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Dithiolane
A dithiolane is a sulfur heterocyclic compound, heterocycle derived from cyclopentane by replacing two methylene bridges (-- units) with thioether groups. The parent compounds are 1,2-dithiolane and 1,3-dithiolane. 1,2-Dithiolanes are cyclic disulfides. Some dithiolanes are natural products that can be found in foods, such as asparagusic acid in asparagus. The 4-dimethylamino derivative nereistoxin was the inspiration for insecticides which act by blocking the nicotinic acetylcholine receptor. Lipoic acid is essential for aerobic metabolism in mammals and also has strong affinity with many metals including gold, molybdenum, and tungsten. Other 1,2-dithiolanes have relevance in nanomaterials such as gold nanoparticles or transition metal dichalcogenide monolayers (TMDs) (MoS2, MoS2 and Tungsten disulfide, WS2). Asparagusic-acid.png, asparagusic acid Nereistoxin.svg, nereistoxin, from which insecticides including cartap and bensultap were derived Lipoic acid.svg, lipoic acid 1,3-Di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asparagusic Acid
Asparagusic acid is an organosulfur compound with the molecular formula C4H6O2S2 and IUPAC nomenclature of organic chemistry, systematically named 1,2-dithiolane-4-carboxylic acid. The molecule consists of a heterocyclic disulfide functional group (a 1,2-dithiolane) with a carboxylic acid side chain. It is found in asparagus and is believed to be the metabolic precursor to odorous sulfur compounds responsible for the distinctive smell of urine which has long been associated with eating asparagus. Isolation and biosynthesis The material was originally isolated from an aqueous extract of ''Asparagus officinalis'', a spring vegetable. It is a derivative (chemistry), derivative of the cyclic disulfide organic compound 1,2-dithiolane with a carboxylic acid functional group bound to carbon-4 of the heterocycle. Biosynthesis, Biosynthetic studies revealed that asparagusic acid is derived from isobutyric acid. Asparagusic acid is a colorless solid with a melting point of 75.7–76.5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethane-1,2-dithiol
Ethane-1,2-dithiol, also known as EDT, is a colorless liquid with the Chemical formula, formula Carbon, CHydrogen, H(Thiol, SH). It has a very characteristic odor which is compared by many people to rotten cabbage. It is a common building block in organic synthesis and an excellent ligand for metal ions. Preparation Ethane-1,2-dithiol is made commercially by the reaction of 1,2-dichloroethane with aqueous sodium bisulfide. In the laboratory, it can also be prepared by the action of 1,2-dibromoethane on thiourea followed by hydrolysis. Applications As a 1,2-dithiol, this compound is widely used in organic chemistry because it reacts with aldehydes and ketones to give 1,3-dithiolanes, which are useful intermediates. R. E. Conrow "Ethanedithiol" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. ::CH(SH) + RR'CO → CHSCRR' + HO Other 1,2- and 1,3-dithiols undergo this reaction to give related 1,3-dithiolanes and 1,3-dithianes ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1,2-ethanedithiol
Ethane-1,2-dithiol, also known as EDT, is a colorless liquid with the formula C H( SH). It has a very characteristic odor which is compared by many people to rotten cabbage. It is a common building block in organic synthesis and an excellent ligand for metal ions. Preparation Ethane-1,2-dithiol is made commercially by the reaction of 1,2-dichloroethane with aqueous sodium bisulfide. In the laboratory, it can also be prepared by the action of 1,2-dibromoethane on thiourea followed by hydrolysis. Applications As a 1,2-dithiol, this compound is widely used in organic chemistry because it reacts with aldehydes and ketones to give 1,3-dithiolanes, which are useful intermediates. R. E. Conrow "Ethanedithiol" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. ::CH(SH) + RR'CO → CHSCRR' + HO Other 1,2- and 1,3-dithiols undergo this reaction to give related 1,3-dithiolanes and 1,3-dithianes (six-membered rings). Diols such as ethy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipoic Acid
Lipoic acid (LA), also known as α-lipoic acid, alpha-lipoic acid (ALA) and thioctic acid, is an organosulfur compound derived from caprylic acid (octanoic acid). ALA is made in animals normally, and is essential for aerobic metabolism. It is also manufactured and is available as a dietary supplement in some countries where it is marketed as an antioxidant, and is available as a pharmaceutical drug in other countries. Lipoate is the conjugate base of lipoic acid, and the most prevalent form of LA under physiological conditions. Only the (''R'')-(+)-enantiomer (RLA) exists in nature and is essential for aerobic metabolism because RLA is an essential cofactor of many enzyme complexes. Physical and chemical properties Lipoic acid (LA), also known as α-lipoic acid, alpha-lipoic acid (ALA), and thioctic acid is an organosulfur compound derived from octanoic acid. LA contains two sulfur atoms (at C6 and C8) connected by a disulfide bond and is thus considered to be oxidized althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nereistoxin
Nereistoxin is a natural product identified in 1962 as the toxic organic compound ''N'',''N''-dimethyl-1,2-dithiolan-4-amine. It had first been isolated in 1934 from the marine annelid ''Lumbriconereis heteropoda'' and acts by blocking the nicotinic acetylcholine receptor. Researchers at Takeda in Japan investigated it as a possible insecticide. They subsequently developed a number of derivatives that were commercialised, including those with the ISO common names bensultap, cartap, thiocyclam and thiosultap. Structures and synthesis Bensultap.svg, bensultap Thiocyclam neutral.svg, thiocyclam Thiosultap.svg, thiosultap Bensultap (R=SO2Ph) was made by the reaction of the sodium salt of benzenethiolsulfonate (PhSO2SNa) with ''N'',''N''-dimethyl 1,3-dichloro-2-propylamine or ''N'',''N''-dimethyl 2,3-dichloropropylamine in ethanol. : Bensultap can be converted to nereistoxin by treatment with alkali. History Japanese fishermen used the annelid worm ''Lumbriconereis heteropoda'' Maren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g. nickel carbonyl). The remainder of this article concerns itself with the organic chemistry definition of carbonyl, where carbon and oxygen share a double bond. Carbonyl compounds In organic chemistry, a carbonyl group characterizes the following types of compounds: Other organic carbonyls are urea and the carbamates, the derivatives of acyl chlorides chloroformates and phosgene, carbonate esters, thioesters, lactones, lactams, hydroxamates, and isocyanates. Examples of inorganic carbonyl compounds are carbon dioxide and carbonyl sulfide. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protecting Group
