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Cuthbert TJ, Li T, Speed AWH, Wulff JE. Structure of the Thermally Induced Cross-Link in C-Linked Methyl Ester-Functionalized Polydicyclopentadiene (fPDCPD). Macromolecules 2018. [DOI: 10.1021/acs.macromol.7b02750] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Tyler J. Cuthbert
- Department of Chemistry, University of Victoria, PO Box 3065 STN CSC, Victoria, British Columbia, Canada V8W 3V6
| | - Tong Li
- Department of Chemistry, University of Victoria, PO Box 3065 STN CSC, Victoria, British Columbia, Canada V8W 3V6
| | - Alexander W. H. Speed
- Department of Chemistry, Dalhousie University, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2
| | - Jeremy E. Wulff
- Department of Chemistry, University of Victoria, PO Box 3065 STN CSC, Victoria, British Columbia, Canada V8W 3V6
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2
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Takahashi H, Marushima Y, Tsuji K, Shibuya K, Kawai A. Addition Rate Constants of Phosphorus- and Carbon-Centered Radicals to Double Bond of Monomers as Studied by a Pulsed Electron Paramagnetic Resonance Method. J Phys Chem A 2015; 119:8261-8. [PMID: 26126155 DOI: 10.1021/acs.jpca.5b04464] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Addition reaction of a radical to the double bond of a monomer, which is important at early stage of photopolymerization, has been studied by time-resolved (TR-) and pulsed electron paramagnetic resonance (EPR) spectroscopic methods. Reactions of one phosphorus-centered and three carbon-centered radicals attacking to several monomers have been employed. Intermediate radicals were identified by analyzing the recorded TR-EPR spectra, and the reaction rate constants were determined by the electron spin-echo detection method proposed by Weber and Turro [J. Phys. Chem. A, 2003, 107 (18), 3326 - 3334]. The quantum chemical calculation shows that the rate constants for the addition reactions are well-explained by introducing two factors of "enthalpy effect" and "polar effect" to control the activation barrier height. It was observed that the rate constants of the phosphorus-centered radical were larger than those of carbon-centered radicals for some monomers. The difference in the rate constants was argued on the basis of frequency factor and activation barrier both of which are influenced by an atom of radical center.
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Affiliation(s)
- Hirona Takahashi
- †Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 H89 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Yutaka Marushima
- †Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 H89 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Kazuhide Tsuji
- ‡National Institute of Technology, Gunma College, 580 Toriba-machi, Maebashi, Gunma 371-8530, Japan
| | - Kazuhiko Shibuya
- †Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 H89 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Akio Kawai
- †Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 H89 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
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3
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Neshchadin D, Gescheidt G. CIDNP as a tool for rapid rearrangements: New insights into cyclobutanoid 4-center/3-electron radical cations. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Dmytro Neshchadin
- Institute of Physical and Theoretical Chemistry; Graz University of Technology; Stremayrgasse 9 8010 Graz Austria
| | - Georg Gescheidt
- Institute of Physical and Theoretical Chemistry; Graz University of Technology; Stremayrgasse 9 8010 Graz Austria
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4
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Dhiman S, Naik D. Pulse radiolysis studies on reactions of α-hydroxyalkyl radicals with nicotinamide and 6-methyl nicotinic acid. Radiat Phys Chem Oxf Engl 1993 2012. [DOI: 10.1016/j.radphyschem.2012.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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5
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Gilmore K, Alabugin IV. Cyclizations of Alkynes: Revisiting Baldwin’s Rules for Ring Closure. Chem Rev 2011; 111:6513-56. [DOI: 10.1021/cr200164y] [Citation(s) in RCA: 387] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Kerry Gilmore
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, 32306-4390
| | - Igor V. Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, 32306-4390
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6
