Consensus Reports
Standards and Recommendations
ACGIH TLV: TWA 100 ppm; STEL 150 ppm; BEI: methyl hippuric acids in urine at end of shift 1.5 g/g creatinine; Not Classifiable as a Human Carcinogen
NIOSH REL: (Xylene) TWA 100 ppm; CL 200 ppm/10M
DOT Classification: 3; Label: Flammable Liquid
Specification
1,2-Dimethylbenzene, also known o-Xylene, is colourless, flammable liquid with aromatic smell. It is an aromatic hydrocarbon, based on benzene with two methyl substituents bonded to adjacent carbon atoms in the aromatic ring (the ortho configuration). What's more, 1,2-Dimethylbenzene is miscible with ethanol, ether, acetone and benzene, insoluble in water.
Preparation: 1,2-Dimethylbenzene was mainly obtained from coal tar originally, but now the majority of domestic and overseas extract this product from oil catalytic reforming and aromatics thermal cracking. As the structure of 1,2-Dimethylbenzene, p-xylene, m-xylene is very similar, their physical parameters vary little. In industry, the separation of 1,2-Dimethylbenzene uses superfractionation. The rectification requires about 150 tower plates and reflux ratio 5-8 and consumes more energy.
Use industrial 1,2-dimethylbenzene as raw material. First, use industrial concentrated sulfuric acid to wash to acid layer colorless. Then wash the mixture with 10% sodium hydroxide solution and water to be qualified. After the separation of water layer, dry with anhydrous calcium chloride. And then rectify until distillate clear. Finally, collecting the midbarrel, the product is pure.
Uses: 1,2-Dimethylbenzene is mainly used as chemical raw material and solvent. It can be used in the production of phthalic anhydride, phthalic nitrile, dimethyl phenol, dimethylaniline, dyes, pesticide, drug (such as vitamin) and so on. It is also used as aviation gasoline additive. In addition, 1,2-Dimethylbenzene is used in organic synthesis. For example: it can react with benzoyl chloride to get 3,4-dimethyl-benzophenone. This reaction which is a kind of Friedel-Crafts acylation needs reagent BiCl3 at temperature of 120 °C. The reaction time is 12 hours. The yield is 93%.
Safty: 1,2-Dimethylbenzene is harmful by inhalation and in contact with skin. It is specially irritating to skin. And people also should avoid contact with eyes. If you want to contact this product, you must wear suitable protective clothing and gloves. In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)
Structure Descriptors:
1. Smiles:c1(c(cccc1)C)C
2. InChI:InChI=1/C8H10/c1-7-5-3-4-6-8(7)2/h3-6H,1-2H3
Toxicity:
| Organism | Test Type | Route | Reported Dose (Normalized Dose) | Effect | Source |
|---|---|---|---|---|---|
| human | LCLo | inhalation | 6125ppm/12H (6125ppm) | Gekkan Yakuji. Pharmaceuticals Monthly. Vol. 22, Pg. 883, 1980. | |
| mammal (species unspecified) | LDLo | intraperitoneal | 1500mg/kg (1500mg/kg) | Journal of Pathology and Bacteriology. Vol. 46, Pg. 95, 1938. | |
| mammal (species unspecified) | LDLo | subcutaneous | 2500mg/kg (2500mg/kg) | Journal of Pathology and Bacteriology. Vol. 46, Pg. 95, 1938. | |
| mouse | LCLo | inhalation | 30gm/m3 (30000mg/m3) | BEHAVIORAL: GENERAL ANESTHETIC LUNGS, THORAX, OR RESPIRATION: RESPIRATORY DEPRESSION CARDIAC: OTHER CHANGES | Naunyn-Schmiedeberg's Archiv fuer Experimentelle Pathologie und Pharmakologie. Vol. 143, Pg. 223, 1929. |
| mouse | LD50 | intraperitoneal | 1550uL/kg (1.55mL/kg) | Archives of Toxicology. Vol. 58, Pg. 106, 1985. | |
| rat | LCLo | inhalation | 6125ppm/12H (6125ppm) | Journal of Pathology and Bacteriology. Vol. 46, Pg. 95, 1938. | |
| rat | LDLo | oral | 5gm/kg (5000mg/kg) | Gekkan Yakuji. Pharmaceuticals Monthly. Vol. 22, Pg. 883, 1980. |