Sodium bromide

Sodium bromide is an inorganic compound with the formula NaBr. It is a high-melting white, crystalline solid that resembles sodium chloride. It is a widely used source of the bromide ion and has many applications.[7]

Sodium bromide
Names
IUPAC name
Sodium bromide
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.028.727
RTECS number
  • anhydrous: VZ3150000
UNII
Properties
NaBr
Molar mass 102.894 g·mol−1
Appearance White powder, hygroscopic
Density 3.21 g/cm3 (anhydrous)
2.18 g/cm3 (dihydrate)
Melting point 747 °C (1,377 °F; 1,020 K)
(anhydrous)
36 °C (97 °F; 309 K)
(dihydrate) decomposes[1]
Boiling point 1,390 °C (2,530 °F; 1,660 K) [1]
71.35 g/100 mL (−20 °C)
79.52 g/100 mL (0 °C)
94.32 g/100 mL (25 °C)[2]
104.9 g/100 mL (40 °C)
116.2 g/100 mL (100 °C)[3]
Solubility Soluble in alcohol, liquid ammonia, pyridine, hydrazine, SO2, amine
Insoluble in acetone, acetonitrile[2]
Solubility in methanol 17.3 g/100 g (0 °C)
16.8 g/100 g (20 °C)
16.1 g/100 g (40 °C)
15.3 g/100 g (60 °C)[2]
Solubility in ethanol 2.45 g/100 g (0 °C)
2.32 g/100 g (20 °C)
2.29 g/100 g (30 °C)
2.35 g/100 g (70 °C)[2]
Solubility in formic acid 19.3 g/100 g (18 °C)
19.4 g/100 g (25 °C)[2]
Solubility in glycerol 38.7 g/100 g (20 °C)[2]
Solubility in dimethylformamide 3.2 g/100 g (10.3 °C)[2]
Vapor pressure 1 torr (806 °C)
5 torr (903 °C)[1]
−41.0·10−6 cm3/mol
Thermal conductivity 5.6 W/m·K (150 K)[4]
1.6428 (24 °C)
nKrF = 1.8467 (24 °C)
nHe–Ne = 1.6389 (24 °C)[5]
Viscosity 1.42 cP (762 °C)
1.08 cP (857 °C)
0.96 cP (937 °C)[2]
Structure
Cubic
a = 5.97 Å[4]
Thermochemistry
51.4 J/mol·K[2]
86.82 J/mol·K[2]
−361.41 kJ/mol[2]
−349.3 kJ/mol[2]
Hazards
Safety data sheet External MSDS
NFPA 704 (fire diamond)
Flash point 800 °C (1,470 °F; 1,070 K)
Lethal dose or concentration (LD, LC):
3500 mg/kg (rats, oral)
Related compounds
Other anions
 Sodium fluoride
Sodium chloride
Sodium iodide
Sodium astatide
Other cations
 Lithium bromide
Potassium bromide
Rubidium bromide
Caesium bromide
Francium bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Synthesis, structure, reactions

NaBr crystallizes in the same cubic motif as NaCl, NaF and NaI. The anhydrous salt crystallizes above 50.7 °C.[7] Dihydrate salts (NaBr·2H2O) crystallize out of water solution below 50.7 °C.[8]

NaBr is produced by treating sodium hydroxide with hydrogen bromide.

Sodium bromide can be used as a source of the chemical element bromine. This can be accomplished by treating an aqueous solution of NaBr with chlorine gas:

2 NaBr + Cl2 → Br2 + 2 NaCl

Applications

Sodium bromide is the most useful inorganic bromide in industry.[7] It is also used as a catalyst in TEMPO-mediated oxidation reactions.[9]

Medicine
See also: Potassium bromide § Medical and Veterinary
Bromo-Seltzer newspaper ad (1908)

Also known as Sedoneural, sodium bromide has been used as a hypnotic, anticonvulsant, and sedative in medicine, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries. Its action is due to the bromide ion, and for this reason potassium bromide is equally effective. In 1975, bromides were removed from drugs in the U.S. such as Bromo-Seltzer due to toxicity.[10]

Preparation of other bromine compounds

Sodium bromide is widely used for the preparation of other bromides in organic synthesis and other areas. It is a source of the bromide nucleophile to convert alkyl chlorides to more reactive alkyl bromides by the Finkelstein reaction:

NaBr + RCl → RBr + NaCl (R = alkyl)

Once a large need in photography, but now shrinking, the photosensitive salt silver bromide is prepared using NaBr.

Disinfectant

Sodium bromide is used in conjunction with chlorine as a disinfectant for hot tubs and swimming pools.

Petroleum industry

Because of its high solubility in water (943.2 g/L or 9.16 mol/L, at 25 °C) sodium bromide is used to prepare dense drilling fluids used in oil wells to compensate a possible overpressure arising in the fluid column and to counteract the associated trend to blow out. The presence of the sodium cation also causes the bentonite added to the drilling fluid to swell, while the high ionic strength induces the bentonite flocculation.

Safety

NaBr has a very low toxicity with an oral LD50 estimated at 3.5 g/kg for rats.[6] However, this is a single-dose value. Bromide ion is a cumulative toxin with a relatively long half life (in excess of a week in humans): see potassium bromide.

References
  1. Pradyot, Patnaik (2003). Handbook of Inorganic Chemicals. The McGraw-Hill Companies, Inc. ISBN 978-0-07-049439-8.
  2. "Sodium bromide".
  3. Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). D. Van Nostrand Company.
  4. "Sodium Bromide (NaBr)". korth.de. Korth Kristalle GmbH. Retrieved 2014-06-11.
  5. Polyanskiy, Mikhail. "Refractive index of NaBr (Sodium bromide) - Li". refractiveindex.info. Retrieved 2014-06-11.
  6. "Sodium bromide MSDS" (PDF). sciencelab.com. Sciencelab.com, Inc. 2013-05-21. Retrieved 2014-06-11.
  7. Michael J. Dagani, Henry J. Barda, Theodore J. Benya, David C. Sanders "Bromine Compounds" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2000. doi:10.1002/14356007.a04_405
  8. Eagleson, Mary (translated by) (1994). Concise Encyclopedia Chemistry (Illustrated, revised, English language ed.). Berlin [u.a.]: Walter De Gruyter. p. 996. ISBN 9783110114515.
  9. Hirota, Masayuki; Tamura, Naoyuki; Saito, Tsuguyuki; Isogai, Akira (2010). "Water dispersion of cellulose II nanocrystals prepared by TEMPO-mediated oxidation of mercerized cellulose at pH 4.8". Cellulose. 17 (2): 279–288. doi:10.1007/s10570-009-9381-2. S2CID 97264888.
  10. "Bromide: Potassium & Sodium". canine-epilepsy.com. Canine-Epilepsy Resources. 2011-05-31. Retrieved 2014-06-11.
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