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Rotary Evaporation
A rotary evaporator (rotovap) is a device used in chemical laboratories for the efficient and gentle removal of solvents from samples by evaporation. When referenced in the chemistry research literature, description of the use of this technique and equipment may include the phrase "rotary evaporator", though use is often rather signaled by other language (e.g., "the sample was evaporated under reduced pressure"). Rotary evaporators are also used in molecular cooking for the preparation of distillates and extracts. A simple rotary evaporator system was invented by Lyman C. Craig. It was first commercialized by the Swiss company Büchi in 1957. The device separates substances with different boiling points, and greatly simplifies work in chemistry laboratories. In research the most common size accommodates round-bottom flasks of a few liters, whereas large scale (e.g., 20L-50L) versions are used in pilot plants in commercial chemical operations. Design The main components of a r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyman C
Lyman may refer to: Places Ukraine * Lyman, Ukraine, a city, formerly the administrative center of Lyman Raion, Donetsk Oblast * Lyman Raion, Donetsk Oblast, Ukraine, a former ''raion'' (district) * Lyman Raion, Odesa Oblast, Ukraine, a former ''raion'' United States * Lyman, Iowa, an unincorporated community * Lyman, Maine, a town * Lyman, Mississippi, a census-designated place * Lyman, Nebraska, a village * Lyman, New Hampshire, a town * Lyman, Oklahoma, a town * Lyman, South Carolina, a town * Lyman County, South Dakota ** Lyman, South Dakota, an unincorporated community in the county * Lyman, Utah, a town * Lyman, Washington, a town * Lyman, Wyoming, a town * Lyman Glacier (Mount Adams), Gifford Pinchot National Forest, Washington state * Lyman Glacier (North Cascades), Wenatchee National Forest, Washington state * Lyman Mountain, Oregon * Lyman Reservoir, Arizona Outer space * Lyman (crater), a lunar impact crater Other uses * Lyman (name), a list of people a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrifugal Evaporation
A centrifugal evaporator is a device used in chemical and biochemical laboratories for the efficient and gentle evaporation of solvents from many samples at the same time, and samples contained in microtitre plates. If only one sample required evaporation then a rotary evaporator is most often used. The most advanced modern centrifugal evaporators not only concentrate many samples at the same time, they eliminate solvent Bumping (chemistry), bumping and can handle solvents with boiling points of up to 220 °C. This is more than adequate for the modern high throughput laboratory. History The centrifugal evaporator dates from the second half of the 1800s. Patent US158764 was granted in 1875 to Conrad Wendel and William Florich for an improvement in centrifugal evaporators. Design A centrifugal evaporator often comprises a vacuum pump connected to a centrifuge chamber in which the samples are placed. Many systems also have a cold trap or solvent condenser placed in line between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vapor Pressure
Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's thermodynamic tendency to evaporate. It relates to the balance of particles escaping from the liquid (or solid) in equilibrium with those in a coexisting vapor phase. A substance with a high vapor pressure at normal temperatures is often referred to as '' volatile''. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the attractive interactions between liquid molecules become less significant in comparison to the entropy of those molecules in the gas phase, increasing the vapor pressure. Thus, liquids with strong intermolecular interactions are likely to have smaller vapor pressures, with the reverse true for weaker interactions. The vapor p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strain Energy
In physics, the elastic potential energy gained by a wire during elongation with a tensile (stretching) or compressive (contractile) force is called strain energy. For linearly elastic materials, strain energy is: : U = \frac 1 2 V \sigma \varepsilon = \frac 1 2 V E \varepsilon^2 = \frac 1 2 \frac V E \sigma^2 where is stress, is strain, is volume, and is Young's modulus: : E = \frac \sigma \varepsilon Molecular strain In a molecule, strain energy is released when the constituent atoms are allowed to rearrange themselves in a chemical reaction.''March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure,'' Michael B. Smith & Jerry March, Wiley-Interscience, 5th edition, 2001, The external work done on an elastic member in causing it to distort from its unstressed state is transformed into strain energy which is a form of potential energy. The strain energy in the form of elastic deformation is mostly recoverable in the form of mechanical work. For exa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetylide
In chemistry, an acetylide is a compound that can be viewed as the result of replacing one or both hydrogen atoms of acetylene (ethyne) by metallic or other cations. Calcium carbide is an important industrial compound, which has long been used to produce acetylene for welding and illumination. It is also a major precursor to vinyl chloride. Other acetylides are reagents in organic synthesis. Nomenclature The term acetylide is used loosely. It apply to an acetylene , where R = H or a side chain that is usually organic. The nomenclature can be ambiguous with regards to the distinction between compounds of the type and . When both hydrogens of acetylene are replaced by metals, the compound can also be called carbide, e.g. calcium carbide , which is calcium acetylide. When only one hydrogen atom is replaced, the anion may be called hydrogen acetylide or the prefix ''mono''- may be attached to the metal, as in monosodium acetylide or sodium hydrogen acetylide, . An acetylide may b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azide
In chemistry, azide (, ) is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant application of azides is as a propellant in air bags. Preparation Sodium azide is made industrially by the reaction of nitrous oxide, with sodium amide in liquid ammonia as solvent: : Many inorganic azides can be prepared directly or indirectly from sodium azide. For example, lead azide, used in detonators, may be prepared from the metathesis reaction between lead nitrate and sodium azide. An alternative route is direct reaction of the metal with silver azide dissolved in liquid ammonia. Some azides are produced by treating the carbonate salts with hydrazoic acid. Bonding Azide is isoelectronic with carbon dioxide , cyanate , nitrous oxide , nitronium ion , molecular beryllium fluoride and cyanogen fluoride FCN. Per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peroxide
In chemistry, peroxides are a group of Chemical compound, compounds with the structure , where the R's represent a radical (a portion of a complete molecule; not necessarily a free radical) and O's are single oxygen atoms. Oxygen atoms are joined to each other and to adjacent elements through Single bond, single covalent bonds, denoted by dashes or lines. The group in a peroxide is often called the peroxide group, though some nomenclature discrepancies exist. This linkage is recognized as a common polyatomic ion, and exists in many molecules. General structure The characteristic structure of any regular peroxide is the oxygen–oxygen covalent single bond, which connects the two main atoms together. In the event that the molecule has no chemical Substituent, substituents, the peroxide group will have a [−2] Formal charge, net charge. Each oxygen atom has a charge of negative one, as 5 of its Valence electron, valence electrons remain in the outermost Atomic orbital, orbital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diethyl Ether
Diethyl ether, or simply ether, is an organic compound with the chemical formula , sometimes abbreviated as . It is a colourless, highly Volatility (chemistry), volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It belongs to the ether class of organic compounds. It is a common solvent and was formerly used as a general anesthetic. Production Most diethyl ether is produced as a byproduct of the vapor-phase Hydration reaction, hydration of ethylene to make ethanol. This process uses solid-supported phosphoric acid Catalysis, catalysts and can be adjusted to make more ether if the need arises: Vapor-phase Dehydration reaction, dehydration of ethanol over some Aluminium oxide, alumina catalysts can give diethyl ether yields of up to 95%. : Diethyl ether can be prepared both in laboratories and on an industrial scale by the acid ether synthesis. Uses The dominant use of diethyl ether is as a solvent. One particular application is in the production of cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Chip
A boiling chip, boiling stone, or porous bit anti-bumping granule is a tiny, unevenly shaped piece of substance added to liquids to make them boil more calmly. Boiling chips are frequently employed in distillation and heating. When a liquid becomes superheated, a speck of dust or a stirring rod can cause violent flash boiling. Boiling chips provide nucleation sites so the liquid boils smoothly without becoming superheated or bumping. Use Boiling chips should not be added to liquid that is already near its boiling point, as this could also induce flash boiling. Boiling chips should not be used when cooking unless they are suitable for food-grade applications. The structure of a boiling chip traps liquid while in use, meaning that they cannot be re-used in laboratory setups. They also don't work well under vacuum; if a solution is boiling under vacuum, it is best to constantly stir it instead. Materials Boiling chips are typically made of a porous material, such as alu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Oven
In chemistry, a vacuum oven is an oven that can also apply a vacuum to its contents. Such devices are useful for removing solvent or dehydrating samples. They are equivalent to Abderhalden's drying pistol in some ways, but vacuum ovens typically can accommodate large samples. A characteristic operation for a vacuum oven is the activation or regeneration of molecular sieves. Vacuum furnaces are related devices that operate at much higher temperatures and much lower pressures. The acetylacetonate complex Mn(acac)2 is obtained by vacuum drying the yellow dihydrate Mn(acac)2(H2O)2.{{cite book , doi=10.1002/9780470132371.ch51 , chapter=Manganese(II) Acetylacetonate , date=1960 , last1=Charles , first1=Robert G. , title=Inorganic Syntheses , volume=6 , pages=164–166 , isbn=978-0-470-13165-7 References [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
