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Thiazoles
Thiazole, or 1,3-thiazole, is a heterocyclic compound that contains both sulfur and nitrogen. The term 'thiazole' also refers to a large family of derivatives. Thiazole itself is a pale yellow liquid with a pyridine-like odor and the molecular formula C3H3NS. The thiazole ring is notable as a component of the vitamin thiamine (B1). Molecular and electronic structure Thiazoles are members of the azoles, heterocycles that include imidazoles and oxazoles. Thiazole can also be considered a functional group. Oxazoles are related compounds, with sulfur replaced by oxygen. Thiazoles are structurally similar to imidazoles, with the thiazole sulfur replaced by nitrogen. Thiazole rings are planar and aromatic. Thiazoles are characterized by larger pi-electron delocalization than the corresponding oxazoles and have therefore greater aromaticity. This aromaticity is evidenced by the chemical shift of the ring protons in proton NMR spectroscopy (between 7.27 and 8.77 ppm), clearly indicatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzothiazole
Benzothiazole is an aromatic heterocyclic compound with the chemical formula . It is colorless, slightly viscous liquid. Although the parent compound, benzothiazole is not widely used, many of its derivatives are found in commercial products or in nature. Firefly luciferin can be considered a derivative of benzothiazole. Structure and preparation Benzothiazoles consist of a 5-membered 1,3-thiazole ring fused to a benzene ring. The nine atoms of the bicycle and the attached substituents are coplanar. Benzothiazoles are prepared by treatment of 2-mercaptoaniline with acid chlorides: :C6H4(NH2)SH + RC(O)Cl → C6H4(NH)SCR + HCl + H2O Uses Benzothiazole occurs naturally in some foods but is also used as a food additive. It has a sulfurous odor and meaty flavor. The European Food Safety Authority assessment had "no safety concern at estimated levels of intake as a flavouring substance". The heterocyclic core of the molecule is readily substituted at the unique methyne ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxazole
Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon. Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak base; its conjugate acid has a p''K''a of 0.8, compared to 7 for imidazole. Preparation Classical oxazole synthetic methods in organic chemistry are * the Robinson–Gabriel synthesis by dehydration of 2-acylaminoketones * the Fischer oxazole synthesis from cyanohydrins and aldehydes * the Bredereck reaction with α-haloketones and formamide * the Van Leusen reaction with aldehydes and TosMIC Other methods: * Oxazolines can also be obtained from cycloisomerization of certain propargyl amides. In one study oxazoles were prepared via a one-pot synthesis consisting of the condensation of propargyl amine and benzoyl chloride to the amide, followed by a Sonogashira coupling of the terminal alkyne end with another equivalent of benzoylchlor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haloketone
In organic chemistry, an α-haloketone is a functional group consisting of a ketone group or more generally a carbonyl group with an α-halogen substituent. α-haloketones are alkylating agents. Prominent α-haloketones include phenacyl bromide and chloroacetone. Structure The general structure is RR′C(X)C(=O)R where R is an alkyl or aryl residue and X any one of the halogens. The preferred conformation of a haloketone is that of a cisoid with the halogen and carbonyl sharing the same plane as the steric hindrance with the carbonyl alkyl group is generally larger. Haloketone synthesis Haloketones and halo carbonyl compounds in general are synthesized by reaction of carbonyl compounds with sources of X+ (X = halogen), which is provided using halogens: :RC(O)CH3 + X2 → RC(O)CH2X + HX Specialized sources of electrophilic halogenating agents include ''N''-Bromosuccinimide and 1,3-dibromo-5,5-dimethylhydantoin (DBDMH). In the Nierenstein reaction an acyl chloride re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxazole
Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon. Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak base; its conjugate acid has a p''K''a of 0.8, compared to 7 for imidazole. Preparation Classical oxazole synthetic methods in organic chemistry are * the Robinson–Gabriel synthesis by dehydration of 2-acylaminoketones * the Fischer oxazole synthesis from cyanohydrins and aldehydes * the Bredereck reaction with α-haloketones and formamide * the Van Leusen reaction with aldehydes and TosMIC Other methods: * Oxazolines can also be obtained from cycloisomerization of certain propargyl amides. In one study oxazoles were prepared via a one-pot synthesis consisting of the condensation of propargyl amine and benzoyl chloride to the amide, followed by a Sonogashira coupling of the terminal alkyne end with another equivalent of benzoylchlor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterocyclic Compound
