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Journal articles on the topic 'Alkyl radical reactions'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Kurandina, Daria, Padon Chuentragool, and Vladimir Gevorgyan. "Transition-Metal-Catalyzed Alkyl Heck-Type Reactions." Synthesis 51, no. 05 (February 7, 2019): 985–1005. http://dx.doi.org/10.1055/s-0037-1611659.

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The Heck reaction is one of the most reliable and useful strategies for the construction of C–C bonds in organic synthesis. However, in contrast to the well-established aryl Heck reaction, the analogous reaction employing alkyl electrophiles is much less developed. Significant progress in this area was recently achieved by merging radical-mediated and transition-metal-catalyzed approaches. This review summarizes the advances in alkyl Heck-type reactions from its discovery early in the 1970s up until the end of 2018.1 Introduction2 Pd-Catalyzed Heck-Type Reactions2.1 Benzylic Electrophiles2.2 α-Carbonyl Alkyl Halides2.3 Fluoroalkyl Halides2.4 α-Functionalized Alkyl Halides2.5 Unactivated Alkyl Electrophiles3 Ni-Catalyzed Heck-Type Reactions3.1 Benzylic Electrophiles3.2 α-Carbonyl Alkyl Halides3.3 Unactivated Alkyl Halides4 Co-Catalyzed Heck-Type Reactions5 Cu-Catalyzed Heck-Type Reactions6 Other Metals in Heck-Type Reactions7 Conclusion

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2

Guin, Joyram, Promita Biswas, and Subhasis Paul. "Synthesis of 3,3-Dialkylated Oxindoles by Oxidative Radical 1,2-Alkylarylation of α,β-Unsaturated Amides." Synlett 28, no. 11 (March 21, 2017): 1244–49. http://dx.doi.org/10.1055/s-0036-1588754.

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3,3-Dialkylated oxindoles (1,3-dihydro-2H-indol-2-ones), particularly those containing C3 quaternary stereogenic centers, occupy an important place in organic synthesis and drug discovery. The radical 1,2-alkylarylation of activated olefins with alkyl radicals has emerged as the most atom- and step-economical approach to 3,3-dialkylated oxindoles. This article covers important developments in the area of oxidative radical alkylation/cyclization cascade reactions of α,β-unsaturated amides toward the synthesis of alkyl-substituted oxindoles by employing a range of alkyl-radical precursors and various reaction conditions.

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3

Griesser, Markus, Jean-Philippe R. Chauvin, and Derek A. Pratt. "The hydrogen atom transfer reactivity of sulfinic acids." Chemical Science 9, no. 36 (2018): 7218–29. http://dx.doi.org/10.1039/c8sc02400f.

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Sulfinic acids are characterized to be very good H-atom donors to each of alkyl and alkoxyl radicals. In order to participate in useful radical chain reactions, the sulfonyl radicals must undergo fast propagating reactions to avoid autoxidation, which is surprisingly rate-limited by the reaction of sulfonyl radicals with oxygen.

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4

Baggott, J. E., H. M. Frey, P. D. Lightfoot, and R. Walsh. "Reactions of the formyl radical with alkyl radicals." Journal of Physical Chemistry 91, no. 12 (June 1987): 3386–93. http://dx.doi.org/10.1021/j100296a057.

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5

Elliot, A. John, Shahsultan Padamshi, and Jana Pika. "Free-radical redox reactions of uranium ions in sulphuric acid solutions." Canadian Journal of Chemistry 64, no. 2 (February 1, 1986): 314–20. http://dx.doi.org/10.1139/v86-053.

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The radiolytic reduction of uranyl ions in degassed sulphuric acid solutions containing various organic solutes was studied. It was shown that while ĊOOH, CO2−, and α-hydroxy-alkyl radicals reduced uranyl ions, the β-hydroxy-alkyl radicals and those derived from gluconic acid could not affect the reduction. The oxidation of uranium(IV) by hydrogen peroxide at pH 0.7 involves hydroxyl radicals in a chain mechanism but at pH 2.0 the oxidation proceeds by a non-radical reaction pathway. From the enhancement of the rate of oxidation of uranium(IV) by oxygen in the presence of 2-propanol, a mechanism involving the perhydroxyl radical, which reconciles earlier published data on kinetics and oxygen tracer studies, is proposed for the oxygen-uranium(IV) reactions.

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6

Murphy, John A. "Free radicals in synthesis. Clean reagents affording oxidative or reductive termination." Pure and Applied Chemistry 72, no. 7 (January 1, 2000): 1327–34. http://dx.doi.org/10.1351/pac200072071327.

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Neurotoxic organotin reagents currently play a key role in radical chemistry. As a result, this is an important area for development of new clean replacement reactions. The pharmaceutical industry in particular has had to avoid use of radical methodology for the formation of carbon_carbon bonds for this reason. With the current dawn in green chemistry, a host of new clean radical methods is beginning to flourish. Our aim has been to develop new nontoxic methodology for carbon_carbon bond formation by radical chemistry, which would provide either reductive termination (giving a hydrogen atom to the ultimate radical, as happens with tributyltin hydride), or oxidative functionalization, installing a useful polar group at the site of the ultimate radical. Two methods for effecting radical reactions in an environmentally friendly way are presented: (i) The tetrathiafulvalene (TTF)-mediated radical-polar crossover reaction converts arenediazonium salts to aryl radicals, which have sufficient lifetime to cyclize onto alkenes—the resulting alkyl radicals couple with TTF+• to afford sulfonium salts which, in turn, undergo solvolysis to alcohols, ethers or amides. The method provides the key step in a synthesis of (±)-aspidospermidine. (ii) Hypophosphite salts and hypophosphorous acid, on the other hand, form C_C bonds with reductive termination. These economical reagents afford radicals efficiently, starting from aryl iodides, alkyl bromides, and alkyl iodides, and give very easy separation of products from by-products.

