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Keeper (chemistry)
Keepers are substances (typically solvents, but sometimes adsorbent solids) added in relatively small quantities during an evaporative procedure in analytical chemistry, such as concentration of an analyte-solvent mixture by rotary evaporation. The purpose of a keeper is to reduce losses of a target analyte during the procedure. Keepers typically have reduced volatility and are added to a more volatile solvent. In the case of volatile target analytes, it is difficult to totally avoid loss of the analyte in an evaporative procedure, but the presence of a keeper solvent or solid is intended to preferentially solvate or adsorb the analyte, so that the volatility of the analyte is reduced as the evaporative procedure continues. In the case of non-volatile target analytes, the presence of the keeper solvent or solid is intended to prevent all the solvent from being evaporated off, thereby preventing the loss of analytes which might irreversibly adsorb to the container walls when completel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar molecules and the most common solvent used by living things; all the ions and proteins in a cell are dissolved in water within the cell. The quantity of solute that can dissolve in a specific volume of solvent varies with temperature. Major uses of solvents are in paints, paint removers, inks, and dry cleaning. Specific uses for organic solvents are in dry cleaning (e.g. tetrachloroethylene); as paint thinners (toluene, turpentine); as nail polish removers and solvents of glue (acetone, methyl acetate, ethyl acetate); in spot removers (hexane, petrol ether); in detergents ( citrus terpenes); and in perfumes (ethanol). Solvents find various applications in chemical, pharmaceutical, oil, and gas industries, including in chemical syn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isooctane
2,2,4-Trimethylpentane, also known as isooctane or iso-octane, is an organic compound with the formula (CH3)3CCH2CH(CH3)2. It is one of several isomers of octane (C8H18). This particular isomer is the standard 100 point on the octane rating scale (the zero point is ''n''-heptane). It is an important component of gasoline, frequently used in relatively large proportions (around 10%) to increase the knock resistance of fuel. Strictly speaking, if the standard meaning of ‘iso’ is followed, the name ''isooctane'' should be reserved for the isomer 2-methylheptane. However, 2,2,4-trimethylpentane is by far the most important isomer of octane and historically it has been assigned this name. Production Isooctane is produced on a massive scale in the petroleum industry by alkylation of isobutene with isobutane. This process is conducted in alkylation units in the presence of acid catalysts. It can also be produced from isobutylene by dimerization using an Amberlyst catalyst to pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1-hexanol
1-Hexanol (IUPAC name hexan-1-ol) is an organic alcohol with a six-carbon chain and a condensed structural formula of CH3(CH2)5OH. This colorless liquid is slightly soluble in water, but miscible with diethyl ether and ethanol. Two additional straight chain isomers of 1-hexanol, 2-hexanol and 3-hexanol, exist, both of which differing by the location of the hydroxyl group. Many isomeric alcohols have the formula C6H13OH. It is used in the perfume industry. Preparation Hexanol is produced industrially by the oligomerization of ethylene using triethylaluminium followed by oxidation of the alkylaluminium products.. An idealized synthesis is shown: :Al(C2H5)3 + 6C2H4 → Al(C6H13)3 :Al(C6H13)3 + O2 + 3H2O → 3HOC6H13 + Al(OH)3 The process generates a range of oligomers that are separated by distillation. Alternative methods Another method of preparation entails hydroformylation of 1-pentene followed by hydrogenation of the resulting aldehydes. This method is practiced in indu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dodecane
Dodecane (also known as dihexyl, bihexyl, adakane 12, or duodecane) is an oily liquid ''n''-alkane hydrocarbon with the chemical formula C12H26 (which has 355 isomers). It is used as a solvent, distillation chaser, and scintillator component. It is used as a diluent for tributyl phosphate (TBP) in nuclear reprocessing plants. Combustion reaction The combustion reaction of dodecane is as follows: :2 C12H26(''l'') + 37 O2(''g'') → 24 CO2(''g'') + 26 H2O(''g'') : Δ''H''° = −7513 kJ One litre of fuel needs about 15 kg of air to burn, and generates 2.3 kg (or 1.2 m3) of CO2 upon complete combustion. Jet fuel surrogate In recent years, ''n''-dodecane has garnered attention as a possible surrogate for kerosene-based fuels such as Jet-A, S-8, and other conventional aviation fuels. It is considered a second-generation fuel surrogate designed to emulate the laminar flame speed, largely supplanting ''n''-decane, primarily due to its higher molecular mass and l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tricaprin
