1-Bromopropane

n-Propyl bromide

Names
IUPAC name 1-bromopropane
Other names bromomethylethane, 1-propyl bromide, 1-bromopropane, nPB
Identifiers
CAS Number	106-94-5 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1230095 N
ECHA InfoCard	100.003.133
RTECS number	TX4110000
CompTox Dashboard (EPA)	DTXSID6021874
SMILES CCCBr
Properties
Chemical formula	C3H7Br
Molar mass	122.99
Appearance	Colorless liquid
Density	1.353
Melting point	−109.9 °C (−165.8 °F; 163.2 K)
Boiling point	71.0 °C (159.8 °F; 344.1 K)
Solubility in water	0.25 g/100 mL at 20 °C
Solubility in ethanol	fully miscible
Solubility in diethyl ether	fully miscible
Refractive index (nD)	1.43414
Viscosity	6.509 cP at 0 °C 5.241 cP at 20 °C
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Highly Flammable (Closed Cup ; No flash point observed via TCC)
NFPA 704 (fire diamond)	2 3 0
Flash point	22°C** (CLOSED CUP) ; **NOTE: Various flash points are published for N-Propyl Bromide. The above flash point is from the Federal Register, vol 68, no 106, June 3, 2003, page 33303 (EPA, 40 CFR Part 82). Hazardous Substances Data Bank, (HSDB 2006/04/20) refers to it as “highly flammable” & “dangerous fire hazard”, but gives no flash point. The U.S. DOT (49 CFR) lists “bromopropanes” as Flammable Liquids, Class 3, Packing Group II, effective August 1, 2007. The European Chemical Substance Information System lists 1-bromopropane as “highly flammable”. Only Scientific Material International, Miami (March 2005) states 1-bromopropane is not flammable: “no flash point observed to 160°F” – by 3 protocols: ASTM D92 (COC), ASTM D 93(P-M CC), & ASTM D 56 (TAG CC). Although the material is commonly believed to be non-hazardous with no flash point and transported as such, it is in fact listed as "Highly Flammable" under the following international regulations: - WHMIS (Canada) - EINECS - DSCL (EEC) - HMIS (U.S.A.) - NFPA (U.S.A.) Both HMIS and NFPA Fire, Health, and Reactivity hold the same ratings. It holds no "Specific Hazard" under NFPA, however under HMIS lists an "H" under Personal Protection. All information above has been valid since August 1, 2007 and is accurate as of January 26, 2012.
Related compounds
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

n-Propyl bromide (also 1-bromopropane or 1-propyl bromide or NPB) is a colorless to off-white, non-flammable chemical compound. It has the chemical formula C₃H₇Br. It is an organic solvent used for the cleaning of metal surfaces, removal of soldering residues from electronic circuit boards, and as an adhesive solvent. It has a characteristic hydrocarbon odor.

Use as a degreasing agent

N-propyl bromide (1-bromopropane) is an example of an untested substance being substituted for possibly less potent materials that were more strictly regulated in the occupational and general environment. For example, NIOSH reported two cases involving workers exposed to 1-BP and diagnosed with clinical manifestations of neurotoxicity. The cases, when coupled with previously reported studies of workers exposed to 1-BP, illustrate potential health risks of 1-BP exposure. Clinicians and public health professionals should be alert to potential health effects among workers exposed to 1-BP, particularly in dry cleaning and other workplaces where 1-BP use might be increasing, and effective control methods to limit exposure to 1-BP should be implemented at worksites.

In the early 1990s, it was discovered that n-propyl bromide had been wrongly classified as a flammable solvent in reference books of the United Kingdom. In the USA, it has been proven to not be a flammable solvent as tested under the standard tests for flammability from the American Society for Testing and Materials (ASTM). Since that time, the use of n-propyl bromide (NPB) has flourished. In most of the modern world, NPB has seen increased use as a solvent for vapor degreasing of metals in industrial processes, defluxing of electronic circuit cards to remove flux, ionics, and particulates, also used as a diluent in the manufacturing of medicinal tablets, an extraction agent for the purification of herbs and natural plant extracts, and in some countries NPB is used in adhesive formulations and as a solvent in aerosol formulations.

