In chemistry, protonation is the addition of a Proton Hydrogen ion proton H sup sup to an atom , molecule , or ion . ref Zumdahl, S. S. Chemistry Heath, 1986 Lexington, MA. ISBN 0 669 04529 2. ref Some classic examples include the protonation of water by sulfuric acid H sub 2 sub SO sub 4 sub H sub 2 sub O H sub 3 sub O sup sup HSO sub 4 sub sup sup the protonation of isobutene in the formation of a carbocation CH sub 3 sub sub 2 sub C CH sub 2 sub HBF sub 4 sub CH sub 3 sub sub 3 sub C sup sup BF sub 4 sub sup sup the protonation of ammonia in the formation of ammonium chloride from ammonia and hydrogen chloride NH sub 3 sub HCl NH sub 4 sub sup sup Cl sup sup Protonation is a fundamental chemical reaction and is a step in many stoichiometry stoichiometric and catalysis catalytic processes . Some ions and molecules can undergo more than one protonation and are labeled polybasic, which is true of many biological macromolecule s. Protonation and deprotonation occur in most acid base reaction s they are the core of most acid base reaction theories. A Br nsted Lowry acid base theory Bronsted Lowry acid is defined as a chemical substance that protonates another substance. Upon protonating a substrate, the mass and the charge of the species each increase by one unit. Protonating or deprotonating ... , among others. Protonation is also an essential step in certain analytical procedures such as electrospray mass spectrometry . Rates of protonation and deprotonation Protonations are often rapid, in part because of the high mobility of protons in water. The reaction rate rate of protonation is related ... acids. The rates of protonation and deprotonation can be especially slow when protonation induces ... are reversible and the conjugate base is unchanged by being protonated. In some cases protonation ... de Protonierung es Protonaci n fr Protonation it Protonazione he mk nl Protonering ja pt Protona o simple Protonation zh ... more details
Multiple issues unreferenced June 2010 expert subject June 2010 original research June 2010 The catalytically competent protonation state CCPS is the catalytically active protonation state of an enzyme . An enzyme is a protein , which catalyzes a chemical reaction. Proteins and enzymes consist of Amino acids , some of which are titratable i.e. they can alter their charge when the pH of the solution changes , and an enzyme commonly needs a set of specific residues in its Active site to occupy a specific protonation state to be catalytically active. An example of this phenomenon is provided by Hen Egg White Lysozyme HEWL a Lysozyme , which has two acidic residues in its active site that are important for catalytic activity Glu35 and Asp 52. For HEWL to be catalytically active, Glu35 must be neutral i.e. be protonated , whereas Asp 52 must be negatively charged i.e. it has lost its proton . The protonation state Glu35H,Asp52 is thus the catatlytically competent protonation state of HEWL, where H denotes the protonated form of the Glutamic acid Glu . pH activity profiles Since an enzyme is active only when it is in the CCPS i.e. it occupies a specific protonation state , it follows that the fraction of enzyme molecules in the CCPS determines how active a population of enzyme molecules are. The fractional population of the CCPS is thus a significant quantity, and the pH dependence of the fractional population of the CCPS determines the pH activity profile of the enzyme. The population of a CCPS can be predicted using Protein pKa calculations . DEFAULTSORT Catalytically Competent Protonation State Category Enzyme kinetics enzyme stub ... more details
Orphan date January 2011 In chemistry , a lyonium ion is the cation derived by the protonation of a solvent molecule. ref http goldbook.iupac.org L03654.html IUPAC Gold Book lyonium ion ref For example a Hydronium hydronium ion is formed from the protonation of water and carbon C hydrogen H sub 3 sub oxygen O hydrogen H sub 2 sub sup sup is the cation formed by the protonation of methanol . See also lyate ion which is the anion formed by the deprotonation of a solvent molecule. References reflist Category Acids Category Cations chem stub ... more details
