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Lactones
Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the corresponding hydroxycarboxylic acids, which takes place spontaneously when the ring that is formed is five- or six-membered. Lactones with three- or four-membered rings (α-lactones and β-lactones) are very reactive, making their isolation difficult. Special methods are normally required for the laboratory synthesis of small-ring lactones as well as those that contain rings larger than six-membered. Nomenclature Lactones are usually named according to the precursor acid molecule (''aceto'' = 2 carbon atoms, ''propio'' = 3, ''butyro'' = 4, ''valero'' = 5, ''capro'' = 6, etc.), with a ''-lactone'' suffix and a Greek letter prefix that specifies the number of carbon atoms in the heterocycle — that is, the distance between the relevant -OH ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactone Types
Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the corresponding hydroxycarboxylic acids, which takes place spontaneously when the ring that is formed is five- or six-membered. Lactones with three- or four-membered rings (α-lactones and β-lactones) are very reactive, making their isolation difficult. Special methods are normally required for the laboratory synthesis of small-ring lactones as well as those that contain rings larger than six-membered. Nomenclature Lactones are usually named according to the precursor acid molecule (''aceto'' = 2 carbon atoms, ''propio'' = 3, ''butyro'' = 4, ''valero'' = 5, ''capro'' = 6, etc.), with a ''-lactone'' suffix and a Greek letter prefix that specifies the number of carbon atoms in the heterocycle — that is, the distance between the relevant -OH ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kavain
Kavain is the main kavalactone found mostly in the roots of the kava plant. Pharmacology Kavain has anticonvulsive properties, attenuating vascular smooth muscle contraction through interactions with voltage-dependent and channels. How this effect is mediated and to what extent this mechanism is involved in the anxiolytic and analgesic effects of kavalactones on the central nervous system is unknown. The recent finding that kavain can reversibly inhibit both monoamine oxidase A and monoamine oxidase B suggests that kavain may exert some of its effects by modulating serotonin, norepinephrine, and dopamine signaling. However, the precise mechanisms underlying the psychotropic, sedative, and anxiolytic actions of kavain and related kavalactones are still debated. Direct binding to the benzodiazepine/flumazenil binding site of the GABA-A receptor does not occur with kavain enantiomers. Many studies involved kava extracts from different plant parts and are, therefore, not applica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrolide
The Macrolides are a class of natural products that consist of a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered. Macrolides belong to the polyketide class of natural products. Some macrolides have antibiotic or antifungal activity and are used as pharmaceutical drugs. Rapamycin is also a macrolide and was originally developed as an antifungal, but is now used as an immunosuppressant drug and is being investigated as a potential longevity therapeutic. Macrolides are bacteriostatic in that they suppress or inhibit bacterial growth rather than killing bacteria completely. Definition In general, any macrocyclic lactone having greater than 8-membered rings are candidates for this class. The macrocycle may contain amino nitrogen, amide nitrogen (but should be differentiated from cyclopeptides), an oxazole ring, or a thiazole ring. Benzene rings are exclude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehydration Reaction
In chemistry, a dehydration reaction is a chemical reaction that involves the loss of water from the reacting molecule or ion. Dehydration reactions are common processes, the reverse of a hydration reaction. Dehydration reactions in organic chemistry Esterification The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol to give an ester :RCO2H + R′OH RCO2R′ + H2O Often such reactions require the presence of a dehydrating agent, i.e. a substance that reacts with water. Etherification Two monosaccharides, such as glucose and fructose, can be joined together (to form saccharose) using dehydration synthesis. The new molecule, consisting of two monosaccharides, is called a disaccharide. Nitrile formation Nitriles are often prepared by dehydration of primary amides. :RC(O)NH2 → RCN + H2O Ketene formation Ketene is produced by heating acetic acid and trapping the product: :CH3CO2H → CH2=C= ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascorbic Acid
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) and wrinkles on the face. It is used to prevent and treat scurvy. Vitamin C is an essential nutrient involved in the repair of tissue, the formation of collagen, and the enzymatic production of certain neurotransmitters. It is required for the functioning of several enzymes and is important for immune system function. It also functions as an antioxidant. Most animals are able to synthesize their own vitamin C. However, apes (including humans) and monkeys (but not all primates), most bats, some rodents, and certain other animals must acquire it from dietary sources. There is some evidence that regular use of supplements may reduce the duration of the common cold, but it does not appear to prevent infection. It is unclear whether supp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barrel-aged Beer
A barrel-aged beer is a beer that has been aged for a period of time in a wooden barrel. Typically, these barrels once housed bourbon, whisky, wine, or, to a lesser extent, brandy, sherry, or port.Craft Beer and Brewing. ''Barrel-aging.'' Retrieved 21 April 2020. There is a particular tradition of barrel ageing beer in , notably of lambic beers.The High Council for Artisanal Lambic Beers. ''Lambiek.'' (in Dutch) Retriev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ullmann's Encyclopedia Of Industrial Chemistry
