Tetrabromomethane

Tetrabromomethane, CBr4, also known as carbon tetrabromide, is a carbon bromide. Both names are acceptable under IUPAC nomenclature.

Tetrabromomethane
Stereo, skeletal formula of tetrabromomethane
Stereo, skeletal formula of tetrabromomethane
Spacefill model of tetrabromomethane
Names
IUPAC name
Tetrabromomethane[2]
Other names
  • Carbon(IV) bromide
  • Carbon bromide
  • Carbon tetrabromide
[1]
Identifiers
3D model (JSmol)
Abbreviations R-10B4
1732799
ChEBI
ChemSpider
ECHA InfoCard 100.008.355
EC Number
  • 209-189-6
26450
MeSH carbon+tetrabromide
RTECS number
  • FG4725000
UN number 2516
Properties
CBr4
Molar mass 331.627 g·mol−1
Appearance Colorless to yellow-brown crystals
Odor sweet odor
Density 3.42 g mL−1
Melting point 94.5 °C; 202.0 °F; 367.6 K
Boiling point 189.7 °C; 373.4 °F; 462.8 K decomposes
0.024 g/100 mL (30 °C)
Solubility soluble in ether, chloroform, ethanol
Vapor pressure 5.33 kPa (at 96.3 °C)
-93.73·10−6 cm3/mol
1.5942 (100 °C)
Structure
Monoclinic
Tetragonal
Tetrahedron
0 D
Thermochemistry
0.4399 J K−1 g−1
212.5 J/mol K
26.0–32.8 kJ mol−1
47.7 kJ/mol
−426.2–−419.6 kJ mol−1
Hazards
Safety data sheet inchem.org
GHS pictograms GHS05: Corrosive GHS07: Harmful
GHS signal word DANGER
H302, H315, H318, H335
P261, P280, P305+351+338
NFPA 704
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
2
0
Flash point noncombustible [3]
Lethal dose or concentration (LD, LC):
  • 56 mg kg−1 (intravenous, mouse)
  • 1.8 g kg−1 (oral, rat)
US health exposure limits (NIOSH):
PEL (Permissible)
none[3]
REL (Recommended)
TWA 0.1 ppm (1.4 mg/m3) ST 0.3 ppm (4 mg/m3)[3]
IDLH (Immediate danger)
N.D.[3]
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Physical properties

Tetrabromomethane has two polymorphs: crystalline II or β below 46.9 °C (320.0 K) and crystalline I or α above 46.9 °C. Monoclinic polymorph has space group C2/c with lattice constants: a = 20.9, b = 12.1, c = 21.2 (.10−1 nm), β = 110.5°.[4] Bond energy of C-Br is 235 kJ.mol−1.[5]

Due to its symmetrically substituted tetrahedral structure, its dipole moment is 0 Debye. Critical temperature is 439 °C (712 K) and critical pressure is 4.26 MPa.[4]

Plastic crystallinity

The high temperature α phase is known as a plastic crystal phase. Roughly speaking, the CBr4 are situated on the corners of the cubic unit cell as well as on the centers of its faces in an fcc arrangement. It was thought in the past that the molecules could rotate more or less freely (a 'rotor phase'), so that on a time average they would look like spheres. Recent work [6] has shown, however, that the molecules are restricted to only 6 possible orientations (Frenkel disorder). Moreover, they cannot take these orientations entirely independently from each other because in some cases the bromine atoms of neighboring molecules would point at each other leading to impossibly short distances. This rules out certain orientational combinations when two neighbor molecules are considered. Even for the remaining combinations displacive changes occur that better accommodate neighbor to neighbor distances. The combination of censored Frenkel disorder and displacive disorder implies a considerable amount of disorder inside the crystal which leads to highly structured sheets of diffuse scattered intensity in X-ray diffraction. In fact, it is the structure in the diffuse intensity that provides the information about the details of the structure.

