Carbon disulfide

Carbon disulfide is an inorganic compound with the chemical formula CS2. It is a colorless, flammable, and neurotoxic liquid. This means it is a substance that can harm the nervous system. In chemistry, it is often used as a building block for organic synthesis. This is a process where scientists use it to create new, complex molecules. While pure carbon disulfide has a pleasant, ether-like odor, commercial versions are usually yellowish. These commercial samples often smell foul due to various impurities.

Scientists have studied this compound for over two centuries. In 1796, German chemist Wilhelm August Lampadius first prepared it. He created it by heating pyrite with moist charcoal. At that time, he called it "liquid sulfur." Later, in 1813, the exact composition was determined by a team. This team included Swedish chemist Jöns Jacob Berzelius and Swiss-British chemist Alexander Marcet. Their analysis confirmed the empirical formula as CS2. Another notable discovery involved Percy Williams Bridgman. He discovered that carbon disulfide can polymerize under high pressure or photolysis. This process creates an insoluble semiconductor material known as car-sul or "Bridgman's black."

There are several ways to manufacture carbon disulfide. One historical method involved combining carbon, or coke, with sulfur at temperatures between 800 and 1000 °C. A different, lower-temperature method requires only 600 °C. This modern process uses natural gas as the carbon source. It also requires catalysts like silica gel or alumina to help the reaction happen. This reaction is similar to the combustion of methane. In the environment, small amounts of the compound are released naturally by marshes and volcanic eruptions.

Carbon disulfide is highly useful as a solvent. A solvent is a substance that can dissolve other materials. It can dissolve many nonpolar chemicals. These include phosphorus, sulfur, selenium, bromine, and iodine. It can also dissolve fats, resins, rubber, and asphalt. Beyond dissolving things, it is used in specific chemical reactions to create important products. For example, reacting it with amines produces dithiocarbamates. Reacting it with alkoxides forms xanthates. This specific reaction is the foundation for making regenerated cellulose. This material is the main ingredient in viscose, rayon, and cellophane. It is also used in mineral processing as a flotation agent.

Global production and consumption of carbon disulfide are quite large. Approximately one million tonnes are produced and used every year. China is the largest consumer, using 49% of the global supply. India follows with 13% of the consumption, primarily for making rayon fiber. In 2007, the United States produced 56,000 tonnes. Much of the global emissions come from rayon factories. Producing one kilogram of rayon can emit about 250 grams of carbon disulfide. Other sources include the production of carbon black and sulfur recovery. In Japan, some industries use incinerators to destroy 99% of emissions. However, in other parts of the world, emissions are often less controlled.

Because it is a neurotoxin, carbon disulfide poses significant health risks. High concentrations, between 500 and 3000 mg/m3, can cause acute poisoning. This can lead to encephalopathia sulfocarbonica, which involves neurological and psychiatric symptoms. These symptoms include hallucinations, paranoia, and mood changes like irritability. Lower concentrations can also cause serious issues. These include problems with hearing, vision, and the heart. It can also lead to reproductive problems, such as increased miscarriages. The World Health Organization has set safety guidelines to manage these risks. They suggest keeping levels below 100 μg/m3 over a 24-hour period.

Industrial history shows how dangerous this substance can be. Around 1900, it was widely used in making vulcanized rubber. Workers often suffered from psychosis after just six months of exposure. One historical account mentions a factory that had to install bars on windows. This was to prevent workers from leaping out due to their mental state. In the late 1930s, a study of rayon workers in the US found severe effects in 30% of the workforce. More recently, scientists have looked for this compound even beyond Earth. In March 2024, the James Webb Space Telescope detected possible traces of CS2 in the atmosphere of the planet TOI-270 d.