Unreferenced date December 2009 An Endoglycosidase is an enzyme that releases oligosaccharide s from glycoprotein s or glycolipid s. Or it merely cleaves polysaccharide chains between residues that are not the terminal residue, although releasing oligosaccharides from conjugated protein and lipid molecules is more common. It breaks the glycosidic bonds between two sugar monomer in the polymer . It is different from exoglycosidase that it does not do so at the terminal residue. Hence, it is used to release long carbohydrates from conjugated molecules. If an exoglycosidase were used, every monomer in the polymer would have to be removed, one by one from the chain, taking a long time. An endoglycosidase cleaves, giving a polymeric product. PROTEIN x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 ... xn Mechanism Overview The mechanism is an enzymatic hydrolysis that requires two critical molecules a proton donor most likely an acid and a nucleophile most likely a base . 1 The Endoglycosidases mechanism has two forms an acid catalyzed protonation of the glycosidic oxygen yielding stereochemical retention at the anomeric carbon or an acid catalyzed protonation of the glycosidic oxygen with a concomitant attack of a water molecule activated by the base residue yielding a stereochemical inversion. 1 Both mechanisms exhibit the same distance between the proton donor and the glycosidic oxygen, situating the proton donor close enough to the glycosidic oxygen for hydrogen bonding. 1 It is the distance between the nucleophile and the anomeric carbon where the two mechanisms begin to diverge. Because the inversion mechanism must accommodate enough space for the water molecule, the nucleophile is situated further away from the anomeric carbon. In the inversion mechanism, this distance is only 5.5 angstroms but increases to 10 angstroms in the retention mechanism. Furthermore, the inversion mechanism was found to proceed through a single displacement mechanism involving an oxocarbenium ion like ... more details
The Bamberger rearrangement is the chemical reaction of N phenylhydroxylamines with strong aqueous acid , which will rearrangement reaction rearrange to give 4 aminophenols. ref name bamberger1894 cite journal last Bamberger first E. journal Chemische Berichte Chem. Ber. year 1894 volume 27 pages 1347 & 1548 1557 title Uber das Phenylhydroxylamin doi 10.1002 cber.18940270276 url http gallica.bnf.fr ark 12148 bpt6k907342 f376.table issue 2 ref ref name os1955 cite journal last Harman first R. E. journal Organic Syntheses title Chloro p benzoquinone volume 35 pages 22 year 1955 url http www.orgsyn.org orgsyn prep.asp?prep cv4p0148 also in the http www.orgsyn.org orgsyn pdfs CV4P0148.pdf Collective Volume 1963 4 148 PDF . ref It is named for the German chemist Eugen Bamberger 1857 1932 . Image Bamberger Rearrangement Scheme.png center 350px The Bamberger rearrangement N Phenylhydroxylamines are typically synthesized from nitrobenzene s by redox reduction using rhodium ref name oxley1989 cite journal author Oxley, P. W. Adger, B. M. Sasse, M. J. Forth, M. A. journal Organic Syntheses url http www.orgsyn.org orgsyn prep.asp?prep cv8p0016 volume 67 pages 187 year 1989 title N Acetyl N phenylhydroxylamine via Catalytic Transfer Hydrogenation of Nitrobenzene using Hydrazine and Rhodium on Carbon also in the http www.orgsyn.org orgsyn pdfs cv8p0016.pdf Collective Volume 1993 8 16 PDF . ref or zinc ref name kamm1925 cite journal last Kamm first O. journal Organic Syntheses url http www.orgsyn.org orgsyn prep.asp?prep cv1p0445 volume 4 pages 57 year 1925 title Phenylhydroxylamine also in the http www.orgsyn.org orgsyn pdfs cv1p0445.pdf Collective Volume 1941 1 445 PDF . ref . Reaction mechanism The mechanism of the Bamberger rearrangement proceeds from the monoprotonation of N phenylhydroxylamine 1 . N protonation 2 is favored, but unproductive. O protonation 3 can form the nitrenium ion 4 , which can react with nucleophiles water molecule H sub 2 sub O to form the desired 4 ... more details