Chemical reactions

In combination with triphenylphosphine, CBr4 is used in the Appel reaction, which converts alcohols to alkyl bromides. Similarly, CBr4 is used in combination with triphenylphosphine in the first step of the Corey-Fuchs reaction, which converts aldehydes into terminal alkynes. It is significantly less stable than lighter tetrahalomethane bromination using HBr or Br2. It can be also prepared by more economical reaction of tetrachloromethane with aluminium bromide at 100 °C.[5]

Uses

It is used as a solvent for greases, waxes and oils, in plastic and rubber industry for blowing and vulcanization, further for polymerization, as a sedative and as an intermediate in manufacturing agrochemicals. Due to its non-flammability it is used as an ingredient in fire-resistant chemicals. It is also used for separating minerals because of its high density.

References

  1. ^ "Carbon compounds: carbon tetrabromide". Retrieved 22 February 2013.
  2. ^ "carbon tetrabromide - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification. Retrieved 18 June 2012.
  3. ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0106". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ a b F. Brezina, J. Mollin, R. Pastorek, Z. Sindelar. Chemicke tabulky anorganickych sloucenin (Chemical tables of inorganic compounds). SNTL, 1986.
  5. ^ a b N. N. Greenwood, A. Earnshaw. Chemie prvku (Chemistry of the Elements). Informatorium, Prague, 1993.
  6. ^ Coupled orientational and displacive degrees of freedom in the high-temperature plastic phase of the carbon tetrabromide α-CBr4 Jacob C. W. Folmer, Ray L. Withers, T. R. Welberry, and James D. Martin. Physical Review B 77 in press

External links

1,1-Dibromoethane

1,1-Dibromoethane is a clear, slightly brown, flammable chemical compound. It is classified as the organobromine compound, and has the chemical formula C2H4Br2 and it is a position isomer of 1,2-dibromoethane. It is commonly seen in industrial chemistry, where it is used as a fuel additive. It is also used as a grain and soil fumigant for insect control.

1,2-Dibromoethane

1,2-Dibromoethane, also known as ethylene dibromide (EDB), is an organobromine compound with the chemical formula (CH2Br2). Although trace amounts occur naturally in the ocean, where it is formed probably by algae and kelp, it is mainly synthetic. It is a dense colorless liquid with a faint sweet odor, detectable at 10 ppm, is a widely used and sometimes-controversial fumigant. The combustion of 1,2-dibromoethane produces hydrogen bromide gas that is significantly corrosive.

Bingel reaction

The Bingel reaction in fullerene chemistry is a fullerene cyclopropanation reaction to a methanofullerene first discovered by C. Bingel in 1993 with the bromo derivative of diethyl malonate in the presence of a base such as sodium hydride or DBU. The preferred double bonds for this reaction on the fullerene surface are the shorter bonds at the junctions of two hexagons (6-6 bonds) and the driving force is relief of steric strain.

The reaction is of importance in the field of chemistry because it allows the introduction of useful extensions to the fullerene sphere. These extensions alter their properties, for instance solubility and electrochemical behavior, and therefore widen the range of potential technical applications.

Bromoform

Bromoform (CHBr3) is a brominated organic solvent, colorless liquid at room temperature, with a high refractive index, very high density, and sweet odor is similar to that of chloroform. It is a trihalomethane, and is one of the four haloforms, the others being fluoroform, chloroform, and iodoform. Bromoform can be prepared by the haloform reaction using acetone and sodium hypobromite, by the electrolysis of potassium bromide in ethanol, or by treating chloroform with aluminium bromide. Currently its main use is as a laboratory reagent.

Carbon tetrachloride

Carbon tetrachloride, also known by many other names (the most notable being tetrachloromethane, also recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVACR) is an organic compound with the chemical formula CCl4. It is a colourless liquid with a "sweet" smell that can be detected at low levels. It has practically no flammability at lower temperatures. It was formerly widely used in fire extinguishers, as a precursor to refrigerants and as a cleaning agent, but has since been phased out because of toxicity and safety concerns. Exposure to high concentrations of carbon tetrachloride (including vapor) can affect the central nervous system, degenerate the liver and kidneys. Prolonged exposure can be fatal.

Diamondoid

In chemistry, diamondoids are variants of the carbon cage molecule known as adamantane (C10H16), the smallest unit cage structure of the diamond crystal lattice. Diamondoids also known as nanodiamonds or condensed adamantanes may include one or more cages (adamantane, diamantane, triamantane, and higher polymantanes) as well as numerous isomeric and structural variants of adamantanes and polymantanes. These diamondoids occur naturally in petroleum deposits and have been extracted and purified into large pure crystals of polymantane molecules having more than a dozen adamantane cages per molecule. These species are of interest as molecular approximations of the diamond cubic framework, terminated with C−H bonds. Cyclohexamantane may be thought of as a nanometer-sized diamond of approximately 5.6×10−22 grams.

