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2,5-Dihydroxycinnamic Acid
2,5-Dihydroxycinnamic acid is a hydroxycinnamic acid. It is an isomer of caffeic acid. Preparation 2,5-Dihydroxycinnamic acid is produced by Elbs persulfate oxidation of o-Coumaric acid. See also * Homogentisic acid *Gentisic acid Gentisic acid is a dihydroxybenzoic acid. It is a derivative of benzoic acid and a minor (1%) product of the metabolic break down of aspirin, excreted by the kidneys. It is also found in the African tree ''Alchornea cordifolia'' and in wine. Pro ... References Hydroxycinnamic acids Hydroquinones Vinylogous carboxylic acids {{aromatic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which ''bonds'' between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the ''relative positions'' of the atoms differ. Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest. The English word "isomer" () is a back-for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caffeic Acid
Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is an intermediate in the biosynthesis of lignin, one of the principal components of woody plant biomass and its residues. Natural occurrences Caffeic acid can be found in the bark of ''Eucalyptus globulus'' the barley grain ''Hordeum vulgare'' and the herb ''Dipsacus asperoides''. It can also be found in the freshwater fern ''Salvinia molesta'' and in the mushroom ''Phellinus linteus''. Occurrences in food Free caffeic acid can be found in a variety of beverages, including brewed coffee at 0.13 mg per 100 ml and red wine at 2 mg per 100 ml. It is found at relatively high levels in herbs of the mint family, especially thyme, sage and spearmint (at about 20 mg per 100 g), and in spices, such as Ceylon cinnamon and star anise (at about 22 mg per 100 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elbs Persulfate Oxidation
The Elbs persulfate oxidation is the organic reaction of phenols with alkaline potassium persulfate to form ''para''-diphenols. The reaction is generally performed in water at room temperatures or below, using equimolar quantities of reagents. Several reviews have been published. Scope and mechanism The reaction is disadvantaged by moderate to low chemical yields with recovery of starting material and complete consumption of the persulfate. It is suggested that the phenol in many cases is a catalyst converting the persulfate into a sulfate. Despite this, the Elbs reaction remains generally useful in a research setting, as it is simple to perform and is tolerant of a wide range of other functional groups, which are not oxidised under these conditions. A reaction mechanism has been postulated which accounts for the observed ''para'' substitution featuring the tautomeric ''para'' carbanion of the starting phenolate ion:{{cite journal , author = Behrman, E. J. , title = The Elbs a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
O-Coumaric Acid
''o''-Coumaric acid is a hydroxycinnamic acid, an organic compound that is a hydroxy derivative of cinnamic acid. There are three isomers of coumaric acids — ''o''-coumaric acid, ''m''-coumaric acid, and ''p''-coumaric acid — that differ by the position of the hydroxy substitution of the phenyl group. Natural occurrence ''o''-Coumaric acid can be found in vinegar Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth .... 2-Coumarate reductase is an enzyme that produces 2-coumarate from 3-(2-hydroxyphenyl)propanoate and NAD+. This enzyme participates in phenylalanine metabolism. References External links ''o''-Coumaric acid at www.phenol-explorer.eu Hydroxycinnamic acids Vinylogous carboxylic acids {{aromatic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homogentisic Acid
Homogentisic acid (2,5-dihydroxyphenylacetic acid) is a phenolic acid usually found in ''Arbutus unedo'' (strawberry-tree) honey. It is also present in the bacterial plant pathogen ''Xanthomonas campestris'' pv. ''phaseoli'' as well as in the yeast ''Yarrowia lipolytica'' where it is associated with the production of brown pigments. It is oxidatively dimerised to form hipposudoric acid, one of the main constituents of the 'blood sweat' of hippopotamuses. It is less commonly known as melanic acid, the name chosen by William Prout. Human pathology Accumulation of excess homogentisic acid and its oxide, named alkapton, is a result of the failure of the enzyme homogentisic acid 1,2-dioxygenase (typically due to a mutation) in the degradative pathway of tyrosine, consequently associated with alkaptonuria. Intermediate It is an intermediate in the catabolism of aromatic amino acids such as phenylalanine and tyrosine. 4-Hydroxyphenylpyruvate (produced by transamination of tyrosin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gentisic Acid
Gentisic acid is a dihydroxybenzoic acid. It is a derivative of benzoic acid and a minor (1%) product of the metabolic break down of aspirin, excreted by the kidneys. It is also found in the African tree ''Alchornea cordifolia'' and in wine. Production Gentisic acid is produced by carboxylation of hydroquinone.Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 2005 Wiley-VCH, Weinheim. . :C6H4(OH)2 + CO2 → C6H3(CO2H)(OH)2 This conversion is an example of a Kolbe–Schmitt reaction. Alternatively the compound can be synthesized from salicylic acid via Elbs persulfate oxidation. Reactions In the presence of the enzyme gentisate 1,2-dioxygenase, gentisic acid reacts with oxygen to give maleylpyruvate: :2,5-dihydroxybenzoate + O2 \rightleftharpoons maleylpyruvate Applications As a hydroquinone, gentisic acid is readily oxidised and is used as an antioxidant excipient in some pharmaceutical preparations. In the la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxycinnamic Acids
Hydroxycinnamic acids (hydroxycinnamates) are a class of aromatic acids or phenylpropanoids having a C6–C3 skeleton. These compounds are hydroxy derivatives of cinnamic acid. In the category of phytochemicals that can be found in food, there are : * α-Cyano-4-hydroxycinnamic acid * Caffeic acid – burdock, hawthorn, artichoke, pear, basil, thyme, oregano, apple * Cichoric acid * Cinnamic acid – aloe * Chlorogenic acid – echinacea, strawberries, pineapple, coffee, sunflower, blueberries * Diferulic acids * Coumaric acid * Ferulic acid (3-methoxy-4-hydroxycinnamic acid) – oats, rice, artichoke, orange, pineapple, apple, peanut * Sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid or sinapic acid) Hydroxycinnamoyltartaric acids * Caftaric acid – grapes and wine, mainly the ''trans'' isomer * Coutaric acid – grapes and wine, both ''trans'' and ''cis'' isomers * Fertaric acid Fertaric acid is a hydroxycinnamic acid found in wine and grapes. It is an ester formed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroquinones
Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a ''para'' position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843. Production Hydroquinone is produced industrially in two main ways.Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 2005 Wiley-VCH, Weinheim. . * The most widely used route is similar to the cumene process in reaction mechanism and involves the dialkylation of benzene with propene to give 1,4-diisopropylbenzene. This compound reacts with air to afford the bis(hydroperoxide), which is structurally similar to cumene hydroperoxide and rearranges in acid to give acetone and hydroquinone. * A sec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
