unreferenced date May 2009 In thermochemistry chemical thermodynamics , an endergonicreaction also called an unfavorable reaction or a nonspontaneous reaction is a chemical reaction in which the standard ... in Free Energy process. Pull Reagents can be pulled through an endergonicreaction, if the reaction products are cleared rapidly by a subsequent exergonic reaction. The concentration of the products of the endergonicreaction thus always remains low, so the reaction can proceed. A classic example of this might be the first stage of a reaction which proceeds via a transition state . The process of getting to the top of the activation energy activation energy barrier to the transition state is endergonic. However, the reaction can proceed because having reached the transition state, it rapidly evolves via an exergonic process to the more stable final products. Push Endergonic reactions can be pushed by coupling them to another reaction which is strongly exergonic, through a shared intermediate ... an endergonicreaction occur, is so common in cell biochemistry that ATP is often called the universal energy currency of all living organisms. See also Endergonic Exergonic Exergonic reaction ... the total amount of energy is a loss it takes more energy to start the reaction than what you ... Exergonic reaction Exergonic Reaction . Under constant temperature and constant pressure conditions ... 0 math for the reaction at standard state ie at standard pressure 1 Bar unit bar , and standard concentrations ... constant for the reaction is related to G by the relation math K e frac Delta G circ RT math where ... math K 1 , math so that starting from molar stoichiometric quantities such a reaction would move backwards toward equilibrium, not forwards. Nevertheless, endergonic reactions are quite common in nature, especially in biochemistry and physiology . Examples of endergonic reactions in cells include ... conduction and muscle contraction . Making Endergonic reactions happen Endergonic reactions can be achieved ... more details
For Exergonic and Endergonic reactions , see the separate articles Endergonicreaction Exergonic reaction See also Exergonic Endergonic Exothermic Endothermic Disambig ... more details
Unreferenced date May 2009 Merge to anabolism date September 2010 Endergonic from the suffix endo , derived for the Greek word endon , within and the English suffix ergonic, derived from the Greek word ergon , work thermodynamics work means absorbing energy in the form of work. Endergonic reactions are not spontaneous. By thermodynamic standards, work, a form of energy , is defined as moving from the wikt surroundings surroundings the external region to the system the internal region . Thus, an endergonic process, as contrasted with an exergonic process, is one wherein the system absorbs energy from the surroundings. As a result, during an endergonic process, energy is put into the system. If the transformation occurs at constant pressure and temperature, G 0 . An endergonicreaction is a chemical reaction that absorbs energy in the form of work. A good example of an endergonicreaction is photosynthesis . Also, in metabolism , an endergonicreaction is anabolic , meaning, the break down of energy. In metabolism, catabolic and anabolic are coupled by Adenosine triphosphate ATP . An endergonicreaction is, in essence, the opposite of an exergonic reaction. Since endergonic reactions require energy, they form molecular bonds, which decreases entropy . These bonds are energy carriers, so the formation of these bonds requires some energy input. Cold packs, which become cold after mixing two liquids, exploit this property. In fact, a common reaction that is clearly endergonic is the mixing of ammonium chloride and water. There is a net drop in temperature of the reaction as a result of the solvation of ammonium ion s. See also col begin col break Exergonic Exergonic reaction Exothermic Endothermic col break Exothermic reaction Endothermic reaction Warm blooded Endotherm Warm blooded Exotherm col end Category Thermodynamics Category Chemical thermodynamics ar hu Endergonikus reakci nl Endergoon ... more details
