Name | o-Xylene |
Synonyms | XYLOL Xylene XYLENES o-Xylene 1,2-xylene ortho-xylene Dimethylbenzene AKOS BBS-00004266 1,2-Dimethylbenzene 1,2-DIMETHYLBENZENE O-XYLENE FOR SYNTHESIS 1,2-Xylene standard in Methanol |
CAS | 95-47-6 |
EINECS | 202-422-2 |
InChI | InChI=1/C8H10/c1-7-5-3-4-6-8(7)2/h3-6H,1-2H3 |
InChIKey | CTQNGGLPUBDAKN-UHFFFAOYSA-N |
Molecular Formula | C8H10 |
Molar Mass | 106.17 |
Density | 0.879 g/mL at 20 °C (lit.) |
Melting Point | -26--23 °C (lit.) |
Boling Point | 143-145 °C (lit.) |
Flash Point | 90°F |
Water Solubility | Sparingly soluble in water. (0.2g/L) |
Solubility | water: partially soluble0.1705 g/L at 25°C |
Vapor Presure | <0.1 atm ( 21.1 °C) |
Vapor Density | 3.7 (vs air) |
Appearance | Solid or Crystalline Powder |
Color | Yellow to beige |
Odor | Benzene-like; characteristic aromatic. |
Exposure Limit | NIOSH REL: 100 ppm (435 mg/m3), STEL 150 ppm (655 mg/m3), IDLH 900ppm; OSHA PEL: TWA 100 ppm; ACGIH TLV: TWA 100 ppm, STEL 150 ppm (adopted). |
Maximum wavelength(λmax) | ['λ: 288 nm Amax: 1.00', , 'λ: 300 nm Amax: 0.40', , 'λ: 325 nm Amax: 0.05', , 'λ: 35 |
Merck | 14,10081 |
BRN | 1815558 |
pKa | >15 (Christensen et al., 1975) |
Storage Condition | Store below +30°C. |
Stability | Stable. Incompatible with oxidizing agents. Flammable. Hygroscopic. |
Explosive Limit | 1.0-7.6%(V) |
Refractive Index | n20/D 1.505(lit.) |
Physical and Chemical Properties | Characteristics of colorless transparent liquid, aromatic odor. melting point -25.2 ℃ boiling point 144.4 ℃ relative density 0.8802 refractive index 1.5055 flash point 34.4 ℃ solubility, acetone and benzene miscible, insoluble in water. |
Use | Used as raw materials for phthalic anhydride and other organic synthesis |
Risk Codes | R10 - Flammable R20/21 - Harmful by inhalation and in contact with skin. R38 - Irritating to the skin R39/23/24/25 - R23/24/25 - Toxic by inhalation, in contact with skin and if swallowed. R11 - Highly Flammable |
Safety Description | S25 - Avoid contact with eyes. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S36/37 - Wear suitable protective clothing and gloves. S16 - Keep away from sources of ignition. S7 - Keep container tightly closed. |
UN IDs | UN 1307 3/PG 3 |
WGK Germany | 2 |
RTECS | ZE2450000 |
TSCA | Yes |
HS Code | 29024100 |
Hazard Class | 3 |
Packing Group | II |
Toxicity | Acute oral LD50 in rats is approximately 5 g/kg (quoted, RTECS, 1992). |
colorless transparent liquid with aromatic odor. The relative density was 0.89679. Melting Point -25.2 °c. Boiling point 144.4 °c. The refractive index was 1. 5016. Flash point 32. 0C. Spontaneous ignition point 500 ℃, with ethanol, ether, acetone and benzene miscible, insoluble in water. Viscosity (20 ℃)0.92mPa · s, explosion limit 1.1% ~ 6.4% (volume). Motor octane number 100.
The xylene fraction obtained by the platinum reforming method is fed to an O-xylene column, and then subjected to (refining) distillation to obtain ortho-, meta-and para-xylene.
olfactory Threshold | 0.38ppm |
Henry's Law Constant | 14.0 at 45.00 °C, 16.4 at 50.00 °C, 19.0 at 55.00 °C, 21.3 at 60.00 °C, 26.3 at 70.00 °C (static headspace-GC, Park et al., 2004) |
LogP | 3.16 at 20℃ |
NIST chemical information | information provided by: webbook.nist.gov (external link) |
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
xylene | xylene is an aromatic hydrocarbon in which two hydrogen atoms on the benzene ring are substituted by two methyl groups. It has three isomers: O-xylene, M-xylene, P-xylene. Industrial product is a mixture of three isomers, Ortho-10%, meta-70%, para-20%. In the coking industry, it is one of the refined products of crude benzene. O-xylene (OX) can be used in the production of phthalic anhydride (phthalic anhydride, PA), pesticides, solvents and other chemical products, the vast majority of its used in the production of phthalic anhydride. O-Xylene is mainly obtained by separation of mixed xylene, including the following routes: co-production method, pyrolysis gasoline method, combined production of reformate and pyrolysis gasoline, etc. xylene is a colorless flammable liquid; The melting points of O-, m-and p-xylene are -25.2 ℃,-47.9 ℃ and 13.3 ℃, and the boiling points are 144.4 ℃,139.1 ℃ and 138.3 ℃, the relative density were 0.8802,0.8642 and 0.8611; Insoluble in water, can be miscible with many organic solvents. Phthalic anhydride, isophthalic acid and terephthalic acid were produced by catalytic oxidation. xylene is also one of the important raw materials of organic chemical industry. It is naturally found in coal tar and some petroleum, and can be obtained by fractionation of light oil part of coal tar or catalytic reforming light gasoline. The extraction of the C8 fraction in the naphtha reformate is industrially the main one. Can also be derived from toluene in the catalyst and high temperature, high pressure, through the differentiation. At present, freeze crystallization, adsorption, complex formation or molecular sieve are used in the industry to separate them. The boiling point of O-Xylene is relatively high, which can be separated by distillation method, P-xylene has a high melting point and is purified by fractional crystallization. Mixed xylene without separation can be directly used as a solvent, and can be added to gasoline to improve the Antiknock, which is a component of aviation gasoline. O-Xylene is mainly used for the preparation of phthalic anhydride, which is an important raw material for the manufacture of a variety of dyes and indicators (such as phenolphthalein). In addition, O-xylene can also be used to prepare polyester resins, insect repellents, plasticizers and dyes. 4, 6-dimethyl-1, 3-phenylenediamine produced by nitration and reduction of M-Xylene is an intermediate for the synthesis of dyes, and M-xylene can also be used as a raw material for the synthesis of fragrances (such as Musk xylene). P-xylene is mainly used in the manufacture of terephthalic acid, which is an important raw material for the synthesis of polyester fiber (polyester). FIG. 1 shows the chemical structural formulas of O-xylene, M-xylene and p-xylene of three xylene isomers. |