Tricaprin or tridecanoin is a triglyceride of capric acid and a component of MCT oil. Its formula is . Occurrence Tricaprin occurs naturally in the seeds of ''Umbellularia californica'', a hardwood tree native to North America. Production Tricaprin and other medium-chain triglycerides (MCTs) are either isolated from natural or genetically engineered sources in the production of MCT oils, or are synthesized on a large scale through the esterification of medium-chain fatty acids with glycerol, specifically capric acid in the case of tricaprin. These esterification reactions have been investigated with a focus on enzyme catalysis as an alternative to traditional manufacturing processes that take place at high temperature and pressure, which result in poorer quality product at low yield. Compared to similar reactions used in the synthesis of other MCTs, tricaprin has a slow conversion rate from capric acid in the presence of lipozyme. Uses Tricaprin is used as an additive to dies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethyl Sulfoxide
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula ( CH3)2. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is miscible in a wide range of organic solvents as well as water. It has a relatively high boiling point. DMSO has the unusual property that many individuals perceive a garlic-like taste in the mouth after DMSO makes contact with their skin. In terms of chemical structure, the molecule has idealized Cs symmetry. It has a trigonal pyramidal molecular geometry consistent with other three-coordinate S(IV) compounds, with a nonbonded electron pair on the approximately tetrahedral sulfur atom. Synthesis and production Dimethyl sulfoxide was first synthesized in 1866 by the Russian scientist Alexander Zaytsev, who reported his findings in 1867. Dimethyl sulfoxide is produced industrially from dimethyl sulfide, a by-product of the Kraf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undecane
Undecane (also known as hendecane) is a liquid alkane hydrocarbon with the chemical formula CH3(CH2)9CH3. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants.Hölldobler B, Wilson EO (1990). ''The Ants''. Harvard University Press. , p. 287 It has 159 isomers. Undecane may also be used as an internal standard in gas chromatography when working with other hydrocarbons. Since the boiling point of undecane (196 °C) is well known, it may be used as a comparison for retention times in a gas chromatograph for molecules whose structure has been freshly elucidated. For example, if one is working with a 50 m crosslinked methyl silicone capillary column with an oven temperature increasing slowly, beginning around 60 °C, an 11-carbon molecule like undecane may be used as an internal standard to be compared with the retention times of other 10-, 11-, or 12- carbon molecules, depending on their structures. Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decane
Decane is an alkane hydrocarbon with the chemical formula C10H22. Although 75 structural isomers are possible for decane, the term usually refers to the normal-decane ("''n''-decane"), with the formula CH3(CH2)8CH3. All isomers, however, exhibit similar properties and little attention is paid to the composition. These isomers are flammable liquids. Decane is present in small quantities (less than 1%) in gasoline (petrol) and kerosene. Like other alkanes, it is a nonpolar solvent, and does not dissolve in water, and is readily combustible. Although it is a component of fuels, it is of little importance as a chemical feedstock, unlike a handful of other alkanes. Reactions Decane undergoes combustion, just like other alkanes. In the presence of sufficient oxygen, it burns to form water and carbon dioxide. :2 C10H22 + 31 O2 → 20 CO2 + 22 H2O With insufficient oxygen, carbon monoxide is also formed. Other It has a surface tension of 0.0238 N·m−1.Website of Krüss'' ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylene Glycol
Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odorless, colorless, flammable, viscous liquid. Ethylene glycol has a sweet taste, but it is toxic in high concentrations. Production Industrial routes Ethylene glycol is produced from ethylene (ethene), via the intermediate ethylene oxide. Ethylene oxide reacts with water to produce ethylene glycol according to the chemical equation: This reaction can be catalyzed by either acids or bases, or can occur at neutral pH under elevated temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large excess of water. Under these conditions, ethylene glycol yields of 90% can be achieved. The major byproducts are the oligomers diethylene glycol, triethylene glycol, and tetraethylene glycol. The separation of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adsorption
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a fluid (the ''absorbate'') is dissolved by or permeates a liquid or solid (the ''absorbent''). Adsorption is a '' surface phenomenon'', while absorption involves the whole volume of the material, although adsorption does often precede absorption. The term ''sorption'' encompasses both processes, while ''desorption'' is the reverse of it. Like surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent or metallic) of the constituent atoms of the material are fulfilled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
