1-Bromopropane

Description

1-Bromopropane is a simple bromoalkane frequently used as an industrial solvent and degreasing agent. It is prepared commercially via the free-radical anti-Markovnikov hydrobromination of propylene.
Since 2000, 1-bromopropane has increasingly replaced toxic, ozone-depleting chlorocarbons and chlorofluorocarbons as dry-cleaning solvents. But using this brominated hydrocarbon presents many hazards (see hazard information table).
The US Environmental Protection Agency recently began to evaluate the health hazards of 1-bromopropane to workers. In its draft assessment, the agency reported that the solvent could pose “unreasonable risks to workers, occupational nonusers, consumers, and bystanders under certain conditions of use.” EPA is accepting comments on the draft until October 11.

Description

Bromopropane is a toxic and highly flammable, colorless liquid; Flash point # 22℃. Molecularweight=123.0 (1-bromopropane); 123.0 (2-bromopropane); Boiling point=71℃ (1-bromopropane); 59.4℃(2-bromopropane); Freezing/Melting point=-110℃ (1-bromopropane); - 89℃ (2-bromopropane); Specificgravity (H2O:1): 1.35 (1-bromopropane); Flash point=-10℃ (cc) (1-bromopropane); Autoignitiontemperature=490℃ (1-bromopropane). Explosive Limitsin air: LEL=4.6%; UEL=unknown. HazardIdentification (based on NFPA-704 M Rating System): (asn-propyl bromide): Health 2, Flammability 3, Reactivity0; (2-bromopropane) Health 2, Flammability 3, Reactivity3. Soluble in water; solubility=0.25% at 20℃ (1-bromopropane).

Chemical properties

1-Bromopropane(1-BP), also known as n-propyl bromide, is a colourless to pale yellow liquid with a strong, characteristic sweet odour. It is soluble in some organic solvents and slightly soluble in water. 1-BP is a highly flammable liquid with flash point of 220℃. Its vapor is also flammable.

1-Bromopropane is a solvent that is used in degreasing, dry cleaning, spray adhesives,aerosol solvents and resins and is primarily used as a chemical intermediate in the production of pesticides, quaternary ammonium compounds, flavours and fragrances, and pharmaceuticals in closed processes (NTP, 2013). In the mid-to-late 1990s, 1-bromopropane was introduced as a non-toxic, fast-drying solvent that does not leave surface residue for cleaning metals, plastics, and optical, electrical and electronic components (NTP, 2011; NIOSH, 2013). It was marketed as a substitute solvent for ozone-depleting and other solvents such as trichloroethylene, tetrachloroethylene (perchloroethylene) and methylene chloride. 1-Bromopropane is used for vapour degreasing and immersion cleaning, liquid and spray adhesive applications, fabric dry cleaning, and aerosol spray products (Blando et al., 2010; NTP, 2013).

The Uses of 1-Bromopropane

1-bromopropane was used primarily as a solvent for fats, waxes or resins and as an intermediate in the synthesis of other compounds including pharmaceuticals, insecticides, quaternary ammonium compounds, flavors and fragrances in generally well-controlled, closed processes. 1-Bromopropane is now used as a solvent cleaner in vapor and immersion cleaning and degreasing operations for optics, electronics and metals and as a solvent in industries that use spray-applied adhesives. Its use as a solvent substitute for ozone-depleting chlorofluorohydrocarbons (freons) or suspect carcinogens (e.g., trichloroethylene, methylene chloride) has prompted the dry cleaning industry to view it as a replacement for perchloroethylene (“perc”), especially in states that are proposing to ban the use of the latter chemical in dry cleaning.
1-Bromopropane is one of several chemicals included in the Environmental Protection Agency’s Significant New Alternatives Policy (SNAP) that has been approved as a substitute for ozone-depleting solvents currently in use in certain applications. Specifically, 1-bromopropane has been approved as an acceptable substitute for CFC-113 (1,1,2-Trichloro1,2,2-trifluoroethane, Freon 113) and methyl chloroform (1,1,1-trichloroethane) in non-aerosol electronics, metal and precision cleaning.

The Uses of 1-Bromopropane

1-Bromopropane is used as a solvent for adhesives, degreasing plastics and optics. It is used in the production of asphalt, synthetic fiber and aerosols. It is employed for cleaning the metal surfaces, electronic circuit boards, and multi-layered OLEDs (Organic Light Emitting Diodes). It serves to replace perchloroethylene as a dry cleaning solvent.

Definition

ChEBI: 1-bromopropane is a bromoalkane that is propane carrying a bromo substituent at position 1. It has a role as a neurotoxin and a solvent. It is a bromoalkane and a bromohydrocarbon.

Preparation

1-Bromopropane can be synthesized by reacting n-propyl alcohol (n-propanol) with excess hydrobromic acid. Water formed as a by-product is quickly removed from the resulting crude product before purification to give the final product. A modification of this reaction procedure involves using bromine with a reducing agent such as sulfur, sulfur dioxide, phosphorus or sodium borohydride. The overall reaction with hydrobromic acid is depicted below.
n-C3H7OH + HBr => n-C3H7Br + H2O
The prefix n (or normal) refers to a “straight chain” hydrocarbon component as opposed to a branched hydrocarbon component, such as the isopropyl group in isopropyl alcohol (i-propyl alcohol or i-propanol) where the hydroxyl (−OH) group is attached to the middle carbon.

