Organosilicon chemistry
Study of carbon–silicon bond compounds, key to silicones and industry.
Organosilicon chemistry focuses on compounds that feature direct bonds between carbon and silicon. These organosilicon compounds are typically colorless, flammable, hydrophobic, and stable in air, though silicon carbide is classified as an inorganic substance. The field began in 1863 when Charles Friedel and James Crafts synthesized the first organochlorosilane and also described a polysilicic acid ether while preparing ethyl- and methyl-o-silicic acid. Extensive early research was conducted by Frederic S. Kipping, who coined the term "silicone" in 1904, despite the name's misleading implication of a ketone-like structure. Kipping used Grignard reagents to produce alkylsilanes and arylsilanes and was the first to prepare silicone oligomers and polymers. In 1945, Eugene G. Rochow described the Müller-Rochow process, a major industrial method. Most organosilicon compounds are derived from organosilicon chlorides, which are produced via the direct process reacting methyl chloride with a silicon-copper alloy; dimethyldichlorosilane is the primary product, with about one million tons of organosilicon compounds made annually this way. Another key formation method is hydrosilylation, where Si–H bonds add to unsaturated substrates like alkenes using platinum group metal catalysts. Carbon–silicon bonds are longer and weaker than carbon–carbon bonds, and the C–Si bond is somewhat polarized toward carbon due to silicon's lower electronegativity. Silicon is susceptible to nucleophilic attack by oxygen, chlorine, or fluorine, and the Si–O bond is notably strong. Organosilicon compounds appear widely in commercial products, including antifoamers, caulks, adhesives, and coatings. Although carbon–silicon bonds are absent in biology, enzymes have been used to create them artificially in living microbes. Silafluofen is an organosilicon pyrethroid insecticide, and several such compounds have been investigated as pharmaceuticals.
- field
- Organometallic chemistry
- key_compounds
- Organosilicon compounds (e.g., silicones, silyl chlorides)
- annual_production
- About 1 million tons of organosilicon compounds
Lore & Background
Frederic S. Kipping pioneered early 20th-century research into organosilicon compounds, using Grignard reagents to produce alkylsilanes and arylsilanes and creating silicone oligomers and polymers for the first time. He coined the term "silicone" in 1904, though the name's resemblance to ketones is misleading. In the 1960s, the Dow Chemical Company established an award recognizing significant contributions to silicon chemistry in his honor. Eugene G. Rochow later described the Müller-Rochow process, a major industrial method for producing organosilicon chlorides by reacting methyl chloride with a silicon-copper alloy, yielding dimethyldichlorosilane as the primary product alongside trimethylsilyl chloride and methyltrichlorosilane; about one million tons of organosilicon compounds are prepared annually this way. The first organosilicon compound, tetraethylsilane, was synthesized in 1863 by Charles Friedel and James Crafts from tetrachlorosilane and diethylzinc. Organosilicon compounds are generally colorless, flammable, hydrophobic, and air-stable. They are widely used in commercial products such as antifoamers, caulks, adhesives, and coatings made from silicones, as well as in agricultural adjuvants with herbicides and fungicides. Carbon–silicon bonds do not occur naturally in biology, though enzymes have been used to create them artificially in microbes. Silafluofen is an organosilicon pyrethroid insecticide, and several such compounds have been investigated as pharmaceuticals.
Reader's Guide
Organosilicon chemistry is significant for its wide-ranging applications in commercial products, including antifoamers, caulks, adhesives, and coatings made from silicones. The field also contributes to agriculture through adjuvants used with herbicides and fungicides, and to medicine via investigated pharmaceuticals and the insecticide silafluofen. Industrially, the direct process produces key methyl chlorosilanes like dimethyldichlorosilane, with about 1 million tons prepared annually. Hydrosilylation is another major method for forming Si–C bonds, using platinum group metal catalysts. The unique bonding of silicon—longer and weaker C–Si bonds, high Si–O bond energy, and susceptibility to nucleophilic attack—underpins many reactions such as the Sakurai reaction and Brook rearrangement. While carbon–silicon bonds are absent in biology, enzymes have been used to create them artificially in living microbes. The legacy of Kipping and Rochow endures in the industrial and synthetic importance of organosilicon compounds.
Did You Know?
- Carbon–silicon bonds are absent in biology, but enzymes have been used to artificially create them in living microbes.
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