м-ксилола

Химические свойства

Xylene exists in three isomeric forms, ortho-, meta-, and para-xylene. Commercial xylene is a mixture of these three isomers and may also contain ethylbenzene as well as small amounts of toluene, trimethylbenzene, phenol, thiophene, pyridine, and other nonaromatic hydrocarbons. m-Xylene is predominant in commercial xylene.

Физические свойства

Clear, colorless, watery liquid with a sweet, aromatic odor. An odor threshold concentration of 48 ppbv was reported by Nagata and Takeuchi (1990).

Использование

m-Xylene is used in the production of isophthalic acid, which is a monomer and utilized in preparation of polyethylene terephthalate. It is used as an important starting material in the production of 2,4- and 2,6-xylidine. It is used as solvent in histology.

Определение

ChEBI: A xylene carrying methyl groups at positions 1 and 3.

Общее описание

A colorless watery liquid with a sweet odor. Less dense than water. Insoluble in water. Irritating vapor.

Реакции воздуха и воды

Highly flammable. Insoluble in water.

Профиль реактивности

m-Xylene may react with oxidizing materials. .

Угроза здоровью

Vapors cause headache and dizziness. Liquid irritates eyes and skin. If taken into lungs, causes severe coughing, distress, and rapidly developing pulmonary edema. If ingested, causes nausea, vomiting, cramps, headache, and coma; can be fatal. Kidney and liver damage can occur.

Пожароопасность

Behavior in Fire: Vapor is heavier than air and may travel considerable distance to a source of ignition and flash back.

Химическая реактивность

Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.

Профиль безопасности

Moderately toxic by intraperitoneal route. Wdly toxic by ingestion, skin contact, and inhalation. An experimental teratogen. Human systemic effects by inhalation: motor activity changes, ataxia, and irritabihty. Experimental reproductive effects. A severe skin irritant. A common air contaminant. A very dangerous fire hazard when exposed to heat or flame; can react with oxidzing materials. Explosive in the form of vapor when exposed to heat or flame. To fight fire, use foam, CO2, dry chemical. Emitted from modern building materials (CENEAR 69,22,91). When heated to decomposition it emits acrid smoke and irritating fumes. See also other xylene entries.

Возможный контакт

Xylene is used as a solvent; as a constituent of paint, lacquers, varnishes, inks, dyes, adhesives, cements, cleaning fluids, and aviation fuels; and as a chemical feed-stock for xylidines, benzoic acid; phthalic anhydride; isophthalic, and terephthalic acids; as well as their esters (which are specifically used in the manufacture of plastic materials and synthetic textile fabrics). Xylene is also used in the manufacture of quartz crystal oscillators, hydrogen peroxide; perfumes, insect repellants; epoxy resins; pharmaceuticals; and in the leather industry. m-Xylene is used as an intermediate in preparation of isophthalic acid; o-xylene is used in manufacture of phthalic anhydride and in pharmaceutical and insecticide synthesis. p-xylene is used in pharmaceutical and insecticide synthesis and in production of polyester.

Перевозки

UN1307 Xylenes, Hazard Class: 3; Labels: 3-Flammable liquid.

Методы очистки

The general purification methods listed under xylene are applicable. The o-and p-isomers can be removed by their selective oxidation when a m-xylene sample containing them is boiled with dilute HNO3 (one part conc acid to three parts water). After washing with water and alkali, the product can be steam distilled, collected as for o-xylene, then distilled and purified further by sulfonation. [Clarke & Taylor J Am Chem Soc 45 831 1923.] m-Xylene is selectively sulfonated when a mixture of xylenes is refluxed with the theoretical amount of 50-70% H2SO4 at 85-95o under reduced pressure. By using a still resembling a Dean and Stark apparatus, water in the condensate can be progressively withdrawn while the xylene is returned to the reaction vessel. After cooling, then adding water, unreacted xylenes are distilled off under reduced pressure. The m-xylene sulfonic acid is subsequently hydrolysed by steam distillation up to 140o, the free m-xylene is washed, dried with silica gel and again distilled. It is stored over molecular sieves Linde type 4A. [Beilstein 5 H 370, 5 I 182, 5 II 287, 5 III 823, 5 IV 932.]

Несовместимости

Vapor may form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, and epoxides. Electrostatic charges can be generated from agitation or flow.

Утилизация отходов

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration.