Carbon tetrabromide

Source: Wikipedia, the free encyclopedia.
"CBr4" redirects here. For the Transport Canada location, see Clinton/Bleibler Ranch Aerodrome.
Carbon tetrabromide
Stereo, skeletal formula of tetrabromomethane
Stereo, skeletal formula of tetrabromomethane
Stereo, skeletal formula of tetrabromomethane
Spacefill model of tetrabromomethane
Spacefill model of tetrabromomethane
Names
Preferred IUPAC name
Tetrabromomethane[2]
Other names
  • Carbon(IV) bromide
  • Carbon bromide, neutral (1:4)
  • Carbon tetrabromide
[1]
Identifiers
3D model (
JSmol
)
Abbreviations R-10B4[citation needed]
1732799
ChEBI
ChemSpider
ECHA InfoCard
 100.008.355 Edit this at Wikidata
EC Number
  • 209-189-6
26450
MeSH carbon+tetrabromide
RTECS number
  • FG4725000
UNII
UN number 2516
  • InChI=1S/CBr4/c2-1(3,4)5 checkY
    Key: HJUGFYREWKUQJT-UHFFFAOYSA-N checkY
  • BrC(Br)(Br)Br
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
Std enthalpy of
formation
(ΔfH⦵298)
 26.0–32.8 kJ mol−1
47.7 kJ/mol
Std enthalpy of
combustion
(ΔcH⦵298)
 −426.2–−419.6 kJ mol−1
Hazards
GHS labelling:
GHS05: Corrosive GHS07: Exclamation mark
Danger
H302, H315, H318, H335
P261, P280, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
Flash point noncombustible[3]
Lethal dose or concentration (LD, LC):
  • 56 mg kg−1 (intravenous, mouse)
  • 100 mg kg−1 (oral, rat)
NIOSH (US health exposure limits):
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]
Safety data sheet (SDS) inchem.org
Related compounds
Other anions
 Carbon tetrafluoride
Carbon tetrachloride
Carbon tetraiodide
Other cations
 Silicon tetrabromide
Germanium tetrabromide
Tin(IV) bromide
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Carbon tetrabromide, CBr4, also known as tetrabromomethane, is a

IUPAC nomenclature
.

Production

CBr4 can be obtained by the

methyl bromide, dibromomethane and bromoform) and hydrogen bromide
. This process is analogous to the chlorination of methane:

Br2 + hν → 2 Br·;
Br· + CH4 → ·CH3 + HBr.
·CH3 + Br2 → CH3Br + Br·.
CH3Br + Br· → ·CH2Br + HBr,
·CH2Br + Br2 → CH2Br2 + Br·,
CH2Br2 + Br· → ·CHBr2 + HBr,
·CHBr2 + Br2 → CHBr3 + Br·,
CHBr3 + Br· → ·CBr3 + HBr,
·CBr3 + Br2 → CBr4 + Br·

Halogen exchange of carbon tetrachloride with aluminium bromide gives higher yields with aluminium chloride as the byproduct:[4]

4 AlBr3 + 3 CCl4 → 4 AlCl3 + 3 CBr4

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°.[5] Bond energy of C-Br is 235 kJ.mol−1.[6]

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.[5]

Plastic crystallinity

The high temperature α phase is known as a

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

tetrachloromethane with aluminium bromide at 100 °C.[6]

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. ^ N. N. Greenwood, A. Earnshaw: Chemie der Elemente, 1. Auflage, VCH, Weinheim 1988, ISBN 3-527-26169-9, S. 359.
  5. ^ a b F. Brezina, J. Mollin, R. Pastorek, Z. Sindelar. Chemicke tabulky anorganickych sloucenin (Chemical tables of inorganic compounds). SNTL, 1986.
  6. ^ a b N. N. Greenwood, A. Earnshaw. Chemie prvku (Chemistry of the Elements). Informatorium, Prague, 1993.
  7. ^ 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

Retrieved from "https://en.wikipedia.org/w/index.php?title=Carbon_tetrabromide&oldid=1202886658"