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7

Renaud, Philippe, Alice Beauseigneur, Andrea Brecht-Forster, Barbara Becattini, Vincent Darmency, Sarkunam Kandhasamy, Florian Montermini, et al. "Boron: A key element in radical reactions." Pure and Applied Chemistry 79, no. 2 (January 1, 2007): 223–33. http://dx.doi.org/10.1351/pac200779020223.

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Boron derivatives are becoming key reagents in radical chemistry. Here, we describe reactions where an organoboron derivative is used as a radical initiator, a chain-transfer reagent, and a radical precursor. For instance, B-alkylcatecholboranes, easily prepared by hydroboration of alkenes, represent a very efficient source of primary, secondary, and tertiary alkyl radicals. Their very high sensitivity toward oxygen- and heteroatom-centered radicals makes them particularly attractive for the development of radical chain processes such as conjugate addition, allylation, alkenylation, and alkynylation. Boron derivatives have also been used to develop an attractive new procedure for the reduction of radicals with alcohols and water. The selected examples presented here demonstrate that boron-containing reagents can efficiently replace tin derivatives in a wide range of radical reactions.

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8

Fantin, Marco, Francesca Lorandi, Armando Gennaro, Abdirisak Isse, and Krzysztof Matyjaszewski. "Electron Transfer Reactions in Atom Transfer Radical Polymerization." Synthesis 49, no. 15 (July 4, 2017): 3311–22. http://dx.doi.org/10.1055/s-0036-1588873.

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Electrochemistry may seem an outsider to the field of polymer science and controlled radical polymerization. Nevertheless, several electrochemical methods have been used to determine the mechanism of atom transfer radical polymerization (ATRP), using both a thermodynamic and a kinetic approach. Indeed, electron transfer reactions involving the metal catalyst, initiator/dormant species, and propagating radicals play a crucial role in ATRP. In this mini-review, electrochemical properties of ATRP catalysts and initiators are discussed, together with the mechanism of the atom and electron transfer in ATRP.1 Introduction2 Thermodynamic and Electrochemical Properties of ATRP Catalysts3 Thermodynamic and Electrochemical Properties of Alkyl Halides and Alkyl Radicals4 Atom Transfer from an Electrochemical and Thermodynamic Standpoint5 Mechanism of Electron Transfer in ATRP6 Electroanalytical Techniques for the Kinetics of ATRP Activation7 Electrochemically Mediated ATRP8 Conclusions

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9

Sharma, Simmi, Shaista Sultan, Shekaraiah Devari, and Bhahwal Ali Shah. "Radical–radical cross coupling reactions of photo-excited fluorenones." Organic & Biomolecular Chemistry 14, no. 40 (2016): 9645–49. http://dx.doi.org/10.1039/c6ob01879c.

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Radical–radical cross coupling reactions of photoexcited 9-fluorenones have been accomplished for the first time, leading to the synthesis of 9-alkyl, pyrollidinyl and spiro-THF derivatives of 9-fluorenones.

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10

Eastwood, FW, RD Mifsud, and P. Perlmutter. "Acyclic Stereocontrol of Free Radical Reactions Involving Alkyl 2-(1-Hydroxyalkyl)propenoates." Australian Journal of Chemistry 47, no. 12 (1994): 2187. http://dx.doi.org/10.1071/ch9942187.

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The addition of cyclohexyl and t-butyl free radicals to silylated derivatives of alkyl 2-(1-hydroxyalkyl) propenoates was found to be stereoselective . In the case of the cyclohexyl radical the stereoselectivity was dependent upon the conditions used to generate the free radical and to quench the intermediate. Stereoselectivity in additions of the t-butyl radical was found to be temperature-dependent. In all cases stereoselectivity increased as the steric bulk of the group attached to the carbinol oxygen increased. A simple model which accounts for the stereoselectivity is proposed.

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11

Sahharova, Liliya T., Evgeniy G. Gordeev, Dmitry B. Eremin, and Valentine P. Ananikov. "Computational Design of Radical Recognition Assay with the Possible Application of Cyclopropyl Vinyl Sulfides as Tunable Sensors." International Journal of Molecular Sciences 22, no. 14 (July 16, 2021): 7637. http://dx.doi.org/10.3390/ijms22147637.

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The processes involving the capture of free radicals were explored by performing DFT molecular dynamics simulations and modeling of reaction energy profiles. We describe the idea of a radical recognition assay, where not only the presence of a radical but also the nature/reactivity of a radical may be assessed. The idea is to utilize a set of radical-sensitive molecules as tunable sensors, followed by insight into the studied radical species based on the observed reactivity/selectivity. We utilize this approach for selective recognition of common radicals—alkyl, phenyl, and iodine. By matching quantum chemical calculations with experimental data, we show that components of a system react differently with the studied radicals. Possible radical generation processes were studied involving model reactions under UV light and metal-catalyzed conditions.

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12

Naito, Takeaki. "Heterocycle synthesis via radical reactions." Pure and Applied Chemistry 80, no. 4 (January 1, 2008): 717–26. http://dx.doi.org/10.1351/pac200880040717.

