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Rap–Stoermer Condensation
Salicylic aldehyde (2-hydroxybenzaldehyde) is the organic compound with the formula (C7 H6 O2) C6H4CHO-2-OH. Along with 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde, it is one of the three isomers of hydroxybenzaldehyde. This colorless oily liquid has a bitter almond odor at higher concentration. Salicylaldehyde is a key precursor to a variety chelating agents, some of which are commercially important. Production Salicylaldehyde is prepared from phenol and chloroform by heating with sodium hydroxide or potassium hydroxide in a Reimer–Tiemann reaction: : Alternatively, it is produced by condensation of phenol or its derivatives with formaldehyde to give hydroxybenzyl alcohol, which is oxidized to the aldehyde. Salicylaldehydes in general may be prepared by other ortho-selective formylation reactions from the corresponding phenol, for instance by the Duff reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and a base. Natural o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Society Of Chemistry
The Royal Society of Chemistry (RSC) is a learned society (professional association) in the United Kingdom with the goal of "advancing the chemistry, chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Royal Institute of Chemistry, the Faraday Society, and the Society for Analytical Chemistry with a new Royal Charter and the dual role of learned society and professional body. At its inception, the Society had a combined membership of 34,000 in the UK and a further 8,000 abroad. The headquarters of the Society are at Burlington House, Piccadilly, London. It also has offices in Thomas Graham House in Cambridge (named after Thomas Graham (chemist), Thomas Graham, the first president of the Chemical Society) where ''RSC Publishing'' is based. The Society has offices in the United States, on the campuses of The University of Pennsylvania and Drexel University, at the University City Science Center in Philadelphia, Pennsylvania, in both Beijing a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duff Reaction
The Duff reaction or hexamine aromatic formylation is a formylation reaction used in organic chemistry for the synthesis of benzaldehydes with hexamine as the formyl carbon source. It is named after James Cooper Duff, who was a chemist at the College of Technology, Birmingham, around 1920–1950. The electrophilic species in this electrophilic aromatic substitution reaction is the iminium ion CH2+NR2. The initial reaction product is an iminium which is hydrolyzed to the aldehyde. See mechanism below. The reaction requires strongly electron donating substituents on the aromatic ring such as in a phenol. Formylation occurs '' ortho'' to the electron donating substituent preferentially, unless the ''ortho'' positions are blocked, in which case the formylation occurs at the ''para'' position. Examples are the synthesis of 3,5-di-''tert''-butylsalicylaldehyde: and the synthesis of syringaldehyde: If both ''ortho'' positions are vacant then a diformylation is possible, as in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dakin Reaction
The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an '' ortho''- or ''para''-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidized, and the hydrogen peroxide is reduced. The Dakin oxidation, which is closely related to the Baeyer–Villiger oxidation, is not to be confused with the Dakin–West reaction, though both are named after Henry Drysdale Dakin. Reaction mechanism The Dakin oxidation starts with nucleophilic addition of a hydroperoxide anion to the carbonyl carbon, forming a tetrahedral intermediate (2). The intermediate collapses, causing ,2aryl migration, hydroxide elimination, and formation of a phenyl ester (3). The phenyl ester is subsequently hydrolyzed: nucleophilic addition of hydroxide from solution to the ester carbonyl carbon forms a second tetrahedral intermediate (4), which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catechol
Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is a toxic organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It was first discovered by destructive distillation of the plant extract catechin. About 20,000 tonnes of catechol are now synthetically produced annually as a commodity organic chemical, mainly as a precursor to pesticides, flavors, and fragrances. Catechol occurs as feathery white crystals that are very rapidly soluble in water. Isolation and synthesis Catechol was first isolated in 1839 by Edgar Hugo Emil Reinsch (1809–1884) by distilling it from the solid tannic preparation catechin, which is the residuum of catechu, the boiled or concentrated juice of ''Mimosa catechu'' (''Acacia catechu''). Upon heating catechin above its decomposition point, a substance that Reinsch first named ''Brenz-Katechusäure'' (burned catechu acid) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%–6% by weight) in water for consumer use, and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or " high-test peroxide", decomposes explosively when heated and has been used as a propellant in rocketry. Hydrogen peroxide is a reactive oxygen species and the simplest peroxide, a compound having an oxygen–oxygen single bond. It decomposes slowly when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a stabilizer in a weakly acidic solution in a dark bottle to block light. Hydrogen peroxide is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as peroxidases. Properties The boiling poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salicylaldehyde Derivatives