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Poutsma ML. Comparison of mechanistic models for correlation of activation energies of liquid-phase addition of carbon-centered radicals to terminal olefins. J PHYS ORG CHEM 2008. [DOI: 10.1002/poc.1375] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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7
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Hirunsit P, Balbuena PB. Addition Reactions of Alkyl and Carboxyl Radicals to Vinylidene Fluoride. J Phys Chem A 2008; 112:4483-9. [DOI: 10.1021/jp711101b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- P. Hirunsit
- Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843
| | - P. B. Balbuena
- Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843
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8
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Dhiman SB, Naik DB. Addition-elimination in the reaction of alpha-hydroxyalkyl radicals with 3,5-pyridinedicarboxylic acid and nicotinic acid: example of inner sphere organic electron transfer. J Phys Chem A 2007; 111:11493-9. [PMID: 17941618 DOI: 10.1021/jp075157t] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reactions of alpha-hydroxyalkyl radicals with 3,5-pyridinedicarboxylic acid (3,5-PDCA) and nicotinic acid (NA) were studied at appropriate pHs in aqueous solutions by pulse radiolysis technique. At pH 1, CH(3)C*HOH and *CH(2)OH radicals were found to react with 3,5-PDCA by rate constants of 2.2 x 10(9) and 5.1 x 10(8) dm(3) mol(-1) s(-1), respectively, giving radical adduct species. The adduct species formed in the reaction of CH(3)C*HOH radicals with 3,5-PDCA underwent unimolecular decay (k = 9.8 x 10(4) s(-1)) giving pyridinyl radicals. Reaction of (CH(3))(2)C*OH, CH(3)C*HOH, and *CH(2)OH radicals with NA at pH 3.3 gave the adduct species which subsequently decayed to the pyridinyl radicals. At pH 1, wherein NA is present in the protonated form, (CH(3))(2)C*OH radicals directly transfer electrons to NA, whereas CH(3)C*HOH and *CH(2)OH radicals react with higher rate constants compared with those at pH 3.3, initially giving the adduct species which subsequently undergo elimination reaction giving pyridinyl radicals. Reactions of alpha-hydroxyalkyl radicals with 3,5-pyridinedicarboxylic acid and nicotinic acid are found to proceed by an addition-elimination pathway that provides one of the few examples of organic inner sphere electron-transfer reactions. Rate constant for the addition reaction as well as rate of elimination varies with the reduction potential of alpha-hydroxyalkyl radicals.
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Affiliation(s)
- Surajdevprakash B Dhiman
- Radiation and Photochemsitry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
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9
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Lalevée J, Allonas X, Morlet-Savary F, Fouassier JP. Respective Contributions of Polar vs Enthalpy Effects in the Addition/Fragmentation of Mercaptobenzoxazole-Derived Thiyl Radicals and Analogues to Double Bonds. J Phys Chem A 2006; 110:11605-12. [PMID: 17034153 DOI: 10.1021/jp062991u] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The formation and the reactivity of three selected sulfur-centered radicals formed from mercaptobenzoxazole, mercaptobenzimidazole, and mercaptobenzothiazole toward four double bonds (methyl acrylate, acrylonitrile, vinyl ether, and vinyl acetate) are investigated. The reversibility of the addition/fragmentation reaction in these widely used photoinitiating systems of radical polymerization was studied, for the first time, through the measurement of the corresponding rate constants by time-resolved laser spectroscopy. The combination of these results with quantum mechanical calculations clearly evidences that, contrary to previous studies on other aryl thiyl radicals, the addition rate constants (ka) are governed here by the polar effects associated with the very high electrophilic character of these radicals. However, interestingly, the back-fragmentation reaction (k-a) is mainly influenced by the enthalpy effects as supported by the relationship between the rate constants and the addition reaction enthalpy DeltaHR. The addition and fragmentation rate constants calculated from the transition state theory (TST) are in satisfactory agreement with the experimental ones. Therefore, molecular orbital (MO) calculations offered new opportunities for a better understanding of the sulfur-centered radical reactivity.
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Affiliation(s)
- J Lalevée
- Department of Photochemistry, UMR 7525 CNRS, University of haute Alsace, ENSCMu, 3 rue Alfred Werner, 68093 Mulhouse Cedex France.
