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Pyridine N-oxide
Pyridine-''N''-oxide is the heterocyclic compound with the formula C5H5NO. This colourless, hygroscopic solid is the product of the oxidation of pyridine. It was originally prepared using peroxyacids as the oxidising agent. The compound is used infrequently as an oxidizing reagent in organic synthesis. Structure The structure of pyridine-N-oxide is very similar to that of pyridine with respect to the parameters for the ring. The molecule is planar. The N-O distance is 1.34Å. The C-N-C angle is 124°, 7° wider than in pyridine. Synthesis The oxidation of pyridine can be achieved with a number of peracids including peracetic acid and perbenzoic acid. Oxidation can also be effected by a modified Dakin reaction using a urea-hydrogen peroxide complex, and sodium perborate or, using methylrhenium trioxide () as catalyst, with sodium percarbonate. Reactions Pyridine ''N''-oxide is five orders of magnitude less basic than pyridine, but it is isolable as a hydrochloride salt ... [...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] |
Sodium Percarbonate
Sodium percarbonate is a chemical substance with formula . It is an adduct of sodium carbonate ("soda ash" or "washing soda") and hydrogen peroxide (that is, a perhydrate) whose formula is more properly written as 2 · 3 . It is a colorless, crystalline, hygroscopic and water-soluble solid. It is sometimes abbreviated as SPC. It contains 32.5% by weight of hydrogen peroxide. The product is used in some eco-friendly bleaches and other cleaning products itation needed History Sodium percarbonate was first prepared in 1899 by Russian chemist Sebastian Moiseevich Tanatar (7 October 1849 – 30 November 1917). Structure At room temperature, solid sodium percarbonate has the orthorhombic crystal structure, with the ''Cmca'' crystallographic space group. The structure changes to ''Pbca'' as the crystals are cooled below about −30 °C. Chemistry Dissolved in water, sodium percarbonate yields a mixture of hydrogen peroxide (which eventually decomposes t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omeprazole
Omeprazole, sold under the brand names Prilosec and Losec, among others, is a medication used in the treatment of gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger–Ellison syndrome. It is also used to prevent upper gastrointestinal bleeding in people who are at high risk. Omeprazole is a proton-pump inhibitor (PPI) and its effectiveness is similar to other PPIs. It can be taken by mouth or by injection into a vein. It is also available in the fixed-dose combination medication omeprazole/sodium bicarbonate as Zegerid. Common side effects include nausea, vomiting, headaches, abdominal pain, and increased intestinal gas. Serious side effects may include ''Clostridium difficile'' colitis, an increased risk of pneumonia, an increased risk of bone fractures, and the potential of masking stomach cancer. It is unclear if it is safe for use in pregnancy. It works by blocking the release of stomach acid. Omeprazole was patented in 1978, and approved for me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pranoprofen
Pranoprofen (INN) is a nonsteroidal anti-inflammatory drug (NSAID) used in ophthalmology Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medic .... References Nonsteroidal anti-inflammatory drugs {{Musculoskeletal-drug-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niflumic Acid
Niflumic acid is a drug used for joint and muscular pain. It is categorized as an inhibitor of cyclooxygenase-2. In experimental biology, it has been employed to inhibit chloride channels. It has also been reported to act on GABA-A and NMDA channel ''N''-methyl--aspartic acid or ''N''-methyl--aspartate (NMDA) is an amino acid derivative that acts as a specific agonist at the NMDA receptor mimicking the action of glutamate, the neurotransmitter which normally acts at that receptor. Unl ...s and to block T-type calcium channels. References Aminopyridines Anilines Trifluoromethyl compounds Calcium channel blockers GABAA receptor positive allosteric modulators NMDA receptor antagonists Aromatic acids Chloride channel blockers {{musculoskeletal-drug-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicotinic Acid
Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variety of whole and processed foods, with highest contents in fortified packaged foods, meat, poultry, red fish such as tuna and salmon, lesser amounts in nuts, legumes and seeds. Niacin as a dietary supplement is used to treat pellagra, a disease caused by niacin deficiency. Signs and symptoms of pellagra include skin and mouth lesions, anemia, headaches, and tiredness. Many countries mandate its addition to wheat flour or other food grains, thereby reducing the risk of pellagra. The amide derivative nicotinamide (niacinamide) is a component of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP+). Although niacin and nicotinamide are identical in their vitamin activity, nicotinamide doe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicotinic Acid N-oxide
Nicotinic acid ''N''-oxide is an organic compound with the formula (HO2C)C5H4NO. It is the ''N''-oxide of nicotinic acid ((HO2C)C5H4N). It is prepared by oxidation of nicotinic acid or the hydrolysis of 3-cyanopyridine ''N''-oxide. The compound is a precursor to the popular drugs niflumic acid and pranoprofen Pranoprofen (INN) is a nonsteroidal anti-inflammatory drug (NSAID) used in ophthalmology Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physi ....{{Ullmann, doi=10.1002/14356007.a22_399, chapter=Pyridine and Pyridine Derivatives, year=2000, last1=Shimizu, first1=Shinkichi, last2=Watanabe, first2=Nanao, last3=Kataoka, first3=Toshiaki, last4=Shoji, first4=Takayuki, last5=Abe, first5=Nobuyuki, last6=Morishita, first6=Sinji, last7=Ichimura, first7=Hisao, isbn=3527306730 References Amine oxides Pyridinium compounds Carboxylic acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pergamon Press
Pergamon Press was an Oxford-based publishing house, founded by Paul Rosbaud and Robert Maxwell, that published scientific and medical books and journals. Originally called Butterworth-Springer, it is now an imprint of Elsevier. History The core company, Butterworth-Springer, started in 1948 to bring the "Springer know-how and techniques of aggressive publishing in science"Joe Haines (1988) ''Maxwell'', Houghton Mifflin, p. 137. to Britain. Paul Rosbaud was the man with the knowledge. When Maxwell acquired the company in 1951, Rosbaud held a one-quarter share. They changed the house name to Pergamon Press, using a logo that was a reproduction of a Greek coin from Pergamon. Maxwell and Rosbaud worked together growing the company until May 1956, when, according to Joe Haines, Rosbaud was sacked. When Pergamon Press started it had only six serials and two books. Initially the company headquarters was in Fitzroy Square in West End of London. In 1959, the company moved into Headingt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorus Oxychloride
Phosphoryl chloride (commonly called phosphorus oxychloride) is a colourless liquid with the formula . It hydrolyses in moist air releasing phosphoric acid and fumes of hydrogen chloride. It is manufactured industrially on a large scale from phosphorus trichloride and oxygen or phosphorus pentoxide. It is mainly used to make phosphate esters such as tricresyl phosphate. Structure Like phosphate, is tetrahedral in shape. It features three P−Cl bonds and one strong P=O double bond, with an estimated bond dissociation energy of 533.5 kJ/mol. On the basis of bond length and electronegativity, the Schomaker-Stevenson rule suggests that the double bond form is dominant, in contrast with the case of . The P=O bond involves the donation of the lone pair electrons on oxygen ''p''-orbitals to the antibonding combinations associated with phosphorus-chlorine bonds, thus constituting ''π'' bonding. Phosphoryl chloride exists as neutral molecules in the solid, liquid and gas s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordination Chemistry
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many metal-containing compounds, especially those that include transition metals (elements like titanium that belong to the Periodic Table's d-block), are coordination complexes. Nomenclature and terminology Coordination complexes are so pervasive that their structures and reactions are described in many ways, sometimes confusingly. The atom within a ligand that is bonded to the central metal atom or ion is called the donor atom. In a typical complex, a metal ion is bonded to several donor atoms, which can be the same or different. A polydentate (multiple bonded) ligand is a molecule or ion that bonds to the central atom through several of the ligand's atoms; ligands with 2, 3, 4 or even 6 bonds to the central atom are common. These compl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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