In practically all of the uses for NPB the solvent replaces the use of dangerous chlorinated solvents such as trichloroethylene (TCE), perchloroethylene (PCE), Dichloromethane (DCM or methylene chloride), and trans, dichloroethylene (Trans DCE). TCE, PCE, and DCM are rated as "Hazardous Air Pollutants" or HAPs in the United States and many other countries. HAPs have been identified by the US Government as Cancer-Causing products in most instances and therefore are under tighter environmental and personal exposure limits. N-propyl bromide is not a HAP, so many companies are turning to NPB as the best alternative in order to achieve the final goal of cleaning parts or extracting herbs and so forth.

Competition to n-propyl bromide (NPB) is traced back to the manufacturers of chlorinated solvents as well as high-cost "fluorinated solvents" that tend to be promoted as alternatives to cleaning with chlorinated solvents. The fluorinated solvent options are generally safer to use in the manufacturing processes, however they are much less effective. So much so, that they are typically blended with a stronger solvent, such as the flammable trans, dichloroethylene, in order to increase the solubility of various contaminants in the solvent blend.

1-Bromopropane was subjected to 2-year bioassay by the U.S. National Toxicology Program. There was some evidence of carcinogenic activity of 1-bromopropane in male F344/N rats based on the occurrence of rare adenomas of the large intestine and increased incidences of neoplasms of the skin. Increased incidences of malignant mesothelioma and pancreatic islet adenoma may also have been related to 1-bromopropane exposure. There was clear evidence of carcinogenic activity of 1-bromopropane in female F344/N rats based on increased incidences of adenoma of the large intestine. Increased incidences of neoplasms of the skin may also have been related to 1-bromopropane exposure. There was clear evidence of carcinogenic activity of 1-bromopropane in female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms. There was no evidence of carcinogenic activity of 1-bromopropane in male B6C3F1 mice exposed to concentrations of 62.5, 125, or 250 ppm 1-bromopropane.

Exposure to 1-bromopropane resulted in increased incidences of nonneoplastic lesions in the nose of rats and mice, the larynx of rats and male mice, the trachea of female rats and male and female mice, and the lung of mice. Suppurative inflammatory lesions with Splendore-Hoeppli material were present primarily in the nose and skin of male and female rats exposed to 1-bromopropane.

The flammable characteristics of n-propyl bromide are contained to a narrow concentration in air between approximately 4% and 7% by volume. It is unusual for NPB to ever catch fire because the solvent is "self-extinguishing". Self-extinguishing refers to a chemical property where a solvent that has caught fire will overcome itself and consume or inhibit the available oxygen that is supporting the flame. This is the case with NPB. The vapor above the solvent can be lit to catch fire, however within a few moments the vapor loses the fuel and the fire will snuff itself out. This has been shown in several videos produced by Enviro Tech International Inc where the same test is conducted with other solvents and they all continue to burn, yet when a flame hovers over a solution of NPB, the bromine in the NPB apparently suffocates the oxygen from the vapor over the mixture and the flame disappears.

The atmospheric properties of n-propyl bromide are short-lived and it's a hydrocarbon, so by default NPB has been classified as a Volatile Organic Compound by the US Environmental Protection Agency. Recent studies by Whitten and Yarwood published in the Journal of the Air & Waste Management Association state that NPB is actually a VOC inhibitor, of sorts. The details of this argument are left to the reader to pursue, but these peer-reviewed and published results are not the first case to show that NPB should be delisted as a VOC. The US EPA has not moved forward on the idea of delisting NPB as a VOC.

The application of NPB should probably be confined to industrial uses where the users will be properly outfitted with safety glasses, gloves, and in some cases, half-face respirators, at their leisure. All chemicals, and solvents, should be handled with the utmost care. The use of NPB is no different in that regard.

References

• EPA’s Proposed Regulation of n-Propyl Bromide [1]
• USEPA SNAP Approval of n propyl bromide [2]
• NTP Toxicology and Carcinogenesis Studies of 1-Bromopropane (CAS No. 106-94-5) in F344/N Rats and B6C3F1 Mice (Inhalation studies)

http://ntp.niehs.nih.gov/INDEXF0D9_2.HTM?objectid=4E0C03A9-F1F6-975E-79F1E370B9027815

• Neurologic Illness Associated with Occupational Exposure to the Solvent 1-Bromopropane --- New Jersey and Pennsylvania, 2007--2008

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5748a2.htm