Bromomethane

• Methyl bromide
• Bromomethyl
• Monobrommethan
• Methylbromuer

Colorless and odorless gas, sweetish chloroform -like smell in high concentrations

Gaseous

3.97 kg · m 3 (0 ° C, 1013 hPa)

-93.66 ° C

3.56 ° C

189 kPa ( 20 ° C)

• Moderately in water ( 17.5 g · l-1 at 20 ° C)
• In a liquid state indefinitely soluble in ethanol, diethyl ether and chloroform

1.822 D (6.08 · 10-30 C · m)

Risk

Not determined, as carcinogenic

5 (relative to 100 years)

-35.4 KJ / mol

Template: Infobox chemical / molecular formula search available

Methyl bromide is a haloalkane. It should not be confused with bromoethane.

Representation

In the laboratory, haloalkanes are often represented by reaction of alcohols with phosphorus halides such as PCl3, PCl5 or PBr3.

Properties

Methyl bromide is toxic and harmful to the central nervous system. One of the contact and respiratory poisons. In the atmosphere, it affects strongly detrimental effect on the ozone layer and increases the greenhouse effect. Therefore, its application in the Montreal Protocol was limited; the practical implementation is handled internationally very different. In bromomethane the halogen atom is negative ( δ - ) is polarized, the adjacent carbon atom is positive ( δ ) polarized:

Use

Methyl bromide is used because of its toxicity, mainly for pest control, especially for the fumigation of containers, for controlling animal pests, for example, wood used in construction, as well as for disinfestation of soil.

In international trade, it is used for fumigation of containers in order to avoid the introduction of animal pests that have taken root in vegetable raw materials or in the packaging material. Compared with other methods, the fumigation with methyl bromide is considered one of the most effective. Since 1 January 2008, a marking for transport container is over 33 amendment IMDG Code provides: " This container HAS BEEN fumigated. " Also, to prevent health hazards, the bromomethane must be removed before opening the container. The Federal Office of Consumer Protection and Food Safety ( BVL), the use of methyl bromide as a fumigant in Germany prohibited with effect from 1 September 2006. In order to combat pests in rice methyl bromide is still used in the rice -producing countries, especially for transport and storage protection.

In 2004, alone in the U.S. state of California, according to the local authority ( California Department of Pesticide Regulation) 3500 tonnes of methyl bromide used as a pesticide on agricultural land.

Natural Occurrence

Significant amounts of methyl bromide are released as a natural defense substances of marine life, kelp, the family of cruciferous plants ( Brassicaceae), such as cabbage and oilseed rape plants as well as in the combustion of biomass, such as forest fires. The so escaping amounts of methyl bromide in the atmosphere is estimated to be 10,000 to 50,000 tonnes per year; the emission by rape alone is specified with 6,600 tons worldwide.