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The Doebner-Miller reaction is the organic reaction of an aniline with α,β-unsaturated carbonyl compounds to form quinolines. Organic reactions are Chemical reactions involving Organic compounds The basic Organic chemistry reaction types are Addition reactions Elimination Aniline, phenylamine or aminobenzene is an Organic compound with the formula C6H7N In Organic chemistry, a carbonyl group is a Functional group composed of a Carbon Atom double-bonded to an Oxygen Quinoline, also known as 1-azanaphthalene, 1-benzazine, or benzopyridine, is a Heterocyclic Aromatic Organic compound. [1][2][3][4]

Scheme 1. The Doebner-Miller reaction

This reaction is also known as the Skraup-Doebner-Von Miller quinoline synthesis, and is named after the Czech chemist Zdenko Hans Skraup (1850-1910), and the Germans Oscar Döbner (Doebner) (1850-1907) and Wilhelm von Miller (1848-1899). Zdenko Hans Skraup ( March 3, 1850 &ndash September 10, 1910 was a Czech Austrian chemist who discovered the Skraup reaction, the first Quinoline For the game see 1850 (board game. 1850 ( MDCCCL) was a Common year starting on Tuesday (link Year 1910 ( MCMX) was a Common year starting on Saturday (link will display calendar of the Gregorian calendar (or a Common year starting For the game see 1850 (board game. 1850 ( MDCCCL) was a Common year starting on Tuesday (link Year 1907 ( MCMVII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common year Year 1848 ( MDCCCXLVIII) was a Leap year starting on Saturday (link will display the full calendar of the Gregorian Calendar (or a Leap Year 1899 ( MDCCCXCIX) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a Common When the α,β-unsaturated carbonyl compound is prepared in situ from two carbonyl compounds (via an Aldol condensation), the reaction is known as the Beyer method for quinolines. In Organic chemistry, a carbonyl group is a Functional group composed of a Carbon Atom double-bonded to an Oxygen In situ (ɪn siːˈtuː is a Latin phrase meaning in the place. An Aldol condensation is an Organic reaction in which an Enolate ion reacts with a Carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone followed

The reaction is catalyzed by lewis acids such as tin tetrachloride and scandium(III) triflate and bronsted acids such as p-toluenesulfonic acid, perchloric acid, amberlite and iodine. Tin(IV chloride, also known as tin tetrachloride or stannic chloride is a Chemical compound with the formula Sn[[chlorine Cl]]4 Scandium Triflate or Sc(OTf3 is a Chemical compound composed of Scandium with Triflate Counterions Scandium triflate is used as a In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are p -Toluenesulfonic acid (PTSA is an Organic compound with the formula CH3[[benzene C6H4]] SO3H Perchloric acid, HClO4 is an Oxoacid of Chlorine and is a colorless liquid soluble in water. ion-exchange resin is an insoluble matrix (or support structure normally in the form of small (1-2 mm diameter beads usually white or yellowish fabricated from an organic Polymer Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic

Reaction mechanism

The reaction mechanism for this reaction and the related Skraup synthesis is a matter of debate. Chemistry, a reaction mechanism is the step by step Sequence of Elementary reactions by which overall Chemical change occurs. The Skraup synthesis is a Chemical reaction used to synthesize Quinolines It is named after the Czech chemist Zdenko Hans Skraup (1850-1910 A 2006 study [5] proposes a fragmentation-recombination mechanism based on carbon isotope scrambling experiments. Carbon-14, 14C, or radiocarbon, is a Radioactive isotope of Carbon discovered on February 27, 1940, by In this study 4-isopropylaniline 1 is reacted with a mixture (50:50)of ordinary pulegone and the 14C-enriched isomer 2 and the reaction mechanism is outlined in scheme 2 with the labeled carbon identified with a red dot. Pulegone is a naturally occurring Organic compound obtained from the Essential oils of a variety of plants such as Nepeta cataria ( Catnip The first step is a nucleophilic conjugate addition of the amine with the enol to the amine ketone 3 in a reversible reaction. Nucleophilic conjugate addition is a type of Organic reaction. Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair. Enols (also known as alkenols) are Alkenes with a Hydroxyl group affixed to one of the carbon atoms composing the Double bond. A reversible reaction is a Chemical reaction that results in an equilibrium mixture of Reactants and products. This intermediate then fragmentates to the imine 4a and the saturated cyclohexanone 4b in a non-reversible reaction and both fragments recombine in a condensation reaction to the conjugated imine 5. An imine is a Functional group or Chemical compound containing a Carbon – Nitrogen Double bond. Cyclohexanone is a six-carbon cyclic molecule with a Ketone functional group A condensation reaction is a Chemical reaction in which two Molecules or moieties ( Functional groups) combine to form one single molecule together with A chemically conjugated system is a system of atoms Covalently bonded with alternating single and multiple (e In the next step 5 reacts with a second aniline molecule in a nucleophilic conjugate addition to imine 6 and subsequent electrophilic addition and proton transfer to leads to 7. In Organic chemistry, an electrophilic addition reaction is an Addition reaction where in a Chemical compound, a Pi bond is removed by the creation elimination of one aniline molecule through 8 and rearomatization leads to final product 9. An elimination reaction is a type of Organic reaction in which two Substituents are removed from a molecule in either a one or two-step mechanism. Because α-amino protons are not available in this model compound the reaction is not taken to the fully fledged quinoline.

Scheme 2. Doebner-Miller reaction mechanism

The fragmentation to 4a and 4b is key to this mechanism because it explains the isotope scrambling results. In the reaction only half the pulegone reactant (2) is labeled and on recombining a labeled imine fragment can react with another labeled ketone fragment or an unlabeled fragment and likewise a labeled ketone fragment can react with a labeled or unlabeled imine fragment. The resulting product distribution is confirmed by mass spectroscopy of the final product 9. Mass spectrometry is an analytical technique that identifies the chemical composition of a compound or sample based on the Mass-to-charge ratio of charged particles [6]

References

  1. ^ Doebner, O. ; Miller, W. v. Ber. 1881, 14, 2812. See also Anales de Química Bulletin des Sociétés Chimiques Belges Bulletin de la Société Chimique de France
  2. ^ Doebner, O. ; Miller, W. v. Ber. 1883, 16, 1664 & 2464. See also Anales de Química Bulletin des Sociétés Chimiques Belges Bulletin de la Société Chimique de France
  3. ^ Doebner, O. ; Miller, W. v. Ber. 1884, 17, 1712. See also Anales de Química Bulletin des Sociétés Chimiques Belges Bulletin de la Société Chimique de France
  4. ^ Bergström, F. W. Chem. Rev. 1944, 35, 153. Chemical Reviews (usually abbreviated as Chem Rev) is a peer-reviewed Scientific journal, published since 1924 by the American Chemical Society (Review)
  5. ^ On the Mechanism of the Skraup-Doebner-Von Miller Quinoline Synthesis Scott E. Denmark and Srikanth Venkatraman J. Org. Chem.; 2006; 71(4) pp 1668 - 1676; Abstract
  6. ^ each ion peak M, M+1, M+2, M+3 is equally represented and given the reaction conditions pulegone itself does not fragmentate in absence of amine. The Journal of Organic Chemistry (abbreviated as J Org Chem or JOC) is a Scientific journal for original contributions of fundamental

See also

The Combes quinoline synthesis is a Chemical reaction involving the condensation of unsubstituted Anilines ( 1) with β-di Ketones ( The Doebner reaction is the Chemical reaction of an Aniline with an Aldehyde and Pyruvic acid to form Quinoline -4- Carboxylic The Gould-Jacobs reaction is an Organic synthesis for the preparation of Quinolines. The Knorr quinoline synthesis is an Intramolecular Organic reaction converting a β-ketoanilide to a 2-hydroxyquinoline using Sulfuric acid The Skraup synthesis is a Chemical reaction used to synthesize Quinolines It is named after the Czech chemist Zdenko Hans Skraup (1850-1910
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