In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.
A Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, is a catalyst used in the synthesis of polymers of 1-alkenes (alpha-olefins). Two broad classes of Ziegler–Natta catalysts are employed, distinguished by their solubility:
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces double and triple bonds in hydrocarbons.
In chemistry, halogenation is a chemical reaction which introduces one or more halogens into a chemical compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, drugs. This kind of conversion is in fact so common that a comprehensive overview is challenging. This article mainly deals with halogenation using elemental halogens. Halides are also commonly introduced using salts of the halides and halogen acids. Many specialized reagents exist for and introducing halogens into diverse substrates, e.g. thionyl chloride.
In organic chemistry, an allyl group is a substituent with the structural formula −CH2−HC=CH2. It consists of a methylene bridge attached to a vinyl group. The name is derived from the scientific name for garlic, Allium sativum. In 1844, Theodor Wertheim isolated an allyl derivative from garlic oil and named it "Schwefelallyl". The term allyl applies to many compounds related to H2C=CH−CH2, some of which are of practical or of everyday importance, for example, allyl chloride.
In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is R−:C−R' or R=C: where the R represents substituents or hydrogen atoms.
In organic chemistry, free-radical halogenation is a type of halogenation. This chemical reaction is typical of alkanes and alkyl-substituted aromatics under application of UV light. The reaction is used for the industrial synthesis of chloroform (CHCl3), dichloromethane (CH2Cl2), and hexachlorobutadiene. It proceeds by a free-radical chain mechanism.
In organic chemistry, olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry.
Organotin chemistry is the scientific study of the synthesis and properties of organotin compounds or stannanes, which are organometallic compounds containing tin–carbon bonds. The first organotin compound was diethyltin diiodide, discovered by Edward Frankland in 1849. The area grew rapidly in the 1900s, especially after the discovery of the Grignard reagents, which are useful for producing Sn–C bonds. The area remains rich with many applications in industry and continuing activity in the research laboratory.
A transition metal carbene complex is an organometallic compound featuring a divalent carbon ligand, itself also called a carbene. Carbene complexes have been synthesized from most transition metals and f-block metals, using many different synthetic routes such as nucleophilic addition and alpha-hydrogen abstraction. The term carbene ligand is a formalism since many are not directly derived from carbenes and most are much less reactive than lone carbenes. Described often as =CR2, carbene ligands are intermediate between alkyls (−CR3) and carbynes (≡CR). Many different carbene-based reagents such as Tebbe's reagent are used in synthesis. They also feature in catalytic reactions, especially alkene metathesis, and are of value in both industrial heterogeneous and in homogeneous catalysis for laboratory- and industrial-scale preparation of fine chemicals.
In organic chemistry, hydroboration refers to the addition of a hydrogen-boron bond to certain double and triple bonds involving carbon. This chemical reaction is useful in the organic synthesis of organic compounds.
Dichlorocarbene is the reactive intermediate with chemical formula CCl2. Although this chemical species has not been isolated, it is a common intermediate in organic chemistry, being generated from chloroform. This bent diamagnetic molecule rapidly inserts into other bonds.
Tebbe's reagent is the organometallic compound with the formula (C5H5)2TiCH2ClAl(CH3)2. It is used in the methylidenation of carbonyl compounds, that is it converts organic compounds containing the R2C=O group into the related R2C=CH2 derivative. It is a red solid that is pyrophoric in the air, and thus is typically handled with air-free techniques. It was originally synthesized by Fred Tebbe at DuPont Central Research.
Organoaluminium chemistry is the study of compounds containing bonds between carbon and aluminium. It is one of the major themes within organometallic chemistry. Illustrative organoaluminium compounds are the dimer trimethylaluminium, the monomer triisobutylaluminium, and the titanium-aluminium compound called Tebbe's reagent. The behavior of organoaluminium compounds can be understood in terms of the polarity of the C−Al bond and the high Lewis acidity of the three-coordinated species. Industrially, these compounds are mainly used for the production of polyolefins.
Organozirconium chemistry is the science of exploring the properties, structure, and reactivity of organozirconium compounds, which are organometallic compounds containing chemical bonds between carbon and zirconium. Organozirconium compounds have been widely studied, in part because they are useful catalysts in Ziegler-Natta polymerization.
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes.
Catalytic chain transfer (CCT) is a process that can be incorporated into radical polymerization to obtain greater control over the resulting products.
In organic chemistry, ethenolysis is a chemical process in which internal olefins are degraded using ethylene as the reagent. The reaction is an example of cross metathesis. The utility of the reaction is driven by the low cost of ethylene as a reagent and its selectivity. It produces compounds with terminal alkene functional groups (α-olefins), which are more amenable to other reactions such as polymerization and hydroformylation.
The Kharasch–Sosnovsky reaction is a method that involves using a copper or cobalt salt as a catalyst to oxidize olefins at the allylic position, subsequently condensing a peroxy ester or a peroxide resulting in the formation of allylic benzoates or alcohols via radical oxidation. This method is noteworthy for being the first allylic functionalization to utilize first-row transition metals and has found numerous applications in chemical and total synthesis. Chiral ligands can be used to render the reaction asymmetric, constructing chiral C–O bonds via C–H bond activation. This is notable as asymmetric addition to allylic groups tends to be difficult due to the transition state being highly symmetric. The reaction is named after Morris S. Kharasch and George Sosnovsky who first reported it in 1958. This method is noteworthy for being the first allylic functionalization to utilize first-row transition metals and has found numerous applications in chemical and total synthesis.
tert-Butyl peroxybenzoate (TBPB) an organic compound with the formula C6H5CO3CMe3 (Me = CH3). It is the most widely produced perester; it is an ester of peroxybenzoic acid (C6H5CO3H). It is often used as a radical initiator in polymerization reactions, such as the production of LDPE from ethylene, and for crosslinking, such as for unsaturated polyester resins.