CCPS is an abbreviation that may refer to One of several school districts in the United States District School Board of Collier County , a school district in Southwest Florida Charlotte County Public Schools , a school district in Southwest Florida Chesterfield County Public Schools , a school division in Virginia Camden City Public Schools , a school district in New Jersey Cobb County Public Schools , a school district in Georgia Carroll County Public Schools Maryland , a school district in Maryland Culpeper County Public Schools Center for Chemical Process Safety, an initiative of the American Institute of Chemical Engineers Center for Congressional and Presidential Studies , a teaching and study program Consumer Council for Postal Services , the official monitoring body for the British Royal Mail Catalytically competent protonation state , the catalytically active protonation state of an enzyme See also CCP disambiguation disambig ... more details
Orphan date January 2011 In chemistry , a lyate ion is the anion derived by the deprotonation of a solvent molecule. ref http goldbook.iupac.org L03653.html IUPAC Gold Book lyate ion ref For example a hydroxide hydroxide ion is formed from the deprotonation of water and methoxide carbon C hydrogen H sub 3 sub oxygen O sup sup is the anion formed by the deprotonation of methanol . See also lyonium ion which is the cation formed by the protonation of a solvent molecule. References reflist Category Bases Category Anions chem stub ... more details
Summary Information Description PPI protonation Source I Eydis E created this work entirely by myself. Date 5 nov2010 Author Eydis E other versions Licensing PD self date November 2010 Category PD chem Category Classified Chemical Structures Should be SVG chemical Convert to SVG and copy to Wikimedia Commons ... more details
determines the structure of the product. With an electron donor as methoxy MeO or alkyl protonation .... Other investigators have thought the protonation is meta 1,3 to the substituent. Arthur Birch favored meta protonation. With electron withdrawing substituents protonation has been thought to come at the site ... step of the reaction. This is followed by protonation by the alcohol to form a cyclohexadienyl radical ... C C C C in a six ring and charged minus . Then this cyclohexadienyl anion is Protonation protonated by the alcohol present. The protonation takes place in the middle of the cyclohexadienyl system ... determines the structure of the product. With an electron donor as methoxy MeO or alkyl protonation ... investigators have thought the protonation is meta 1,3 to the substituent. Arthur Birch favored meta protonation. With electron withdrawing substituents protonation has been thought to come at the site ... proceeds. In the case of donating groups A. J. Birch s preference for meta protonation of the radical ... radical anion protonation to suggesting a mixture of ortho and meta protonation. In 1990 and 1993 an esoteric test was devised which showed that ortho protonation of the radical anion was preferred over ... groups there are literature examples demonstrating the nature of the carbanion just before final protonation. This revealed that the initial radical anion protonation occurs para to the withdrawing substituent. The remaining item for discussion is the final protonation of the cyclohexadienyl anion. In 1961 ... protonation sites. However, when the computations were modified with somewhat more realistic assumptions ... mechanism suggested that the initial radical anion protonation was meta to the ring methoxy and alkyl groups and the last step, protonation of a cyclohexadienyl anion, was ortho. Birch s original mechanism ... and continued publications suggesting meta protonation of the radical anion. He suggested the meta ... meta protonation ref name Krapcho as had been suggested previously by Birch. Burnham in 1969 concluded ... more details
control kinetic protonation of enolic species proceeds with an early transition state with the alpha ... d the Birch reduction of enone s e the deprotonation protonation of carbonyl compounds f the dehalogenation ..., 1637 1646. ref ref name HEZ 1987 e Kinetic Protonation of Enols, Enolates and Analogs The Stereochemistry ... Inter and Intramolecular Stereoselective Protonation of Enols , Zimmerman, H. E. Wang, P., J. Org. Chem. 2002, 69, 9216 9226. ref Kinetic or thermodynamic control Protonation from the less hindered face ... of the stereochemistry of kinetic protonation of an enol ref name Linder With an Acid catalysis ... pyridyl isomer on the left, the usual steric hindrance control blocks protonation from above. That is, the phenyl group is positioned directly above the enolic alpha carbon and protonation must occur ... of the less stable cis product. ref The Stereochemistry of Protonation. XI, Zimmerman, H. E. Mariano ... more details