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A novel synthetic method for the preparation of nitrogen-containing heterocycles via the route involving domino-type radical addition/cyclization reaction of oxime ethers is described. Alkyl radical addition/cyclization of oxime ethers carrying an appropriate leaving group proceeded smoothly to form the alkylated nitrogen-containing heterocyclic compounds. Additionally, tin-mediated radical addition/cyclization/elimination (RACE) reaction of oxime ethers is newly found and successfully applied to an asymmetric total synthesis of (-)-martinellic acid.

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13

Monika, Monika, and Sermadurai Selvakumar. "Recent Developments in Direct C–H Functionalization of Quinoxalin-2(1H)-ones via Radical Addition Processes." Synthesis 51, no. 22 (September 24, 2019): 4113–36. http://dx.doi.org/10.1055/s-0037-1611910.

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This review article covers the recent developments in direct C–H functionalization of quinoxalin-2(1H)-one derivatives via radical additions at the C3 position. Reaction types have been categorized depending on the kind of radical used, with representative examples and insightful mechanistic details provided.1 Introduction2 Reactions with Alkyl Radicals3 Reactions with Acyl Radicals4 Reactions with Aryl Radicals5 Reactions with Perfluoroalkyl Radicals6 Reactions with Alkoxycarbonyl Radicals7 Reactions with Nitrogen Radicals8 Reactions with Oxygen Radicals9 Reactions with Phosphorus Radicals10 Conclusion

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14

Zerk, Timothy J., Lawrence R. Gahan, Elizabeth H. Krenske, and Paul V. Bernhardt. "The fate of copper catalysts in atom transfer radical chemistry." Polymer Chemistry 10, no. 12 (2019): 1460–70. http://dx.doi.org/10.1039/c8py01688g.

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The pathway of atom transfer radical polymerisation (ATRP) is influenced by the nature of the alkyl bromide initiator (RBr) to the extent that reactions between the radical R˙ and the original copper(i) catalyst can divert the reaction toward different products.

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15

Arnold, Donald R., Kimberly A. McManus, and Mary S. W. Chan. "Photochemical nucleophile–olefin combination, aromatic substitution (photo-NOCAS) reaction, Part 13. The scope and limitations of the reaction with cyanide anion as the nucleophile." Canadian Journal of Chemistry 75, no. 8 (August 1, 1997): 1055–75. http://dx.doi.org/10.1139/v97-126.

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The scope of the photochemical nucleophile–olefin combination, aromatic substitution (photo-NOCAS) reaction has been extended to include cyanide anion as the nucleophile. Highest yields of adducts were obtained when the alkene or diene has an oxidation potential less than ca. 1.5 V (SCE). No adducts were obtained from 2-methylpropene (9), oxidation potential 2.6 V. Oxidation of cyanide anion, by the radical cation of the alkene or diene, can compete with the combination. With the alkenes, 2,3-dimethyl-2-butene (2) and 2-methyl-2-butene (10), both nitriles and isonitriles were obtained; isonitriles were not detected from the reactions involving the dienes, 2-methyl-1,3-butadiene (11), 2,3-dimethyl-1,3-butadiene (12), 4-methyl-1,3-pentadiene (13), 2,4-dimethyl-1,3-pentadiene (14), and 2,5-dimethyl-2,4-hexadiene (6). The specificity, nitrile versus isonitrile, is explained in terms of the Hard-Soft-Acid-Base (HSAB) principle. The photo-NOCAS reaction also occurs with the allene, 2,4-dimethyl-2,3-pentadiene (15), cyanide combining at the central carbon. Factors influencing the regiochemistry of the combination step, Markovnikov versus anti-Markovnikov, have been defined. Cyanide anion adds preferentially to the less alkyl-substituted, less sterically hindered, end of an unsymmetric alkene or conjugated diene radical cation, forming the more heavily alkyl-substituted radical intermediate. High-level abinitio molecular orbital calculations (MP2/6-31G*//HF/6-31G*) have been used to determine the effect of alkyl substitution on the stability of the intermediates, β-cyano and β-isocyano alkyl radicals, and products, alkyl cyanides and isocyanides. The more heavily alkyl-substituted radical is not necessarily the more stable. The product ratio (Markovnikov versus anti-Markovnikov) must be kinetically controlled. Keywords: photochemistry, radical ions, electron transfer, nitriles, isonitriles.

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16

Yao, Hongjun, Wenfei Hu, and Wei Zhang. "Difunctionalization of Alkenes and Alkynes via Intermolecular Radical and Nucleophilic Additions." Molecules 26, no. 1 (December 28, 2020): 105. http://dx.doi.org/10.3390/molecules26010105.

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Popular and readily available alkenes and alkynes are good substrates for the preparation of functionalized molecules through radical and/or ionic addition reactions. Difunctionalization is a topic of current interest due to its high efficiency, substrate versatility, and operational simplicity. Presented in this article are radical addition followed by oxidation and nucleophilic addition reactions for difunctionalization of alkenes or alkynes. The difunctionalization could be accomplished through 1,2-addition (vicinal) and 1,n-addition (distal or remote) if H-atom or group-transfer is involved in the reaction process. A wide range of moieties, such as alkyl (R), perfluoroalkyl (Rf), aryl (Ar), hydroxy (OH), alkoxy (OR), acetatic (O2CR), halogenic (X), amino (NR2), azido (N3), cyano (CN), as well as sulfur- and phosphorous-containing groups can be incorporated through the difunctionalization reactions. Radicals generated from peroxides or single electron transfer (SET) agents, under photoredox or electrochemical reactions are employed for the reactions.

