Материалы II студенческой межфакультетсткой конференции первокурсников по биоорганической химии
PYRAZOLE Spoorthi Kempegowda, group 10. Scientific adviser is Kozub Svetlana
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- Heterocyclic Amines
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PYRAZOLESpoorthi Kempegowda, group 10. Scientific adviser is Kozub Svetlana.Pyrazole is the organic compound with the formula C3H3N2H. It is a heterocycle characterized by a 5-membered ring of three carbonatoms and two adjacent nitrogen centres. Pyrazoles are also the class of compounds that have the ring C3N2 with adjacent nitrogen centres.[1] Notable drug that is a pyrazole is Celebrex. Preparation and reactions[edit] Pyrazoles are synthesized by the reaction of α,β-unsaturated aldehydes with hydrazine and subsequent dehydrogenation:[2]
CH3C(O)CH2C(O)CH3 + N2H4 → (CH3)2C3HN2H + 2 H2O History The term pyrazole was given to this class of compounds by German Chemist Ludwig Knorr in 1883.[citation needed] In a classical method developed by German chemist Hans von Pechmann in 1898, pyrazole was synthesized from acetylene and diazomethane.[4] Conversion to scorpionates Pyrazoles react with potassium borohydride to form a class of ligands known as scorpionate. Pyrazole itself reacts with potassium borohydride to form a tridentate ligand known as Tp ligand: KBH4 + 3 C3H3N2H → KBH(C3H3N2)3 + 3 H2 Occurrence and uses In medicine, derivatives of pyrazoles are used for their analgesic, anti-inflammatory, antipyretic, antiarrhythmic, tranquilizing, muscle relaxing, psychoanaleptic, anticonvulsant, monoamineoxidase inhibiting, antidiabetic and antibacterial activities. In 1959, the first natural pyrazole, 1-pyrazolyl-alanine, was isolated from seeds of watermelons[5][6] Related heterocycles Imidazole is an analog of pyrazole with two non-adjacent nitrogen atoms. In isoxazole, another analog, the nitrogen atom in position 1 replaced by oxygen. Heterocyclic AminesMaher Mounir Zakaria, group 11. Scientific adviser is Levashova Olga.Heterocyclic Amines (HCAs) are carcinogenic compounds that form during cooking of all meats, including fish. In general, grilling causes the greatest amount of HCA formation, followed by pan–frying. More than ten kinds of HCAs, actually produced by cooking or heating of meat or fish, have now been isolated and their structures determined, most being previously unregistered compounds. Heterocyclic amines produced from overcooked foods are extremely mutagenic in numerous in vitro and in vivo test systems. One of these mutagens, 2-amino-1-methyl-6-phenylimidazo [4, 5-b] pyridine (PhIP), induces breast tumors in rats and has been implicated in dietary epidemiology studies as raising the risk of breast cancer in humans. Features of PhIP: -Description: A grey-white crystal -Melting-point: 327-328*C (according to Knize & Felton ) -Spectroscopy data: Ultra-violet mass, proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, infrared absorbance spectra have been reported . -Solubility: Soluble in methanol and in dimethyl sulfoxide. -Stability: Stable under moderately acidic and basic conditions (according to Sugimura, 1983 ) -Formation of PhIP: The isolation and identification of PhIP were first reported by Felton. (1986).Its structure was confirmed by chemical synthesis (Knize & Felton, 1986). PhIP was made by catalytic tritiation of 2'-bromo-PhIP. 2'-Bromo-PhIP was made by diazotization of bromobenzene and 2,5-diaminopyridine, the product of which was brominated at the 3-position of pyridine and then displaced with methylamine and cyclized with cyanogen bromide in analogy with the original synthesis of PhIP. Pentadeutero-PhIP was made from 5-amino-2-chloropyridine by a four-step synthetic route . PhIP is produced commercially in small quantities for research purposes. Several cancers are associated with HCAs (PhlP), including those arising in the colon and rectum, stomach, breast, lung, and prostate. Prophylaxis:- Modification of cooking methods (such as microwaving) and reducing meat consumption are effective preventive steps. Moreover, The intake of cruciferous vegetables, such as broccoli and Brussels sprouts, have been found to increase HCA metabolism in humans by induction of hepatic detoxification enzymes . References:-
http://monographs.iarc.fr/ENG/Monographs/vol56/mono56-13.pdf THIOPHENEJolene Effie Oye Ekuban, group 12. Scientific adviser is Larisa Lukyanova.Thiophene, also commonly called thiofuran, is a heterocyclic compound with the formula C4H4S. Consisting of a flat five-membered ring, it is aromatic as indicated by its extensive substitution reactions. Related to thiophene are benzothiophene and dibenzothiophene, containing the thiophene ring fused with one and two benzene rings, respectively. Compounds analogous to thiophene include furan (C4H4O) and pyrrole (C4H4NH). Thiophene was discovered as a contaminant in benzene.[1] It was observed that isatin forms a blue dye if it is mixed with sulfuric acidand crude benzene. The formation of the blue indophenin was long believed to be a reaction with benzene. Victor Meyer was able to isolate the substance responsible for this reaction from benzene. This new heterocyclic compound was thiophene.[2] Thiophene and its derivatives occur in petroleum, sometimes in concentrations up to 1–3%. The thiophenic content of oil and coal is removed via the hydrodesulfurization (HDS) process. In HDS, the liquid or gaseous feed is passed over a form of molybdenum disulfide catalyst under a pressure of H2. Thiophenes undergo hydrogenolysis to form hydrocarbons and hydrogen sulfide. Thus, thiophene itself is converted to butane and H2S. More prevalent and more problematic in petroleum are benzothiophene anddibenzothiophene. The molecule is flat; the bond angle at the sulphur is around 93 degrees, the C-C-S angle is around 109, and the other two carbons have a bond angle around 114 degrees. The C-C bonds to the carbons adjacent to the sulphur are about 1.34A, the C-S bond length is around 1.70A, and the other C-C bond is about 1.41A (figures from the Cambridge Structural Database). Desulfurization by Raney nickel. Desulfurization of thiophene with Raney nickel affords butane. When coupled with the easy 2,5-difunctionalization of thiophene, desulfurization provides a route to 1,4-disubstituted butanes.. Coordination chemistry. Thiophene exhibits little thioether-like character, but it does serve as a pi-ligand forming piano stool complexes such as Cr(η5-C4H4S)(CO)3 Uses Thiophenes are important heterocyclic compounds that are widely used as building blocks in many agrochemicals and pharmaceuticals.[3] The benzene ring of a biologically active compound may often be replaced by a thiophene without loss of activity.[14] This is seen in examples such as the NSAID lornoxicam, the thiophene analog of piroxicam. Polythiophene. The polymer formed by linking thiophene through its 2,5 positions is called polythiophene. Polythiophene itself has poor processing properties. More useful are polymers derived from thiophenes substituted at the 3- and 3- and 4- positions. Polythiophenes become electrically conductive upon partial oxidation, i.e. they become "organic metals. жүктеу/скачать 3.18 Mb. Достарыңызбен бөлісу:
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