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of these heterocycles. Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass (cellulose and related materials), and many natural and synthetic dyes. More than half of known compounds are heterocycles. 59% of US FDA-approved drugs contain nitrogen heterocycles. Classification The study of heterocyclic chemistry focuses especially on unsaturated derivatives, and the preponderance of work and applications involves unstrained 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and furan are quinol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Functional Group
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables systematic prediction of chemical reactions and behavior of chemical compounds and the design of chemical synthesis. The reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis. A functional group is a group of atoms in a molecule with distinctive chemical properties, regardless of the other atoms in the molecule. The atoms in a functional group are linked to each other and to the rest of the molecule by covalent bonds. For repeating units of polymers, functional groups attach to their nonpolar core of carbon atoms and thus add chemical character to carbon chains. Fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fungicide
Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, and profit. Fungicides are used both in agriculture and to fight fungal infections in animals. Chemicals used to control oomycetes, which are not fungi, are also referred to as fungicides, as oomycetes use the same mechanisms as fungi to infect plants. Fungicides can either be contact, translaminar or systemic. Contact fungicides are not taken up into the plant tissue and protect only the plant where the spray is deposited. Translaminar fungicides redistribute the fungicide from the upper, sprayed leaf surface to the lower, unsprayed surface. Systemic fungicides are taken up and redistributed through the xylem vessels. Few fungicides move to all parts of a plant. Some are locally systemic, and some move upwardly. Most fungicides that can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroacetone
Chloroacetone is a chemical compound with the formula . At STP it is a colourless liquid with a pungent odour. On exposure to light, it turns to a dark yellow-amber colour. It was used as a tear gas in World War I. Synthesis Chloroacetone may be synthesized from the reaction between chlorine and diketene, or by the chlorination of acetone. Applications Chloroacetone is used to make dye couplers for colour photography, and is an intermediate in chemical manufacturing. It is also used in the Feist-Benary synthesis of furans. *Reaction of phenoxide with chloroacetone gives phenoxyacetone, which is used to make a wide variety of different pharmaceuticals. A catalytic amount of potassium iodide is also necessary to facilitate a Finkelstein reaction. Purification Chloroacetone purchased from commercial suppliers contains 5% impurities including mesityl oxide, which is not removed by distillation. Mesityl oxide can be oxidized using acidified KMnO4 to form a diol (followed by s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thioacetamide
Thioacetamide is an organosulfur compound with the chemical formula, formula carbon, C2hydrogen, H5nitrogen, Nsulfur, S. This white crystalline solid is soluble in water and serves as a source of sulfide ions in the synthesis of organic and inorganic compounds. It is a prototypical thioamide. Research Thioacetamide is known to induce acute or chronic liver disease (fibrosis and cirrhosis) in the experimental animal model. Its administration in rat induces hepatic encephalopathy, metabolic acidosis, increased levels of transaminases, abnormal coagulopathy, and centrilobular necrosis, which are the main features of the clinical chronic liver disease so thioacetamide can precisely replicate the initiation and progression of human liver disease in an experimental animal model. Coordination chemistry Thioacetamide is widely used in classical qualitative inorganic analysis as an in situ source for sulfide ions. Thus, treatment of aqueous solutions of many metal cations to a solution ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thioamide
A thioamide (rarely, thionamide, but also known as thiourylenes) is a functional group with the general structure R–CS–NR′R″, where R, R′, and R″ are organic groups. They are analogous to amides but they exhibit greater multiple bond character along the C-N bond, resulting in a larger rotational barrier. One of the best-known thioamides is thioacetamide, which is used as a source of the sulfide ion and is a building block in heterocyclic chemistry. Thioamides or anti-thyroid drugs are also a class of drugs that are used to control thyrotoxicosis. Preparation and structure Thioamides are typically prepared by treating amides with phosphorus sulfides such as phosphorus pentasulfide, a reaction first described in the 1870s. Alternative routes include the use of Lawesson's reagent or the reaction of nitriles with hydrogen sulfide: The Willgerodt-Kindler reaction also affords benzylthioamides. The C2NH2S core of thioamides is planar. Using thioacetamide as represent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