separation of O-xylene and p-xylene by precision distillation | xylene is present in coking crude benzene and petroleum cracked oil. Crude benzene by preliminary distillation, sulfuric acid washing and distillation, separation of benzene and toluene, and then by distillation can be obtained xylene, also known as coking xylene. The quality of coking xylene depends on the separation capacity, overhead temperature and reflux ratio of the rectification column. China will be coking xylene products are divided into three levels. Coking xylene generally contains O-xylene 16%, M-xylene 50%, p-xylene 21%, ethylbenzene 7%. In xylene produced by petroleum industry, the content of M-Xylene is lower and the content of ethylbenzene is higher. Industrial xylene is a solvent and additive for the rubber and coating industries, as well as for aviation and power fuels. O-xylene, M-xylene and p-xylene separated from industrial xylene are raw materials of phthalic acid, isophthalic acid and terephthalic acid, respectively. Phthalic acid and terephthalic acid are used in the production of plasticizers, polyester resins and polyester fibers. M-xylene can be used alone as solvent and fuel additive. The boiling point difference between O-xylene and other isomers in industrial xylene is greater than 5.2 ℃. O-xylene with a purity of more than 95% can be separated by precise distillation, and then purified by sulfonation and distillation, higher purity of O-xylene can also be obtained. xylene belongs to the group of Lewis bases, which can form polar complexes with HF-BF3 (Lewis acid). M-Xylene is about 100 times more alkaline than other C8 aromatics, and when a mixture of isomers of xylene is contacted with a HF-BF3 solvent, M-xylene forms a complex with fluoride and is preferentially extracted into the fluoride phase. The fluoride phase containing m-Xylene is heated at a lower pressure to decompose the complex, thereby separating M-xylene from the mixture. HF-BF3 the solvent can be recovered by distillation and then recycled. If the raw material is a mixture of three isomers of O-xylene, M-xylene and p-xylene, O-xylene and p-xylene are separated by precision distillation after extraction of M-xylene. Figure 2 separation of O-xylene and p-xylene by precision distillation. |
Application | mainly used for the production of phthalic anhydride O-Xylene is a bactericide, the starting material of tetrachlorobenzene peptide and the herbicide bensulfuron-methyl, used in the manufacture of O-Toluic acid as an intermediate. mainly used as chemical raw materials and solvents. Can be used for the production of phthalic anhydride, dyes, pesticides and drugs, such as vitamins. It can also be used as an additive for aviation gasoline. used as raw material for phthalic anhydride and other organic synthesis used as solvent. used as standard substance and solvent for chromatography |
production method | ortho-Xylene is industrially separated from mixed xylene by ultra-distillation. The boiling point difference between O-xylene and other components in mixed xylene is more than 5 ℃, the number of plates is about 150, the reflux ratio is 5-8, and more energy needs to be consumed during rectification. O-xylene was originally mainly prepared from coal tar, and now most of them are extracted from petroleum catalytic reforming and thermal cracking aromatics at home and abroad. Because the structures of O-xylene, p-xylene and M-xylene in xylene are very similar, their physical parameters also have little difference. Industrial separation of ortho-xylene using super-distillation method, first of all, the separation of ortho-xylene and ethylbenzene from mixed xylene, to the 100~150 plate of the distillation column, and then the ortho-xylene and ethylbenzene separation, pure O-xylene was obtained. |
category | flammable liquid |
toxicity grade | poisoning |
Acute toxicity | oral-rat LDL0: 5000 mg/kg; Abdominal injection-mouse LD50: 1364 mg/kg |
explosive hazard characteristics | explosive when mixed with air |
flammability hazard characteristics | open flame, combustible heat and oxidant; Combustion emission stimulus smoke |
storage and transportation characteristics | The warehouse is ventilated and dried at low temperature, separate from oxidants and acids |
extinguishing agent | water mist, foam, sand, carbon dioxide, 1211 extinguishing agent |
Occupational Standards | TLV-TWA 100 PPM (440 mg/m3); Tel 150 PPM(655 mg/m3) |
spontaneous combustion temperature | 867 ° F. |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
immediate life-and health-threatening concentration | 900 ppm |
mainly used as chemical raw materials and solvents. Can be used for the production of phthalic anhydride, dyes, pesticides and drugs, such as vitamins. It can also be used as an additive for aviation gasoline.
see benzene.