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11
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Kosobutskii VS. Structure and reactions of carbon-centered α-oxy(Oxo)Radicals. HIGH ENERGY CHEMISTRY 2006. [DOI: 10.1134/s0018143906050018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Pickard FC, Shepherd RL, Gillis AE, Dunn ME, Feldgus S, Kirschner KN, Shields GC, Manoharan M, Alabugin IV. Ortho Effect in the Bergman Cyclization: Electronic and Steric Effects in Hydrogen Abstraction by 1-Substituted Naphthalene 5,8-Diradicals. J Phys Chem A 2006; 110:2517-26. [PMID: 16480313 DOI: 10.1021/jp0562835] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a detailed theoretical study of geometries, electronic structure, and energies of transition states and intermediates completing the full Bergman cycloaromatization pathway of ortho-substituted enediynes with a focus on polar and steric contributions to the kinetics and thermodynamics of hydrogen abstraction. This study provides a rare unambiguous example of remote substitution that affects reactivity of a neutral reactive intermediate through an sigma framework.
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Affiliation(s)
- Frank C Pickard
- Department of Chemistry, Hamilton College, Clinton, New York 13323, USA
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14
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Heuts JP, Russell GT. The nature of the chain-length dependence of the propagation rate coefficient and its effect on the kinetics of free-radical polymerization. 1. Small-molecule studies. Eur Polym J 2006. [DOI: 10.1016/j.eurpolymj.2005.09.022] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Alabugin IV, Manoharan M. Thermodynamic and Strain Effects in the Competition between 5-Exo-dig and 6-Endo-dig Cyclizations of Vinyl and Aryl Radicals. J Am Chem Soc 2005; 127:12583-94. [PMID: 16144406 DOI: 10.1021/ja052677y] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electronic and structural factors controlling the competition between 5-exo-dig and 6-endo-dig cyclizations of sp2-radicals were analyzed using a combination of available experimental data and computation. Although the stereoelectronically favored 5-exo pathways usually has the lower activation energy, formation of a new aromatic ring not only makes the 6-endo process favorable thermodynamically in conjugated systems but also lowers its activation barrier to the extent where the 5-exo/6-endo selectivity is controlled by subtle factors such as the different sensitivity of the two pathways to strain effects in polycyclic systems. In particular, the stronger sensitivity of the 5-exo pathway to strain leads to a crossover in selectivity. The 6-endo cyclization is kinetically favored in smaller (and strained) cycles, whereas the 5-exo cyclization has lower barriers in the larger rings.
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Affiliation(s)
- Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA.
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16
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Yadav P, Madhava Rao BS, Batchelor SN, O'Neill P. From Alcohols to SugarsHow Does the Reactivity of α-Hydroxyalkyl Radicals Change with Structure? A Quantitative Examination by Pulse Radiolysis. J Phys Chem A 2005; 109:2039-42. [PMID: 16838972 DOI: 10.1021/jp050216t] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rate constants are reported for the 1-electron reduction of the azo dye Orange II in water (pH 7.0) by 10 different alpha-hydroxy radicals. The radicals were created by pulse radiolysis of aqueous solutions of the corresponding alcohol/sugar. The rate constants varied from 1 x 10(8) to 2.7 x 10(9) mol(-1) dm(3) s(-1) and radicals with beta-hydroxy groups had the lowest rate constant. The reaction was found to be controlled by the reduction potentials of the radicals, with steric influences having little effects. Good fits of the data were obtained using the Marcus equation with lambda =140 kJ/mol.
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17
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Lalevée J, Allonas X, Fouassier JP. Addition of Carbon-Centered Radicals to Double Bonds: Influence of the Alkene Structure. J Org Chem 2004; 70:814-9. [PMID: 15675837 DOI: 10.1021/jo048381c] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The radical addition reaction to the double bond is well-recognized in organic chemistry as a powerful tool for C-C bond formation. The reactivity of three selected carbon centered radicals (aminoalkyl, methyl, and cyanomethyl) toward five double bonds, also representative of widespread monomers (vinyl ether, vinyl acetate, acrylonitrile, methyl acrylate, and ethylene), was examined in detail by using molecular orbital calculations. The observed reactivity is strongly influenced by the reaction exothermicity demonstrating that the energy barrier is governed in large part by the enthalpy term. The polar effect, as computed by molecular orbital calculations from the transition state structures, can drastically enhance the reactivity. A clear separation and quantification of the relative role of the polar and enthalpy effects in the different radical/double bond systems are obtained and the observed trend of reactivity is discussed. In addition to the effect of the charge-transfer configurations on the barrier, a large influence on the transition state geometry was evidenced.
