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Persulfide
In chemistry, persulfide refers to the functional group R-S-S-H. Persulfides are intermediates in the biosynthesis of iron-sulfur proteins and are invoked as precursors to hydrogen sulfide, a signaling molecule. Nomenclature The nomenclature used for organosulfur compounds is often non-systematic. Sometimes persulfides are called hydrodisulfides to further avoid confusion with disulfides with the grouping R-S-S-R, by emphasizing the presence of an H at one end of a disulfide bond. Properties Compared to thiols (R-S-H), persulfides are uncommon. They are thermodynamically unstable with respect to loss of elemental sulfur: :RSSH → RSH + 1/8 S8 Nonetheless, persulfides are often kinetically stable. The S-H bond is both more acidic and more fragile than in thiols. This can be seen in the bond dissociation energy of a typical persulfide, which is 22 kcal/mol weaker than a typical thiol, and the lower pKa of about 6.2 for persulfides compared to 7.5 for thiols. Thus, persulfides e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a Chemical reaction, reaction with other Chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylphosphine Sulfide
Triphenylphosphine sulfide (IUPAC name: triphenyl-''λ''5-phosphanethione) is the organophosphorus compound with the formula , usually written (where Ph = phenyl). It is a colourless solid, which is soluble in a variety of organic solvents. Structurally, the molecule resembles the corresponding oxide, with idealized C3 symmetry group, point group symmetry. It is weakly nucleophilic at the sulfur atom. Applications Organic synthesis Triphenylphosphine sulfide is useful for the conversion of epoxides to the corresponding episulfides: : Analytical chemistry In analytical chemistry, triphenylphosphine is used for the analysis of certain kinds of sulfur compounds. Elemental sulfur (), as occurs in some oils, and labile organosulfur compounds, such as organic trisulfides, react with triphenylphosphine to give , which can be detected by gas chromatography. References {{reflist Organophosphine sulfides Phenyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-Mercaptopyruvic Acid
3-Mercaptopyruvic acid is an intermediate in cysteine metabolism. It has been studied as a potential treatment for cyanide poisoning, but its half-life is too short for it to be clinically effective. Instead, prodrugs, such as sulfanegen, are being evaluated to compensate for the short half-life of 3-mercaptopyruvic acid. See also * 3-mercaptopyruvate sulfurtransferase In enzymology, a 3-mercaptopyruvate sulfurtransferase () is an enzyme that catalyzes the chemical reactions of 3-mercaptopyruvate. This enzyme belongs to the family of transferases, specifically the sulfurtransferases. This enzyme participate ... References Carboxylic acids Thiols Alpha-keto acids {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Disulfide
Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non-polar solvent. It has an "ether-like" odor, but commercial samples are typically contaminated with foul-smelling impurities.. It is of comparable toxicity to carbon monoxide. History In 1796, the German chemist Wilhelm August Lampadius (1772–1842) first prepared carbon disulfide by heating pyrite with moist charcoal. He called it "liquid sulfur" (''flüssig Schwefel''). The composition of carbon disulfide was finally determined in 1813 by the team of the Swedish chemist Jöns Jacob Berzelius (1779–1848) and the Swiss-British chemist Alexander Marcet (1770–1822). Their analysis was consistent with an empirical formula of CS2. Occurrence, manufacture, properties Small amounts of carbon disulfide are released by volcanic eruptio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cystine
Cystine is the oxidized derivative of the amino acid cysteine and has the formula (SCH2CH(NH2)CO2H)2. It is a white solid that is poorly soluble in water. As a residue in proteins, cystine serves two functions: a site of redox reactions and a mechanical linkage that allows proteins to retain their three-dimensional structure. Formation and reactions Structure Cystine is the disulfide derived from the amino acid cysteine. The conversion can be viewed as an oxidation: : Cystine contains a disulfide bond, two amine groups, and two carboxylic acid groups. As for other amino acids, the amine and carboxylic acid groups exist is rapid equilibrium with the ammonium-carboxylate tautomer. The great majority of the literature concerns the ''l,l-''cystine, derived from ''l''-cysteine. Other isomers include ''d,d''-cystine and the meso isomer d,l-cystine, neither of which is biologically significant. Occurrence Cystine is common in many foods such as eggs, meat, dairy products, and whole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cystathionase
