Description One of the most commonly used chemicals in industry, xylene is commonly found in inks, rubber, varnishes, adhesives, jet fuel, gasoline, pesticides, perfumes, pharmaceuticals, and more. It can be used as a solvent and cleaner for concrete acrylic antique sealers, paint thinner, transfer agent for printed materials, and many
As one of the most commonly used chemicals in industry, xylene is commonly found in inks, rubber, varnishes, adhesives, jet fuel, gasoline, pesticides, perfumes, pharmaceuticals, and more. It can be used as a solvent and cleaner for concrete acrylic antique sealers, paint thinner, transfer agent for printed materials, and many other uses. In histology, it is used as a clearing agent to prepare coverslip samples and for tissue processing and staining. As a wax solvent, it removes paraffin from slides before use. Paraxylene, one of its isomers, is also used as a precursor to terephthalic acid and dimethyl terephthalate, both of which are used in the production of polyethylene terephthalate (PET) An important raw material, PET is a plastic commonly used in bottles and other packaging. Various isomers of xylene are also used as precursors for polyester fabrics, tear gas, and other chemicals.
Use xylene as solvent. In this application, the mixture of isomers is generally referred to as xylene or xylene. The solvent xylene usually contains small amounts of ethylbenzene. Like the individual isomers, the mixture is colorless, sweet-smelling and highly flammable. Xylene is used in a wide variety of applications including but not limited to the printing, rubber and leather industries. Likewise, it is used as a cleaning agent for steel and silicon wafers. In the petroleum industry, xylene is also a common component of paraffin solvents, used when pipes become clogged with paraffin. Xylene is incompatible with strong oxidizing agents and can cause fire and explosion. There are three forms of xylene in which the methyl group on the benzene ring differs: (i) m-xylene, (ii) ortho-xylene, and (iii) p-xylene. These forms are called isomers. Xylene is a colorless, sweet-tasting liquid. Xylene occurs naturally in petroleum and coal tar. The chemical industry produces xylene from petroleum. It is also used as a cleaner and thinner for paints, paints, glues, printing inks and varnishes. Xylene rapidly evaporates from soil and surface water into the air.
chemical properties
C6H4(CH3)2, also known as xylene, is an isomeric mixture of 0-m-xylene and p-xylene. It is a clear liquid of various brands with different boiling points. It is insoluble in water and soluble in ethanol and ether. It is used in aviation gasoline, coatings, varnishes, rubber cement, organic synthesis, and polyester resin manufacturing.
chemical properties
Xylene is present in the manufacture of different petroleum products and as an impurity in benzene and toluene. It is a colorless flammable liquid. Commercial xylene is a mixture of three isomers, ortho, meta and para. It is widely used in different industries such as paint, rubber, ink, resin, adhesive, paper coating, solvent and emulsifier. In addition, xylene is used as an important raw material in the manufacture of plasticizers, glass-reinforced polyesters and alkyd resins.
physical properties
Xylene is benzene with two methyl groups added to two carbon atoms of the benzene ring. The addition of two methyl groups gives three isomers of xylene labeled according to the relative positions of the methyl groups. Ortho-xylene has methyl groups on consecutive carbons in the ring, m-xylene has methyl groups separated by a single carbon bonded to a hydrogen atom, and para-xylene has methyl groups on carbon atoms on opposite sides of the ring. The three xylene isomers are abbreviated as ortho, meta and para, respectively, represented by o-, m-, p-. Xylene is available both as a mixture (called dimethylbenzene or dimethylbenzene) and as individual isomers. Because of their close boiling points, they are difficult to separate by distillation. Therefore, techniques such as recrystallization and adsorption are used to separate isomers. Xylene is a flammable, colorless liquid with a pleasant odor. Xylene was first isolated from coal tar in the mid-19th century. The name xylene comes from the Greek word for "wood xulon" because xylene is obtained by distilling wood under oxygen-free conditions.