property in determining protonation energies. Determinining pKa values from titration curves or free ... Hasselbalch pKa value can be computed from the protonation free energy via math mathrm p ... in turn related to the protonation free energy of the site via math Delta G mathrm prot mathrm pH mathrm RT ln10 mathrm pH mathrm p K mathrm a mathrm HH math The protonation free energy can in principle be computed from the protonation probability of the group math var x var pH which can be read ... and accurate protonation free energies from titration curves if math var x var is close to a value of 1 or 0. In this case, one can use various free energy calculation methods to obtain the protonation ... more details
a shift in geometry from a linear to bent geometry. Two protonation s of the nitrogen lead to an increased N O bond distance. The resulting intermediate is a hydroxylamine . further protonation of the hydroxylamine ... II sup to Fe sup III sup , coupled with a further protonation of nitrogen leads to the release of ammonia ... more details
The Schmidt reaction is an organic reaction involving alkyl migration over the carbon nitrogen chemical bond in an azide with expulsion of nitrogen. ref cite book author Plagens, Andreas Laue, Thomas M. title Named organic reactions edition 2nd publisher John Wiley & Sons location Chichester year 2005 pages isbn 0 470 01041 X oclc doi accessdate ref ref Wolff, H. Organic Reactions Org. React. 1946 , 3 . ref A key reagent introducing this azide group is hydrazoic acid and the reaction product depends on the type of reactant Carboxylic acid s form amine s through an isocyanate intermediate 1 and ketone s form amide s 2 File Schmidt reaction.png 800px A catalyst that can be a protic acid usually sulfuric acid or a Lewis acid is required. The reaction was discovered in 1924 by Karl Friedrich Schmidt 1887 1971 , ref cite doi 10.1002 cber.19240570423 ref who successfully converted benzophenone and hydrazoic acid to benzanilide . It is a tool regularly used in organic chemistry for the synthesis of new organic compounds, for example, in that of the unusual 2 quinuclidone . Reaction mechanism The carboxylic acid Schmidt reaction starts with acylium ion 1 obtained from protonation and loss of water. Reaction with hydrazoic acid forms the protonated azido ketone 2 , which goes through a rearrangement reaction with the alkyl group R, migrating over the C N bond with expulsion of nitrogen. The protonated isocyanate is attacked by water forming carbamate 4 , which after deprotonation loses carbon dioxide to the amine . Image Schmidtreactionmechanismamine.png 500px center Schmidt reaction mechanism amine formation The reaction is related to the Curtius rearrangement except that in this reaction the azide is protonated and hence with different intermediates. In the reaction mechanism for the ketone Schmidt reaction, the carbonyl group is activated by protonation for nucleophilic addition by the azide, forming intermediate 3 , which loses water in a elimination reaction to temporar ... more details
Hydrogen ion is recommended by IUPAC as a general term for all ion s of hydrogen and its isotope s. ref Compendium of Chemical Terminology , 2nd edition McNaught, A.D. and Wilkinson, A. Blackwell Science, 1997 ISBN 0 86542 684 8 , also http www.iupac.org publications compendium index.html online ref Depending on the electric charge charge of the ion, two different classes can be distinguished positively charged ions and negatively charged ions. Under aqueous conditions found in biochemistry , hydrogen ions exist as the hydrated form hydronium , H sub 3 sub O sup sup , but these are often still referred to as hydrogen ions or even proton s by biochemists. Cation positively charged Main Hydron chemistry Image Hydronium 3D balls.png thumb Hydronium ion Image Zundel cation.JPG thumb Zundel cation When hydrogen