The enzyme cystathionine γ-lyase (EC 4.4.1.1, CTH or CSE; also cystathionase; systematic name L-cystathionine cysteine-lyase (deaminating; 2-oxobutanoate-forming)) breaks down cystathionine into cysteine, 2-oxobutanoate ( α-ketobutyrate), and ammonia: :L-cystathionine + H2O = L-cysteine + 2-oxobutanoate + NH3 (overall reaction) ::(1a) L-cystathionine = L-cysteine + 2-aminobut-2-enoate ::(1b) 2-aminobut-2-enoate = 2-iminobutanoate (spontaneous) ::(1c) 2-iminobutanoate + H2O = 2-oxobutanoate + NH3 (spontaneous) Pyridoxal phosphate is a prosthetic group of this enzyme. Cystathionine γ-lyase also catalyses the following elimination reactions: * L- homoserine to form H2O, NH3 and 2-oxobutanoate * L- cystine, producing thiocysteine, pyruvate and NH3 * L-cysteine producing pyruvate, NH3 and H2S In some bacteria and mammals, including humans, this enzyme takes part in generating hydrogen sulfide. Hydrogen sulfide is one of a few gases that was recently discovered to have a r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiamine
Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thiamine are required for some metabolic reactions, including the breakdown of glucose and amino acids. Food sources of thiamine include whole grains, legumes, and some meats and fish. Grain processing removes much of the vitamin content, so in many countries cereals and flours are enriched with thiamine. Supplements and medications are available to treat and prevent thiamine deficiency and disorders that result from it include beriberi and Wernicke encephalopathy. They are also used to treat maple syrup urine disease and Leigh syndrome. Supplements and medications are typically taken by mouth, but may also be given by intravenous or intramuscular injection. Thiamine supplements are generally well tolerated. Allergic reactions, including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-Thiouridine
4-Thiouridine is an atypical nucleotide formed with the 4-thiouracil base found in transfer RNA Transfer RNA (abbreviated tRNA and formerly referred to as sRNA, for soluble RNA) is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes), that serves as the physical link between the mRNA and the amino ac ... (tRNA). Its biosynthesis has been determined. References Nucleosides Pyrimidines Hydroxymethyl compounds {{heterocyclic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylmethanethiol
Triphenylmethanethiol is an organosulfur compound with the formula (C6H5)3CSH. It is the thiol derivative of the bulky substituent triphenylmethyl (called trityl). The compound forms a number of unusual derivatives that are more stable than less bulky analogues. The sulfenyl chloride In organosulfur chemistry, a sulfenyl chloride is a functional group with the connectivity , where R is alkyl or aryl. Sulfenyl chlorides are reactive compounds that behave as sources of . They are used in the formation of and bonds. According ... (C6H5)3CSCl is obtained from the thiol with sulfuryl chloride. It in turn reacts with ammonia to form the sulfenamide (C6H5)3CSNH2. The thiol reacts with nitrous acid to give ''S''-nitrosotriphenylmethanethiol (C6H5)3CSNO.{{cite journal, last1=Arulsamy, first1=N., last2=Bohle, first2=D. S., last3=Butt, first3=J. A., last4=Irvine, first4=G. J., last5=Jordan, first5=P. A., last6=Sagan, first6=E., date=1999, title=Interrelationships between conform ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether. Preparation and structure Triphenylphosphine can be prepared in the laboratory by treatment of phosphorus trichloride with phenylmagnesium bromide or phenyllithium. The industrial synthesis involves the reaction between phosphorus trichloride, chlorobenzene, and sodium: :PCl3 + 3 PhCl + 6 Na → PPh3 + 6 NaCl Triphenylphosphine crystallizes in triclinic and monoclinic modification. In both cases, the molecule adopts a pyramidal structure with propeller-like arrangement of the three phenyl groups. Principal reactions with chalcogens, halogens, and acids Oxidation Triphenylphosphine undergoes slow ... [...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] |
X-ray Crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
