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Polymethine Dyes
Methine dyes (polymethine dyes) are dyes whose chromophoric system consists of conjugated double bonds (polyenes) flanked by two end groups: an electron acceptor A and an electron donor D. Structural of methine dyes Methine dyes comprise an odd number of methine groups. The end groups can also be part of a heterocycle or the double bonds part of an aromatic system: The methine dye subclasses are based on these structural differences. Methine dyes can furthermore be classified as cationic, anionic or neutral. If one or more methine groups are replaced by a heteroatom - usually nitrogen - one speaks of heteroanalogous (aza-analogous) methine dyes. General properties and classification Methine dyes can be characterized as polyene dyes with terminal electron donating and accepting groups. In the majority of cases, these terminal groups contain nitrogen or oxygen atoms. However, while the naturally occurring polyene dyes (such as carotenoids) are limited to yellow to yellow-red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromophore
A chromophore is the part of a molecule responsible for its color. The color that is seen by our eyes is the one not absorbed by the reflecting object within a certain wavelength spectrum of visible light. The chromophore is a region in the molecule where the energy difference between two separate molecular orbitals falls within the range of the visible spectrum. Visible light that hits the chromophore can thus be absorbed by exciting an electron from its ground state into an excited state. In biological molecules that serve to capture or detect light energy, the chromophore is the moiety that causes a conformational change in the molecule when hit by light. Conjugated pi-bond system chromophores Just like how two adjacent p-orbitals in a molecule will form a pi-bond, three or more adjacent p-orbitals in a molecule can form a conjugated pi-system. In a conjugated pi-system, electrons are able to capture certain photons as the electrons resonate along a certain distanc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PH Indicator
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually or spectroscopically by changes in absorption and/or emission properties. Hence, a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+) in the Arrhenius model. Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C ( standard laboratory conditions). Solutions with a pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic. Since most naturally occurring organic compounds are weak electrolytes, such as carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylmethane
Triphenylmethane, or triphenyl methane, is the hydrocarbon with the formula (C6H5)3CH. This colorless solid is soluble in nonpolar organic solvents and not in water. Triphenylmethane is the basic skeleton of many synthetic dyes called triarylmethane dyes, many of them are pH indicators, and some display fluorescence. A trityl group in organic chemistry is a triphenylmethyl group Ph3C, e.g. triphenylmethyl chloride (trityl chloride) and the triphenylmethyl radical (trityl radical). Preparation Triphenylmethane was first synthesized in 1872 by the German chemist August Kekulé and his Belgian student Antoine Paul Nicolas Franchimont (1844–1919) by heating diphenylmercury (Hg(C6H5)2, ''Quecksilberdiphenyl'') with benzal chloride (C6H5CHCl2, ''Benzylenchlorid''). Triphenylmethane can be synthesized by Friedel–Crafts reaction from benzene and chloroform with aluminium chloride catalyst: :3 C6H6 + CHCl3 → Ph3CH + 3 HCl Alternatively, benzene may react with carbon tetr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthesis Disperse Yellow 31
Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organic compounds ***Total synthesis, the complete organic synthesis of complex organic compounds, usually without the aid of biological processes ***Convergent synthesis or linear synthesis, a strategy to improve the efficiency of multi-step chemical syntheses **Dehydration synthesis, a chemical synthesis resulting in the loss of a water molecule * Biosynthesis, the creation of an organic compound in a living organism, usually aided by enzymes **Photosynthesis, a biochemical reaction using a carbon molecule to produce an organic molecule, using sunlight as a catalyst **Chemosynthesis, the synthesis of biological compounds into organic waste, using methane or an oxidized molecule as a catalyst **Amino acid synthesis, the synthesis of an amino aci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethyl Cyanoacetate
Ethyl cyanoacetate is an organic compound that contains a carboxylate ester and a nitrile. It is a colourless liquid with a pleasant odor. This material is useful as a starting material for synthesis due to its variety of functional groups and chemical reactivity. Production Ethyl cyanoacetate may be prepared in various ways: * Kolbe nitrile synthesis using ethyl chloroacetate and sodium cyanide. * Fischer esterification of cyanoacetic acid with ethanol in the presence of a strong mineral acids (e.g. concentrated sulfuric acid). The cyanoacetic acid can be prepared via Kolbe nitrile synthesis using sodium chloroacetate and sodium cyanide. *Reaction of the sodium cyanoacetate with ethyl bromide in an aqueous–organic two-phase system in the presence of a phase transfer catalyst. *Oxidation of 3-ethoxypropionitrile, an ether, with oxygen under pressure in the presence of cobalt(II) acetate tetrahydrate as catalyst and ''N''-hydroxyphthalimide as a radical generator. Propertie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyester Fibers
Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in plants and insects, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing. Polyester fibers are sometimes spun together with natural fibers to produce a cloth with blended properties. Cotton-polyester blends can be strong, wrinkle- and tear-resistant, and reduce shrinking. Synthetic fibers using polyester have high water, wind and environmental resistance compared to plant-derived fibers. They are less fire-resistant and can melt when ignited. Liquid crystalline polyesters are among the first industrially used liquid crystal polymers. They are used for their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disperse Dye
Disperse dye is a category of synthetic dye intended for polyester and related hydrophobic fibers. Disperse dyes are polar molecules containing anthraquinone or azo groups. It is estimated that 85% of disperse dyes are azos or anthraquinone dyes. History The history of disperse dye production is closely related to the synthesis of cellulose acetate fibres. Disperse dyes were invented in 1923-24. Fundamentals of dyeing Disperse dyes are non-ionic in nature and partially soluble in water. The interaction of dye molecule and polymer takes place with Van der Waals and dipole forces. Disperse dyes have better diffusion at boiling to a higher temperature. Examples * Disperse Orange 1 is an azo dye. * Disperse Red 9 is a red dye derived from anthraquinone. * Disperse Red 11, also called C.I. 62015 and 1,4-diamino-2-methoxy anthraquinone, is another anthraquinone dye. * Disperse Red 60 is also an anthraquinone dye. * Disperse Yellow 26 is a yellow disperse dye. * Disper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Styrene
Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concentrations have a less pleasant odor. Styrene is the precursor to polystyrene and several copolymers. Approximately 25 million tonnes of styrene were produced in 2010, increasing to around 35 million tonnes by 2018. Natural occurrence Styrene is named after storax balsam (often commercially sold as ''styrax''), the resin of Liquidambar trees of the Altingiaceae plant family. Styrene occurs naturally in small quantities in some plants and foods (cinnamon, coffee beans, balsam trees and peanuts) and is also found in coal tar. History In 1839, the German apothecary Eduard Simon isolated a volatile liquid from the resin (called ''storax'' or ''styrax'' (Latin)) of the American sweetgum tree (''Liquidambar styraciflua''). He called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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