use
Xylene is used as a chemical raw material in the chemical industry. Xylene can undergo oxidation, in which the pendant methyl group is oxidized to give a carboxyl group (COOH), thereby producing carboxylic acid. The specific acid produced depends on the isomer being oxidized. Phthalic acid is produced when paraxylene is oxidized, and terephthalic acid is produced when paraxylene is oxidized. Terephthalic acid is one of the main raw materials for making polyester. Terephthalic acid reacts with ethylene glycol to form the ester polyethylene terephthalate (PET). PET is one of the most commonly used plastics for food and beverage containers. PET containers contain a recycling symbol with the number 1. PET is marketed under a variety of trade names; the most common is polyester. It is also a material known as polyester. Mylar is PET in film form. Although all three isomers of xylene are used as chemical raw materials, the greatest demand is for paraxylene in the production of terephthalic acid. The minimum requirement is m-xylene. Worldwide, approximately 30 million tons of xylene are used annually.
use
Solvents; manufacture of certain organic compounds; cleaning agents; components of fuels.
use
Aviation gasoline; protective coatings; solvents for alkyd resins, varnishes, enamels, rubber cements; synthesis of organic chemicals.
production method
Xylene is produced by catalytic reforming, and depending on the raw material, the yield can reach >85%. Commercially, xylene is also recovered from coal tar, yielding a typical mixture of about 10-20% ortho, 40-70% meta and 10-25% para isomers. Impurities include ethylbenzene, benzene, toluene, phenol, thiophene, and pyridine (53, 438).
definition
Organic hydrocarbons present in the light oil fraction of crude oil. It is widely used as a solvent. There are three isomeric compounds with this name and formula, which are classified into 1,2-, 1,3- and 1,4-dimethylbenzene according to the position of the methyl group on the benzene ring.
general instructions
Light to colorless liquid with hydrocarbon odor. Flash point between 52 - 93°F. Less dense than water. Vapor is heavier than air. Vapors may irritate eyes, nose, throat and respiratory tract. High vapor concentrations may cause central nervous system depression or damage. Liquid contact may irritate eyes and skin. Prolonged liquid contact with the pads can cause degreasing and drying of the skin. Avoid ingestion.
air and water reaction
Highly flammable. Insoluble in water.
reactive profile
These materials may react violently, sometimes resulting in explosion, in contact with strong oxidizing agents. They react exothermically with bases and diazonium compounds. Substitution on the benzene core occurs via halogenation (acid catalyst), nitration, sulfonation, and Friedel-Crafts reactions.
health hazard
Inhalation or contact with material may cause irritation or burns to skin and eyes. Fires may produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from firefighting or dilution water may cause contamination.
health hazard
Exposure to xylene can cause toxic and adverse health effects in animals and humans. Acute and chronic exposure to xylene can adversely affect the skin and respiratory systems of animals and humans. Prolonged exposure to xylene can cause burning effects, skin dryness, degreasing, eye irritation, pulmonary congestion, central nervous system irritation, depression, mucous membrane bleeding, and mild liver damage
Security overview
The intraperitoneal and subcutaneous routes are moderately toxic. Severely toxic if ingested and inhaled. An experimental teratogen. Systemic effects of inhalation: olfactory changes, conjunctival irritation, and pulmonary changes. Experimental reproductive effects. Report mutation data. It is irritating to human eyes and has serious irritating effects on experimental skin and eyes. Some temporary corneal effects were noted, as well as some conjunctival irritation from instillation (one drop at a time into the eye). Irritation may occur at concentrations of 200 ppm. Very dangerous fire hazard when exposed to heat or flame; can react with oxidizing materials. When extinguishing fire, use foam, carbon dioxide, dry chemical. When heated and decomposed, acrid and irritating fumes are released. See also other xylene entries.
