Names | |||
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IUPAC name Hydrogen bromide | |||
Preferred IUPAC name Bromane [1] | |||
Identifiers | |||
3D model (JSmol) | |||
3587158 | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
ECHA InfoCard | 100.030.090 | ||
EC Number |
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KEGG | |||
MeSH | Hydrobromic+Acid | ||
PubChem CID | |||
RTECS number |
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UNII | |||
UN number | 1048 | ||
CompTox Dashboard (EPA) | |||
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Properties | |||
HBr | |||
Molar mass | 80.91 g/mol | ||
Appearance | Colorless gas | ||
Odor | Acrid | ||
Density | 3.307 g/mL (25 °C) [2] | ||
Melting point | −86.9 °C (−124.4 °F; 186.2 K) | ||
Boiling point | −66.8 °C (−88.2 °F; 206.3 K) | ||
221 g/100 mL (0 °C) 204 g/100 mL (15 °C) 193 g/100 mL (20 °C) 130 g/100 mL (100 °C) | |||
Solubility | Soluble in alcohol, organic solvents | ||
Vapor pressure | 2.308 MPa (at 21 °C) | ||
Acidity (pKa) | −8.8 (±0.8); [3] ~−9 [4] | ||
Basicity (pKb) | ~23 | ||
Conjugate acid | Bromonium | ||
Conjugate base | Bromide | ||
Refractive index (nD) | 1.325[ citation needed ] | ||
Structure | |||
Linear | |||
820 mD | |||
Thermochemistry | |||
Heat capacity (C) | 350.7 mJ/(K·g) | ||
Std molar entropy (S⦵298) | 198.696–198.704 J/(K·mol) [5] | ||
Std enthalpy of formation (ΔfH⦵298) | −36.45...−36.13 kJ/mol [5] | ||
Hazards | |||
Occupational safety and health (OHS/OSH): | |||
Main hazards | Highly corrosive | ||
GHS labelling: | |||
Danger | |||
H314, H335 | |||
P261, P280, P305+P351+P338, P310 | |||
NFPA 704 (fire diamond) | |||
Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration) | 2858 ppm (rat, 1 h) 814 ppm (mouse, 1 h) [6] | ||
NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 3 ppm (10 mg/m3) [7] | ||
REL (Recommended) | TWA 3 ppm (10 mg/m3) [7] | ||
IDLH (Immediate danger) | 30 ppm [7] | ||
Safety data sheet (SDS) | hazard.com | ||
Related compounds | |||
Related compounds | Hydrogen fluoride Hydrogen chloride Hydrogen iodide Hydrogen astatide | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Hydrogen bromide is the inorganic compound with the formula HBr. It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temperature. Aqueous solutions that are 47.6% HBr by mass form a constant-boiling azeotrope mixture that boils at 124.3 °C (255.7 °F). Boiling less concentrated solutions releases H2O until the constant-boiling mixture composition is reached.
Hydrogen bromide, and its aqueous solution, hydrobromic acid, are commonly used reagents in the preparation of bromide compounds.
Hydrogen bromide and hydrobromic acid are important reagents in the production of organobromine compounds. [8] [9] [10] In an electrophilic addition reaction, HBr adds to alkenes:
The resulting alkyl bromides are useful alkylating agents, e.g., as precursors to fatty amine derivatives. Related free radical additions to allyl chloride and styrene give 1-bromo-3-chloropropane and phenylethylbromide, respectively.
Hydrogen bromide reacts with dichloromethane to give bromochloromethane and dibromomethane, sequentially:
These metathesis reactions illustrate the consumption of the stronger acid (HBr) and release of the weaker acid (HCl).
Allyl bromide is prepared by treating allyl alcohol with HBr:
HBr adds to alkynes to yield bromoalkenes. The stereochemistry of this type of addition is usually anti:
Also, HBr adds epoxides and lactones, resulting in ring-opening.
With triphenylphosphine, HBr gives triphenylphosphonium bromide, a solid "source" of HBr. [11]
Vanadium(III) bromide and molybdenum(IV) bromide were prepared by treatment of the higher chlorides with HBr. These reactions proceed via redox reactions: [12]
Hydrogen bromide (along with hydrobromic acid) is produced by combining hydrogen and bromine at temperatures between 200 and 400 °C. The reaction is typically catalyzed by platinum or asbestos. [9] [13]
HBr can be prepared by distillation of a solution of sodium bromide or potassium bromide with phosphoric acid or sulfuric acid: [14]
Concentrated sulfuric acid is less effective because it oxidizes HBr to bromine:
The acid may be prepared by:
Anhydrous hydrogen bromide can also be produced on a small scale by thermolysis of triphenylphosphonium bromide in refluxing xylene. [11]
Hydrogen bromide prepared by the above methods can be contaminated with Br2, which can be removed by passing the gas through a solution of phenol at room temperature in tetrachloromethane or other suitable solvent (producing 2,4,6-tribromophenol and generating more HBr in the process) or through copper turnings or copper gauze at high temperature. [13]
HBr is highly corrosive and, if inhaled, can cause lung damage.[ citation needed ]
Bromine is a chemical element; it has symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig and Antoine Jérôme Balard, its name was derived from the Ancient Greek βρῶμος (bromos) meaning "stench", referring to its sharp and pungent smell.