''Ullmann's Encyclopedia of Industrial Chemistry'' is a major reference work related to industrial chemistry by Chemist Fritz Ullmann, first published in 1914, and exclusively in German as "Enzyklopädie der Technischen Chemie" until 1984. History Ullmann's Encyclopedia of Industrial Chemistry is a major reference work related to industrial chemistry by chemist Fritz Ullmann. Its 1st edition was published in German by Fritz Ullmann in 1914. The 4th edition, published 1972 to 1984, already contained 25 volumes. The 5th edition, published 1985 to 1996, was the first version available in English. In 1997, the first online version was published. 2014 marked its centenary. As of 2016, Ullmann's Encyclopedia was in its 7th edition, in 40 volumes including one index volume and more than 1,050 articles (200 more than the 6th edition), approx. 30,000 pages, 22,000 images, 8,000 tables, 19,000 references and 85,000 indices. Editions * 1914–1922: 1st edition in 12 volumes, which can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galium Odoratum
''Galium odoratum'', the sweet woodruff or sweetscented bedstraw, is a flowering perennial plant in the family Rubiaceae, native to much of Europe from Spain and Ireland to Russia, as well as Western Siberia, Turkey, Iran, the Caucasus, China and Japan. It is also sparingly naturalized in scattered locations in the United States and Canada. It is widely cultivated for its flowers and its sweet-smelling foliage. A herbaceous plant, it grows to long, often lying flat on the ground or supported by other plants. It owes its sweet smell to the odoriferous agent coumarin, and is sometimes used as a flavouring agent due to its chemical content. Description The leaves are simple, lanceolate, glabrous, long, and borne in whorls of 6–9. The small (4–7 mm diameter) flowers are produced in cymes, each white with four petals joined together at the base. The fruits are 2–4 mm diameter, produced singly, and each is covered in tiny hooked bristles which help disperse them b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coumarin
Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered heterocycle that shares two carbons with the benzene ring. It can be placed in the benzopyrone chemical class and considered as a lactone. Coumarin is a colorless crystalline solid with a sweet odor resembling the scent of vanilla and a bitter taste. It is found in many plants, where it may serve as a chemical defense against predators. By inhibiting synthesis of vitamin K, a related compound is used as the prescription drug warfarin – an anticoagulant – to inhibit formation of blood clots, deep vein thrombosis, and pulmonary embolism. Etymology Coumarin is derived from ''coumarou'', the French word for the tonka bean. The word ''tonka'' for the tonka bean is taken from the Galibi (Carib) tongue spoken by natives of French G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lovage
Lovage (), ''Levisticum officinale'', is a tall perennial plant, the sole species in the genus ''Levisticum'' in the family Apiaceae, subfamily Apioideae. It has been long cultivated in Europe, the leaves being used as a herb, the roots as a vegetable, and the seeds as a spice, especially in southern European cuisine. Description Lovage is an erect, herbaceous, perennial plant growing to tall, with a basal rosette of leaves and stems with further leaves, the flowers being produced in umbels at the top of the stems. The stems and leaves are shiny glabrous green to yellow-green and smell somewhat similar to celery when crushed. The larger basal leaves are up to long, tripinnate, with broad triangular to rhomboidal, acutely pointed leaflets with a few marginal teeth; the stem leaves are smaller, and less divided with few leaflets. The flowers are yellow to greenish-yellow, diameter, produced in globose umbels up to diameter; flowering is in late spring. The fruit is a dry two-p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Celery
Celery (''Apium graveolens'') is a marshland plant in the family Apiaceae that has been cultivated as a vegetable since antiquity. Celery has a long fibrous stalk tapering into leaves. Depending on location and cultivar, either its stalks, leaves or hypocotyl are eaten and used in cooking. Celery seed powder is used as a spice. Description Celery leaves are pinnate to bipinnate with rhombic leaflets long and broad. The flowers are creamy-white, in diameter, and are produced in dense compound umbels. The seeds are broad ovoid to globose, long and wide. Modern cultivars have been selected for either solid petioles, leaf stalks, or a large hypocotyl. A celery stalk readily separates into "strings" which are bundles of angular collenchyma cells exterior to the vascular bundles. Wild celery, ''Apium graveolens'' var. ''graveolens'', grows to tall. Celery is a biennial plant that occurs around the globe. It produces flowers and seeds only during its second year. The first cul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phthalides
Phthalide is an organic chemical compound with the molecular formula C8H6O2. A white solid, it is the simplest benzo lactone. It is prepared from hydroxymethylbenzoic acid. Phthalides The phthalide core is found a variety of more complex chemical compounds including dyes (such as phenolphthalein Phenolphthalein ( ) is a chemical compound with the chemical formula, formula carbon, C20hydrogen, H14oxygen, O4 and is often written as "HIn", "HPh", "phph" or simply "Ph" in shorthand notation. Phenolphthalein is often used as an indicator in ...), fungicides (such as tetrachlorophthalide, often referred to simply as "phthalide"), and natural oils (such as butylphthalide). Examples File:phenolphthalein.svg, Phenolphthalein File:tetrachlorophthalide.svg, Tetrachlorophthalide FIle:Butylphthalide.svg, Butylphthalide References {{reflist Phthalides, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