loses its electron , the following cation s can be formed Hydron chemistry Hydron general name referring to the positive ion of any hydrogen isotope H sup sup Proton sup 1 sup H sup sup i.e. the cation of Hydrogen atom protium Deuteron sup 2 sup H sup sup , D sup sup Triton physics Triton sup 3 sup H sup sup , T sup sup In addition, the ions produced by the reaction of these cations with water as well as their hydrates are called hydrogen ions Hydronium ion H sub 3 sub O sup sup Zundel cation H sub 5 sub O sub 2 sub sup sup named for Georg Zundel Eigen cation H sub 9 sub O sub 4 sub sup sup named for Manfred Eigen Zundel cations and Eigen cations play an important role in proton diffusion according to the Grotthuss mechanism . In connection with acids, hydrogen ions typically refers to Hydron chemistry hydrons . Anion negatively charged main Hydrogen anion Hydrogen anion s are formed when additional electrons are acquired Hydride general name referring to the negative ion of any hydrogen isotope H sup &minus sup Deuteride sup 2 sup H sup &minus sup , D sup &minus sup Tritide sup 3 sup H sup &minus sup , T sup &minus sup See also Acid Protonation Dihydrogen cation ... more details
Image Cyanohydrin general 2D skeletal.png thumb right size The structure of a general cyanohydrin. A cyanohydrin is a functional group found in organic compound s. Cyanohydrins have the formula R sub 2 sub C OH CN, where R is H, alkyl , or aryl . Cyanohydrins are industrially important precursors to carboxylic acid s and some amino acid s. Cyanohydrins can be formed by the cyanohydrin reaction , which involves treating a ketone or an aldehyde with hydrogen cyanide HCN in the presence of excess amounts of sodium cyanide NaCN as a catalyst RR C O HCN RR C OH CN In this reaction, the nucleophilic CN sup sup ion attacks the electrophilic carbonyl carbon in the ketone, followed by protonation by HCN, thereby regenerating the cyanide anion . Cyanohydrins are also prepared by displacement of sulfite by cyanide salts ref name Corson OrgSynth author Corson, B. B. Dodge, R. A. Harris, S. A. Yeaw, J. S. title Mandelic Acid collvol 1 collvolpages 336 year 1941 prep cv1p0336 ref Image Cyanation of aldehyde with bisulfate.svg 300px Cyanohydrins are intermediates in the Strecker amino acid synthesis . Acetone cyanohydrins Acetone cyanohydrin , CH sub 3 sub sub 2 sub C OH CN is the cyanohydrin of acetone . It is generated as an intermediate in the industrial production of methyl methacrylate . ref William Bauer, Jr. Methacrylic Acid and Derivatives in Ullmann s Encyclopedia of Industrial Chemistry 2002, Wiley VCH, Weinheim. doi 10.1002 14356007.a16 441 . Article Online Posting Date June 15, 2000 ref In the laboratory, this liquid serves as a source of HCN, which is inconveniently volatile. ref Haroutounian, S. A. Acetone Cyanohydrin Encyclopedia of Reagents for Organic Synthesis 2001, John Wiley & Sons. doi 10.1002 047084289X.ra014 ref Thus, acetone cyanohydrin can be used for the preparation of other cyanohydrins, for the transformation of HCN to Michael addition Michael acceptor s, and for the Gattermann Koch reaction formylation of arene s. Treatment of this cyanohydrin with lit ... more details
The Fischer indole synthesis is a chemical reaction that produces the aromatic Heterocyclic compound heterocycle indole from a substituted phenylhydrazine and an aldehyde or ketone under acid ic conditions. ref cite doi 10.1002 cber.188301602141 ref ref cite doi 10.1002 cber.188401701155 ref The reaction was discovered in 1883 by Hermann Emil Fischer . Today migraine antimigraine drugs of the triptan class are often synthesized by this method. Image Fischer Indole Reaction Scheme.png center 400px The Fischer indole synthesis The choice of acid catalyst is very important. Br nsted acid s such as HCl , sulfuric acid H sub 2 sub SO sub 4 sub , polyphosphoric acid and p toluenesulfonic acid have been used successfully. Lewis acid s such as boron