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17

Yoshikai, Naohiko, and Ke Gao. "Cobalt-catalyzed directed alkylation of arenes with primary and secondary alkyl halides." Pure and Applied Chemistry 86, no. 3 (March 20, 2014): 419–24. http://dx.doi.org/10.1515/pac-2014-5005.

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Abstract A cobalt–N-heterocyclic carbene catalyst allows ortho-alkylation of aromatic imines with unactivated primary and secondary alkyl chlorides and bromides under room-temperature conditions. The scope of the reaction encompasses or complements that of cobalt-catalyzed ortho-alkylation reactions with olefins as alkylating agents that we developed previously. Stereochemical outcomes of secondary alkylation reactions suggest that the reaction involves single-electron transfer from a cobalt species to the alkyl halide to generate the corresponding alkyl radical. A cycloalkylated product obtained by this method can be transformed into unique spirocycles through manipulation of the directing group and the cycloalkyl groups.

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18

Taiwo, F. A., H. J. Powers, E. Nakano, H. R. Griffiths, and D. F. Nugent. "Free radical reactions in atherosclerosis; An EPR spectrometry study." Spectroscopy 20, no. 2 (2006): 67–80. http://dx.doi.org/10.1155/2006/474183.

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The copper catalysed oxidation of homocysteine has been studied by electron paramagnetic resonance (EPR) spectroscopy and spin trapping techniques to determine the nature of free radical species formed under varying experimental conditions. Three radicals; thiyl, alkyl and hydroxyl were detected with hydroxyl being predominant. A reaction mechanism is proposed involving Fenton chemistry. Inclusion of catalase to test for intermediate generation of hydrogen peroxide showed a marked reduction in amount of hydroxyl radical generated. In contrast, the addition of superoxide dismutase showed no significant effect on the level of hydroxyl radical formed. Enhanced radical formation was observed at higher levels of oxygen, an effect which has consequences for differential oxygen levels in arterial and venous systems. Implications are drawn for a higher incidence of atherosclerotic plaque formation in arteries versus veins.

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19

LaVerne, Jay A., and Laszlo Wojnarovits. "Rates of Alkyl Radical-Radical, Alkyl Radical-Iodine, and Iodine Atom-Atom Reactions in Normal Alkanes and Cycloalkanes." Journal of Physical Chemistry 98, no. 48 (December 1994): 12635–40. http://dx.doi.org/10.1021/j100099a029.

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20

Gorokhovik, Ioulia, Samuel Rieder, Guillaume Povie, and Philippe Renaud. "Radical chain reactions involving 9-alkyl-9-borafluorenes." Arkivoc 2014, no. 3 (April 26, 2014): 274–86. http://dx.doi.org/10.3998/ark.5550190.p008.548.

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21

Gassman, Paul G., and Bruce A. Hay. "Alkyl group migration in photoinduced cation radical reactions." Journal of the American Chemical Society 107, no. 13 (June 1985): 4075–76. http://dx.doi.org/10.1021/ja00299a052.

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22

Russell, Glen A. "Free radical chain reactions involving alkyl- and alkenylmercurials." Accounts of Chemical Research 22, no. 1 (January 1989): 1–8. http://dx.doi.org/10.1021/ar00157a001.

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23

Hu, Xiao-Qiang, Zi-Kui Liu, and Wen-Jing Xiao. "Radical Carbonylative Synthesis of Heterocycles by Visible Light Photoredox Catalysis." Catalysts 10, no. 9 (September 14, 2020): 1054. http://dx.doi.org/10.3390/catal10091054.

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Visible light photocatalytic radical carbonylation has been established as a robust tool for the efficient synthesis of carbonyl-containing compounds. Acyl radicals serve as the key intermediates in these useful transformations and can be generated from the addition of alkyl or aryl radicals to carbon monoxide (CO) or various acyl radical precursors such as aldehydes, carboxylic acids, anhydrides, acyl chlorides or α-keto acids. In this review, we aim to summarize the impact of visible light-induced acyl radical carbonylation reactions on the synthesis of oxygen and nitrogen heterocycles. The discussion is mainly categorized based on different types of acyl radical precursors.

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24

Zhao, Wenyi, and Henry J. Shine. "Primary and secondary 5-(alkyloxy)thianthrenium perchlorates. Characterization with 1H NMR spectroscopy, reactions with iodide and bromide ion, and thermal decomposition in solution." Canadian Journal of Chemistry 76, no. 6 (June 1, 1998): 695–702. http://dx.doi.org/10.1139/v98-010.

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A series of 5-(alkyloxy)thianthrenium perchlorates has been made in which the alkyl group is primary (1a-1p) and secondary (2a-2g). Preparations were carried out by reaction of the corresponding alkanol with thianthrene cation radical perchlorate in CH2Cl2 solution followed by precipitation of the perchlorate salt with dry ether. 1H NMR spectroscopy reveals that the presence of a stereogenic center in the alkyl group causes inequivalence in the ordinarily paired protons (e.g., H-4, H-6) of the thianthrenium ring. Reaction of iodide and bromide ion with primary alkyl-group compounds (e.g., methyl, ethyl, propyl, butyl) gave the alkyl halide in very good yield and by a second-order kinetic displacement. The second product was thianthrene 5-oxide (ThO). Rate constants for some of these reactions are reported. Reaction of secondary alkyl group compounds (e.g., 2-propyl, 2-pentyl, 2-hexyl, and 3-hexyl) with iodide ion gave good yields of alkyl iodide but also increasing evidence for a side reaction at the sulfonium sulfur, leading to I2, thianthrene, and secondary alkanol. Decomposition of some compounds at 100°C in solution (acetonitrile or 1,2-dichloroethane) was studied and gave alkene(s) and ThO.Key words: thianthrene cation radical, 5-(alkyloxy)thianthrenium perchlorates.