Wiktionary reactionReaction may refer to Response disambiguation Response to another event Adverse drug reaction Chemical reaction Emotional reaction Light reaction Nuclear reaction TNA Reaction , a documentary show of Total Nonstop Action Wrestling TNA behind scenes. Reaction physics , as defined by Newton s third law Reactionary , a political tendency Reflex reaction other uses Reaction Records , a record label ReAction GUI a GUI toolkit used on AmigaOS Reaction software , a Perl application framework A single by Dead Letter Circus Disambiguation als Reaktion bg cs Reakce de Reaktion el et Reaktsioon es Reacci n eo Reakcio fa fr R action gl Reacci n hr Reakcija it Reazione nl Reactie ja no Reaksjon pl Reakcja pt Rea o ro Reac ie ru simple Reaction fi Reaktio uk zh ... more details
An exergonic reaction is a chemical reaction where the change in the Gibbs free energy is negative, ref IUPAC Gold Book definition http www.iupac.org goldbook E02262.pdf search Exergonic 20reaction exergonic exoergic reaction ref indicating a spontaneous reaction . Symbolically, the release of Gibbs free energy, G , in an exergonic reaction is denoted as math Delta G G rm products G rm reactants 0. , math Although exergonic reactions are said to occur spontaneously , this does not imply that the reaction will take place at an observable Reaction rate rate . For instance, the Catalysis Background disproportionation of hydrogen peroxide is very slow in the absence of a suitable catalyst. It has been suggested that eager would be a more intuitive term in this context. ref cite journal doi 10.1021 ed061p710 last Hamori first Eugene coauthors James E. Muldrey date 1984 title Use of the world eager instead of spontaneous for the description of exergonic reactions journal Journal of Chemical Education volume 61 issue 8 pages 710 ref More generally, the terms exergonic and endergonic relate to the Gibbs free energy change in any process, not just chemical reactions. An example of an exergonic reaction is cellular respiration. The terms exothermic and endothermic reactions relate to the enthalpy change of a process. See also Endergonicreaction A References reflist Category thermochemistry de Exergon pl Reakcja egzoenergetyczna ... more details
change in any process, not just chemical reactions. In endergonicreaction s and exergonic reaction s it is the sign of the Gibbs free energy that determines the equilibrium point, and not enthalpy . The related concepts endergonic and exergonic apply to all physical processes. the conceptually ... Exergonic Endergonicreaction Exergonic reaction Exothermic Endothermic reaction Warm blooded ...Image ThermiteFe2O3.JPG thumb right A thermite reaction using Iron III Oxide An exothermic reaction is a chemical reaction that releases energy in the form of light or heat . It is the opposite of an endothermic reaction . Expressed in a chemical equation reactants products energy Overview An exothermic reaction is a chemical reaction that is accompanied by the release of heat. In other words, the energy needed for the reaction to occur is less than the total energy released. As a result of this, the extra ... the medium in which the reaction is taking place gains heat, the reaction is exothermic. The absolute ... change, H, of a chemical reaction is much easier to measure and calculate. A bomb calorimeter is very suitable for measuring the energy change, H, of a combustion reaction. Measured and calculated ... in bond making products Image ac com.svg 300px thumb right A sketch of an exothermic reaction by definition the enthalpy change has a negative value H 0 For an exothermic reaction, this gives a negative value for H, since a larger value the energy released in the reaction is subtracted from a smaller value the energy used for the reaction . For example, when hydrogen burns 2H sub 2 sub O ... such as direct reaction of acid and base Adding concentrated acid to water Burning of a substance Adding water to anhydrous copper II sulfate The thermite reaction Reactions taking place in a self heating ... 4 fall to n 2, energy is released so, it is exothermic. Where an exothermic reaction causes heating of the reaction vessel which is not controlled, the rate of reaction can increase, in turn causing heat ... more details