Durbecq ref name Street Cite pmid 7908830 ref The origin of the initial protonation step has not been ... to protonation by water. ref name Zhang Cite pmid 17137593 ref IPP isomerase also requires ... protonation. Biological Function The protonation of an inactivated double bond is rarely seen in nature ... more details
Image Iminium 2D.png thumb right 150px The general structure of an iminium cation An iminium salt or cation in organic chemistry has the general structure R sup 1 sup R sup 2 sup C N sup sup R sup 3 sup R sup 4 sup sup sup and is as such a protonation protonated or Substitution reaction substituted imine . ref GoldBookRef file I02958 title iminium compounds ref It is an intermediate in many organic reaction s such as the Beckmann rearrangement , Vilsmeier Haack reaction , Stephen reaction or the Duff reaction . The use of the alternative names imonium compounds and immonium compounds is discouraged. Reactions involving iminium salts Beckmann rearrangement Eschenmoser s salt Duff reaction Stephen aldehyde synthesis Stephen reaction Vilsmeier Haack reaction Pictet Spengler Iminylium ions Iminylium ions have the general structure R sub 2 sub C N sup sup . They form a subclass of nitrenium ion s. ref GoldBookRef title iminylium ions file I02964 ref See also ammonium External links reflist Category functional groups Category Chemistry suffixes es Iminio fr Iminium it Imminio nl Iminium pt Im nio zh ... more details
Thioenols also known as alkenthiols are alkene s with a thiol group affixed to one of the carbon atoms composing the double bond . Alkenes with a thiol group on both sides of the double bond are called enedithiols . Deprotonation Deprotonated anions of thioenols are called thioenolates . The C C double bond with adjacent alcohol gives thioenols and enedithiols their chemical characteristics, by which they present keto enol tautomerism . In keto enol tautomerism, thioenols interconvert with thioketone s or thioaldehyde s. The words thioenol and alkenthiol come from the words alkene or just ene , the suffix given to C C double bonded alkenes and thiol which represents the thioenol s thiol group . Thioketo thioenol tautomerism Thioenols interconvert with thio carbonyl compound s that have an hydrogen , like thioketone s and thioaldehyde s. The compound is Deprotonation deprotonated on one side and Protonation protonated on another side, whereas a single bond and a double bond are exchanged. This is called keto enol tautomerism . See also Enol External links http www.nrcresearchpress.com doi abs 10.1139 v98 027 Canadian journal of chemistry Category Sulfur compounds ... more details
morefootnotes date July 2011 The oxonium ion in chemistry is any oxygen cation with three chemical bond bonds . ref JerryMarch ref The simplest oxonium ion is the hydronium ion H sub 3 sub O sup sup . Another oxonium ion frequently encountered in organic chemistry is obtained by protonation or alkylation of a carbonyl group e.g. R C O sup sup R which forms a resonance structure with the fully fledged carbocation R C sup sup O R and is therefore especially stable center Image Carbonyl oxonium resonance 2D skeletal.png 250px center Stable alkyl oxonium salts exist they are extensively used as alkylating agents. For example, triethyloxonium tetrafluoroborate Chem Et 3 O Chem BF 4 is a white crystalline solid. It is a powerful ethylating agent. It can be used, for example, to produce ethyl esters when the conditions of traditional Fischer esterification are unsuitable. center align center class wikitable center Image Oxonium ion 2D.png 100px center center Image Trimethyloxonium 2D skeletal.png 100px center center Image Trimethyloxonium 3D balls.png 100px center center Image Trimethyloxonium 3D vdW.png 100px center center general trigonal pyramidal molecular geometry pyramidal br oxonium ion center center skeletal formula of the br trimethyloxonium cation center center ball and stick model br of trimethyloxonium center center space filling model br of trimethyloxonium center center Other hydrocarbon oxonium ions are formed by protonation or alkylation of alcohol s or ethers Chem R C O R 1 R 2 . In acidic media, the oxonium functional group produced by protonating an alcohol can be a leaving group in the Elimination reaction E2 elimination reaction, because when it receives an electron, it becomes a water molecule. The product is an alkene . Extreme acidity, heat and dehydrating conditions are usually required. Oxatriquinane and oxatriquinacene are unusually stable oxonium ions, first described in 2008. Oxatriquinane does not react with boiling water or with alcohols , th ... more details