trifluoride , zinc chloride , iron chloride , and aluminium chloride are also useful catalysts. Several reviews have been published. ref cite doi 10.1021 cr60095a004 ref ref cite doi 10.1021 cr60224a003 ref ref cite doi 10.1021 cr60258a004 ref Reaction mechanism The reaction of a substituted phenyl hydrazine with an aldehyde or ketone initially forms a phenylhydrazone which isomerization isomerizes to the respective enamine or ene hydrazine . After protonation , a cyclic sigmatropic rearrangement 3,3 sigmatropic rearrangement occurs producing an imine . The resulting imine forms a cyclic aminoacetal or aminal , which under acid catalyst catalysis that eliminates Ammonia NH sub 3 sub , resulting in the energetically favorable aromatic indole. Image Fischer indole synthesis.png center The mechanism of the Fischer indole synthesis Isotopic labelling studies show that the aryl nitrogen N1 of the starting phenylhydrazine is incorporated into the resulting indole. ref cite doi 10.1021 ja01244a033 ref ref cite journal author Clusius, K. Weisser, H. R. title Reaktionen mit sup 15 sup N. III. Zum Mechanismus der Fischer schen Indolsynthese journal Helvetica Chimica Acta year 1952 volume 35 issue 1 pages 400 406 doi 10.1002 hlca.195203501 ... more details
Unreferenced date December 2009 Orphan date December 2009 border 0 cellpadding 5 cellspacing 0 style margin 1em float right class wikitable colspan 3 Basic aromatic ring systems align center valign bottom Image Pyridine structure.png 67px br Pyridine Image Quinoline structure.png 119px br Quinoline Image Isoquinoline structure.png 126px br Isoquinoline align center valign bottom Image Acridine structure.png 171px br Acridine align center valign bottom Image Pyrazine structure.png 67px br Pyrazine Image Quinoxaline structure.png 119px br Quinoxaline align center valign bottom Image Imidazole structure.png 63px br Imidazole Image Benzimidazole structure.png 113px br Benzimidazole Image Purine structure.png 113px br Purine align center valign bottom Image Pyrazole structure.png 70px br Pyrazole Image Indazole structure.png 120px br Indazole align center valign bottom Image Pyrimidine structure.png 74px br Pyrimidine Image Quinazoline structure.png 126px br Quinazoline align center valign bottom Image Pyridazine structure.png 74px br Pyridazine Image Cinnoline structure.png 126px br Cinnoline Basic aromatic rings are simple aromatic ring aromatic rings in which the lone pair of electron s of a ring nitrogen atom is not part of the aromatic system and extends in the plane of the ring. This lone pair is responsible for the Base chemistry basicity of these nitrogenous base s, similar to the nitrogen atom in amine s. In these compounds the nitrogen atom is not connected to a hydrogen atom. Basic aromatic compounds get Protonation protonated and form aromatic cation s e.g. pyridinium under acid ic conditions. Typical examples of basic aromatic rings are pyridine or quinoline . Several rings contain basic as well as non basic nitrogen atoms, e.g. imidazole and purine . In non basic aromatic rings the lone pair of electron s of the nitrogen atom is delocalized and contributes to the aromatic pi electron system. In these compounds the nitrogen atom is connected to a hydrogen at ... more details
Ionbox ImageFile Phosphonium 3D balls.png ImageFile Ref chemboximage correct ?? ImageSize 121 ImageName Ball and stick model of phosphonium SystematicName Phosphanium ref name phosphonium CHEBI 30282 Cite web url http www.ebi.ac.uk chebi searchId.do?chebiId CHEBI 30282 title phosphonium CHEBI 30282 work Chemical Entities of Biological Interest ChEBI location UK publisher European Bioinformatics Institute ref substitutive br Tetrahydridophosphorus 1 ref name phosphonium CHEBI 30282 additive Section1 Chembox Identifiers PubChem 5460504 PubChem Ref Pubchemcite correct pubchem ChemSpiderID 4574014 ChemSpiderID Ref chemspidercite correct chemspider ChEBI 30282 Gmelin 292 SMILES PH4 