A reaction step of a chemical reaction is defined as An elementary reaction , constituting one of the stages of a stepwise reaction in which a reaction intermediate or, for the first step, the reactants is converted into the next reaction intermediate or, for the last step, the product chemistry products in the sequence of intermediates between reactants and products . ref http goldbook.iupac.org R05178.html IUPAC Gold Book definition of reaction step ref Notes reflist physical chemistry stub Category Chemical kinetics pt Etapa de rea o ... more details
The Carbylamine reaction is a chemical test for detection of primary amine s. In this reaction, the analyte is heated with alcoholic potassium hydroxide and chloroform. If a primary amine is present, the isocyanide is formed. For example, the reaction with ethylamine Image Carbylamine.png 500px The carbylamine reaction with ethyl amine The reaction with aniline File Aniline carbylamine reaction.png 500px The carbylamine reaction with aniline The carbylamine test does not give a positive reaction with secondary and tertiary amines. References http www.books about california.com Pages Experimental Organic Chemistry Ex Organic Chem Chap 09.html Carbylamine reaction Category Organic reactions Category Chemical tests es Reacci n carbilamina ta ... more details
Unreferenced stub auto yes date December 2009 Orphan date December 2009 The np reaction is an example of a nuclear reaction . It is the reaction which occurs when a neutron enters a atomic nucleus nucleus and a proton leaves the nucleus simultaneously. For example sulfur 32 and nitrogen 14 both undergo this reaction when neutron irradiation bombarded with neutrons , thus forming phosphorus 32 and carbon 14 . DEFAULTSORT Np Reaction Particle stub Category Nucleosynthesis ... more details
The Bunsen Reaction is a chemical reaction that describes water, sulfur dioxide , and iodine reacting to form sulfuric acid and hydrogen iodide . This reaction is the first step in the Sulfur iodine cycle to produce hydrogen . 2H sub 2 sub O SO sub 2 sub I sub 2 sub H sub 2 sub SO sub 4 sub 2HI The reaction is named after Robert Bunsen . A similar reaction is the basis for Karl Fischer titration . unreferenced date October 2007 Category Inorganic reactions reaction stub ... more details
The Pellizzari reaction is the chemical reaction of an amide and a hydrazide to form a 1,2,4 triazole . ref Pellizzari, G. Gazz. Chim. Ital. 1911 , 41 , 20. ref Image Pellizzari Reaction Scheme.png center 400px The Pellizzari reaction References Reflist See also Einhorn Brunner reactionreaction stub Category Condensation reactions Category Heterocycle forming reactions Category Name reactions es Reacci n de Pellizzari id Reaksi Pellizzari ja zh ... more details
The Kochi reaction is an organic reaction for the decarboxylation of carboxylic acid s to alkyl halide s with lead tetraacetate and a lithium chloride or other lithium salts ref A New Method for Halodecarboxylation of Acids Using Lead IV Acetate Jay K. Kochi J. Am. Chem. Soc. 1965 87 11 2500 2502. DOI 10.1021 ja01089a041 ref . Image Kochi reaction.png The Kochi reaction 550px The reaction is a variation of the Hunsdiecker reaction . References Reflist DEFAULTSORT Kochi Reaction Category Organic reactions Category Name reactions de Kochi Reaktion pl Reakcja Kochiego zh Kochi ... more details
The Fernandez reaction is reaction that occurs to signal a positive result in the lepromin skin test for leprosy . The reaction occurs in the skin at the site of injection if the body possesses antibody antibodies to the Dharmendra antigen , one of the antigen s found in Mycobacterium leprae , the bacteria that causes leprosy. The reaction occurs via a delayed type hypersensitivity mechanism. This reaction occurs within 48 hours of injection of lepromin and is seen in both lepromatous and tuberculoid forms of leprosy. In contrast, the Mitsuda reaction occurs 5 6 weeks after injection of lepromin and is only seen in patients with the tuberculoid form of leprosy not the lepromatous form, in which the body does not mount a strong response against the bacterium . In terms of mechanism of action and appearance, the reaction is similar to the tuberculin reaction of a positive Mantoux test for tuberculosis . Category Skin tests Category Leprosy medical stub ... more details