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25

Goez, Martin, Isabell Frisch, and Ingo Sartorius. "Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP." Beilstein Journal of Organic Chemistry 9 (February 26, 2013): 437–46. http://dx.doi.org/10.3762/bjoc.9.46.

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The photoreactions of diazabicyclo[2,2,2]octane (DABCO) and triisopropylamine (TIPA) with the sensitizers anthraquinone (AQ) and xanthone (XA) or benzophenone (BP) were investigated by time-resolved photo-CIDNP (photochemically induced dynamic nuclear polarization) experiments. By varying the radical-pair concentration, it was ensured that these measurements respond only to self-exchange reactions of the free amine-derived radicals (radical cations DH • + or α-amino alkyl radicals D • ) with the parent amine DH; the acid–base equilibrium between DH • + and D • also plays no role. Although the sensitizer does not at all participate in the observed processes, it has a pronounced influence on the CIDNP kinetics because the reaction occurs through successive radical pairs. With AQ, the polarizations stem from the initially formed radical-ion pairs, and escaping DH • + then undergoes electron self-exchange with DH. In the reaction sensitized with XA (or BP), the polarizations arise in a secondary pair of neutral radicals that is rapidly produced by in-cage proton transfer, and the CIDNP kinetics are due to hydrogen self-exchange between escaping D • and DH. For TIPA, the activation parameters of both self-exchange reactions were determined. Outer-sphere reorganization energies obtained with the Marcus theory gave very good agreement between experimental and calculated values of ∆G ‡ 298.

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26

Liu, Mengli, Yannan Zheng, Guanyinsheng Qiu, and Jie Wu. "Striving to exploit alkyl electrophiles: challenge and choice in transition metal-catalyzed cross-coupling reactions of sulfones." Organic Chemistry Frontiers 5, no. 17 (2018): 2615–17. http://dx.doi.org/10.1039/c8qo00632f.

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27

Fukuyama, Takahide, Takuji Kawamoto, Mikako Kobayashi, and Ilhyong Ryu. "Flow Giese reaction using cyanoborohydride as a radical mediator." Beilstein Journal of Organic Chemistry 9 (September 3, 2013): 1791–96. http://dx.doi.org/10.3762/bjoc.9.208.

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Tin-free Giese reactions, employing primary, secondary, and tertiary alkyl iodides as radical precursors, ethyl acrylate as a radical trap, and sodium cyanoborohydride as a radical mediator, were examined in a continuous flow system. With the use of an automated flow microreactor, flow reaction conditions for the Giese reaction were quickly optimized, and it was found that a reaction temperature of 70 °C in combination with a residence time of 10–15 minutes gave good yields of the desired addition products.

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28

Almatarneh, Mansour H., Imarat Y. Alnemrat, Reema A. Omeir, Lawrence M. Pratt, Thi Xuan Thi Luu, Minh Bui, and Dickens Saint Hilaire. "Mechanistic Investigation of the Pyrolysis of Brown Grease." Journal of Chemistry 2020 (December 22, 2020): 1–11. http://dx.doi.org/10.1155/2020/8844225.

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The conversion of brown grease using pyrolysis reactions represents a very promising option for the production of renewable fuels and chemicals. Brown grease forms a mixture of alkanes, alkenes, and ketones at a temperature above 300°C at atmospheric pressure. This work is a computational study of the detailed reaction mechanisms of brown grease pyrolysis using DFT methodology. Prior experimental investigations confirmed product formation consistent with a set of radical reactions with CO2 elimination, as well as ketone by product formation, CO forming reactions, and formation of alcohols and aldehydes as minor byproducts. In this work, computational quantum chemistry was used to explore these reactions in greater detail. Particularly, a nonradical pathway formed ketone byproducts via the ketene, which we refer to as Pathways A1 and A2. Radical formation by thermal decomposition of unsaturated fatty acids initiates a set of reactions which eliminate CO2, regenerating alkyl radicals leading to hydrocarbon products (Pathway B). A third pathway (Pathway C) is an alternative set of radical reactions, resulting in decarbonylation and formation of minor byproducts. The results of the calculations are in good agreement with recent experimental studies.

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29

Guérin, B., C. Chabot, N. Mackintosh, W. W. Ogilvie, and Y. Guindon. "Free radicals and Lewis acid. Chelation-controlled radical allylations of substituted α-halo- or α-phenylseleno-β-alkoxy esters. The endocyclic effect." Canadian Journal of Chemistry 78, no. 6 (June 1, 2000): 852–67. http://dx.doi.org/10.1139/v00-074.

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The radical allylation of a series of α-halo or α-phenylseleno-β-alkoxy esters in the presence of MgBr2·OEt2 is reported and compared with analogous reactions under non-chelating conditions. The addition of MgBr2·OEt2 gives excellent selectivity favoring anti products; in some cases ratios >100:1 are obtained. Varying the substrate substituents reveals that these reactions are quite tolerant of alkyl functionalities at the β-position. Changes to the alkoxy function indicate that a chelate is involved in the reaction. The reactions are successful with secondary iodides, bromides, and phenylselenides, as well as tertiary iodides, which all give very high ratios under chelation control. Performing less well under the same conditions are substrates with a radical exocyclic to a tetrahydrofuran ring. EDTA titration is used to determine the amount of Mg2+ dissolved in the allylation reaction mixture, and 13C NMR is employed to better define the nature of the complex formed (chelate or monodentate) prior to the reaction. Competition experiments suggest that the chelate and monodentate pathways are in competition for the radical allylation with allyltributyltin.Key words: allylation, radicals, Lewis acid, stereoselectivity, 1,2-induction.