What are the applications of Application

1-Bromopropane is used as a component of various models of binary mixtures, prepared to study their properties such as viscosity and refractive index.
It can be used as an alkylating reagent:
For the functionalization of seleno-substituted imidazo[1,2-α]pyridine derivatives.
For the synthesis of 1,4-dihydroxy-2-propoxy anthraquinone derivatives.
It can also be used as a reactant:
For the synthesis of Berberine-benzimidazole derivatives.
For the synthesis of alkyl aryl ketones via carbonylative Barbier-Negishi coupling with aryl iodides.

General Description

1-bromopropane appears as a colorless liquid. Slightly denser than water and slightly soluble in water. Flash point below 75 °F. When heated to high temperatures may emit toxic fumes.   Special Hazards of Combustion Products: Toxic fumes of Hydrogen Bromide (USCG, 1999)

Air & Water Reactions

Highly flammable. Slightly soluble in water.

Reactivity Profile

Halogenated aliphatic compounds, such as 2-BROMOPROPANE, are moderately or very reactive. Reactivity generally decreases with increased degree of substitution of halogen for hydrogen atoms. Low molecular weight haloalkanes are highly flammable and can react with some metals to form dangerous products. Materials in this group are incompatible with strong oxidizing and reducing agents. Also, they are incompatible with many amines, nitrides, azo/diazo compounds, alkali metals, and epoxides. Emits toxic fumes of bromine when burned.

Hazard

1-Bromopropane is classified as a Category 2 flammable liquid. It has an autoignition temperature of 914 degrees F and a flash point of less than 72 degrees F. Although a specific upper explosive (flammability) limit has not been determined, it has a lower explosive limit of 4.6 percent by volume in air. 1-Bromopropane decomposes when burned to emit hydrogen bromide (HBr) gas.

Health Hazard

Occupational exposure to 1-bromopropane occurs primarily through inhalation and skin contact, although exposure through ingestion and the eyes are other possible routes. Short-term exposure to the chemical can result in irritation of the eyes, nose, throat or respiratory tract.
Chronic (long-term) exposure to 1-bromopropane can adversely affect peripheral nerves and the central nervous system. Symptoms that have been reported include joint pain or leg weakness and pain leading to difficulty standing and walking; muscle twitching or numbness, tingling and prickling in the hands or feet, loss of vibration sense; and anxiety, apathy, insomnia, and difficulties with concentration and memory.
Other health effects that may also occur include dermatitis, nausea and vomiting, diarrhea, difficulty in swallowing, disruption or failure of menstruation, urinary difficulties, anemia or low hematocrit (red blood cell count), liver damage, and lung disease.

Flammability and Explosibility

Highly flammable

Safety Profile

Moderately toxic by ingestion and intraperitoneal routes. Mildly toxic by inhalation. Experimental reproductive effects. Mutation data reported. Dangerous fire hazard when heated or exposed to flame or oxidizers. To fight fire, use water, foam, CO2, dry chemical. When heated to decomposition it emits toxic fumes of Br-. See also BROMIDES.

Potential Exposure

Tumorigen;Reproductive Effector. Used for making other chemicals.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.

storage

Color Code—Red: Flammability Hazard: Store ina flammable liquid storage area or approved cabinet awayfrom ignition sources and corrosive and reactive materials.Protect against physical damage. Outside or detached storage is preferred. Prior to working with Bromopropane youshould be trained on its proper handling and storage. Storein tightly closed containers in a cool, well-ventilated areaaway from incompatible materials listed above. Metal containers involving the transfer of this chemical should begrounded and bonded. Drums must be equipped with selfclosing valves, pressure vacuum bungs, and flame arresters.Use only nonsparking tools and equipment, especially whenopening and closing containers of this chemical. Sources ofignition, such as smoking and open flames, are prohibitedwhere this chemical is used, handled, or stored in a mannerthat could create a potential fire or explosion hazard.

Shipping

2-Bromopropane requires a “FLAMMABLELIQUID” label. It falls in Hazard Class 3, PackingGroup II.

Purification Methods

Likely contaminants include n-propyl alcohol and isopropyl bromide. The simplest purification procedure uses drying with MgSO4 or CaCl2 (with or without a preliminary wash of the bromide with aqueous NaHCO3, then water), followed by fractional distillation away from bright light. Chien and Willard [J Am Chem Soc 79 4872 1957] bubbled a stream of oxygen containing 5% ozone through n-propyl bromide for 1hour, then shook it with 3% hydrogen peroxide solution, neutralised it with aqueous Na2CO3, washed it with distilled water and dried it. This was followed by vigorous stirring with 95% H2SO4 until fresh acid did not discolour within 12hours. The propyl bromide was separated, neutralised, washed, dried with MgSO4 and fractionally distilled. The centre cut was stored in the dark. Instead of ozone, Schuler and McCauley [J Am Chem Soc 79 821 1957] added bromine and stored it for 4 weeks, the bromine then being extracted with aqueous NaHSO3 before the sulfuric acid treatment was applied and finally distilled. Further purification is by preparative gas chromatography on a column packed with 30% SE-30 (General Electric ethylsilicone rubber) on 42/60 Chromosorb P at 150o and 40psi, using helium. [Chu J Phys Chem 41 226 1964, Beilstein 1 IV 205.]

Incompatibilities

Strong oxidants; strong bases