Carcinogenicity
Mixed xylenes and individual xylene isomers were negative in various genotoxicity assays; they are considered nonmutagenic. The International Agency for Research on Cancer (IARC) has determined that there is insufficient evidence that xylenes are carcinogenic to humans and laboratory animals.
environmental fate
Xylene is an eight-carbon aromatic hydrocarbon compound that is a minor component of all gasoline. Xylene is a colorless, flammable liquid about 14% lighter than water. It has a sweet and spicy smell. The molecular weight of xylene is 106.7 g mol 1. The solubility of xylene in water at 25°C is 106 mg l 1 , the estimated vapor pressure is 6.6–8.8 mm Hg, and the Henry's law constant ranges from 5.18 10 3 to 7.18 10 3 atm- m3 Mole 1. The logarithm of the octanol/water partition coefficient is 3.12. The conversion factor for xylene in air is as follows: 1 mgm 3 ? 0.23 ppm; 1 ppm? 4.36 mg 3. If released to the air, the moderate vapor pressure indicates that xylene will exist only in vapor form in the surrounding atmosphere. Vapor-phase xylene is degraded in the atmosphere by reaction with photochemically generated hydroxyl radicals; the half-life of this reaction in air is estimated to be 2 days. Xylene does not contain chromophores that absorb at wavelengths >290 nm and is therefore not expected to be subject to direct photolysis by sunlight. If released into water, xylene would only be moderately adsorbed to suspended solids and sediment based on an estimated Koc range of 36-365. Based on the estimated Henry's Law constants, volatilization from the water surface is expected to be the dominant fate process. The estimated volatilization half-lives are 1 hour and 4 days for the model river and model lake, respectively. Using standard biochemical oxygen demand (BOD) dilution techniques and activated sewage inoculum, a mixture of xylene isomers with a theoretical BOD of 72% was observed over a 20-day incubation period, suggesting that biodegradation is an important environmental fate in water process. Hydrolysis is not expected to be an important environmental fate process because the compound lacks functional groups for hydrolysis under ambient conditions. If released into soil, xylene is expected to have high to moderate mobility in the subsurface based on the known range of Koc values. Xylene volatilization from moist soil surfaces is expected to be an important fate process. Based on moderate vapor pressure, xylene may volatilize from dry soil surfaces. USEPA's EPI Suite computer program estimated the bioconcentration factor and bioaccumulation factor to be 110.7 using the measured log Kow of 3.12. These predicted bioaccumulation and biomagnification values are relatively low. Therefore, xylene is not expected to be found in fish or wildlife tissues because (1) xylene does not contain persistent functional groups (e.g., chlorine, bromine); (2) exposure is expected to be relatively high due to its short half-life in the environment Low; (3) Following exposure, trace amounts of xylene are rapidly metabolized by the liver (similar to the situation with other organic compounds).
Purification method
Common impurities are ethylbenzene, paraffin, traces of sulfur compounds and water. Although ortho-xylene can be fractionated from an isomer mixture by a sufficiently efficient still, it is impractical to separate the meta- and para-isomers of xylene by fractional distillation. Purified (and dried) from LiAlH4, P2O5, CaH2 or sodium by fractional distillation. Prior to this treatment, it can be shaken sequentially with concentrated sulfuric acid, water, 10% aqueous NaOH, water and mercury, and dried with CaCl2 for several days. Xylene can be purified by azeotropic distillation with 2-ethoxyethanol or 2-methoxyethanol, and the distillate is washed with water to remove the alcohol, then dried and fractionated. [Berstein 5 H 360. ]
Toxicity evaluation
Its mechanism of toxicity is suspected to be similar to other solvents that rapidly induce anesthetic-like effects, namely "non-specific anesthesia" due to disruption (dissolution) of central nervous system (CNS) cell membrane integrity. The effect is similar to the "high" experienced when exposed to other hydrocarbon solvents. As seen with exposure to other hydrocarbon solvents, xylene is moderately toxic when inhaled and may cause respiratory irritation and anesthesia. Xylene appears to have reversible effects on the liver, kidneys, and nervous system. The nervous system appears to be most sensitive to the effects of xylene. Exposure to high levels of xylene can cause uncoordinated movements, ataxia, confusion, and eventually death. Acute exposure to lower levels in humans produces dizziness, excitement, and confusion. Although the actual biochemical mechanism of toxicity is unknown, the observed anesthetic effects are likely related to its physical solvent properties.
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