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Polyvinyl Ether
Polyvinyl ethers are a class of Organic compound, organic polymers derived from enol ether, vinyl ethers. Common monomers include methyl vinyl ether and ethyl vinyl ether, the polymer having the formula [CH2CH(OR)]n (R = methyl, ethyl). Commercial interest has also focused on polymers derived from ethyl, isobutyl, octadecyl substituents in place of methyl. Like other vinyl polymers, the polymers exhibit tacticity. Polymerization is typically initiated with Lewis acids such as boron trifluoride.{{Ullmann, title=Poly(Vinyl Ethers), authors=Gerd Schröder, year=2012, doi=10.1002/14356007.a22_011 References [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals. The term "polymer" derives from the Greek word πολύς (''polus'', meaning "many, much") and μέρος (''meros'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enol Ether
In organic chemistry an enol ether is an alkene with an alkoxy substituent. The general structure is R2C=CR-OR where R = H, alkyl or aryl. A common subfamily of enol ethers are vinyl ethers, with the formula ROCH=CH2. Important enol ethers include the reagent 3,4-dihydropyran and the monomers methyl vinyl ether and ethyl vinyl ether. Reactions and uses Akin to enamines, enol ethers are electron-rich alkenes by virtue of the electron-donation from the heteroatom via pi-bonding. Enol ethers have oxonium ion character. By virtue of their bonding situation, enol ethers display distinctive reactivity. In comparison with simple alkenes, enol ethers exhibit enhanced susceptibility to attack by electrophiles such as Bronsted acids. Similarly, they undergo inverse demand Diels-Alder reactions. The reactivity of enol ethers is highly dependent on the presence of substituents alpha to oxygen. The vinyl ethers are susceptible to polymerization to give polyvinyl ethers. Some vinyl ethers al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Vinyl Ether
Methyl vinyl ether is an organic compound with the chemical formula CH3OCH=CH2. A colorless gas, it is the simplest enol ether. It is used as a synthetic building block, as is the related compound ethyl vinyl ether (a liquid at room temperature). Preparation Methyl vinyl ether can be made by reaction of acetylene and methanol in presence of a base. Reactions The alkene portion of the molecule is reactive in many ways. It is prone to polymerization, leading to formation of polyvinyl ethers. Polymerization is typically initiated with Lewis acids such as boron trifluoride. This mode of reactivity is analogous to the way vinyl acetate and vinyl chloride can be polymerized to form polyvinyl acetate and polyvinyl chloride, respectively. Methyl vinyl ether also participates in +2cycloaddition reactions. Its reaction with acrolein is the first step in the commercial synthesis of glutaraldehyde. The alkene can be deprotonated at the vinyl carbon adjacent to the oxygen. In particu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethyl Vinyl Ether
Ethyl vinyl ether is an organic compound with the chemical formula CH3CH2OCH=CH2. It is the simplest enol ether that is liquid at room temperature. It is used as a synthetic building block and a monomer. Preparation and reactions Ethyl vinyl ether is made by reaction of acetylene and ethanol in presence of a base. The alkene portion of the molecule is reactive in many ways. It is prone to polymerization, leading to formation of polyvinyl ethers. Polymerization is typically initiated with Lewis acids such as boron trifluoride. Ethyl vinyl ether participates in many reactions of interest to organic synthesis. With catalytic amounts of acids, ethyl vinyl ether adds to alcohols to give the mixed acetal: :EtOCH=CH2 + ROH → EtOCH(OR)CH3 This alcohol protection reaction is akin to the behavior of dihydropyran. Ethyl vinyl ether also participates in inverse demand [4+2] cycloaddition reactions. Deprotonation with butyl lithium gives the acetyl anion equivalent: :EtOCH=CH2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tacticity
Tacticity (from el, τακτικός, taktikos, "relating to arrangement or order") is the relative stereochemistry of adjacent chiral centers within a macromolecule. The practical significance of tacticity rests on the effects on the physical properties of the polymer. The regularity of the macromolecular structure influences the degree to which it has rigid, crystalline long range order or flexible, amorphous long range disorder. Precise knowledge of tacticity of a polymer also helps understanding at what temperature a polymer melts, how soluble it is in a solvent and its mechanical properties. A tactic macromolecule in the IUPAC definition is a macromolecule in which essentially all the configurational (repeating) units are identical. Tacticity is particularly significant in vinyl polymers of the type - where each repeating unit with a substituent R on one side of the polymer backbone is followed by the next repeating unit with the substituent on the same side as the previous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