StdInChI 1S H3P h1H3 p 1 StdInChI Ref stdinchicite correct chemspider StdInChIKey XYFCBTPGUUZFHI UHFFFAOYSA O StdInChIKey Ref stdinchicite correct chemspider Section2 Chembox Properties Formula Chem PH 4 MolarMass 35.00552 g mol sup 1 sup ExactMass 35.005061640 g mol sup 1 sup Section3 Chembox Related OtherCations Ammonium The phosphonium more obscurely phosphinium cation describes positively electrically charged charged polyatomic ion polyatomic cation s with the chemical formula Chem PR 4 . ref D. E. C. Corbridge Phosphorus An Outline of its Chemistry, Biochemistry, and Technology 5th Edition Elsevier Amsterdam 1995. ISBN 0 444 89307 5. ref Salts of the parent PH sub 4 sub sup sup are rarely encountered, but this ion is an intermediate in the preparation of the industrially useful tetrakis hydroxymethyl phosphonium chloride PH sub 3 sub HCl 4 CH sub 2 sub O P CH sub 2 sub OH sub 4 sub sup sup Cl sup sup Organic phosphonium salts are common reagents in the laboratory. Those with a P H bond are produced through protonation of phosphine Phosphines phosphines PR sub 3 sub H sup sup HPR sub 3 sub sup sup Many organic quaternary phosphonium cations Chem P R 4 are produced by alkylation of organophosphines. For example the reaction of triphenylphosphine with methyl iodide gives methyltriphenylphosp ... more details
Image SodiumBicarbonate.png thumb right Structure of sodium bicarbonate Acid salt is a somewhat obscure fact date April 2012 term for a class of salt chemistry salts formed by the partial neutralization chemistry neutralization of diprotic or polyprotic acid s. Because the parent acid is only partially neutralized, one or more replaceable hydrogen atoms remain. Typical acid salts have one or more alkali metal alkali alkaline metal ions as well as one or more hydrogen atoms. Well known examples are sodium bicarbonate NaHCO sub 3 sub , sodium hydrosulfide NaHS , sodium bisulfate NaHSO sub 4 sub , monosodium phosphate NaH sub 2 sub PO sub 4 sub , and disodium phosphate Na sub 2 sub HPO sub 4 sub . Often acid salts are used as Buffer solution buffer s. ref Most introductory chemistry textbooks discuss this area, representative is Zumdahl, S. S. Chemistry Heath, 1986 Lexington, MA. ISBN 0 669 04529 2. ref For example, the acid salt sodium bisulfate is the main species formed upon the half neutralization of sulfuric acid with sodium hydroxide H sub 2 sub SO sub 4 sub NaOH & x2192 NaHSO sub 4 sub H sub 2 sub O Acid salts compounds can act either as an acid or a base chemistry base addition of a suitably strong acid will protonation protonate anions, and addition of a suitably strong base will deprotonation split off H sup sup . The pH of a solution of an acid salt will depend on the relevant equilibrium constants and the amounts of any additional base or acid. A comparison between the K sub b sub and K sub a sub will indicate this if K sub b sub > K sub a sub , the solution will be basic, whereas if K sub b sub < K sub a sub , the solution will be acidic. Use in food main baking powder Some acid salts are used in baking. They are found in baking powders and are typically divided into low temperature or single acting and high temperature or double acting acid salts. Common low temperature acid salts react at room temperature to produce a lea ... more details
Chembox PIN Hydroperoxyl SystematicName Dioxidanyl OtherNames Peroxyl radical Section1 Chembox Identifiers CASNo 3170 83 0 CASNo Ref cascite correct ?? PubChem 520535 PubChem Ref Pubchemcite correct PubChem ChemSpiderID 454055 ChemSpiderID Ref chemspidercite correct chemspider ChEBI 25935 Gmelin 506 SMILES O O StdInChI 1S HO2 c1 2 h1H StdInChI Ref stdinchicite correct chemspider StdInChIKey OUUQCZGPVNCOIJ UHFFFAOYSA N StdInChIKey Ref stdinchicite correct chemspider Section2 Chembox Properties H 1 O 2 ExactMass 32.997654276 g mol sup 1 sup The hydroperoxyl radical chemistry radical , also known as the perhydroxyl radical , is the protonated form of