The deliming operation in leather processing is a drum paddle or pit based operation where two main objectives are met ref citation title Leather Technician s Handbook first J.H. last Sharphouse page 104 publisher Leather Producer s Association isbn 0950228516 year 1983 ref Removal of alkali from the pelt and the consequent deswelling of the fibre s. Lowering of the liquor pH to the values used in the bating process. Deliming operations of cattle hides usually last 2 hours and are generally associated with the alkaline phase of beamhouse operations . The progress of deliming in pelts is monitored by the checking of pH values of process liquors and in the cutting of a pelt cross section . Phenolphthalein is used to monitor deliming pelt cross sectional progress. Removal of pelt alkali and deswelling As an acid is added it lowers the pH value of the internal pelt solution. This neutralization neutralizes the solution alkalinity. The lowering of the pH results in rapid protonation of the collagen basic groups. HI Lowering of liquor pH The acid present in the deliming agents neutralizes the process liquor pH. Typical values after effective, thorough deliming will range from 6 to 9. Ammonium salt deliming pH values should be pH 8 to 9. Deliming types The deliming process can be done with acids that can be rapid in their pH adjustment. Buffering salts like ammonium salts predominated the 20th century. Ammonium sulfate and ammonium chloride can be used as deliming agents and they follow the following chemistry NH sub 4 sub SO sub 4 sub NH sub 4 sub sup sup ammonium SO sub 4 sub sup 2 sup sulfate The ammonium ion is then free to penetrate the pelt cross section and further ionise to act as an acid NH sub 4 sub sup sup ammonium H sub 2 sub O NH sub 3 sub ammonia H sub 3 sub O sup sup hydronium The protons can then serve two functions, namely to Protonation protonate basic groups of the collagen and neutralization neutralize solution alkali chemicals. Other weak acids can be ... more details
Transition metal carbyne complexes are organometallic compound s with triple bond between carbon and the transition metal . They are also called metal alkylidynes the carbon is a carbyne ligand. Such compounds are useful in organic synthesis of alkyne s and nitrile s. They have been the focus on much fundamental research. ref Elschenbroich, C. Organometallics 2006 Wiley VCH Weinheim. ISBN 978 3 29390 6. ref Synthesis Transition metal carbyne complexes are most common for the early transition metals, especially Nb, Ta, Mo, W, and Re. The first example of a metal carbyne complex was prepared by Fischer school by treatment of Cr CO sub 5 sub C OMe Ph with boron trichloride Cr CO sub 5 sub C OMe Ph BBr sub 3 sub BrCr CO sub 4 sub CPh CO BBr sub 2 sub OMe Many high valent carbyne complexes have since been prepared, often by dehydrohalogenation of carbene complexes. Alternatively, amino substituted carbyne ligands sometime form upon protonation of electron rich isonitrile complexes. Similarly, O protonation of sub 3 sub CO ligands in clusters gives hydroxycarbyne complex. Many cluster bound carbyne complexes are known. These do not feature MC triple bonds, but the carbyne carbon is tetrahedral. One of the best known are the tricobalt derivatives, which are prepared from haloforms ref Dietmar Seyferth, Mara O. Nestle, John S. Hallgren sub 3 sub Alkylidyne Tris Trigarbonylcobalt Compounds Organocobalt Cluster Complexes Inorganic Syntheses, 1980, Volume 20, 224 226. DOI 10.1002 9780470132517.ch52 . ref 2 HCBr sub 3 sub 9 2 Co sub 2 sub CO sub 8 sub 2 HCCo sub 3 sub CO sub 9 sub 18 CO 3 CoBr sub 2 sub Structure Metal carbyne complexes exist as monomers, with fairly linear M C R linkages. The carbyne ligand can also serve as a bridging ligand . Dimerization of metal carbynes affords dimetallacycobutadienes. The M C distance is typically short. Reactions and applications Metal alkylidyne complexes have mainly been used for specialized reactions in the laboratory, the main u ... more details