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Affiliation(s)
- Jacques Lalevée
- Département de Photochimie Générale, UMR 7525 CNRS, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France
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18
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Lalevée J, Allonas X, Fouassier JP. Reactivity of Carbon-Centered Radicals toward Acrylate Double Bonds: Relative Contribution of Polar vs Enthalpy Effects. J Phys Chem A 2004. [DOI: 10.1021/jp037766g] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jacques Lalevée
- Département de Photochimie Générale, UMR 7525 CNRS, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France
| | - Xavier Allonas
- Département de Photochimie Générale, UMR 7525 CNRS, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France
| | - Jean-Pierre Fouassier
- Département de Photochimie Générale, UMR 7525 CNRS, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France
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19
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Nakagawa T, Ozaki H, Kamitanaka T, Takagi H, Matsuda T, Kitamura T, Harada T. Reactions of supercritical alcohols with unsaturated hydrocarbons. J Supercrit Fluids 2003. [DOI: 10.1016/s0896-8446(02)00269-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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20
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Hunt P, Worrall DR, Wilkinson F, Batchelor SN. Quantitative rate constants for the reaction of dyes and alkenes with alpha-hydroxyalkyl radicals, measured by laser flash photolysis. Photochem Photobiol Sci 2003; 2:518-23. [PMID: 12803074 DOI: 10.1039/b212051h] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rate constants are measured for the addition reactions of 1-hydroxy-1-cyclohexyl (1HC) and 2-hydroxy-2-propyl (2HP) radicals to 7 alkenes and for the 1-electron reduction of 16 organic dyes by 1HC, and a subset of 5 of these dyes by 2HP. This was done to determine to what extent the many reported rate constants for reactions of 2-hydroxy-2-propyl radicals (2HP) may be used to predict the rates of reactions of other tertiary alpha-hydroxy-alkyl radicals, and to give a better understanding of the factors that control dye reduction. The dyes were chosen to represent a wide range of dye types (azo, anthraquinone, phthalocyanine, triaryl-methane, indocyanine and azine dyes). Radicals were produced by laser flash photolysis of the corresponding tertiary alpha-hydroxyketone giving carbonyl and tertiary alpha-hydroxy-alkyl radicals. Control experiments with a bis-acylphosphine oxide were carried out which clearly demonstrated that the carbonyl radicals did not interfere with the kinetics. On average the addition and reduction rate constants for 1HC are only 20% lower than for 2HP. Larger decreases are observed for sterically congested alkenes due to the increased steric bulk of 1HC. The rate constants for 1-electron reduction of the dyes are in the range 4 x 10(7) to 6 x 10(9) mol-1 1 s-1 and may be predicted, reasonably well using the Marcus equation with a reorganisation energy, lambda = 182 kJ mol-1.