superoxide with the chemical formula hydrogen H oxygen O sub 2 sub . Formation Hydroperoxyl is formed through the transfer of a proton to an oxygen atom. ref name amsglossary cite journal title Hydroperoxyl radical journal Glossary of Meteorology ref Reactivity The superoxide anion, O sub 2 sub sup sup , and the hydroperoxyl radical are in chemical equilibrium equilibrium in aqueous solution O sub 2 sub sup sup H sub 2 sub O Eqm HO sub 2 sub OH sup sup The protonation deprotonation equilibrium exhibits a Acid dissociation constant p K sub a sub of 4.88 ref http openlibrary.org b OL14350787M Reactivity of HO2 O2 Radicals in Aqueous Solution Reactivity of HO sub 2 sub O sub 2 sub sup sup Radicals in Aqueous Solution . J Phys Chem Ref Data, 1985. 14 4 p. 1041 1091 ref consequently, about 0.3 of any superoxide present in the cytosol of a typical cell is in the protonated form. Unlike O sub 2 sub sup sup , which predominantly acts as a reductant, HO sub 2 sub can act as an oxidant in a number of biologically important reactions, such as the abstraction of hydrogen atoms from tocopherol and polyunstaturated fatty acid s in the lipid bilayer . As such, it may be an important initiator of lipid peroxidation . Because dielectric constant has a strong effect on p K sub a sub , and the dielectric constant of air is quite low, superox ... more details
The Dieckmann condensation is the intramolecular chemical reaction of ester diester s with base to give ketoesters. ref Dieckmann, W. Chemische Berichte Ber. 1894, 27 , 102 & 965 ref ref Dieckmann, W. Chemische Berichte Ber. 1900, 33 , 595 & 2670 ref ref Dieckmann, W. Ann. 1901, 317 , 51 & 93 ref ref cite journal author Schaefer, J. P. Bloomfield, J. J. title The Dieckmann Condensation Including the Thorpe Ziegler Condensation journal Organic Reactions year 1967 volume 15 pages 1 203 doi 10.1002 0471264180.or015.01 ref ref Davis, B. R. Garrett, P. J. Comp. Org. Syn. 1991, 2 , 806 829. Review ref It is named after the German chemist Walter Dieckmann 1869 1925 . The equivalent intermolecular reaction is the Claisen condensation . Image DieckmannCondensation.png center 350px The Dieckmann condensation Reaction Mechanism The acidic hydrogen between the two carbonyl groups is deprotonated in step four. Protonation with a Br nsted Lowry acid H sub 3 sub O sup sup for example re forms the keto ester. ref cite book author Janice Gorzynski Smith title Organic Chemistry edition 2nd year 2007 pages 932 933 isbn 978 0073327495 ref This deprotonation step is the driving force for this reaction. Image DieckmannCondensationMechanism.png center 635px Dieckmann Condensation reaction mechanism for the example given. Owing to the steric stability of five and six membered ring structures, these will preferentially be formed. 1,4 and 1,6 diesters will form five membered cyclic &beta keto esters, while 1,5 and 1,7 diesters will form six membered &beta keto esters. ref cite web publisher Organic Chemistry Portal title Dieckmann Condensation url http www.organic chemistry.org namedreactions dieckmann condensation.shtm ref See also Claisen condensation Gabriel Colman rearrangement References Reflist Category Intramolecular condensation reactions ca Condensaci de Dieckmann de Dieckmann Kondensation es Condensaci n de Dieckmann it Condensazione di Dieckmann nl Dieckmann condensatie ja ... more details
Phosphazenes are a class of chemical compound s in which a phosphorus atom is covalent bond covalently linked to a nitrogen atom by a double bond and to three other atoms or free radical radicals by single bonds. While other substitutions produce relatively persistent compounds, in organic synthesis the term largely refers to species with three amino substituents bound to phosphorus. The compounds are unusually stable examples of the phosphorane class of molecules and have a remarkable proton affinity . As such, they are one of the eminent examples of neutral, organic superbase superbases . ref