The Doebner reaction is the chemical reaction of an aniline with an aldehyde and pyruvic acid to form quinoline 4 carboxylic acid s. ref Doebner, O. Ann. 1887 , 242 & 265. ref ref Bergstrom, F. W. Chem. Rev. 1944 , 35 , 156. Review ref Image Doebner Reaction Scheme.png center 350px The Doebner reaction References Reflist See also Conrad Limpach reaction Doebner Miller reactionreaction stub Category Carbon carbon bond forming reactions Category Condensation reactions Category Quinoline forming reactions Category Multiple component reactions Category Name reactions es S ntesis de quinolinas de Doebner zh ... more details
In chemistry , a concerted reaction is a chemical reaction in which all bond breaking and bond making occurs in a single step. Reactive intermediate s or other unstable high energy intermediates are not involved. Concerted reaction rate s tend not to depend on solvent Chemical polarity polarity ruling out large buildup of electrical charge charge in the transition state . Pericyclic reactions are concerted reactions. In the SN2 S sub N sub 2 reaction a concerted reaction also takes place. Because the reaction rate is bimolecular there are two molecular species controlling the rate of the reaction. Because the rate is dependent on two molecules the reaction does not have any intermediate steps, only a transition state . This means that all the bond making and bond breaking takes place in a single step. In order for the reaction to occur both molecules must be situated correctly. Therefore, the reaction is said to be concerted because it occurs in one step. References Carey, Francis A. Sundberg, Richard J. 1984 . Advanced Organic Chemistry Part A Structure and Mechanisms 2nd ed. . New York N.Y. Plenum Press. ISBN 0 306 41198 9. Category organic reactions ar es Reacci n concertada nl Concerted reactie pl Reakcja skoordynowana pt Rea o concertada zh ... more details
The Thorpe reaction is a chemical reaction described as a self condensation of aliphatic nitrile s catalyzed by Base chemistry base to form enamine s. Ref Baron1904 Ref Ziegler1933 Ref Schaefer1967 The reaction was discovered by Jocelyn Field Thorpe . Image Thorpe Reaction Scheme.png center 500px The Thorpe reaction Thorpe Ziegler reaction The Thorpe Ziegler reaction named after Jocelyn Field Thorpe and Karl Ziegler , or Ziegler method , is the intramolecular modification with a dinitrile as a reactant and a cyclic ketone as the final reaction product after acidic hydrolysis. The reaction is conceptually related to the Dieckmann condensation . External links Thorpe Ziegler reaction 4 Phosphorinanone, 1 phenyl Organic Syntheses , Coll. Vol. 6, p.932 1988 Vol. 53, p.98 1973 http www.orgsynth.org orgsyn pdfs CV6P0932.pdf Link References Note Baron1904 Baron, H. Remfry, F. G. P. Thorpe, Y. F. J. Chem. Soc. 1904 , 85 , 1726. Note Ziegler1933 Karl Ziegler et al. Ann. 1933 , 504 , 94. Note Schaefer1967 Schaefer, J. P. Bloomfield, J. J. Org. React. 1967 , 15 , 1. Review Category Carbon carbon bond forming reactions Category Condensation reactions Category Name reactions de Thorpe Ziegler Reaktion ja ru zh ... more details
The Bosch reaction is a chemical reaction between carbon dioxide and hydrogen that produces elemental carbon graphite , water and a 10 return of invested heat . This reaction requires the introduction of iron as a catalyst and requires a temperature level of 530 730 degrees Celsius. ref Messerschmid, Ernst and Reinhold Bertrand. Space Stations. Springer. 