|
Diacetyl Tartaric Anhydride
Diacetyl ( ; IUPAC systematic name: butanedione or butane-2,3-dione) is an organic compound with the chemical formula (CH3CO)2. It is a yellow liquid with an intensely buttery flavor. It is a vicinal diketone (two C=O groups, side-by-side). Diacetyl occurs naturally in alcoholic beverages and some cheeses and is added as a flavoring to some foods to impart its buttery flavor. Chronic inhalation exposure to diacetyl fumes is a causative agent of the lung disease bronchiolitis obliterans, commonly known as "popcorn lung". Chemical structure A distinctive feature of diacetyl (and other vicinal diketones) is the long C–C bond linking the carbonyl centers. This bond distance is about 1.54 Å, compared to 1.45 Å for the corresponding C–C bond in 1,3-butadiene. The elongation is attributed to repulsion between the polarized carbonyl carbon centers. Occurrence and biosynthesis Diacetyl arises naturally as a byproduct of fermentation. In some fermentative bacteria, it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IUPAC
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is a member of the International Science Council (ISC). IUPAC is registered in Zürich, Switzerland, and the administrative office, known as the "IUPAC Secretariat", is in Research Triangle Park, North Carolina, United States. IUPAC's executive director heads this administrative office, currently Greta Heydenrych. IUPAC was established in 1919 as the successor of the International Congress of Applied Chemistry for the advancement of chemistry. Its members, the National Adhering Organizations, can be national List of chemistry societies, chemistry societies, national Academy of Sciences, academies of sciences, or other bodies representing chemists. There are fifty-four National Adhering Organizations and three Associate National Adhering Organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetoin
Acetoin, also known as 3-hydroxybutanone or acetyl methyl carbinol, is an organic compound with the formula CH3CH(OH)C(O)CH3. It is a colorless liquid with a pleasant, buttery odor. It is chiral. The form produced by bacteria is (''R'')-acetoin.Albert Gossauer: ''Struktur und Reaktivität der Biomoleküle'', Verlag Helvetica Chimica Acta, Zürich, 2006, Seite 285, . Production in bacteria Acetoin is a neutral, four-carbon molecule used as an external energy store by a number of fermentative bacteria. It is produced by the decarboxylation of alpha- acetolactate, a common precursor in the biosynthesis of branched-chain amino acids. Owing to its neutral nature, production and excretion of acetoin during exponential growth prevents over-acidification of the cytoplasm and the surrounding medium that would result from accumulation of acidic metabolic products, such as acetic acid and citric acid. Once superior carbon sources are exhausted, and the culture enters stationary phase, ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chardonnay
Chardonnay (, ; ) is a green-skinned grape variety used in the production of white wine. The variety originated in the Burgundy wine region of eastern France, but is now grown wherever wine is produced, from England to New Zealand. For new and developing wine regions, growing Chardonnay is seen as a 'rite of passage' and an easy entry into the international wine market. The Chardonnay grape itself is neutral, with many of the flavors commonly associated with the wine being derived from such influences as ''terroir'' and oak.Robinson, 2006, pp. 154–56. It is vinified in many different styles, from the lean, crisply mineral wines of Chablis, France, to New World wines with oak and tropical fruit flavors. In cool climates (such as Chablis and the Carneros AVA of California), Chardonnay wine tends to be medium to light body with noticeable acidity and flavors of green plum, apple, and pear. In warmer locations (such as the Adelaide Hills and Mornington Peninsula in Austral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketone
In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone (where R and R' are methyl), with the formula . Many ketones are of great importance in biology and industry. Examples include many sugars (ketoses), many steroids, ''e.g.'', testosterone, and the solvent acetone. Nomenclature and etymology The word ''ketone'' is derived from ''Aketon'', an old German word for ''acetone''. According to the rules of IUPAC nomenclature, ketone names are derived by changing the suffix ''-ane'' of the parent alkane to ''-anone''. Typically, the position of the carbonyl group is denoted by a number, but traditional nonsystematic names are still generally used for the most important ketones, for example acetone and benzophenone. These nonsystematic names are considered retained IUPAC names, although some introdu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decarboxylation
Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is the first chemical step in photosynthesis, is called carboxylation, the addition of CO2 to a compound. Enzymes that catalyze decarboxylations are called decarboxylases or, the more formal term, carboxy-lyases (Enzyme Commission number, EC number 4.1.1). In organic chemistry The term "decarboxylation" usually means replacement of a carboxyl group () with a hydrogen atom: : Decarboxylation is one of the oldest known organic reactions. It is one of the processes assumed to accompany pyrolysis and destructive distillation. Overall, decarboxylation depends upon stability of the carbanion synthon , although the anion may not be a true chemical intermediate. Typically, carboxylic acids decarboxylate slowly, but carboxylic acids with an α el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetolactate
α-Acetolactic acid is a precursor in the biosynthesis of the branched chain amino acids valine and leucine. α-Acetolactic acid is produced from two molecules of pyruvic acid by acetolactate synthase. α-Acetolactic acid can also be decarboxylated by alpha- acetolactate decarboxylase to produce acetoin. The name α-acetolactate is used for anion (conjugate base), salts, and ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...s of α-acetolactic acid. References {{Reflist Alpha hydroxy acids Beta-keto acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valine
Valine (symbol Val or V) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH3+ form under biological conditions), an α- carboxylic acid group (which is in the deprotonated −COO− form under biological conditions), and a side chain isopropyl group, making it a non-polar aliphatic amino acid. Valine is essential in humans, meaning the body cannot synthesize it; it must be obtained from dietary sources which are foods that contain proteins, such as meats, dairy products, soy products, beans and legumes. It is encoded by all codons starting with GU (GUU, GUC, GUA, and GUG). History and etymology Valine was first isolated from casein in 1901 by Hermann Emil Fischer. The name valine comes from its structural similarity to valeric acid, which in turn is named after the plant valerian due to the presence of the acid in the roots of the plant. Nomenclature According to IUPAC, carbon atoms forming v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beer In The Czech Republic
Beer () has a long history in what is now the Czech Republic, with brewing taking place in Břevnov Monastery in 993. The city of Brno had the right to brew beer from the 12th century, while Plzeň and České Budějovice (Pilsen and Budweis in German), had breweries in the 13th century. The most common Czech beers are pale lagers of the pilsner type, with a characteristic transparent golden colour, high foaminess, and lighter flavour. The Czech Republic has the highest beer consumption per capita in the world. The largest Czech beer breweries are Pilsner Urquell ( Plzeňský prazdroj, Gambrinus, Radegast, Master); Staropramen (Staropramen, Ostravar, Braník, Velvet); and Budweiser Budvar. Other top-selling brands include Krušovice, Starobrno, Březňák, Zlatopramen, Lobkowicz, Bernard, and Svijany. History During the Middle Ages, the Church began to brew beer on Czech territory. Among the oldest monastery breweries in Bohemia were Libušinka in Prague, at th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Cigarette
An electronic cigarette (e-cigarette), or vape, is a device that simulates smoking. It consists of an atomizer, a power source such as a battery, and a container such as a cartridge or tank. Instead of smoke, the user inhales vapor. As such, using an e-cigarette is often called "vaping". The atomizer is a heating element that vaporizes a liquid solution called e-liquid that cools into an aerosol of tiny droplets, vapor and air. The vapor mainly comprises propylene glycol and/or glycerin, usually with nicotine and flavoring. Its exact composition varies, and depends on matters such as user behavior. E-cigarettes are activated by taking a puff or pressing a button. Some look like traditional cigarettes, and most kinds are reusable. Nicotine is highly addictive. Users become physically and psychologically dependent. Limited evidence indicates that e-cigarettes are less addictive than smoking, with slower nicotine absorption rates. , quote="There is moderate evidence that r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Construction Of Electronic Cigarettes
An electronic cigarette is a handheld battery-powered vaporizer that simulates smoking, but without tobacco combustion. E-cigarette components include a mouthpiece (drip tip), a cartridge (liquid storage area), a heating element/ atomizer, a microprocessor, a battery, and some of them have an LED light on the end. An atomizer consists of a small heating element, or coil, that vaporizes e-liquid and a wicking material that draws liquid onto the coil. When the user inhales, a flow sensor activates the heating element that atomizes the liquid solution; most devices are manually activated by a push-button. The e-liquid reaches a temperature of roughly within a chamber to create an aerosolized vapor. The user inhales an aerosol, which is commonly but inaccurately called vapor, rather than cigarette smoke. Vaping is different from smoking, but there are some similarities, including the hand-to-mouth action of smoking and an aerosol that looks like cigarette smoke. The aerosol p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margarine
Margarine (, also , ) is a Spread (food), spread used for flavoring, baking, and cooking. It is most often used as a substitute for butter. Although originally made from animal fats, most margarine consumed today is made from vegetable oil. The spread was originally named ''oleomargarine'' from Latin for ''oleum'' (olive oil) and Greek language, Greek ''margarite'' ("pearl", indicating luster). The name was later shortened to ''margarine'', or sometimes ''oleo'' (particularly in the Deep South). Margarine consists of a water-in-fat emulsion, with tiny droplets of water dispersed uniformly throughout a fat phase (chemistry), phase in a stable solid form. While butter is made by concentrating the butterfat of milk through centrifugation, modern margarine is made through a more intensive processing of refined vegetable oil and water. Per US federal regulation, products must have a minimum fat content of 80% (with a maximum of 16% water) to be labeled as such in the United States, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