Superbases for Organic Synthesis ref Two examples are hexachlorocyclotriphosphazene and bis triphenylphosphine iminium chloride . Phosphazenes are also known as iminophosphoranes and phosphine imides . The corresponding polymer s are polyphosphazene s. Phosphazene bases Phosphazene bases are strong non metallic non ionic and nucleophilicity low nucleophilic bases. They are stronger base chemistry bases than regular amine or amidine bases such as N,N Diisopropylethylamine H nig s base or DBU chemistry DBU . Protonation takes place at a doubly bonded nitrogen atom. Related to phosphazene bases are the proazaphosphatrane bases, which have a saturated P NR sub 3 sub structure and protonate at phosphorus. Though the simplest phosphazene superbase, P1 Me , was first synthesized in 1975, chemists assumed that the compounds were highly unstable, like their alkyl substituted derivatives. The species was regarded at that time as little more than an academic curiosity. Image PhosphazeneBases.png center 400px Phosphazene Base By now phosphazene bases are established reagents in organic synthesis. Perhaps the best known phosphazene bases are BEMP with an acetonitrile pKa of the conjugate acid of 27.6 and the phosphorimidic triamide t Bu P4 pK sub BH sub 42.7 also known as Schwesinger base after one of its inventors. ref Peralkylated Polyaminophosphazenes Extremely Strong, Neutral Nitrogen ... more details
Orphan date January 2011 Chembox verifiedrevid 455176045 ImageFileL1 Fluoronium dimensions 2D.png ImageFileL1 Ref chemboximage correct ?? ImageSizeL1 121 ImageNameL1 Skeletal formula of fluoronium with assorted dimensions Citation last Diercksen first G. H. F. last2 von Niessen first2 W. last3 Kraemer first3 W. P. title SCF LCGO MO studies on the fluoronium ion FH sub 2 sub sup sup and its hydrogen bonding interaction with hydrogen fluoride FH journal Theoretical Chemistry Accounts Theory, Computation, and Modeling Theoretica Chimica Acta volume 31 issue 3 pages 205 214 date September year 1973 url http www.springerlink.com content v517wg14w47676r4 doi 10.1007 BF00526510 ImageFileR1 Fluoronium 3D vdW.png ImageFileR1 Ref chemboximage correct ?? ImageSizeR1 121 ImageNameR1 Spacefill model of fluoronium IUPACName Fluoronium SystematicName Fluoranium ref Cite web title Fluoronium CHEBI 50314 url https www.ebi.ac.uk chebi searchId.do?chebiId 50314 work Chemical Entities of Biological Interest ChEBI location UK publisher European Bioinformatics Institute ref Section1 Chembox Identifiers ChemSpiderID 19122106 ChemSpiderID Ref chemspidercite correct chemspider ChEBI Ref ebicite correct EBI ChEBI 50314 SMILES FH2 StdInChI 1S FH2 h1H2 q 1 StdInChI Ref stdinchicite correct chemspider InChI 1 FH2 h1H2 q 1 StdInChIKey YNESUKSMQODWNS UHFFFAOYSA N StdInChIKey Ref stdinchicite correct chemspider InChIKey YNESUKSMQODWNS UHFFFAOYAK Section2 Chembox Properties Formula H sub 2 sub F sup sup MolarMass 21.01428 g mol sup 1 sup ExactMass 21.014053269 g mol sup 1 sup The fluoronium cation , H sub 2 sub F sup sup , is a polyatomic ion formed by protonation or self ionic dissociation of hydrogen fluoride HF H sup sup H sub 2 sub F sup sup or 3HF unicode H sub 2 sub F sup sup Bifluoride HF sub 2 sub sup sup The fluoronium ion is isoelectronic with Properties of water water and the Sodium amide amide ion . Unlike for halonium ion s based on chlorine , bromine or iodine chloronium, H sub 2 sub ... more details