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30

Zou, Jian-Ping, Wei Zhang, Cheng-Kun Li, Dong-Liang Zhang, Ogundipe Olamiji, Pei-Zhi Zhang, and Adedamola Shoberu. "Mn(OAc)3-Mediated Regioselective Radical Alkoxycarbonylation of Indoles, Pyrimidinones, and Pyridinones." Synthesis 50, no. 15 (July 4, 2018): 2968–73. http://dx.doi.org/10.1055/s-0037-1610039.

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Mn(OAc)3-mediated alkoxycarbonylation of indoles, pyrimidinones, and pyridinones with alkyl carbazates is reported. The reactions proceed through a radical process to afford regioselectively 3-carboxylated indoles, 5-carboxylated pyrimidinones, and 3-carboxylated pyridinones in moderate to good yields under mild reaction conditions.

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31

Smith, Rebecca L., Kami K. Thoen, Krista M. Stirk, and Hilkka I. Kenttämaa. "Reactions of alkyl halides with distonic acylium radical cations." International Journal of Mass Spectrometry and Ion Processes 165-166 (November 1997): 315–25. http://dx.doi.org/10.1016/s0168-1176(97)00194-8.

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32

Benati, Luisa, Rino Leardini, Matteo Minozzi, Daniele Nanni, Rosanna Scialpi, Piero Spagnolo, Samantha Strazzari, and Giuseppe Zanardi. "A Novel Tin-Free Procedure for Alkyl Radical Reactions." Angewandte Chemie International Edition 43, no. 27 (July 5, 2004): 3598–601. http://dx.doi.org/10.1002/anie.200454245.

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33

Benati, Luisa, Rino Leardini, Matteo Minozzi, Daniele Nanni, Rosanna Scialpi, Piero Spagnolo, Samantha Strazzari, and Giuseppe Zanardi. "A Novel Tin-Free Procedure for Alkyl Radical Reactions." Angewandte Chemie 116, no. 27 (July 5, 2004): 3682–85. http://dx.doi.org/10.1002/ange.200454245.

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34

Weidner, Karin, and Philippe Renaud. "Kinetic Study of the Radical Azidation with Sulfonyl Azides." Australian Journal of Chemistry 66, no. 3 (2013): 341. http://dx.doi.org/10.1071/ch12523.

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Rate constants for the reaction between a secondary alkyl radical and two different sulfonyl azides were determined using bimolecular competing radical reactions. The rates of azidation were determined by competition with hydrogen atom transfer from tris(trimethylsilyl)silane ((TMS)3SiH) of the 4-phenylcyclohexyl radical. 3-Pyridinesulfonyl azide and trifluoromethanesulfonyl azide were found to have rate constants for azidation of 2 × 105 M–1 s–1 and 7 × 105 M–1 s–1 at 80°C, respectively.

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35

Kundu, S., R. Fisseha, A. L. Putman, T. A. Rahn, and L. R. Mazzoleni. "High molecular weight SOA formation during limonene ozonolysis: insights from ultrahigh-resolution FT-ICR mass spectrometry characterization." Atmospheric Chemistry and Physics 12, no. 12 (June 25, 2012): 5523–36. http://dx.doi.org/10.5194/acp-12-5523-2012.

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Abstract. The detailed molecular composition of laboratory generated limonene ozonolysis secondary organic aerosol (SOA) was studied using ultrahigh-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Approximately 1200 molecular formulas were identified in the SOA over the mass range of 140 to 850 Da. Four characteristic groups of high relative abundance species were observed; they indicate an array of accretion products that retain a large fraction of the limonene skeleton. The identified molecular formulas of each of the groups are related to one another by CH2, O and CH2O homologous series. The CH2 and O homologous series of the low molecular weight (MW) SOA (m/z < 300) are explained with a combination of functionalization and fragmentation of radical intermediates and reactive uptake of gas-phase carbonyls. They include isomerization and elimination reactions of Criegee radicals, reactions between alkyl peroxy radicals, and scission of alkoxy radicals resulting from the Criegee radicals. The presence of compounds with 10–15 carbon atoms in the first group (e.g. C11H18O6) provides evidence for SOA formation by the reactive uptake of gas-phase carbonyls during limonene ozonolysis. The high MW compounds (m/z > 300) were found to constitute a significant number fraction of the identified SOA components. The formation of high MW compounds was evaluated by molecular formula trends, fragmentation analysis of select high MW compounds and a comprehensive reaction matrix including the identified low MW SOA, hydroperoxides and Criegee radicals as building blocks. Although the formation of high MW SOA may occur via a variety of radical and non-radical reaction channels, the combined approach indicates a greater importance of the non-condensation reactions over aldol and ester condensation reaction channels. Among these hemi-acetal reactions appear to be most dominant followed by hydroperoxide and Criegee reaction channels.

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36

Cho, Chang Ho, and Sunggak Kim. "β Elimination of a phosphonate group from an alkoxyl radical — Intramolecular acylation using acylphosphonate derivatives as carbonyl group acceptors." Canadian Journal of Chemistry 83, no. 6-7 (June 1, 2005): 917–21. http://dx.doi.org/10.1139/v05-099.