1999. ref The overall reaction is as follows CO sub 2 sub gas g 2 H sub 2 sub g C solid s 2 H sub 2 sub O g The above reaction is actually the result of two reactions. The first reaction, the reverse water gas shift reaction , is a fast one. CO sub 2 sub H sub 2 sub CO H sub 2 sub O The second reaction controls the reaction rate . CO H sub 2 sub C H sub 2 sub O The overall reaction produces 2.3× 10 sup 3 sup joule s for every gram of carbon produced at 650 Celsius C . Reaction temperatures are in the range of 450 to 600 C. The reaction can be accelerated in the presence of an iron , cobalt or nickel catalyst . Ruthenium also serves to speed up the reaction. Together with the Sabatier reaction the Bosch reaction is studied as a way to remove carbon dioxide and to generate clean water aboard a space station ref http oregonstate.edu atwaterj h2o gen.htm Methods of water production ref The reaction is also used to produce graphite for radiocarbon dating with Accelerator Mass Spectrometry . It is named after the German chemist Carl Bosch . Citation needed date March 2008 The Bosch reaction is being investigated for use in maintaining space station life support. Though the Bosch reaction would present a completely closed hydrogen and oxygen cycle which only produces atomic carbon as waste, difficulties maintaining its higher required temperature and properly handling carbon deposits mean significantly more research ... of elemental carbon tends to foul the catalyst s surface, which is detrimental to the reaction s efficiency ... 1971002858.pdf A carbon dioxide reduction unit using Bosch reaction Category Organic redox reactions ... more details
The Ullmann reaction or Ullmann coupling ref cite journal title The Ullmann Synthesis of Biaryls author ... ref is a coupling reaction between aryl halide s with copper . The reaction is named after Fritz Ullmann ... reaction, note the unusual reaction medium, which, at these temperatures , is ordinary sand The traditional version of the Ullmann reaction requires harsh reaction conditions, and the reaction ... of the Ullmann Reaction author J. Hassan, M. Sevignon, C. Gozzi, E. Schulz, M. Lemaire journal Chemical Reviews volume 102 issue pages 1359 1470 year 2002 url doi 10.1002 cber.190103402141 ref The reaction mechanism of the Ullmann reaction is extensively studied. Electron spin resonance rules out ... with palladium catalysts is unlikely for copper because copper III is rarely observed. The reaction ... bond bond Metathesis reaction metathesis ref Derek van Allen, PhD Thesis, University of Massachusetts ... Ullmann reaction is limited to electron deficient aryl halides and requires harsh reaction conditions. Modern variants of the Ullman reaction employing palladium and nickel have widened the substrate scope of the reaction and rendered reaction conditions more mild. Yields are generally still ... 10.1002 0471264180.or063.03 10.1002 0471264180.or063.03 ref In organic synthesis this reaction is often replaced by palladium coupling reactions such as the Heck reaction , the Hiyama coupling and the Sonogashira coupling . In a variation of the Ullmann reaction, 2 bromo vinyl benzene is reacted ..., Weiliang Bao and Yong Jiang, L Proline promoted Ullmann type reaction of vinyl bromides with imidazoles ... CC article.asp?doi b501628b Abstract ref The reaction requires L proline L proline catalysis . Image UllmannReactionWang2005.svg center Imidazole Ullmann reaction. Note the reaction medium BMIMBF4 Note ... I thiophene 2 carboxylate , a copper reagent used in the Ullmann reaction References Reflist DEFAULTSORT Ullmann Reaction Category Condensation reactions Category Carbon carbon bond forming reactions ... more details
An elementary reaction is a chemical reaction in which one or more of the chemical species react directly to form products in a single reaction step and with a single transition state . ref GoldBookRef file E02035 title elementary reaction ref In a unimolecular elementary reaction a molecule , A, Dissociation chemistry dissociates or Isomerisation isomerises to form the products s . math mbox A rightarrow mbox products math The reaction rate rate of such a reaction, at constant temperature, is proportional to the concentration of the species A math frac d mbox A dt k mbox A math In a bimolecular elementary reaction, two atom s, molecule s, ion s or Radical chemistry radical s, A and B, react together to form the product s math mbox A B rightarrow mbox products math The rate of such a reaction, at constant temperature, is proportional to the product of the concentrations of the species A and B. math frac d mbox A dt frac d mbox B dt k mbox A mbox B math This rate expression can be derived from first