Bromoform is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

. It is a colorless

liquid Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...

at room temperature, with a high

refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

and a very high

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

. Its sweet odor is similar to that of chloroform. It is one of the four

haloform In chemistry, trihalomethanes (THMs) are chemical compounds in which three of the four hydrogen atoms of methane () are replaced by halogen atoms. Trihalomethanes with all the same halogen atoms are called haloforms. Many trihalomethanes find uses ...

s, the others being

fluoroform Fluoroform, or trifluoromethane, is the chemical compound with the formula . It is a hydrofluorocarbon as well as being a part of the haloforms, a class of compounds with the formula (X = halogen) with C3v symmetry. Fluoroform is used in divers ...

chloroform Chloroform, or trichloromethane (often abbreviated as TCM), is an organochloride with the formula and a common solvent. It is a volatile, colorless, sweet-smelling, dense liquid produced on a large scale as a precursor to refrigerants and po ...

, and

iodoform Iodoform (also known as triiodomethane) is the organoiodine compound with the chemical formula . It is a pale yellow, crystalline, volatile substance, with a penetrating and distinctive odor (in older chemistry texts, the smell is sometimes refe ...

. It is a brominated organic

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

. Currently its main use is as a laboratory

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

. It is very slightly soluble in water (one part bromoform in 800 parts water) and is miscible with alcohol, benzene, chloroform, ether,

petroleum ether Petroleum ether is the petroleum fraction consisting of aliphatic hydrocarbons and boiling in the range 35–60 °C, and commonly used as a laboratory solvent. Despite the name, petroleum ether is not an ether; the term is used only figurativ ...

acetone Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a charact ...

and oils.

Structure

The molecule adopts

tetrahedral molecular geometry In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are arccos(−) = 109.4712206...° ≈ 109.5° when all four substituents are ...

with C_3v

symmetry Symmetry () in everyday life refers to a sense of harmonious and beautiful proportion and balance. In mathematics, the term has a more precise definition and is usually used to refer to an object that is Invariant (mathematics), invariant und ...

Synthesis

Bromoform was discovered in 1832 by Löwig who distilled a mixture of bromal and

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

, as analogous to preparation of chloroform from chloral. Bromoform can be prepared by the

haloform reaction In chemistry, the haloform reaction (also referred to as the Lieben haloform reaction) is a chemical reaction in which a haloform (, where X is a halogen) is produced by the exhaustive halogenation of an acetyl group (, where R can be either a ...

using

and sodium hypobromite, by the

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of c ...

potassium bromide Potassium bromide ( K Br) is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the US. Its action is due to the bromide ion ( sodium bromide is equa ...

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

, or by treating chloroform with aluminium bromide.

Uses

Only small quantities of bromoform are currently produced industrially in the United States. In the past, it was used as a

sedative A sedative or tranquilliser is a substance that induces sedation by reducing irritability or Psychomotor agitation, excitement. They are central nervous system (CNS) Depressant, depressants and interact with brain activity, causing its decelera ...

and

flame retardant Flame retardants are a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an combustion, ignition source and pr ...

, but now it is mainly used as a laboratory

, for example as an extraction solvent. Bromoform's high density makes it useful for separation of minerals by

. When two samples are mixed with bromoform and then allowed to settle, the top layer will contain minerals less dense than bromoform, and the bottom layer will contain denser minerals. Slightly less dense minerals can be separated in the same way by mixing the bromoform with a small amount of a less dense and miscible solvent. Bromoform is known as an inhibitor of

methanogenesis Methanogenesis or biomethanation is the formation of methane coupled to energy conservation by microbes known as methanogens. It is the fourth and final stage of anaerobic digestion. Organisms capable of producing methane for energy conservation h ...

and is a common component of

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

. Following research by

CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications. CSIRO works with leading organisations arou ...

and its spin-off

FutureFeed FutureFeed is a ruminant livestock feed ingredient based on seaweed that can reduce methane emissions, established by Australia's CSIRO, Commonwealth Scientific and Industrial Research Organisation (CSIRO). FutureFeed holds the global intellectua ...

, several companies are now growing seaweed, in particular from the genus ''

Asparagopsis ''Asparagopsis'' is a genus of edible red algae, red macroalgae (Rhodophyta). The species ''Asparagopsis taxiformis'' is found throughout the tropical and subtropical regions, while ''Asparagopsis armata'' is found in temperate climate, warm tem ...

'', to use as a feed additive for livestock to reduce

methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...

from

ruminant Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microb ...

Occurrence

Bromoform is very commonly made by phytoplankton and seaweeds in the ocean. Bromoform is the most abundant halogenated compound in ''

''.

Environment and toxicology

Natural production of bromoform by

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

and

s in the ocean is thought to be its predominant source in the environment.Palmer C J and Reason C J (2009), Relationships of surface bromoform concentrations with mixed layer depth and salinity in the tropical oceans (2009), Global Biogeochemical Cycles, 23, GB2014. However, locally significant amounts of bromoform enter the environment formed as disinfection byproducts known as

trihalomethane In chemistry, trihalomethanes (THMs) are chemical compounds in which three of the four hydrogen atoms of methane () are replaced by halogen atoms. Trihalomethanes with all the same halogen atoms are called haloforms. Many trihalomethanes find uses ...

s when

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

is added to drinking water to kill bacteria. It is somewhat soluble in water and readily evaporates into the air. Bromoform is the main trihalomethane produced in beachfront salt water

swimming pool A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable Human swimming, swimming and associated activities. Pools can be built into the ground (in-ground pools) or built abo ...

s with concentrations as high as 1.2 ppm (

parts per million In science and engineering, the parts-per notation is a set of pseudo-units to describe the small values of miscellaneous dimensionless quantity, dimensionless quantities, e.g. mole fraction or mass fraction (chemistry), mass fraction. Since t ...

). Concentrations in freshwater pools are 1000 times lower. Occupational skin exposure limits are set at 0.5 ppm. The substance may be hazardous to the environment, and special attention should be given to aquatic organisms. Its volatility and environmental persistence makes bromoform's release, either as liquid or vapor, strongly inadvisable. Bromoform can be absorbed into the body by inhalation and through the skin. The substance is irritating to the respiratory tract, the eyes, and the skin, and may cause effects on the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

and liver, resulting in impaired functions. Its LD₅₀ is 7.2 mmol/kg in mice, or 1.8 g/kg. The International Agency for Research on Cancer (IARC) concluded that bromoform is not classifiable as to human carcinogenicity. The EPA classified bromoform as a probable human

carcinogen A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

.ATSDR - https://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=712&tid=128

References

PDF
*U.S. Department of Health and Human Services. Toxicological Profile for Bromoform and Dibromochloromethan

August 2005.

External links

* *
Toxicological profile for bromoform and dibromochlormethaneToxicity summary
*IARC Summaries & Evaluations

{{Authority control Bromoalkanes Halomethanes Halogenated solvents Flame retardants IARC Group 3 carcinogens Halogen-containing natural products Bromine-containing natural products Sweet-smelling chemicals Tribromomethyl compounds