Dibromomethane

Dibromomethane or methylene bromide, or methylene dibromide is a halomethane. It is slightly soluble in water but very soluble in organic solvents. It is a colorless liquid.

Dutch pollutant standards

Dutch Standards are environmental pollutant reference values (i.e., concentrations in environmental medium) used in environmental remediation, investigation and cleanup.Barring a few exceptions, the target values are underpinned by an environmental risk analysis wherever possible and apply to individual substances. In most cases, target values for the various substances are related to a national background concentration that was determined for the Netherlands.

Groundwater target values provide an indication of the benchmark for environmental quality in the long term, assuming that there are negligible risks for the ecosystem. For metals a distinction is made between deep and shallow groundwater. This is because deep and shallow groundwater contain different background concentrations. An arbitrary limit of 10 metres has been adopted. The target values shown below are for 'shallow' groundwater, 0 – 10 m depth.

The soil remediation intervention values indicate when the functional properties of the soil for

humans, plants and animals is seriously impaired or threatened. They are representative of the

level of contamination above which a serious case of soil contamination is deemed to exist. The target values for soil are adjusted for the organic matter (humus) content and soil fraction <0.2 µm (lutum - Latin, meaning "mud" or "clay"). The values below are calculated for a 'Standard Soil' with 10% organic matter and 25% lutum.

A case of environmental contamination is defined as 'serious' if >25 m³ soil or >100 m³ groundwater is contaminated above the intervention value.

The values presented below are from Annex 1, Table 1, "Groundwater target values and soil and groundwater intervention values". In previous versions of the Dutch Standards, target values for soil were also present. However, in the 2009 version, target values for soils have been deleted for all compounds except metals.

Halomethane

Halomethane compounds are derivatives of methane (CH4) with one or more of the hydrogen atoms replaced with halogen atoms (F, Cl, Br, or I). Halomethanes are both naturally occurring, especially in marine environments, and man-made, most notably as refrigerants, solvents, propellants, and fumigants. Many, including the chlorofluorocarbons, have attracted wide attention because they become active when exposed to ultraviolet light found at high altitudes and destroy the Earth's protective ozone layer.

Silicon tetrabromide

Silicon tetrabromide is the inorganic compound with the formula SiBr4. This colorless liquid has a suffocating odor due to its tendency to hydrolyze with release of hydrogen bromide. The general properties of silicon tetrabromide closely resemble those of the more commonly used silicon tetrachloride.

Tetrabromoethane

Tetrabromoethane (TBE) is a halogenated hydrocarbon, chemical formula C2H2Br4. Although three bromine atoms may bind to one of the carbon atoms creating 1,1,1,2-tetrabromoethane this is not thermodynamically favorable, so in practice tetrabromoethane is equal to 1,1,2,2-tetrabromoethane, where each carbon atom binds two bromine atoms.

It has an unusually high density for an organic compound, near 3 g/mL, due largely to the four bromine atoms. TBE is a liquid at room temperature, and is used to separate mineral ores from its supporting rock by means of preferential flotation. Quartz, feldspar, calcite, dolomite and other minerals with low density will float in TBE, while minerals such as sphalerite, galena and pyrite will sink. A related compound, bromoform, is also sometimes used in these applications, however, TBE is more practical because of its wider liquid range and lower vapor pressure. Acute TBE poisoning has been known to occur.

Tetrafluoromethane

Tetrafluoromethane, also known as carbon tetrafluoride or R-14, is the simplest fluorocarbon (CF4). It has a very high bond strength due to the nature of the carbon–fluorine bond. It can also be classified as a haloalkane or halomethane. Tetrafluoromethane is a useful refrigerant but also a potent greenhouse gas.

Bromine compounds
Unsubstituted
Monosubstituted
Disubstituted
Trisubstituted
Tetrasubstituted
Compounds
Carbon ions
Oxides and related

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