principles by using collision theory . The rate expression for an elementary bimolecular reaction is sometimes referred to as the Law of Mass Action as it was first proposed by Guldberg and Waage in 1864. An example of this type of reaction is a cycloaddition reaction. Three chemical species must react simultaneously with each other in a trimolecular elementary reactions. It follows that such reactions are very rare. Any chemical reaction can be broken down into a set of elementary reactions. It is not always possible to derive an overall rate equation for non trivial reaction schemes, but analytical solutions are possible in favourable cases, see, for example, the steady state chemistry steady state approximation or Michaelis Menten kinetics for enzyme based reactions. Notes references Reaction mechanisms Category Chemical kinetics Category Physical chemistry bs Elementarna reakcija de Elementarreaktion et Elementaarreaktsioon es Reacci n elemental fr Processus l mentaire ... more details
The Povarov reaction is an organic reaction described as a formal cycloaddition between an aromatic imine and an alkene . The imine in this organic reaction is a condensation reaction product from an aniline ... be able to donate electrons. Such alkenes are enol ether s and enamine s. The reaction product in the original Povarov reaction is a quinoline . Because the reactions can be carried out with the three components premixed in one reactor it is an example of a multi component reaction . Image Povarov reaction general.svg Povarov reactionReaction mechanism The reaction mechanism for the Povarov reaction ... base in a condensation reaction . The Povarov reaction requires a lewis acid such as boron trifluoride to activate the imine for an electrophilic addition of the activated alkene . This reaction ... substitution . Two additional elimination reaction s create the quinoline ring structure. Image PovarovReaction.gif frame center Scheme 1 . The Povarov reaction The reaction is also classified as a subset of aza Diels Alder reaction s ref Recent synthetic developments in a powerful imino Diels Alder reaction Povarov reaction application to the synthesis of N polyheterocycles and related alkaloids ... ref Examples The reaction depicted in scheme 2 illustrates the Povarov reaction with an imine ... in Povarov reaction of benzylidene 3 nitrophenyl amine Paul J. Stevenson and Isla Graham ... ref . This reaction is regioselective because the iminium ion preverentially attacks the nitro ..., the most electron rich ring position is now ortho and not para. The reaction is also Diastereomer ... 2 regio and diastereoselective Povarov reaction Variations One variation of the Povarov reaction is a four component reaction ref Straightforward Access to a Structurally Diverse Set of Oxacyclic Scaffolds through a Four Component Reaction Oscar Jim nez, Guillermo de la Rosa, Rodolfo Lavilla Angewandte ... cgi bin abstract 112092897 ABSTRACT Abstract ref . Whereas in the traditional Povarov reaction ... more details
Reactionbox verifiedrevid 342064841 Type Condensation reaction NamedAfter William Henry Perkin Section2 Reactionbox Identifiers RSC ontology id verified rsccite RSC ontology id 0000003 Reaction Reactionbox Reaction Reactant1 Aromatic aldehyde Reactant2 Acid anhydride Reagent1 Alkali salt of the acid Product1 Cinnamic acid derivatives The Perkin reaction is an organic reaction developed by Sir William Henry Perkin William Henry Perkin that can be used to make cinnamic acid s by the aldol condensation of aromatic aldehydes and acid anhydride s in the presence of an alkali salt of the acid. ref Perkin, W. H. J. Chem. Soc. 1868 , 21 , 53, 181. ref ref Perkin, W. H. J. Chem. Soc. 1877 , 31 , 388. ref Image Perkin Reaction Scheme.png center 650px The Perkin reaction Several reviews have been written. ref Johnson, J. R. Org. React. 