-MOF), which contains N and S atoms, in one step. Further in-situ carbonization of the Cu-MOF as the precursor was used to synthesize Cu/CuxS-embedded N,S-doped porous carbon (Cu/CuxS/NSC) composites. The catalytic activities of the prepared Cu/CuxS/NSC were investigated through catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The results show that the designed Cu/CuxS/NSC has exceptional catalytic activity and recycling stability, with a reaction rate constant of 0.0256 s?1, and the conversion rate still exceeds 90 % after 15 cycles. Meanwhile, the efficient catalytic reduction of dyes (CR, MO, MB and RhB) confirmed its versatility. Finally, the active sites of the Cu/CuxS/NSC catalysts were analyzed, and a possible multicomponent synergistic catalytic mechanism was proposed.