Dibromomethane
Encyclopedia
Dibromomethane or methylene bromide, or methylene dibromide is a halomethane
. It is slightly soluble in water, but very soluble in carbon tetrachloride
, diethyl ether
and methanol
.
Its refractive index
is 1.5419 (20 °C, D).
by reaction
using sodium arsenite
and sodium hydroxide.
Another way is to prepare it from diiodomethane
and bromine
.
and liberated to the oceans. Releasing on soil causes it to evaporate and leach into the ground. Releasing in water causes it to be lost mainly by volatilisation
with a half life of 5.2 hours. It has no significant degradating biological or abiological effects. In the atmosphere it will be lost because of reaction with photochemically produced hydroxyl
radicals. The estimated half life of this reaction is 213 days.
Halomethane
Halomethane compounds are derivatives of methane with one or more of the hydrogen atoms replaced with halogen atoms . Halomethanes are both naturally occurring, especially in marine environments, and man-made, most notably as refrigerants, solvents, propellants, and fumigants...
. It is slightly soluble in water, but very soluble in carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
, diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
and methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
.
Its refractive index
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
is 1.5419 (20 °C, D).
Preparation
Dibromomethane can be prepared from bromoformBromoform
Bromoform is a pale yellowish liquid with a sweet odor similar to chloroform, a halomethane or haloform. Its refractive index is 1.595 . Bromoform is produced naturally by phytoplankton and seaweeds in the ocean and this is thought to be the predominant source to the environment...
by reaction
- CHBr3 + Na3AsO3 + NaOH → CH2Br2 + Na3AsO4 + NaBr
using sodium arsenite
Sodium arsenite
Sodium arsenite is a compound with formula NaAsO2. It is the sodium salt of arsenous acid. It is a crystalline solid consisting of sodium cations, Na+, and catena-arsenite anions, [AsO2], which are infinite -O-As- chains, similar in structure to selenium dioxide, SeO2.It is a pesticide....
and sodium hydroxide.
Another way is to prepare it from diiodomethane
Diiodomethane
Diiodomethane or methylene iodide, commonly abbreviated "MI", is a liquid organoiodine compound. It is insoluble in water, but soluble in ether and alcohol. It has a relatively high refractive index of 1.741, and a surface tension of 0.0508 N·m−1...
and bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
.
Natural occurrence
It is naturally produced by marine algaeAlgae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
and liberated to the oceans. Releasing on soil causes it to evaporate and leach into the ground. Releasing in water causes it to be lost mainly by volatilisation
Volatilisation
Volatilization is the process whereby a dissolved sample is vaporised. In atomic spectroscopy this is usually a two step process. The analyte is turned into small droplets in a nebuliser which are entrained in a gas flow which is in turn volatilised in a high temperature flame in the case of AAS or...
with a half life of 5.2 hours. It has no significant degradating biological or abiological effects. In the atmosphere it will be lost because of reaction with photochemically produced hydroxyl
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...
radicals. The estimated half life of this reaction is 213 days.