1942 , 1 , 210. Review ref ref House, H. O. Modern Synthetic Reactions W. A. Benjamin, Menlo Park, California, 2nd ed, 1972 pp 660 663. ref ref Rosen, T. Comp. Org. Syn. 1991 , 2 , 395 408. Review ref . The reaction of phenylacetic acid and benzaldehyde with triethylamine and acetic anhydride to alpha phenylcinnamic acid is an example of this reaction type. Reaction mechanism Image Perkin reaction mechanism.svg center 650px The Perkin reaction The above mechanism is not universally accepted, as several versions exist, including decarboxylation without acetic group transfer ref Bansal, Raj K. Organic Reaction Mechanisms , Tata McGraw Hill, 3rd Ed, 1998, pp. 199 201. ref . References reflist See also Erlenmeyer Pl chl azlactone and amino acid synthesis Stobbe condensation DEFAULTSORT Perkin Reaction Category Condensation reactions Category Name reactions sci stub ar ca Reacci de Perkin de Perkin Reaktion it Reazione di Perkin nl Perkin reactie ja pl Kondensacja Perkina ru ta uk zh ... more details
The Appel reaction is an organic reaction that converts an alcohol into an alkyl chloride using triphenylphosphine and carbon tetrachloride . ref cite journal title Tertiary Phosphane Tetrachloromethane, a Versatile Reagent for Chlorination, Dehydration, and P N Linkage author Rolf Appel journal Angewandte Chemie International Edition in English volume 14 issue 12 pages 801 811 year 1975 url doi 10.1002 anie.197508011 ref Image Appel Reaction Scheme.png center 250px The Appel reaction The Appel reaction is a mild method of halide introduction, and is successful on primary, secondary, and most tertiary alcohols. The use of carbon tetrabromide or bromine as a halide source will yield alkyl bromides, while using methyl iodide or iodine will give alkyl iodide s. Reaction mechanism The initial step of the Appel reaction is the formation of the phosphonium salt pair 2 . Deprotonation of the alcohol, forming chloroform 3 , yields an alkoxide ion pair 4 . The nucleophilic displacement of the chloride by the alkoxide yields intermediate 5 . With primary and secondary alcohols, the chloride anion reacts in a SN2 reaction SN2 process forming the desired alkyl chloride 6 and triphenylphosphine oxide 7 . Tertiary alcohols form the products 6 and 7 via a SN1 reaction SN1 mechanism. The driving force behind this and similar reactions is provided by the formation of solid triphenylphosphine oxide, which phase separates from the reaction mixture. The yields are almost quantitative. Image Appel Reaction Mechanism.png center 600px The mechanism of the Appel reaction An example is the chlorination of geraniol to geranyl chloride., ref OrgSynth author Jose G. Calzada and John Hooz title Geranyl chloride collvol 6 collvolpages 634 prep cv6p0634 ref References Reflist See also Mitsunobu reaction Organophosphorus chemistry DEFAULTSORT Appel Reaction Category Substitution reactions Category Name reactions de Appel Reaktion es Reacci n de Appel nl Appel reactie ja zh Appel ... more details
The Barbier reaction is an organic reaction between an alkyl halide and a carbonyl group as an electrophilic substrate in the presence of magnesium , aluminium , zinc , indium , tin or its salts. The reaction product is a primary, secondary or tertiary alcohol . The reaction is similar to the Grignard reaction but the crucial difference is that the Barbier reaction is a one pot synthesis whereas a Grignard reagent is prepared separately before addition of the carbonyl compound. ref cite journal author Barbier, P. url http gallica.bnf.fr ark 12148 bpt6k30841.pleinepage.f110.langFR title Synth se ... it is possible in many cases to run the reaction in water which makes the procedure part of green chemistry . The Barbier reaction is named after Victor Grignard s teacher Philippe Barbier . Examples of Barbier reactions are the reaction of propargylic bromide with butanal with zinc metal in water ref cite journal title Zn Mediated Regioselective Barbier Reaction of Propargylic Bromides in THF ... Image BarbierReaction1.png 507px center Barbier reaction center small With a substituted alkyne instead of a terminal alkyne the allene product is favoured small center the intramolecular Barbier reaction ... and their reaction with samarium diiodide author Tore Skj ret and Tore Benneche journal Arkivoc pages ... 442px center Barbier reaction the reaction of an allyl bromide with formaldehyde ... 502px center Barbier reaction center small The Barbier reaction is accompanied by an allylic rearrangement to a terminal alkene small center or another allyl bromide in a reaction with benzaldehyde ... Mediated Aqueous Barbier Grignard Reaction author Gary W. Breton, John H. Shugart, Christine A. Hughey ... 464px center Barbier reaction center small The observed diastereoselectivity for this reaction is erythro threo 83 17 small center Related reactions Grignard reaction , Nozaki Hiyama Kishi reaction External links Barbier reaction University of Connecticut http orgchem.chem.uconn.edu ... more details