protonation states with the same empirical formula and total charge physics charge . Tautomerizations ... anion e.g., an enolate 3. protonation at a different position of the anion . acid s 1. protonation ... 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
of protonation. A weak base is less protonated, leading to a lower pH and a lower percentage protonated ... concentration of the base, assuming that no protonation has occurred. A typical pH problem Calculate the pH and percentage protonation of a .20 M aqueous solution of pyridine, C sub 5 sub H sub 5 sub ... more details
Unreferenced date December 2009 Deprotonation is the removal of a proton H sup sup from a molecule , forming the conjugate base . The relative ability of a molecule to give up a proton is measured by its pKa pK sub a sub value. A low pK sub a sub value indicates that the compound is acidic and will easily give up its proton to a base chemistry base . The pK sub a sub of a compound is determined by many things, but the most significant is the stability of the conjugate base, which is determined mainly by the ability or inability of the conjugated base to stabilize the negative charge. The negative charge is stabilized when it is distributed on a large surface or a long chain. One of the mechanisms that distribute the negative charge on a longer chain or a ring is resonance structure resonance . The solvent can also assist in the stabilization of the negative charge on a conjugated base. Bases used to deprotonate depend on the pK sub a sub of the compound. When the proton is not particularly acid ic, and, as such, the molecule does not give up its proton easily, a base stronger than the commonly known hydroxide s is required. Hydride s are one of the many types of powerful deprotonating agents. Common hydrides used are sodium hydride and potassium hydride . The hydride forms hydrogen gas with the proton from the other molecule. However, the production of hydrogen also means that deprotonation using agents that release hydrogen is dangerous and should be done in an inert atmosphere e.g., nitrogen , as the hydrogen can ignite with the oxygen in the air. See also Protonation Hydronium Category Acid base chemistry Category Chemical reactions Category Reaction mechanisms Reaction stub ar cs Deprotonace es Deprotonaci n fr D protonation id Deprotonasi he nl Deprotonering ja pt Deprotona o simple Deprotonation sv Deprotonation zh ... more details
Unreferenced stub auto yes date December 2009 Chembox verifiedrevid 444074249 ImageFileL1 Pyridinium.svg ImageSizeL1 80px ImageFileR1 Pyridinium 3D balls.png ImageSizeR1 120px IUPACName pyridinium OtherNames Section1 Chembox Identifiers InChI 1S C5H5N c1 2 4 6 5 3 1 h1 5H p 1 InChIKey1 JUJWROOIHBZHMG UHFFFAOYSA O InChI1 1S C5H5N c1 2 4 6 5 3 1 h1 5H p 1 CASNo 16969 45 2 CASNo Ref cascite correct CAS PubChem 4989215 ChemSpiderID Ref chemspidercite correct chemspider ChemSpiderID 4169387 StdInChIKey Ref stdinchicite correct chemspider StdInChIKey JUJWROOIHBZHMG UHFFFAOYSA O SMILES nH 1ccccc1 StdInChI Ref stdinchicite correct chemspider StdInChI 1S C5H5N c1 2 4 6 5 3 1 h1 5H p 1 Section2 Chembox Properties C 5 H 6 N 1 Appearance Density MeltingPt BoilingPt Solubility Section3 Chembox Hazards MainHazards FlashPt Autoignition Pyridinium refers to the cationic form of pyridine . This can either be due to protonation of the ring nitrogen or because of addition of a substituent to the ring nitrogen, typically via alkylation . The lone pair of electron s on the nitrogen atom of pyridine is not delocalized , and thus pyridine can be protonated easily. Pyridine is often used as an organic base in chemical reactions, thus the pyridinium ion is produced as the counter ion to the leaving group in the reaction. This complex is often insoluble in the organic solvent, so precipitation of the pyridinium leaving group complex is an indication of the progress of the reaction. The pyridinium ion also plays a role in Friedel Crafts acylation . When pyridine is included, it forms a complex with the electrophillic acylium ion, rendering it even more reactive. See also Pyridinium chlorochromate Category Pyridines Organic compound stub es Piridinio fr Ion pyridinium nl Pyridinium ... more details
