1,3-Butadiene is a simple conjugated diene. It is an important industrial chemical used as a monomer in the production of synthetic rubber. When the word butadiene is used, most of the time it refers to 1,3-butadiene.
The butadiene industry originated in the years leading up to World War II. Many of the belligerent nations realized that in the event of war, they could be cut off from rubber plantations controlled by the British Empire, and sought to remove their dependence on natural rubber. In 1929, Eduard Tschunker and Walter Bock, working for IG Farben in Germany, made a copolymer of styrene and butadiene that could be used in automobile tires. Worldwide production quickly ensued, with butadiene being produced from grain alcohol in the Soviet Union and the United States and from coal-derived acetylene in Germany.
Butadiene is typically isolated from the other four-carbon hydrocarbons produced in steam cracking by extraction into a polar aprotic solvent such as acetonitrile or dimethylformamide, from which it is then stripped by distillation.
Butadiene can also be produced by the catalytic dehydrogenation of normal butane. The first such commercial plant, producing 65,000 tons per year of butadiene, began operations in 1957 in Houston, Texas.
In the single-step process developed by Sergei Lebedev, ethanol is converted to butadiene, hydrogen, and water at 400–450 °C over any of a variety of metal oxide catalysts:
This process was the basis for the Soviet Union's synthetic rubber industry during and after World War II, and it remains in limited use in Russia and other parts of eastern Europe.
In the other, two-step process, developed by the Russian chemist Ivan Ostromislensky, ethanol is oxidized to acetaldehyde, which reacts with additional ethanol over a tantalum-promoted porous silica catalyst at 325–350 °C to yield butadiene:
This process was used in the United States to produce government rubber during World War II, and remains in use today in China and India.
Smaller amounts of butadiene are used to make nylon via the intermediate adiponitrile, other synthetic rubber materials such as chloroprene, and the solvent sulfolane. Butadiene is used in the industrial production of cyclododecatriene via a trimerization reaction.
Several studies show butadiene exposure increases risk in cardiovascular diseases and cancer. Animal data suggest the carcinogenic effects of butadiene may have a higher sensitivity to women over men when exposed to the chemical. While these data reveal important implications to the risks of human exposure to butadiene, more data are necessary to draw more conclusive risk assessments. There is also a lack of human data on the effects butadiene has on reproductive and developmental effects shown to occur in mice, but animal studies have shown breathing butadiene during pregnancy can increase the number of birth defects.
Storage of butadiene as a compressed, liquified gas carries a specific and unusual hazard. Over time, polymerization can begin, creating a crust of solidified material (which looks like popcorn) inside the cylinder. If the cylinder is then disturbed, the crust can contact the liquid and initiate an auto-catalytic polymerization. The heat released accelerates the reaction, possibly leading to cylinder rupture. Inhibitors are typically added to reduce this hazard, but butadiene cylinders should still be considered short-shelf life items.