The Tishchenko reaction is a chemical reaction that involves disproportionation of an aldehyde lacking a hydrogen atom in the alpha position in the presence of an alkoxide . Ref 1 The reaction product is an ester . Catalyst s are aluminium alkoxides or sodium alkoxides. Benzaldehyde reacts with sodium benzyloxide generated from sodium and benzyl alcohol to benzyl benzoate . Ref 2 Image Tishchenko reaction.gif center The Tishchenko reaction benzaldehyde reacts to benzyl benzoate, the catalyst is generated in situ from sodium and benzyl alcohol formaldehyde Paraformaldehyde reacts with boric acid to methyl formate . Ref 3 The key step in the reaction mechanism for this reaction is a 1,3 hydride shift in the hemiacetal intermediate formed from two successive nucleophilic addition reactions, the first one from the catalyst. The hydride shift regenerates the alkoxide catalyst. Image Tishchenko reaction mechanism.gif center The Tishchenko reactionreaction mechanism In the related Cannizzaro reaction the base is sodium hydroxide and then the organic oxidation oxidation product is a carboxylic acid and the organic reduction reduction product is an alcohol . Related reactions Aldol Tishchenko reaction Baylis Hillman reaction Cannizzaro reaction Meerwein Ponndorf Verley Reduction Oppenauer Oxidation References Note 1 V. Tishchenko, J. Russ. Phys. Chem. Soc. 1906 , 38 , 355, 482, 540, 547. Note 2 OrgSynth author Kamm, O. Kamm, W. F. title Benzyl benzoate collvol 1 collvolpages 104 year 1941 prep cv1p0104 Note 3 cite journal author Paul R. Stapp journal J. Org. Chem. year 1973 volume 38 issue 7 pages 1433 1434 doi 10.1021 jo00947a049 title Boric acid catalyzed Tishchenko reactions category organic reactions Category Name reactions de Claisen Ti enko Reaktion ja zh ... more details
Unreferenced stub auto yes date December 2009 Reaction shot is a term used in motion picture film production production and cinematography referring to a basic unit of film grammar. It is a shot which cuts away from the main scene in order to show the reaction of a character to it. A reaction shot usually implies the display of some sort of emotion on the face of the actor being shown, and is thus most commonly a close up shot although a group of actors may be shown reacting together . A reaction shot is also generally bereft of dialogue , though this is not an absolute rule. Its main purpose is to show an emotional response to the immediately preceding action or words of another character in the scene, or to an event in the immediately preceding scene which may or may not involve another actor e.g., an explosion, monster, empty room, etc. The assumption behind the logic of the reaction shot is that the emotional reaction of the actor being depicted will either advance the story forward, reveal character traits of the character in the reaction shot, or emphasize character traits of another character that were displayed in the action or dialog present in the preceding shot. A completely unemotional reaction may also be important if it provides information to the audience or is unexpected in the context of the scene. Reaction shots can be especially critical in comedy , as the reaction of an actor or actors to a dramatic incident provides a psychological cue to the audience about how to respond to that incident themselves. In some cases the deliberate avoidance of showing a reaction shot can be used by a filmmaker to dramatic effect for instance, if the filmmaker does not want the audience to see a character s reaction to a particular incident at that point in time. DEFAULTSORT Reaction Shot Category Film techniques Film term stub ... more details
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