Sulfuric acid or sulphuric acid, known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, and hydrogen, with the molecular formula H2SO4. It is a colorless, odorless, and viscous liquid that is miscible with water.
Hydrobromic acid is an aqueous solution of hydrogen bromide. It is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C (255.7 °F) and contains 47.6% HBr by mass, which is 8.77 mol/L. Hydrobromic acid is one of the strongest mineral acids known.
In chemistry, hydrogen halides are diatomic, inorganic compounds that function as Arrhenius acids. The formula is HX where X is one of the halogens: fluorine, chlorine, bromine, iodine, astatine, or tennessine. All known hydrogen halides are gases at Standard Temperature and Pressure.
Hydrogen iodide (HI) is a diatomic molecule and hydrogen halide. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a strong acid. Hydrogen iodide and hydroiodic acid are, however, different in that the former is a gas under standard conditions, whereas the other is an aqueous solution of the gas. They are interconvertible. HI is used in organic and inorganic synthesis as one of the primary sources of iodine and as a reducing agent.
Ammonium bromide, NH4Br, is the ammonium salt of hydrobromic acid. The chemical crystallizes in colorless prisms, possessing a saline taste; it sublimes on heating and is easily soluble in water. On exposure to air it gradually assumes a yellow color because of the oxidation of traces of bromide (Br−) to bromine (Br2).
Carbon tetrabromide, CBr4, also known as tetrabromomethane, is a bromide of carbon. Both names are acceptable under IUPAC nomenclature.
Bromoethane, also known as ethyl bromide, is a chemical compound of the haloalkanes group. It is abbreviated by chemists as EtBr. This volatile compound has an ether-like odor.
Cyanogen bromide is the inorganic compound with the formula (CN)Br or BrCN. It is a colorless solid that is widely used to modify biopolymers, fragment proteins and peptides, and synthesize other compounds. The compound is classified as a pseudohalogen.
Hypobromous acid is a weak, unstable acid with chemical formula of HOBr. It is mainly produced and handled in an aqueous solution. It is generated both biologically and commercially as a disinfectant. Salts of hypobromite are rarely isolated as solids.
Zinc bromide (ZnBr2) is an inorganic compound with the chemical formula ZnBr2. It is a colourless salt that shares many properties with zinc chloride (ZnCl2), namely a high solubility in water forming acidic solutions, and good solubility in organic solvents. It is hygroscopic and forms a dihydrate ZnBr2·2H2O.
Vanadium(III) bromide, also known as vanadium tribromide, describes the inorganic compounds with the formula VBr3 and its hydrates. The anhydrous material is a green-black solid. In terms of its structure, the compound is polymeric with octahedral vanadium(III) surrounded by six bromide ligands.
Bromine compounds are compounds containing the element bromine (Br). These compounds usually form the -1, +1, +3 and +5 oxidation states. Bromine is intermediate in reactivity between chlorine and iodine, and is one of the most reactive elements. Bond energies to bromine tend to be lower than those to chlorine but higher than those to iodine, and bromine is a weaker oxidising agent than chlorine but a stronger one than iodine. This can be seen from the standard electrode potentials of the X2/X− couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V). Bromination often leads to higher oxidation states than iodination but lower or equal oxidation states to chlorination. Bromine tends to react with compounds including M–M, M–H, or M–C bonds to form M–Br bonds.
Allyl bromide (3-bromopropene) is an organic halide. It is an alkylating agent used in synthesis of polymers, pharmaceuticals, synthetic perfumes and other organic compounds. Physically, allyl bromide is a colorless liquid with an irritating and persistent smell, however, commercial samples are yellow or brown. Allyl bromide is more reactive but more expensive than allyl chloride, and these considerations guide its use.
Barium bromide is the chemical compound with the formula BaBr2. It is ionic and hygroscopic in nature.
Beryllium bromide is the chemical compound with the formula BeBr2. It is very hygroscopic and dissolves well in water. The compound is a polymer with tetrahedral coordinated Be centres.
Cobalt(II) bromide (CoBr2) is an inorganic compound. In its anhydrous form, it is a green solid that is soluble in water, used primarily as a catalyst in some processes.
Bromous acid is the inorganic compound with the formula of HBrO2. It is an unstable compound, although salts of its conjugate base – bromites – have been isolated. In acidic solution, bromites decompose to bromine.
Organobromine chemistry is the study of the synthesis and properties of organobromine compounds, also called organobromides, which are organic compounds that contain carbon bonded to bromine. The most pervasive is the naturally produced bromomethane.
A halous acid, also known as a halogenous acid, is an oxyacid consisting of a halogen atom in the +3 oxidation state single-bonded to a hydroxyl group and double-bonded to an oxygen atom. Examples include chlorous acid, bromous acid, and iodous acid. The conjugate base is a halite.
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