Carbon tetrabromide

Description

Carbon tetrabromide is considered a highly toxic chemical, may be fatal if inhaled, swallowed, or absorbed through skin. It is metabolized in vitro to produce carbon monoxide but the in vivo significance has not been established. Under anaerobic reducing conditions it forms complexes with ferrous cytochrome P450. Carbon monoxide is detected as a metabolic product of the interaction. Carbon tetrabromide’s production and use in organic syntheses may result in its release to the environment through various waste streams. Carbon tetrabromide has been isolated from red algae, Asparagopsis toxiformis, found in the ocean near Hawaii. It was detected in water from treated chlorinated seawater used for drinking at oil platforms. Occupational exposure to carbon tetrabromide may occur through inhalation and dermal contact with this compound at workplaces where it is produced or used. The general population may be exposed to carbon tetrabromide via ingestion of drinking water. Acute exposures to high concentrations may cause upper respiratory tract irritation and injury to lungs, liver (hepatotoxicity) and kidneys (nephrotoxicity). Chronic exposure effects at very low levels will be almost entirely limited to liver injury. It is a potent lachrymator even at low exposure concentrations. Although carbon tetrabromide may release bromine ions during metabolism, clinical bromism is not expected to occur.

Description

Carbon tetrabromide (CBr4) is most commonly used as a reagent for converting alcohols to bromides in Appel reactions. Carbon tetrabromide is generally not used as a solvent, whereas its chloro analogue, carbon tetrachloride (CCl4), sees frequent use as a solvent.

Chemical properties

Crystalline colorless

Chemical properties

Carbon tetrabromide, is a colorless powder, white crystalline solid, or yellow-brown crystals. Slight odor

The Uses of Carbon tetrabromide

Carbon tetrabromide is used to a limited extent as a chemical intermediate. It has been isolated from red algae, Asparagopsis toxiformis, found in the ocean near Hawaii.

The Uses of Carbon tetrabromide

The SM (6.8 g, 0.036 mol) was taken up in DCM (275 mL) and treated with PPh3 (10.36 g) and CBr4 (13.1 g). The reaction mixture was stirred at RT for 90 min, after which time the solvent was concentrated to a volume of about 50 mL (precipitation occurs). The slurry was added to a pad of silica gel eluting with 20% EtOAc/hexane. Fractions containing the product (least polar) were combined and concentrated to provide the product as a viscous syrup. [6.2 g, 69%]

The Uses of Carbon tetrabromide

Organic synthesis.

The Uses of Carbon tetrabromide

Used to a limited extent as an intermediate in organic synthesis

Definition

ChEBI: A one-carbon compound substituted by 4 bromo groups.

General Description

A colorless crystalline solid. Much more dense than water and insoluble in water. Toxic by ingestion. Vapors are narcotic in high concentration. Used to make other chemicals.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Carbon tetrabromide is incompatible with the following: Strong oxidizers, hexacyclohexyldilead, lithium .

Hazard

A poison; narcotic in high concentration. Liver damage, eye, skin, and upper respiratory tract irritant.

Health Hazard

Highly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Containers may explode when heated. Runoff may pollute waterways.

Safety Profile

Poison by subcutaneous and intravenous routes. Narcotic in high concentration. Mixture with Li particles is an impact-sensitive explosive. Explodes on contact with hexacyclohexylddead. When heated to decomposition it emits toxic fumes of Br-. See also CHLORINATED HYDROCARBONS, ALIPHATIC.

Potential Exposure

CBr4 is used in organic synthesis.

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.Medical observation is recommended for 24-48 h afterbreathing overexposure, as pulmonary edema may bedelayed. As first aid for pulmonary edema, a doctor orauthorized paramedic may consider administering a corticosteroid spray.

Environmental Fate

Carbon tetrabromide inhibits protein synthesis and causes lipid peroxidation, both of which may be involved in cell injury or death mediated by free radicals.

storage

Color Code—Green: General storage may be used.Prior to working with carbon tetrabromide you should betrained on its proper handling and storage. Store in tightlyclosed containers in a cool, well-ventilated area away fromoxidizers and other incompatible materials listed above.

Shipping

UN2516 Carbon tetrabromide, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Purification Methods

Reactive bromide is removed from CBr4 by refluxing with dilute aqueous Na2CO3, then steam distilling, crystallising from EtOH, and drying in the dark under vacuum. [Sharpe & Walker J Chem Soc 157 1962.] It can be sublimed at 70o and low pressure. [Beilstein 1 IV 85.]

Toxicity evaluation

Carbon tetrabromide is a colorless nonflammable solid at room temperature. It is insoluble in water, but soluble in several organic solvents such as alcohol, ether, and chloroform. Its specific gravity is 3.42, melting point is 90°C, boiling point is 189°C, and vapor pressure is 0.72 torr at 25°C. Production and use of carbon tetrabromide may result in its release in the environment through various hazardous waste streams. Carbon tetrabromide is expected to have very high mobility in soil and volatilizes slowly from dry soil surface. Its biodegradation is expected to be slow and to exist solely as a vapor in the ambient atmosphere. It is not expected to adsorb to suspended solids and sediment in the water column. Its potential for bioconcentration in aquatic organisms is moderate.

Incompatibilities

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, lithium and hexacyclohexyldiilead, since violent reactions may occur.

Waste Disposal

Purify by distillation and return to suppliers.