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Affiliation(s)
- Paula Hunt
- Department of Chemistry, University of Technology Loughborough, Leicestershire, UK LE11 3TU
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Weber M, Turro NJ. A Novel Approach for Measuring Absolute Rate Constants by Pulsed Electron Spin Resonance: Addition of Phosphinoyl and 2-Hydroxy-2-propyl Radicals to Several Alkenes,. J Phys Chem A 2003. [DOI: 10.1021/jp021790x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthias Weber
- Chemistry Department, Columbia University, 3000 Broadway, New York, New York 10027
| | - Nicholas J. Turro
- Chemistry Department, Columbia University, 3000 Broadway, New York, New York 10027
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Valderas C, Bertolotti S, Previtali CM, Encinas MV. Influence of the amine structure on the polymerization of methyl methacrylate photoinitiated by aromatic ketone/amine. ACTA ACUST UNITED AC 2002. [DOI: 10.1002/pola.10382] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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23
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Weber M, Khudyakov IV, Turro NJ. Electron Spin Resonance and Laser Flash Photolysis Study of Radical Addition to Vinyl Acrylate and Related Alkenes. J Phys Chem A 2001. [DOI: 10.1021/jp011813s] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthias Weber
- Chemistry Department, Columbia University, New York, New York 10027 and Alcatel Telecommunications Cable, Claremont, North Carolina 28610
| | - Igor V. Khudyakov
- Chemistry Department, Columbia University, New York, New York 10027 and Alcatel Telecommunications Cable, Claremont, North Carolina 28610
| | - Nicholas J. Turro
- Chemistry Department, Columbia University, New York, New York 10027 and Alcatel Telecommunications Cable, Claremont, North Carolina 28610
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Fischer H, Radom L. Factors Controlling the Addition of Carbon‐Centered Radicals to Alkenes—An Experimental and Theoretical Perspective. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3773(20010417)40:8<1340::aid-anie1340>3.0.co;2-%23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Hanns Fischer
- Physikalisch‐Chemisches Institut der Universität Zürich Winterthurerstrasse 190 8057 Zürich (Switzerland) Fax: (+41) 1‐6356856
| | - Leo Radom
- Research School of Chemistry Australian National University Canberra, ACT 0200 (Australia)
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Fischer H, Radom L. Was steuert die Additionen kohlenstoffzentrierter Radikale an Alkene? - Antworten auf experimenteller und theoretischer Grundlage. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3757(20010417)113:8<1380::aid-ange1380>3.0.co;2-e] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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26
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Fischer H, Radom L. Factors Controlling the Addition of Carbon-Centered Radicals to Alkenes-An Experimental and Theoretical Perspective. Angew Chem Int Ed Engl 2001; 40:1340-1371. [PMID: 11317286 DOI: 10.1002/1521-3773(20010417)40:8<1340::aid-anie1340>3.0.co;2-#] [Citation(s) in RCA: 525] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The successful exploitation of syntheses involving the generation of new carbon-carbon bonds by radical reactions rests on some prior knowledge of the rate constants for the addition of carbon-centered radicals to alkenes and other unsaturated molecules, and of the factors controlling them. Two former classical reviews in Angewandte Chemie by Tedder (1982) and by Giese (1983) provided mechanistic insight and led to various qualitative rules on the complex interplay of enthalpic, polar, and steric effects. In the meantime, the field has experienced very rapid progress: many more experimental absolute rate constants have become available, and there have been major advances in the efficiency and reliability of quantum-chemical methods for the accurate calculation of transition structures, reaction barriers, and reaction enthalpies. Herein we review this progress, recommend suitable experimental and theoretical procedures, and display representative data series for radical additions to alkenes. On this basis, and guided by the pictorial tool of the state-correlation diagram for radical additions, we then offer a new and more stringent quantification of the controlling factors. Our analysis leads to a partial revision of the previous qualitative rules, and it more clearly exhibits the interplay of the reaction enthalpy effects, polar charge-transfer contributions, and steric substituent effects on the reaction energy barrier. The various contributions are cast into the form of new, simple, and physically meaningful but non-linear, predictive equations for the preestimation of rate constants. These equations prove successful in several tests but call for additional theoretical and experimental foundation. The kinetics of related reactions such as polymer propagation, copolymerization, and the addition of radicals to alkynes and aromatic compounds is shown to follow the same principles.