A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic synthesis. In many preparations of delicate organic compounds, some specific parts of their molecules cannot survive the required reagents or chemical environments. Then, these parts, or groups, must be protected. For example, lithium aluminium hydride is a highly reactive but useful reagent capable of reducing esters to alcohols. It will always react with carbonyl groups, and this cannot be discouraged by any means. When a reduction of an ester is required in the presence of a carbonyl, the attack of the hydride on the carbonyl has to be prevented. For example, the carbonyl is converted into an acetal, which does not react with hydrides. The acetal is then called a protecting group for the carbonyl. After the step involving the hydride is complete, the acet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tungsten Disulfide
Tungsten disulfide is an inorganic chemical compound composed of tungsten and sulfur with the chemical formula WS2. This compound is part of the group of materials called the transition metal dichalcogenides. It occurs naturally as the rare mineral tungstenite. This material is a component of certain catalysts used for hydrodesulfurization and hydrodenitrification. WS2 adopts a layered structure similar, or isotypic with MoS2, instead with W atoms situated in trigonal prismatic coordination sphere (in place of Mo atoms). Owing to this layered structure, WS2 forms non-carbon nanotubes, which were discovered after heating a thin sample of WS2 in 1992. Structure and physical properties Bulk WS2 forms dark gray hexagonal crystals with a layered structure. Like the closely related MoS2, it exhibits properties of a dry lubricant. Although it has long been thought that WS2 is relatively stable in ambient air, recent reports on the ambient air oxidation of monolayer WS2 have found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MoS2
Molybdenum disulfide (or moly) is an inorganic compound composed of molybdenum and sulfur. Its chemical formula is . The compound is classified as a transition metal dichalcogenide. It is a silvery black solid that occurs as the mineral molybdenite, the principal ore for molybdenum.Sebenik, Roger F. ''et al''. (2005) "Molybdenum and Molybdenum Compounds", ''Ullmann's Encyclopedia of Chemical Technology''. Wiley-VCH, Weinheim. is relatively unreactive. It is unaffected by dilute acids and oxygen. In appearance and feel, molybdenum disulfide is similar to graphite. It is widely used as a dry lubricant because of its low friction and robustness. Bulk is a diamagnetic, indirect bandgap semiconductor similar to silicon, with a bandgap of 1.23 eV. Single layer sheets act as a perfect mirror, reflecting 100% of incident photons. Production MoS2 is naturally found as either molybdenite, a crystalline mineral, or jordisite, a rare low temperature form of molybdenite. Molybdenite ore is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Metal Dichalcogenide Monolayers
Transition-metal dichalcogenide (TMD or TMDC) monolayers are atomically thin semiconductors of the type MX2, with M a transition-metal atom ( Mo, W, etc.) and X a chalcogen atom ( S, Se, or Te). One layer of M atoms is sandwiched between two layers of X atoms. They are part of the large family of so-called 2D materials, named so to emphasize their extraordinary thinness. For example, a MoS2 monolayer is only 6.5 Å thick. The key feature of these materials is the interaction of large atoms in the 2D structure as compared with first-row transition-metal dichalcogenides, e.g., WTe2 exhibits anomalous giant magnetoresistance and superconductivity. The discovery of graphene shows how new physical properties emerge when a bulk crystal of macroscopic dimensions is thinned down to one atomic layer. Like graphite, TMD bulk crystals are formed of monolayers bound to each other by van-der-Waals attraction. TMD monolayers have properties that are distinctly different from those ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobic Metabolism
Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy. Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. The overall reaction occurs in a series of biochemical steps, some of which are redox reactions. Although cellular respiration is technically a combustion reaction, it is an unusual one because of the slow, controlled release of energy from the series of reactions. Nutrients that are commonly used by animal and plant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insecticides
Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to be a major factor behind the increase in the 20th-century's agricultural productivity. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans and/or animals; some become concentrated as they spread along the food chain. Insecticides can be classified into two major groups: systemic insecticides, which have residual or long term activity; and contact insecticides, which have no residual activity. The mode of action describes how the pesticide kills or inactivates a pest. It provides another way of classifying insecticides. Mode of action can be important in understanding whether an insecticide will be toxic to unrelated species, such as fish, birds and mammals. Insecticides may be repellent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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