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The possibility of β elimination of a phosphonate group in radical reactions was studied. The facile β elimination of the phosphonate group from an alkoxyl radical was observed for the first time, whereas the β elimination of the phosphonate group from an aminyl and an alkyl radical did not occur. On the basis of our findings, the use of an acylphosphonate as a carbonyl group radical acceptor was investigated. Radical cyclization of the acylphosphonate in the presence of hexamethylditin in benzene at 300 nm for 2 h gave a cyclopentanone or a cyclohexanone derivative in good yield without the formation of a direct reduction product. The reaction can be carried out in the presence of a catalytic amount of hexamethylditin (0.2 equiv.) under similar conditions. In addition, an alkyl phosphonothiolformate group can act as an alkylthiocarbonyl group equivalent radical acceptor, providing ready access to a thiolactone synthesis.Key words: radical, β elimination, acylation, cyclization, acylphosphonate.

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37

Hammerum, Steen, Kion Norrman, Theis I. Sølling, Peter E. Andersen, Lars Bo Jensen, and Tore Vulpius. "Competing Simple Cleavage Reactions: The Elimination of Alkyl Radicals from Amine Radical Cations." Journal of the American Chemical Society 127, no. 17 (May 2005): 6466–75. http://dx.doi.org/10.1021/ja043481l.

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38

Brinza, Irina M., and Alex G. Fallis. "Tandem Radical Reactions: Carbon Monoxide Addition to Alkyl Radicals and Subsequent Acyl Radical Cyclization ontoN,N-Diphenylhydrazones." Journal of Organic Chemistry 61, no. 11 (January 1996): 3580–81. http://dx.doi.org/10.1021/jo960507l.

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39

Hayen, Ahlke, Rainer Koch, Wolfgang Saak, Detlef Haase, and Jürgen O. Metzger. "1,3-Stereoinduction in Radical Reactions: Radical Additions to Dialkyl 2-Alkyl-4-methyleneglutarates." Journal of the American Chemical Society 122, no. 50 (December 2000): 12458–68. http://dx.doi.org/10.1021/ja003235j.

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40

Molle, G., J. E. Dubois, and P. Bauer. "Contribution à l'étude des réactions d'alkylation et de polyalkylation de l'adamantane et de ses homologues." Canadian Journal of Chemistry 65, no. 10 (October 1, 1987): 2428–33. http://dx.doi.org/10.1139/v87-405.

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A method for preparing alkyl derivatives of cage-structure compounds is proposed. It relies on the use of Grignard reactions with a high boiling point solvent. The reactions take place at atmospheric pressure. Methylation of adamantane, diamantane, and homoadamantane occurs with quantitative yield. With other primary alkyl groups, yields are better than 60%. Competition between alkylation and secondary reactions is discussed on the basis of a free radical mechanism.

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41

Li, Diyuan, Tsz-Kan Ma, Reuben J. Scott, and Jonathan D. Wilden. "Electrochemical radical reactions of alkyl iodides: a highly efficient, clean, green alternative to tin reagents." Chemical Science 11, no. 20 (2020): 5333–38. http://dx.doi.org/10.1039/d0sc01694b.

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42

Pan, Xian-Ming, Eugenie Bastian, and Clemens von Sonntag. "The Reactions of Hydroxyl Radicals with 1,4-and 1,3-Cyclohexadiene in Aqueous Solution." Zeitschrift für Naturforschung B 43, no. 9 (September 1, 1988): 1201–5. http://dx.doi.org/10.1515/znb-1988-0919.

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Abstract The reactions of radiolytically generated hydroxyl radicals and H atoms with 1,4- and 1,3-cyclohexadiene were studied by pulse radiolysis and product analysis. Hydrogen abstraction from these substrates by the OH radical yields the cyclohexadienyl radical (ε (310 nm) = 4400 dm3 mol-1 cm-1 from the reaction of the H atom with benzene) with an efficiency of 50% (0.29 ,μmol J-1) in the case of 1,4-cyclohexadiene and 25% (0.15 ,μmol J-1) in the case of 1,3-cyclohexadiene as determined by pulse radiolysis. The remaining OH radicals add to the olefin. In 1.4-cyclohexa- diene the yield of the resulting adduct radicals has been determined in a steady-state 60Co-γ-irradiation experiment by reducing it with added 1.4-dithiothreitol (DTT) to 4-hydroxycyc- lohexene. There are two sites of OH radical attack in the case of 1.3-cyclohexadiene, and only the alkyl radical is reduced quantitatively by DTT (G(3-hydroxycyclohexene) = 0.15 ,μmol J-1). From material balance considerations it is concluded that the allylic radical must be formed with a G value of 0.28 ,μmol J-1 but largelv escapes reduction by DTT (G(4-hvdroxycyclohexene) = 0.03 ,μmol J-1). H atoms add preferentially to the double bonds of 1,4- and 1,3-cyclohexadiene (78% and 93%, respectively), while the O.- radical (the basic form of the OH radical) undergoes mainly H- abstraction (92% and 83%, respectively). The radicals formed in these systems decay bimolecularly (2k = 2.8 x 109 dm3 mol-1 s-1). In their combination reactions the cyclohexadienyl radicals form the four possible dimers in proportions such that the dienyl radical moiety shows a 2:1 preference to react from its central (1a) rather than from a terminal carbon atom (1b). Cyclohexadienyl radicals and the OH- and H-adduct radicals also cross-tcrminate by disproportionation and dimerization. Material balance has been obtained for the 1,4-cyclohexadiene system in N2O-Saturated solution (10-2 mol dm-3) at a dose rate of 0.14 Gy s-1, the products (G values in ,μmol J-1) being: benzene (0.085), 4-hydroxycyclohexene (0.25), cyclohexadienyl-dimers (0.144). cvclohexadienyl-OH-adduct- dimers (0.02), OH-adduct-dimers (0.02). Some of the 4-hydroxycyclohcxene is formed in an H-abstraction reaction by the OH-adduct radical from 1,4-cyclohexadiene.