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Affiliation(s)
- Hanns Fischer
- Physikalisch-Chemisches Institut der Universität Zürich Winterthurerstrasse 190 8057 Zürich (Switzerland)
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Sobek J, Martschke R, Fischer H. Entropy control of the cross-reaction between carbon-centered and nitroxide radicals. J Am Chem Soc 2001; 123:2849-57. [PMID: 11456972 DOI: 10.1021/ja0036460] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Absolute rate constants for the cross-coupling reaction of several carbon-centered radicals with various nitroxides and their temperature dependence have been determined in liquids by kinetic absorption spectroscopy. The rate constants range from <2 x 10(5) M(-)(1) s(-)(1) to 2.3 x 10(9) M(-)(1) s(-)(1) and depend strongly on the structure of the nitroxide and the carbon-centered radical. Grossly, they decrease with increasing rate constant of the cleavage of the corresponding alkoxyamine. In many cases, the temperature dependence shows a non-Arrhenius behavior. A model assuming a short-lived intermediate that is hindered to form the coupling product by an unfavorable activation entropy leads to a satisfactory analytic description. However, the behavior is more likely due to a barrierless single-step reaction with a low exothermicity where the free energy of activation is dominated by a large negative entropy term.
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Affiliation(s)
- J Sobek
- Physikalisch-Chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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Gatlik I, Rzadek P, Gescheidt G, Rist G, Hellrung B, Wirz J, Dietliker K, Hug G, Kunz M, Wolf JP. Structure−Reactivity Relationships in Radical Reactions: A Novel Method for the Simultaneous Determination of Absolute Rate Constants and Structural Features. J Am Chem Soc 1999. [DOI: 10.1021/ja991008f] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Iwo Gatlik
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Piotr Rzadek
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Georg Gescheidt
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Günther Rist
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Bruno Hellrung
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Jakob Wirz
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Kurt Dietliker
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Gebhard Hug
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Martin Kunz
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
| | - Jean-Pierre Wolf
- Contribution from the Institute of Physical Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland, and Ciba Specialty Chemicals Inc., Additives, 4002 Basel, Switzerland
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Jockusch S, Turro NJ. Radical Addition Rate Constants to Acrylates and Oxygen: α-Hydroxy and α-Amino Radicals Produced by Photolysis of Photoinitiators. J Am Chem Soc 1999. [DOI: 10.1021/ja9837194] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Steffen Jockusch
- Contribution from the Department of Chemistry, Columbia University, New York, New York 10027
| | - Nicholas J. Turro
- Contribution from the Department of Chemistry, Columbia University, New York, New York 10027
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Mezyk SP, Madden KP. Self-Recombination Rate Constants for 2-Propanol and tert-Butyl alcohol Radicals in Water. J Phys Chem A 1998. [DOI: 10.1021/jp981680j] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stephen P. Mezyk
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46656
| | - Keith P. Madden
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46656
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Karatekin E, O'Shaughnessy B, Turro NJ. Time-Resolved EPR: A Novel Method For Studying Living Chains. Macromolecules 1998. [DOI: 10.1021/ma980891j] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Erdem Karatekin
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, New York 10027
| | - Nicholas J. Turro
- Departments of Chemistry and Chemical Engineering, Columbia University, New York, New York 10027
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Weber M, Fischer H. Absolute rate Constants for the Addition of Malonyl Radicals to Alkenes in Solution. Helv Chim Acta 1998. [DOI: 10.1002/hlca.19980810327] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Zytowski T, Fischer H. Absolute Rate Constants and Arrhenius Parameters for the Addition of the Methyl Radical to Unsaturated Compounds: The Methyl Affinities Revisited. J Am Chem Soc 1997. [DOI: 10.1021/ja973128y] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Torsten Zytowski
- Contribution from the Physikalisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Hanns Fischer
- Contribution from the Physikalisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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Martschke R, Farley RD, Fischer H. Rate Constants for the Addition of 2-Hydroxy-2-propyl Radicals to Alkenes in Solution studied by laser flash photolysis. Helv Chim Acta 1997. [DOI: 10.1002/hlca.19970800505] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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36
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Rubin H, Fischer H. The Addition oftert-Butyl (Me3?) and (tert-Butoxy)carbonylmethyl (Me3CO2C?H2) radicals to alkynes in solution studied by ESR spectroscopy. Helv Chim Acta 1996. [DOI: 10.1002/hlca.19960790617] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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