scholarly journals Chain propagation determines the chemo- and regioselectivity of alkyl radical additions to C–O vs. C–C double bonds

2020 ◽  
Vol 11 (3) ◽  
pp. 731-736 ◽  
Author(s):  
Tiffany O. Paulisch ◽  
Felix Strieth-Kalthoff ◽  
Christian Henkel ◽  
Lena Pitzer ◽  
Dirk M. Guldi ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Alkyl Radical ◽  
Radical Addition ◽  
Chain Propagation ◽  
Double Bonds

Reversible radical addition followed by an irreversible electron transfer leads to regio- and chemoselectivity control of radical additions to π-systems.

Photochemically induced radical addition of tertiary amines to C=C and C=O double bonds: A green chemistry contribution to organic synthesis

2007 ◽  
Vol 79 (11) ◽  
pp. 1949-1958 ◽  
Author(s):  
Norbert Hoffmann
Keyword(s):  
Electron Transfer ◽  
Green Chemistry ◽  
Organic Synthesis ◽  
Organic Molecules ◽  
Redox Chemistry ◽  
Heterogeneous Photocatalysis ◽  
Radical Addition ◽  
Tertiary Amines ◽  
Double Bonds ◽  
Alkyl Radicals

Photochemically induced electron transfer considerably enriches the redox chemistry of organic molecules. This primary step has been used to produce α-amino alkyl radicals that can be added to various double bonds. The addition to olefinic and carbonyl bonds is discussed. Homogeneous and heterogeneous photocatalysis methods with various electron-transfer sensitizers are described.

scholarly journals Spectral Probe for Electron Transfer and Addition Reactions of Azide Radicals with Substituted Quinoxalin-2-Ones in Aqueous Solutions

2021 ◽  
Vol 22 (2) ◽  
pp. 633
Author(s):  
Konrad Skotnicki ◽  
Slawomir Ostrowski ◽  
Jan Cz. Dobrowolski ◽  
Julio R. De la Fuente ◽  
Alvaro Cañete ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Density Functional ◽  
Reduction Potential ◽  
Biological Significance ◽  
Radical Cations ◽  
Basis Sets ◽  
Double Bonds ◽  
Reduction Potentials

The azide radical (N3●) is one of the most important one-electron oxidants used extensively in radiation chemistry studies involving molecules of biological significance. Generally, it was assumed that N3● reacts in aqueous solutions only by electron transfer. However, there were several reports indicating the possibility of N3● addition in aqueous solutions to organic compounds containing double bonds. The main purpose of this study was to find an experimental approach that allows a clear assignment of the nature of obtained products either to its one-electron oxidation or its addition products. Radiolysis of water provides a convenient source of one-electron oxidizing radicals characterized by a very broad range of reduction potentials. Two inorganic radicals (SO4●−, CO3●−) and Tl2+ ions with the reduction potentials higher, and one radical (SCN)2●− with the reduction potential slightly lower than the reduction potential of N3● were selected as dominant electron-acceptors. Transient absorption spectra formed in their reactions with a series of quinoxalin-2-one derivatives were confronted with absorption spectra formed from reactions of N3● with the same series of compounds. Cases, in which the absorption spectra formed in reactions involving N3● differ from the absorption spectra formed in the reactions involving other one-electron oxidants, strongly indicate that N3● is involved in the other reaction channel such as addition to double bonds. Moreover, it was shown that high-rate constants of reactions of N3● with quinoxalin-2-ones do not ultimately prove that they are electron transfer reactions. The optimized structures of the radical cations (7-R-3-MeQ)●+, radicals (7-R-3-MeQ)● and N3● adducts at the C2 carbon atom in pyrazine moiety and their absorption spectra are reasonably well reproduced by density functional theory quantum mechanics calculations employing the ωB97XD functional combined with the Dunning’s aug-cc-pVTZ correlation-consistent polarized basis sets augmented with diffuse functions.

Free Radical Addition of Butanethiol to Vegetable Oil Double Bonds

2009 ◽  
Vol 57 (4) ◽  
pp. 1282-1290 ◽  
Author(s):  
Grigor B. Bantchev ◽  
James A. Kenar ◽  
Girma Biresaw ◽  
Moon Gyu Han
Keyword(s):  
Free Radical ◽  
Vegetable Oil ◽  
Radical Addition ◽  
Double Bonds ◽  
Free Radical Addition

Highly cis- and trans-selective alkyl radical addition to α-methylene-γ-phenyl-γ-butyrolactams

2009 ◽  
Vol 50 (12) ◽  
pp. 1301-1302 ◽  
Author(s):  
Tomoko Yajima ◽  
Masako Hamano ◽  
Hajime Nagano
Keyword(s):  
Alkyl Radical ◽  
Radical Addition ◽  
Cis And Trans

scholarly journals Semiconductors as sensitisers for the radical addition of tertiary amines to electron deficient alkenes

2003 ◽  
Vol 5 (3) ◽  
pp. 175-182 ◽  
Author(s):  
Siniša Marinković ◽  
Norbert Hoffmann
Keyword(s):  
Electron Transfer ◽  
Organic Synthesis ◽  
Radical Reaction ◽  
Heterogeneous Photocatalysis ◽  
Radical Addition ◽  
Point Of View ◽  
Tertiary Amines ◽  
Radical Intermediate ◽  
Radical Chain ◽  
High Yields

Using heterogeneous photocatalysis, the radical addition of tertiary amines with electron deficient alkenes can be performed in high yields (up to 98%) and high facial diastereoselectivity. The photochemical induced electron transfer process initiates the radical chain reaction and inorganic semiconductors likeTiO2and ZnS were used. According to the proposed mechanism, the reaction takes place at the surface of the semiconductor and the termination step results from an interfacial electron transfer from the conduction band to the oxoallyl radical intermediate. Frequently, semiconductors are used for the mineralisation of organic compounds in wastewater. However, in this case, they are used in organic synthesis. The process can be performed in a convenient way and is particularly interesting from the ecological and economical point of view. No previous functionalization of the tertiary amines is necessary for C − C bond formation. Further on, the amines are used both as reactant and as solvent. The excess is recycled by distillation and the inexpensive sensitiser can be easily removed by filtration. In this way, products of high interest for organic synthesis are obtained by a diastereoselective radical reaction.

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