enzyme Name abietadiene synthase EC number 4.2.3.18 CAS number 157972 08 2 IUBMB EC number 4 2 3 18 GO code 0050554 image width caption In enzymology , an abietadiene synthase EC number 4.2.3.18 is an enzyme that catalysis catalyzes the chemical reaction copalyl diphosphate math rightleftharpoons math abietadiene diphosphate Hence, this enzyme has one substrate biochemistry substrate , copalyl diphosphate , and two product chemistry products , abietadiene and diphosphate . This enzyme belongs to the family of lyase s, specifically those carbon oxygen lyases acting on phosphates. The systematic name of this enzyme class is copalyl diphosphate diphosphate lyase cyclizing abietadiene forming . This enzyme is also called copalyl diphosphate diphosphate lyase cyclizing . This enzyme participates in diterpenoid biosynthesis . References reflist 1 cite journal author RB date 2000 title Abietadiene synthase from grand fir Abies grandis characterization and mechanism of action of the pseudomature recombinant enzyme journal Biochemistry. volume 39 pages 15592 602 pmid 11112547 doi 10.1021 bi001997l last2 Flory first2 JE last3 Jetter first3 R last4 Ravn first4 MM last5 Lee first5 HJ last6 Coates first6 RM last7 Croteau first7 RB issue 50 cite journal author Peters RJ, Ravn MM, Coates RM, Croteau RB date 2001 title Bifunctional abietadiene synthase free diffusive transfer of the copalyl diphosphate intermediate between two distinct active sites journal J. Am. Chem. Soc. volume 123 pages 8974 8 pmid 11552804 doi 10.1021 ja010670k issue 37 cite journal author Peters RJ, Croteau RB date 2002 title Abietadiene synthase catalysis mutational analysis of a prenyl diphosphate ionization initiated cyclization and rearrangement journal Proc. Natl. Acad. Sci. U. S. A. volume 99 pages 580 4 pmid 11805316 doi 10.1073 pnas.022627099 issue 2 pmc 117348 cite journal author Peters RJ, Croteau RB date 2002 title Abietadiene synthase catalysis conserved residues involved in protonation initiated ... more details
Thiocarbonate describes a family of anion s with the general chemical formula CS sub 3 x sub O sub x sub sup 2 sup x 0, 1, or 2 . Organic compounds structurally related to these anions are also called thiocarbonates. Like the carbonate dianion, the thiocarbonates are planar, with carbon at the center. The average bond order from C to S or O is 1.33. The state of protonation is usually not specified. These anions are good nucleophile s and good ligand s. ref Holleman, A. F. Wiberg, E. Inorganic Chemistry Academic Press San Diego, 2001. ISBN 0 12 352651 5. ref Monothiocarbonate Monothiocarbonate is the dianion CO sub 2 sub S sup 2 sup , which has C sub 2v sub symmetry group symmetry . Monothiocarbonate arises by the hydrolysis of thiophosgene or the reaction of base with carbonyl sulfide COS 2 NaOH Na sub 2 sub CO sub 2 sub S H sub 2 sub O Dithiocarbonates Dithiocarbonate is the dianion COS sub 2 sub sub sup 2 sup , which has C sub 2v sub symmetry. It arises from the reaction of aqueous base with carbon disulfide CS sub 2 sub 2 NaOH Na sub 2 sub COS sub 2 sub H sub 2 sub O Probably the most important dithiocarbonates are the organic derivatives. The xanthate s are organosulfur compound s prepared by the reaction of alkoxide s with carbon disulfide. Charge neutral organic dithiocarbonates, with the formula RS sub 2 sub CO, are also known, often being derived by hydrolysis of the corresponding organic trithiocarbonates. One example is tetrathiapentalenedione, a heterocycle that consists of two dithiocarbonate groups. Trithiocabonates Trithiocarbonate is the dianion CS sub 3 sub sup 2 sup , which has D sub 3h sub symmetry. Trithiocarbonate is derived from the reaction of sulfide sources with carbon disulfide ref OrgSynth author R. E. Strube title Trithiocarbodiglycolic Acid collvol 4 collvolpages 967 year 1963 prep CV4P0967 a procedure for synthesis of K sub 2 sub CS sub 3 sub ref CS sub 2 sub 2 Sodium hydrosulfide NaSH Na sub 2 sub CS sub 3 sub H sub 2 sub S Addition of ... more details
with the protonation of methane ref cite journal author George A. Olah , Schlosberg RH title Chemistry ... 3 sub H SbF sub 5 sub Magic Acid Solution. Protonation of Alkanes and the Intermediacy of CH sub 5 ... more details
in this chain for forming C sub 3 sub H sub 3 sub sup sup . The protonation of NH sub 3 sub ... molecules. Of these, protonation reactions are the most common. Any species of the type HX ... more details
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