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Carbonate Ester
In organic chemistry, a carbonate ester (organic carbonate or organocarbonate) is an ester of carbonic acid. This functional group consists of a carbonyl group flanked by two alkoxy groups. The general structure of these carbonates is and they are related to esters (), ethers () and also to the inorganic carbonates. Monomers of polycarbonate (e.g. Makrolon or Lexan) are linked by carbonate groups. These polycarbonates are used in eyeglass lenses, compact discs, and bulletproof glass. Small carbonate esters like dimethyl carbonate, ethylene carbonate, propylene carbonate are used as solvents, dimethyl carbonate is also a mild methylating agent. Structures Carbonate esters have planar OC(OC)2 cores, which confers rigidity. The unique O=C bond is short (1.173 Å in the depicted example), while the C–O bonds are more ether-like (the bond distances of 1.326 Å for the example depicted). Carbonate esters can be divided into three structural classes: acyclic, cyclic, and polym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethylene Carbonate
Trimethylene carbonate, or 1,3-propylene carbonate, is a 6-membered cyclic carbonate ester. It is a colourless solid that upon heating or catalytic ring-opening converts to poly(trimethylene carbonate) (PTMC). Such polymers are called aliphatic polycarbonates and are of interest for potential biomedical applications. An isomeric derivative is propylene carbonate, a colourless liquid that does not spontaneously polymerize. Preparation This compound may be prepared from 1,3-propanediol and ethyl chloroformate (a phosgene substitute), or from oxetane and carbon dioxide with an appropriate catalyst: :HOC3H6OH + ClCO2C2H5 → C3H6O2CO + C2H5OH + HCl :C3H6O + CO2 → C3H6O2CO This cyclic carbonate undergoes ring-opening polymerization to give poly(trimethylene carbonate), abbreviated PTMC. : Medical devices The polymer PTC is of commercial interest as a biodegradable polymer with biomedical applications. A block copolymer of glycolic acid and trimethylene carbonate (TMC) is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poly(propylene Carbonate)
Polypropylene carbonate (PPC), a copolymer of carbon dioxide and propylene oxide, is a thermoplastic material. Catalysts like zinc glutarate are used in polymerization. Properties Polypropylene carbonate is soluble in chemical polarity, polar solvents like lower ketones, ethyl acetate, dichloromethane and chlorinated hydrocarbons and insoluble in solvents like Alcohol (chemistry), alcohols, water, and aliphatic hydrocarbons. It also forms stable emulsions in water. PPC allows the diffusion of gases like oxygen through it. Having a glass temperature (Tg) between 25 and 45 °C, PPC binders are amorphous. The glass temperature of PPC is slightly greater than polyethylene carbonate (PEC). Its refractive index is 1.46 while its dielectric constant is 3. Applications Polypropylene carbonate is used to increase the toughness of some epoxy resins. It is used as a sacrificial binder in the ceramic industry, which decomposes and evaporates during sintering. It has a low sodium cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethylene Carbonate
Trimethylene carbonate, or 1,3-propylene carbonate, is a 6-membered cyclic carbonate ester. It is a colourless solid that upon heating or catalytic ring-opening converts to poly(trimethylene carbonate) (PTMC). Such polymers are called aliphatic polycarbonates and are of interest for potential biomedical applications. An isomeric derivative is propylene carbonate, a colourless liquid that does not spontaneously polymerize. Preparation This compound may be prepared from 1,3-propanediol and ethyl chloroformate (a phosgene substitute), or from oxetane and carbon dioxide with an appropriate catalyst: :HOC3H6OH + ClCO2C2H5 → C3H6O2CO + C2H5OH + HCl :C3H6O + CO2 → C3H6O2CO This cyclic carbonate undergoes ring-opening polymerization to give poly(trimethylene carbonate), abbreviated PTMC. : Medical devices The polymer PTC is of commercial interest as a biodegradable polymer with biomedical applications. A block copolymer of glycolic acid and trimethylene carbonate (TMC) is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylene Carbonate
Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a transparent crystalline solid, practically odorless and colorless, and somewhat soluble in water. In the liquid state (m.p. 34-37 °C) it is a colorless odorless liquid. JEFFSOL ETHYLENE CARBONATE catalog entry at www.huntsman.com. Accessed on 2010-02-18. Production and reactions Ethylene carbonate is produced by the reaction between and |
Dimethyl Dicarbonate