In organic chemistry ketone halogenation is a special type of halogenation . The position alpha next to the carbonyl group in a ketone is easily halogenated, due to the ability to form an enolate anion enolate in basic chemistry basic solution, or an enol in acidic solution. An example is the bromination of acetone in basic solution big CH sub 3 sub CO CH sub 3 sub OH sup sup CH sub 3 sub CO CH sub 2 sub sup sup H sub 2 sub O big big CH sub 3 sub CO CH sub 2 sub sup sup Br sub 2 sub CH sub 3 sub CO CH sub 2 sub Br Br sup sup big Image with unknown copyright status removed Image Acetone Bromination.GIF In acidic solution, usually only one alpha hydrogen is replaced by a halogen, because each successive halogenation is slower that the first. The halogen decreases the basicity of the carbonyl oxygen, thus making protonation less likely. However, in basic solution successive halogenations are more rapid , because the halogen withdraws electrons by induction and makes remaining hydrogens more acidic. In the case of methyl ketone s, this results in what is called the haloform reaction . ref Organic Chemistry Fifth Edition, by Paula Yurkanis Bruice. Pearson Prentice Hall, Upper Saddle River, NJ, 2007 ref References reflist 2 Category Substitution reactions reaction stub es Halogenaci n de cetonas mk nl Ketonhalogenering pt Halogena o de cetona ... more details
Chembox verifiedrevid 464198688 ImageFile Perbromic acid 3D vdW.png ImageSize ImageAlt IUPACName OtherNames Section1 Chembox Identifiers ChemSpiderID Ref chemspidercite correct chemspider ChemSpiderID 167074 InChI 1 BrHO4 c2 1 3,4 5 h H,2,3,4,5 InChIKey LLYCMZGLHLKPPU UHFFFAOYAZ StdInChI Ref stdinchicite correct chemspider StdInChI 1S BrHO4 c2 1 3,4 5 h H,2,3,4,5 StdInChIKey Ref stdinchicite correct chemspider StdInChIKey LLYCMZGLHLKPPU UHFFFAOYSA N CASNo Ref cascite correct ?? CASNo PubChem 192513 ChEBI Ref ebicite correct EBI ChEBI 29245 SMILES O Br O O O Section2 Chembox Properties H 1 Br 1 O 4 MolarMass 128.91 Appearance Density MeltingPt decomposes before melting, unstable as solid BoilingPt Solubility Section3 Chembox Hazards MainHazards powerful oxidizer FlashPt Autoignition The compound perbromic acid is the inorganic compound with the formula HBrO sub 4 sub . It is an oxoacid of bromine . Perbromic acid is unstable and cannot be formed by displacement of chlorine from perchlorate , as periodates are prepared. It can only be made by protonation of the perbromate ion. Perbromic acid is a strong acid and strongly oxidizing. It is the least stable of the halogen VII oxyacids. It decomposes rapidly on standing to bromic acid and oxygen . It reacts with base chemistry bases to form perbromate salts. See also Perbromate Further reading cite journal doi 10.1021 ic50072a008 title Perbromic acid and perbromates synthesis and some properties year 1969 last1 Appelman first1 Evan H. journal Inorganic Chemistry volume 8 pages 223 issue 2 Hydrogen compounds Category Hydrogen compounds Category Perbromates Category Oxidizing agents Category Oxidizing acids Inorganic compound stub de Perbroms ure it Acido perbromico ja ro Acid perbromic ru simple Perbromic acid zh ... more details
The Feist Benary synthesis is an organic reaction between halogen ketone s and carbonyl dicarbonyl compounds to substituted furan compounds. ref cite journal author Franz Feist title Studien in der Furan und Pyrrol Gruppe pages 1537 1544 doi 10.1002 cber.19020350263 journal Chemische Berichte issue 2 year 1902 volume 35 ref ref cite journal author Erich Benary title Synthese von Pyridin Derivaten aus Dichlor ther und Amino crotons ureester pages 489 493 doi 10.1002 cber.19110440175 journal Chemische Berichte year 1911 volume 44 ref This condensation reaction is catalysis catalyzed by amine s such as ammonia and pyridine . The first step in the ring synthesis is related to the Knoevenagel condensation . In the second step the enolate displaces an alkyl halogen in a nucleophilic aliphatic substitution . Image FeistBenarysynthesis.gif center Feist Benary synthesis A recent modification is the enantioselective interrupted Feist Benary reaction ref cite journal author Calter, M. A. Phillips, R. M. Flaschenriem, C. title Catalytic, Asymmetric, Interrupted Feist B nary Reactions journal Journal of the American Chemical Society year 2005 volume 127 issue 42 pages 14566 14567 doi 10.1021 ja055752d pmid 16231897 ref with a chiral auxiliary based on the cinchona alkaloid quinine based in the presence of proton sponge to the hydroxydihydrofuran. This type of alkaloids is also used in asymmetric synthesis in the AD mix . The alkaloid is protonation protonated throughout the reaction and transfers its Chirality chemistry chirality by interaction of the acidic ammonium salt ammonium hydrogen with the dicarbonyl group of pyruvate ethyl bromopyruvate in a 5 membered transition state . Image InterruptedFeistBenary.gif center interrupted Feist Benary reaction External links http www.wesleyan.edu chem faculty calter Calter group References Reflist Category Heterocycle forming reactions Category Name reactions pt S ntese de Feist Benary zh Feist B nary ... 