Дибромметан

Химические свойства

colourless liquid

Использование

Dibromomethane is used as solvent in organic synthesis. It acts as an intermediate in the manufacture of specialty chemicals, agrochemicals and pharmaceuticals. It is useful as extractant and utilized for the determination of 5-nitroimidazoles (5-NDZ) in environmental waters. It is involved in the convertion of catechols to their methylenedioxy derivatives.

Определение

ChEBI: A member of the class of bromomethanes that is methane substituted by two bromo groups. It is produced by marine algae.

Общее описание

A colorless liquid with a pleasant odor. Insoluble in water and denser than water. May be toxic by ingestion. Used as a solvent and as a motor fuel.

Реакции воздуха и воды

Insoluble in water.

Профиль реактивности

Halogenated aliphatic compounds, such as Dibromomethane, are moderately or very reactive. Reactivity generally decreases with increased degree of substitution of halogen for hydrogen atoms. Low molecular weight haloalkanes are highly flammable and can react with some metals to form dangerous products. Materials in this group are incompatible with strong oxidizing and reducing agents. Also, they are incompatible with many amines, nitrides, azo/diazo compounds, alkali metals (potassium), and epoxides.

Угроза здоровью

INHALATION: Anesthetic effects, nausea and drunkenness. CONTACT WITH SKIN AND EYES: Skin irritation of eyes and nose.

Пожароопасность

Special Hazards of Combustion Products: Dissociation products generated in a fire may be irritating or toxic.

Токсикология

A poison. Moderately toxic by subcutaneous route. Mdly toxic by inhalation. Mutation data reported. mxtures with potassium explode on light impact. When heated to decomposition it emits toxic fumes of Br-. See also BROMIDES

Опасность

In laboratory studies, animals experienced CNS depression at 2400-2800 ppm and liver and kidney damage after repeated exposures to 1000 ppm. Dichloromethane rarely causes hepatotoxicity unless exposure is extremely heavy or agent ingested. If left on clothes, it may cause reddening of skin; may have effects on the nervous system and blood, causing impaired functions, carboxyhemoglobinemia, and lowering of consciousness; chronic exposure may cause liver and kidney effects; an irritant; harmful by inhalation; a simple asphyxiant; may cause blood disorders, cardiac irregularities, and CNS depression;

Синтез

Dibromomethane is synthesized commercially from dichloromethane via bromochloromethane:
6 CH₂Cl₂  + 3 Br₂  + 2 Al  →  6 CH₂BrCl  +  2 AlCl₃
CH₂Cl₂  + HBr  →  CH₂BrCl  +  HCl
The latter route requires aluminium trichloride as a catalyst. The bromochloromethane product from either reaction can further react in a similar manner:
6 CH₂BrCl  + 3 Br₂  + 2 Al  →  6 CH₂Br₂  +  2 AlCl₃
CH₂BrCl  + HBr  →  CH₂Br₂  +  HCl
In the laboratory, it is synthesized from bromoform:
CHBr3 + Na₃AsO₃ + NaOH → CH₂Br₂ + Na₃AsO₄ + NaBr
using sodium arsenite and sodium hydroxide.
Another way is to synthesize it from diiodomethane and bromine. 

Возможный контакт

Methylene bromide is used as a solvent and as a chemical intermediate.

Перевозки

UN2664 Dibromomethane, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Несовместимости

Mixture with potassium forms a shocksensitive explosive. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, sodium amide, strong acids, strong bases, alkaline earth metals, aluminum, magnesium. The substance decomposes on contact with hot surfaces producing hydrogen bromide

Утилизация отходов

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