Dimethyl dicarbonate (DMDC) is a colorless liquid with a pungent odor at high concentration at room temperature. It is primarily used as a beverage preservative, processing aid, or sterilant ( INS No. 242) being highly active against typical beverage spoiling microorganisms like yeast, bacteria, or mould. Usage Dimethyl dicarbonate is used to stabilize beverages by preventing microbial spoilage. It can be used in various non-alcoholic as well as alcoholic drinks like wine, cider, beer-mix beverages or hard seltzers. Beverage spoiling microbes are killed by methoxycarbonylation of proteins. It acts by inhibiting enzymes involved in the microbial metabolism, e.g. acetate kinase and L-glutamic acid decarboxylase. It has also been proposed that DMDC inhibits the enzymes alcohol dehydrogenase and glyceraldehyde 3-phosphate dehydrogenase by causing the methoxycarbonylation of their histidine components. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at normally-encountered concentrations it is odorless. As the source of carbon in the carbon cycle, atmospheric is the primary carbon source for life on Earth. In the air, carbon dioxide is transparent to visible light but absorbs infrared, infrared radiation, acting as a greenhouse gas. Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, and seawater. It is a trace gas Carbon dioxide in Earth's atmosphere, in Earth's atmosphere at 421 parts per million (ppm), or about 0.042% (as of May 2022) having risen from pre-industrial levels of 280 ppm or about 0.028%. Burning fossil fuels is the main cause of these increased concentrations, which are the primary cause of climate change.IPCC (2022Summary for pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a light, Volatility (chemistry), volatile, colorless and flammable liquid with a distinctive alcoholic odor similar to that of ethanol (potable alcohol), but is more acutely toxic than the latter. Methanol acquired the name wood alcohol because it was once produced through destructive distillation of wood. Today, methanol is mainly produced industrially by hydrogenation of carbon monoxide. Methanol consists of a methyl group linked to a polar hydroxyl group. With more than 20 million tons produced annually, it is used as a Precursor (chemistry), precursor to other commodity chemicals, including formaldehyde, acetic acid, methyl tert-butyl ether, methyl ''tert''-butyl ether, methyl benzoate, anisole, peroxyacids, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condensation
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition. Condensation is usually associated with water. Initiation Condensation is initiated by the formation of atomic/molecular clusters of that species within its gaseous volume—like rain drop or snow flake formation within clouds—or at the contact between such gaseous phase and a liquid or solid surface. In clouds, this can be catalyzed by water-nucleating proteins, produced by atmospheric microbes, which are capable of binding gaseous or liquid water molecules. Reversibility scenarios A few distinct rev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transesterification
Transesterification is the process of exchanging the organic functional group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. Strong acids catalyze the reaction by donating a proton to the carbonyl group, thus making it a more potent electrophile. Bases catalyze the reaction by removing a proton from the alcohol, thus making it more nucleophilic. The reaction can also be accomplished with the help of enzymes, particularly lipases (one example is the lipase E.C.3.1.1.3). If the alcohol produced by the reaction can be separated from the reactants by distillation this will drive the equilibrium toward the products. This means that esters with larger alkoxy groups can be made from methyl or ethyl esters in high purity by heating the mixture of ester, acid/base, and large alcohol. Mechanism In the transesterification mechanism, the carbonyl carbon of the starting ester reacts to give a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidative Carbonylation
Oxidative carbonylation is a class of reactions that use carbon monoxide in combination with an oxidant to generate esters and carbonate esters. These transformations utilize transition metal complexes as homogeneous catalysts. Many of these reactions employ palladium catalysts. Mechanistically, these reactions resemble the Wacker process. Illustrative oxidative carbonylations Oxidative carbonylation, using palladium-based catalysts, allows certain alkenes to be converted into homologated esters: :2 RCH=CH2 + 2 CO + O2 + 2 MeOH → 2 RCH=CHCO2Me + 2 H2O Such reactions are assumed to proceed by the insertion of the alkene into the Pd(II)-CO2Me bond of a metallacarboxylic ester followed by beta-hydride elimination (Me = CH3). Arylboronic acids react with Pd(II) compounds to give Pd(II)-aryl species, which undergo carbonylation to give Pd(II)-C(O)aryl. These benzyl-Pd intermediates are intercepted by alkenes, which insert. Subsequent beta-hydride elimination gives the arylk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Monoxide
Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest oxocarbon, carbon oxide. In coordination complexes, the carbon monoxide ligand is called ''metal carbonyl, carbonyl''. It is a key ingredient in many processes in industrial chemistry. The most common source of carbon monoxide is the partial combustion of carbon-containing compounds. Numerous environmental and biological sources generate carbon monoxide. In industry, carbon monoxide is important in the production of many compounds, including drugs, fragrances, and fuels. Indoors CO is one of the most acutely toxic contaminants affecting indoor air quality. CO may be emitted from tobacco smoke and generated from malfunctioning fuel-burning stoves (wood, kerosene, natural gas, propane) and fuel-burning heating systems (wood, oil, n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
