n-Propyl bromide

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n-Propyl bromide
Skeletal formula of n-propyl bromide
Spacefill model of n-propyl bromide
Identifiers
Abbreviations n-PB[citation needed]
CAS number 106-94-5 YesY
PubChem 7840
ChemSpider 7552 N
EC number 203-445-0
UN number 2344
MeSH 1-bromopropane
ChEBI CHEBI:47105 N
ChEMBL CHEMBL1230095 N
RTECS number TX4110000
Beilstein Reference 505936
Jmol-3D images Image 1
Properties
Molecular formula C3H7Br
Molar mass 122.99 g mol−1
Appearance Colorless liquid
Density 1.354 g mL−1
Melting point −110.5 °C; −166.8 °F; 162.7 K
Boiling point 70.3 to 71.3 °C; 158.4 to 160.2 °F; 343.4 to 344.4 K
Solubility in water 2.5 g L−1 (at 20 °C)
Solubility in ethanol Miscible
Solubility in diethyl ether Miscible
log P 2.319
Vapor pressure 19.5 kPa (at 20 °C)
kH 1.4 μmol Pa−1 kg−1
Refractive index (nD) 1.43414
Viscosity 5.241 mPa s (at 20 °C)
Thermochemistry
Specific
heat capacity
C
134.6 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
−125.8–−123.0 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−2.0580–−2.0552 MJ mol−1
Hazards
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H225, H315, H319, H335, H336, H360, H373
GHS precautionary statements P201, P210, P261, P305+351+338, P308+313
EU Index 602-019-00-5
EU classification Highly Flammable F Toxic T
R-phrases R60, R11, R36/37/38, R48/20, R63, R67
S-phrases S53, S45
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 22 °C (72 °F; 295 K)
Explosive limits 4.6–?%
LD50 2.950 mg kg−1 (intraperitoneal, rat)
Related compounds
Related alkanes
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

n-Propyl bromide (nPB or 1-propylbromide) is an organobromine compound with the chemical formula CH3CH2CH2Br. It is a colorless liquid that is used as a solvent. It has a characteristic hydrocarbon odor.

Preparation[edit]

Industrial routes to n-propyl bromide involve free-radical additions to the corresponding alkenes. In this way, the anti-Markovnikov product is obtained.[2]

A laboratory synthesis involves treating propanol with a mixture of hydrobromic and sulfuric acids:

CH3CH2CH2OH + HBr → CH3CH2CH2Br + H2O

An alternate route involves refluxing propanol with phosphorus tribromide is generated in situ.[3]

Applications[edit]

Like other halocarbons, n-propyl bromide finds use as a solvent. It is a solvent for adhesives and has been deployed as a replacement for perchloroethylene as a dry cleaning solvent. It is used for the cleaning of metal surfaces, removal of soldering residues from electronic circuit boards and in the hole transport layer (HTL) of multi-layered OLEDs.

The chemical's increasing use in the 21st century resulted from need for a substitute for chlorofluorocarbons and perchloroethylene (tetrachloroethylene).[4]

Regulation[edit]

Since 2007, it has been approved for use under the U.S. EPA's Significant New Alternatives Policy (SNAP) as a suitable replacement for ozone depleting chemicals.[5] The U.S. EPA announced that, based on a work plan developed under the Toxic Substances Control Act of 1976, in 2013 it will begin a full risk assessment of n-propyl bromide.[6]

The North Carolina Department of Labor’s Occupational Safety and Health Division issued a Hazard Alert in 6/2014, as it "is not regulated to protect workers, consumers or the environment".[7]

IN the EU, nPB has been classified as reproductive toxicant per Registration, Evaluation, Authorisation and Restriction of Chemicals, which makes it a "substance of very high concern".[8]

Safety[edit]

In 2003, the American Conference of Governmental Industrial Hygienists (ACGIH) set the time-weighted average threshold limit value for an 8-hour exposure at 10 parts per million. In 2008 the CDC recommended that use of n-propyl bromide as a replacement for perchloroethylene may require adjustment and modification of equipment, improved ventilation and use of personal protective equipment.[4] In 2013, a peer-review panel convened by the National Toxicology Program unanimously recommended that 1-bromopropane, be classified as reasonably anticipated human carcinogens.[9]

Extended occupational exposure to n-propyl bromide in higher concentrations than recommended has resulted in significant injury to workers in the United States.[10] Its use as a solvent in aerosol glues used to glue foam cushions has been especially problematic.[11] Reported symptoms to overexposure include confusion, dysarthria, dizziness, paresthesias, and ataxia; unusual fatigue and headaches, development of arthralgias, visual disturbances (difficulty focusing), paresthesias, and muscular twitching. Symptoms may persist over one year after termination of exposure.[4] Loss of feeling in the feet, an example of paresthesia, is colloquially called "dead foot" by workers who suffer from it.[11] Of nationwide "more than 140 cushion workers nationwide, mostly from plants in Utah, Mississippi and North Carolina,[...] that had been exposed to dangerous levels of the chemical, many of them sickened and [are] unable to walk".[11] One worker's long-term exposure resulting in neurological damage was interviewed in the NY Times.

References[edit]

  1. ^ "1-bromopropane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 27 March 2005. Identification. Retrieved 15 June 2012. 
  2. ^ David Ioffe, Arieh Kampf “Bromine, Organic Compounds” in Kirk-Othmer Encyclopedia of Chemical Technology 2002 by John Wiley & Sons. doi: 10.1002/0471238961.0218151325150606.a01.
  3. ^ Oliver Kamm and C. S. Marvel (1941), "Alkyl and alkylene bromides", Org. Synth. ; Coll. Vol. 1: 25 
  4. ^ a b c "Neurologic Illness Associated with Occupational Exposure to the Solvent 1-Bromopropane --- New Jersey and Pennsylvania, 2007--2008". Centers for Disease Control. December 5, 2008. Retrieved March 31, 2013. 
  5. ^ "Protection of Stratospheric Ozone: Listing of Substitutes for Ozone- Depleting Substances-n-Propyl Bromide in Solvent Cleaning". Federal Register. U.S. Environmental Protection Agency. May 30, 2007. Retrieved March 31, 2013. "This final rule lists n-propyl bromide (nPB) as an acceptable substitute when used as a solvent in industrial equipment for metals cleaning, electronics cleaning, or precision cleaning. General metals, precision, and electronics cleaning includes cleaning with industrial cleaning equipment such as vapor degreasers, in-line cleaning systems, or automated equipment used for cleaning below the boiling point." 
  6. ^ United States Environmental Protection Agency. "List of Chemicals for Assessment". Retrieved 23 April 2013. 
  7. ^ North Carolina Department of Labor (June 2014). "Hazard Alert". State of North Carolina. Retrieved 6 August 2014. 
  8. ^ "AGREEMENT OF THE MEMBER STATE COMMITTEE ON THE IDENTIFICATION OF 1-BROMOPROPANE [n-PROPYL BROMIDE] AS A SUBSTANCE OF VERY HIGH CONCERN According to Articles 57 and 59 of Regulation (EC) 1907/20061". European Union. 29 November 2012. Retrieved 6 August 2014. 
  9. ^ "Report on Carcinogens Monograph on 1-Bromopropane". National Toxicology Program. 21 March 2013. Retrieved 6 August 2014. 
  10. ^ "1-BROMOPROPANE: Human Health Effects". Hazardous Substances Data Bank. Retrieved March 31, 2013. 
  11. ^ a b c Ian Urbina (March 30, 2013). "As OSHA Emphasizes Safety, Long-Term Health Risks Fester". The New York Times. Retrieved March 31, 2013. 

See also[edit]