Reactions of alicyclic ketones in carbon tetrachloride. II. Kinetics of the chlorination of 2-chlorocyclopentanone and 2-chlorocyclohexanone, catalyzed by hydrogen chloride

Stamhuis, Eize; Maatman, Henk; Joosten, G.E.H.

doi:10.1139/v86-278

Cited by 2 publications

(3 citation statements)

References 7 publications

(12 reference statements)

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“…S(Y), of the 2-chloro ketones never exceeds 86% and even at very low fractional conversions of the ketone a mixture of the three isomeric dichloro ketones is formed. The rate of chlorination of the 2-chloro ketones is much smaller than that of the unsubstituted compounds (16). Therefore a normal consecutive chlorination of the monochloro ketone can be excluded.…”

Section: Proposed Reaction Schemementioning

confidence: 96%

“…[16] [cp] is unknown due to the dimerization. An expression for [cp] in terms of the total ketone concentration [cpIo and the equilibrium constant K A of the self-association can be derived, see Appendix I.…”

Section: Proposed Reaction Schemementioning

confidence: 99%

“…[17] in eq. [16] Table 8) and experimental rates of chlorination of cp. T = 298 K. experimental reaction rates yields the equilibrium constant of the association K A and the concentration independent factor K l k 2 in eq.…”

Section: Proposed Reaction Schemementioning

confidence: 99%

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Reactions of alicyclic ketones in carbon tetrachloride. I, The kinetics of the chlorination of cyclopentanone and cyclohexanone catalyzed by hydrogen chloride

Stamhuis¹,

Maatman²,

Stinissen³

et al. 1986

Can. J. Chem.

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Received July 10, 1 9 S 5 EIZE J. STAMHUIS, HENK MAATMAN, HENK STINISSEN, and GEERT E. H. JOOSTEN. Can. J. Chem. 64, 1681Chem. 64, (1986. The kinetics of the direct chlorination of cyclopentanone (cp) and cyclohexanone (ch) in carbon tetrachloride, catalyzed by hydrogen chloride, was studied. The rate of chlorination, measured by flow and stopped-flow techniques, is zero order in chlorine; the order in cp and ch increases from 1 at [cp] and [ch] of 0.01 M concentration to 2 at concentrations of 1 M. This is explained by self-association of the ketones in carbon tetrachloride solutions. The order in hydrogen chloride is 1. Since this compound is one of the products, the reaction is autocatalytic. Deuterium isotope effects and the kinetic data strongly point to a mechanism in which the oxygen-protonated monomeric ketone is a-carbon deprotonated in a rate-determining step. This step, which is catalyzed by the bases cp or ch, respectively, leads to the corresponding en01 as intermediate. The en01 is then chlorinated very rapidly. In addition to the chloro ketone, very reactive chloride anions are formed. A small fraction of these anions deprotonate a-or a'-carbon atoms of the oxygen-conjugate acid of the monochloro ketone. The remainder are captured by HCI to form energetically more favored CI--(HCl). complexes with n = 1, 2, or 3. This explains why, even at low conversions of the ketones, substantial amounts of the various dichloro isomers are formed in addition to monochloro products. A rate expression is derived, which excellently describes the experimentally obtained rates of chlorination of cp and ch over a range of reaction rates of more than three decades. Puisque le chlorure d'hydrogkne est un des produits, on doit classer la rCaction comme autocatalysique. Les effets isotopiques du deutCrium ainsi que les donnCes cinktiques suggerent fortement un mCcanisme impliquant, dans 1'Ctape qui dCtermine la vitesse, la dtprotonation du carbone-a d'une cCtone monorndre protonte par I'oxygkne. Cettc Ctape, qui est catalysee respectivement par les bases cp etch, conduit aux Cnols correspondants, comme intermtdiaires. L'Cnol est alors chlore tres rapidement. Une petite fraction de ces anions dCprotone les atomes de carbones-a et -a' de l'acide conjug6 de l'oxygbne de la cCtone monochlorCe. Le reste est capturC par le HC1 pour former des complexes C1--(HCI), ( n = 1, 2 et 3) qui sont plus favorists du point de vue CnergCtique. Ceci explique pourquoi, m&me a des taux de conversions en cCtones trbs faibles, il se forme des quantitCs substantielles de diverses cCtones dichlorCes aux cBtCs des produits monochlorCs. On a dCrivC une expression pour les vitesses qui dCcrit d'une f a~o n excellente les vitesses expkrimentales de chloration des cCtones cp et ch, a des taux de rCaction s'Ctalant sur trois ordres de grandeur.[Traduit par la revue]In polar media the acid-catalyzed halogenation of ketones of low dielectric constant appears to be significantly more usually proceeds by a rate-determining base-catalyzed a-carbon compl...

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Section: Proposed Reaction Schemementioning

confidence: 96%

Section: Proposed Reaction Schemementioning

confidence: 99%

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Reactions of alicyclic ketones in carbon tetrachloride. I, The kinetics of the chlorination of cyclopentanone and cyclohexanone catalyzed by hydrogen chloride

Stamhuis¹,

Maatman²,

Stinissen³

et al. 1986

Can. J. Chem.

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Formation of Carbon–Halogen Bonds (Cl,Br,I)

Sasson

2009

Patai's Chemistry of Functional Groups

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Introduction Halogenation in Presence of Solid Supports or Catalysts Halogen Exchange and Transhalogenation Reactions Oxyhalogenations Cohalogenation and Mixed Halogenation Halogen–Halogen Reagents Carbon–Halogen Reagents Nitrogen–Halogen and Phosphorus–Halogen Reagents Oxygen–Halogen Reagents Sulfur–Halogen Reagents Silicon–Halogen Reagents Halogenation with Metal Halides and Halodemetallation Halogenation in Special Environments Carbon–Halogen Bond Formation by Extrusion of CO , CO 2 or SO 2 Ring Opening of Oxiranes

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Reactions of alicyclic ketones in carbon tetrachloride. II. Kinetics of the chlorination of 2-chlorocyclopentanone and 2-chlorocyclohexanone, catalyzed by hydrogen chloride

Cited by 2 publications

References 7 publications

Reactions of alicyclic ketones in carbon tetrachloride. I, The kinetics of the chlorination of cyclopentanone and cyclohexanone catalyzed by hydrogen chloride

Reactions of alicyclic ketones in carbon tetrachloride. I, The kinetics of the chlorination of cyclopentanone and cyclohexanone catalyzed by hydrogen chloride

Formation of Carbon–Halogen Bonds (Cl,Br,I)

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