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 Schaefer, J. P. Bloomfield, J. J. Org. React. 1967, 15 , 1 203. Review 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 Janice Gorzynski Smith. Organic Chemistry Second Ed. 2008. pp 932 933. 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 Organic Chemistry.org. Dieckmann Condensation. 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 pt Condensa o de Dieckmann zh ... more details
Kodiak is a brand of dipping tobacco manufactured by American Snuff Company , a U.S. smokeless tobacco manufacturer that also produces the Grizzly tobacco and Levi Garrett brands. ref http www.investor.reuters.wallst.com stocks company profile.asp?rpc 66&ticker RAI Company Profile for RAI , Reuters ref Introduced in 1981, Fact date June 2007 Kodiak is currently available in three flavours Wintergreen , Mint formerly Ice , and Straight , each featuring a picture of a Kodiak bear on the top label. ref http www.cwdlp.com moistPremium.htm Conwood Products Moist Premium ref The Kodiak Wintergreen variety is a strong brand of dipping tobacco. It is a base chemistry basic mixture with high nicotine content and a pH as high as 8.35. ref name mm 4819fs http www.cdc.gov tobacco data statistics MMWR 1999 mm 4819fs.htm Determination of Nicotine, pH, and Moisture Content of Six U.S. Commercial Moist Snuff Products Florida, January February 1999 Highlights , Centers for Disease Control and Prevention ref It has high levels of protonation unprotonated nicotine , the chemical form... that is most readily absorbed through the mouth into the bloodstream, when compared amongst other brands. ref name mm 4819fs Kodiak recently introduced pouches, which hold the moist snuff in a tea bag like pouch, preventing it from spreading around the mouth and keeping it out of the teeth. See also Snus References reflist External links http www.americansnuff.com American Snuff Co. Reynolds American Category Chewing tobacco brands Product stub ... more details
Acids and bases Unreferenced date April 2009 An organic base is an organic compound which acts as a base chemistry base . Organic bases are usually, but not always, proton acceptors. They usually contain nitrogen atoms, which can easily be protonated. Amines and nitrogen containing heterocyclic compound s are organic bases. Examples include pyridine methyl amine imidazole benzimidazole histidine phosphazene bases Hydroxide s of some organic cations Factors affecting alkalinity While all organic bases are considered to be Weak base weak , many factors can affect the alkalinity of the compounds. One such factor is the inductive effect . A simple explanation of the term would state that electropositive atoms such as carbon groups attached in close proximity to the potential proton acceptor have an electron releasing effect, such that the positive charge acquired by the proton acceptor is distributed over other adjacent atoms in the chain. The converse is also possible as alleviation of alkalinity electronegative atoms or species such as fluorine or the nitro group will have an electron withdrawal effect and thereby reduce the basicity. To this end, trimethylamine is a more potent base than merely ammonia , due to the inductive effect of the methyl groups allowing the nitrogen atom to more readily accept a proton and become a cation being much greater than that of the hydrogen atoms. Citation needed date April 2008 In guanidine s, the protonated form guanidinium chloride guanidinium has three resonance structure s, giving it increased stability and making guanadines stronger bases. Phosphazene bases also contain phosphorus and are, in general, more alkaline than standard amine s and nitrogen based heterocyclics. Protonation takes place at the nitrogen atom, not the phosphorus atom to which the nitrogen is double bonded. Hydroxide donors Some organic bases, such as tetramethylammonium hydroxide , tetrabutylammonium hydroxide , or choline hydroxide are hydroxide donors ra ... more details
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