Salicylic aldehyde (2-hydroxybenzaldehyde) is the organic compound with the formula (C7 H6 O2) C6H4CHO-2-OH. Along with 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde, it is one of the three isomers of hydroxybenzaldehyde. This colorless oily liquid has a bitter almond odor at higher concentration. Salicylaldehyde is a key precursor to a variety chelating agents, some of which are commercially important. Production Salicylaldehyde is prepared from phenol and chloroform by heating with sodium hydroxide or potassium hydroxide in a Reimer–Tiemann reaction: : Alternatively, it is produced by condensation of phenol or its derivatives with formaldehyde to give hydroxybenzyl alcohol, which is oxidized to the aldehyde. Salicylaldehydes in general may be prepared by other ortho-selective formylation reactions from the corresponding phenol, for instance by the Duff reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and a base. Natural occurre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysomela Populi
''Chrysomela populi'' is a species of broad-shouldered leaf beetle belonging to the family Chrysomelidae, subfamily Chrysomelinae. Distribution This species is one of the most widespread and frequent species of leaf beetles from the subfamily Chrysomelinae. These beetles can be found in most of Europe (Austria, Belgium, Czech Republic, France, Germany, Italy, Luxembourg, Poland, Slovakia, Switzerland), in the Palearctic realm and in the Oriental realm (Caucasus, Pakistan, Siberia, Kazakhstan, Central Asia, Far East of Russia, China and Japan). Urban, JOccurrence, bionomics and harmfulness of Chrysomela populi L. (Coleoptera, Chrysomelidae''Journal of Forest Science''. — 2006. — Vol. 52, no. 6 Habitat These beetles mainly inhabit coniferous, mixed and broad-leaved forests, forest fringes and dry meadows with poplars and willow trees. Description Larva description The larvae of the species is white or light grey coloured with black dots. Adult description ''Chrysomela populi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaf Beetle
The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle families. Numerous subfamilies are recognized, but the precise taxonomy and systematics are likely to change with ongoing research. Leaf beetles are partially recognizable by their tarsal formula, which appears to be 4-4-4, but is actually 5-5-5 as the fourth tarsal segment is very small and hidden by the third. As with many taxa, no single character defines the Chrysomelidae; instead, the family is delineated by a set of characters. Some lineages are only distinguished with difficulty from longhorn beetles (family Cerambycidae), namely by the antennae not arising from frontal tubercles. Adult and larval leaf beetles feed on all sorts of plant tissue, and all species are fully herbivorous. Many are serious pests of cultivated plants, f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castor Fiber
The Eurasian beaver (''Castor fiber'') or European beaver is a beaver species that was once widespread in Eurasia, but was hunted to near-extinction for both its fur and castoreum. At the turn of the 20th century, only about 1,200 beavers survived in eight relict populations in Europe and Asia. It has been reintroduced to much of its former range, and now occurs from Spain, Central Europe, Great Britain and Scandinavia to a few regions in China and Mongolia. It is listed as least concern on the IUCN Red List, as it recovered well in most of Europe. It is extirpated in Portugal, Moldova, and Turkey. Taxonomy ''Castor fiber'' was the scientific name used by Carl Linnaeus in 1758, who described the beaver in his work '' Systema Naturae''. Between 1792 and 1997, several Eurasian beaver zoological specimens were described and proposed as subspecies, including: *''C. f. albus'' and ''C. f. solitarius'' by Robert Kerr in 1792 *''C. f. fulvus'' and ''C. f. variegatus'' by Johann M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castor Canadensis
The North American beaver (''Castor canadensis'') is one of two extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and introduced in South America (Patagonia) and Europe (primarily Finland and Karelia). In Canada and the United States, the species is often referred to simply as "beaver", though this causes some confusion because another distantly related rodent, ''Aplodontia rufa'', is often called the "mountain beaver". Other vernacular names, including American beaver and Canadian beaver, distinguish this species from the other extant beaver species, ''Castor fiber'', which is native to Eurasia. The North American beaver is one of the official national wildlife of Canada symbols and is the official state mammal of Oregon and New York. Taxonomy Evolution The first fossil records of beaver are 10 to 12 million years old in Germany, and they are thought to have migrated to North America across the Bering Strait. The oldest foss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castoreum
Castoreum is a yellowish exudate from the castor sacs of mature beavers. Beavers use castoreum in combination with urine to scent mark their territory. Both beaver sexes have a pair of castor sacs and a pair of anal glands, located in two cavities under the skin between the pelvis and the base of the tail. The castor sacs are not true glands ( endocrine or exocrine) on a cellular level, hence references to these structures as preputial glands, castor glands, or scent glands are misnomers. It is used as a tincture in some perfumesInternational Perfume Museum, Grasse, France, Website: and was sometimes used as a food additive in the early 1900s. The sacs brought per ounce when auctioned at the May–June 2016 North American Fur Auction. Chemical composition At least 24 compounds are known constituents of beaver castoreum. Several of these have pheromonal activity, of which the phenols 4-ethylphenol and catechol and the ketones acetophenone and 3-hydroxyacetophenone were s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food Chemistry (journal)
''Food Chemistry'' is a peer-reviewed scientific journal In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. Content Articles in scientific journals are mostly written by active scientists such as s .... It was established in 1976 and is published monthly by Elsevier. External links * Chemistry journals Elsevier academic journals English-language journals Food chemistry Food science journals Publications established in 1976 Semi-monthly journals {{chemistry-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