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43

Ma, Tsz-Kan, Diyuan Li, and Jonathan D. Wilden. "Mechanistic studies of reactive oxygen species mediated electrochemical radical reactions of alkyl iodides." Chemical Communications 57, no. 67 (2021): 8356–59. http://dx.doi.org/10.1039/d1cc03019a.

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44

Breitenfeld, Jan, Jesus Ruiz, Matthew D. Wodrich, and Xile Hu. "Bimetallic Oxidative Addition Involving Radical Intermediates in Nickel-Catalyzed Alkyl–Alkyl Kumada Coupling Reactions." Journal of the American Chemical Society 135, no. 32 (August 2013): 12004–12. http://dx.doi.org/10.1021/ja4051923.

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45

Tian, Hao, Wentao Xu, Yuxiu Liu, and Qingmin Wang. "Radical alkylation of C(sp3)–H bonds with diacyl peroxides under catalyst-free conditions." Chemical Communications 55, no. 98 (2019): 14813–16. http://dx.doi.org/10.1039/c9cc08056b.

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Herein, we describe a protocol for alkylation reactions of C(sp³)–H bonds with diacyl peroxides by means of a process involving cross-coupling between an alkyl radical and an α-aminoalkyl radical.

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46

Boivin, Jean, Jose Camara, and Samir Z. Zard. "Novel radical chain reactions based on O-alkyl tin dithiocarbonates." Journal of the American Chemical Society 114, no. 20 (September 1992): 7909–10. http://dx.doi.org/10.1021/ja00046a045.

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47

Cui, Weihong, and Bradford B. Wayland. "Hydrocarbon C-H bond activation by rhodium porphyrins." Journal of Porphyrins and Phthalocyanines 08, no. 02 (February 2004): 103–10. http://dx.doi.org/10.1142/s108842460400009x.

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Rhodium porphyrins provide a variety of C-H bond reactions with both aromatic and aliphatic hydrocarbons that acquire unusual selectivity in part through the steric requirements of the porphyrin ligand. Rhodium(III) porphyrins selectively react with aromatic C-H bonds by electrophilic substitution with the virtual exclusion of aliphatic C-H bond activation. Rhodium(II) porphyrins react by a metal-centered radical pathway with alkyl aromatics and alkanes selectively at the alkyl C-H bond with total exclusion of aromatic C-H bond activation. Reactions of rhodium(II) metalloradicals with alkyl C-H bonds have large deuterium isotope effects, small activation enthalpies and large negative activation entropies consistent with a near linear symmetrical four-centered transition state ( Rh ˙⋯ H ⋯ C ⋯˙Rh). The nature of this transition state and the dimensions of rhodium porphyrins provide steric constraints that preclude aromatic C-H bond reactions and give high kinetic preference for methane activation as the smallest alkane substrate. Rhodium(II) tethered diporphyrin bimetalloradical complexes convert the C-H bond reactions to bimolecular processes with dramatically increased reaction rates and high selectivity for methane activation.

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48

Choi, Seung-Yong, David Crich, John H. Horner, Xianhai Huang, Felix N. Martinez, Martin Newcomb, Donald J. Wink, and Qingwei Yao. "Absence of Diffusively Free Radical Cation Intermediates in Reactions of β-(Phosphatoxy)alkyl Radicals." Journal of the American Chemical Society 120, no. 1 (January 1998): 211–12. http://dx.doi.org/10.1021/ja973512v.

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49

Ferris, Kim F., James A. Franz, Carlos Sosa, and Rodney J. Bartlett. "Alkyl radical displacement reactions at sulfur: on the question of intermediacy in alkylsulfuranyl radicals." Journal of Organic Chemistry 57, no. 2 (January 1992): 777–78. http://dx.doi.org/10.1021/jo00028a076.

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50

Katritzky, Alan R., Sergei A. Belyakov, H. Dupont Durst, Ruixin Xu, and Naresh S. Dalal. "Syntheses of 3-(substituted)-2,4,6-triphenylverdazyls." Canadian Journal of Chemistry 72, no. 8 (August 1, 1994): 1849–56. http://dx.doi.org/10.1139/v94-235.

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Two series of 2,4,6-triphenylverdazyls substituted at the C(3) position of the heterocyclic ring are obtained using new convenient synthetic methodology. Thus, crown ether assisted solid–liquid phase-transfer catalysis promotes the formation of 3-n-alkyl-substituted 2,4,6-triphenylverdazyls in the reactions of 1,3,5-triphenylformazan with n-alkyl bromides. Under PTC conditions, methylation of 3-(4-nitrophenyl)-1,5-diphenylformazan with methyl iodide exclusively gives the corresponding verdazyl radical. 3-Substituted 2,4,6-triphenylverdazyls containing various di(cyclo)alkylamino moieties at the C(3) position of the verdazyl ring are prepared by the reaction of 1,3,5-triphenylformazan with the corresponding 1-[N,N-di(cyclo)alkylaminomethyl]benzotriazoles under the efficient catalysis of barium hydroxide monohydrate. Sonication of this reaction allows the yields of the verdazyls to be substantially increased. A bis-verdazyl N,N-bonded in the C(3) positions was synthesized. All the radicals obtained were characterized by microanalysis, and by UV–visible and ESR spectroscopy.

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