Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP

• Martin Goez,
• Isabell Frisch and
• Ingo Sartorius

Beilstein J. Org. Chem. 2013, 9, 437–446, doi:10.3762/bjoc.9.46

• . With Equation 2, the free energy of the relayed deprotonation can be estimated from the reduction potential Φred (DH•+) of the radical cation (see, Table 1, but taken relative to NHE instead of SCE), the pKa of the protonated amine (8.9 [43]), and the calculated heats of formation ∆Hf of D• (+208 kJ

• is between 6.9 and 9.2, depending on the water content [47]. Even with the smaller of these values, using the reduction potential of Table 1 and the calculated heats of formation (∆Hf (D•), −33 kJ/mol; ∆Hf (DH), −111 kJ/mol) we arrive at an exergonicity of at least −50 kJ/mol, which means that a

Reduction of benzylic alcohols and α-hydroxycarbonyl compounds by hydriodic acid in a biphasic reaction medium

• Michael Dobmeier,
• Josef M. Herrmann,
• Dieter Lenoir and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 330–336, doi:10.3762/bjoc.8.36

• . Alcohols other than those that were benzylic or α to carbonyl groups were not converted into the corresponding alkanes, and the reaction stopped at the iodoalkanes (Table 3). The reactivity follows the order of primary < secondary < tertiary alcohols, as expected for an SN1 reaction. The reduction

• potential of the nonbenzylic iodoalkanes is not sufficient for reduction by hydriodic acid. The mechanism of reduction by hydriodic acid consists of two steps (Scheme 1): The nucleophilic substitution of the hydroxy group by iodide and the subsequent reduction of the alkyl iodide by hydriodic acid. The

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• electron rich azole rings and methyl substituents make it particularly hard to reduce. Its first reduction potential is −1.21 V and its second was not observed as it occurs outside the solvent window for dichloromethane. Most hexaaryl[3]radialenes are orange or red in colour with UV–visible absorption

Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine, histidine and tryptophan

• Axel G. Griesbeck,
• Jörg Neudörfl and
• Alan de Kiff

Beilstein J. Org. Chem. 2011, 7, 518–524, doi:10.3762/bjoc.7.60

• and ФISC < 0.01 for N-arylphthalimides [1]. If necessary, the population of the triplet state is also possible by sensitization, e.g., with triplet sensitizers such as acetone or benzophenone. With a triplet energy ET of 293–300 kJ mol−1 and a ground-state reduction potential E0 of −1.85 V vs Fc/Fc

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• containing products of mono- and di-substitution. Their lower reactivity [88] is largely due to the greater dissociation energy of the C–Br bond (55 kcal/mol for CF3Br) compared to C–I (28 kcal/mol for CF3I) [172]. In addition, CF3Br has a higher reduction potential than CF3I and prefers to receive two

• of CF3Br as compared to CF3I can be explained, first of all, by the higher reduction potential (−2.07 V against −1.52 V for CF3I on a glass-carbon cathode), and secondly, by the fact that the CF3• radical has a reduction potential (−1.80 V) close to that of CF3Br [173]. Thus trifluoromethyl bromide

• ]. Electrochemical studies involving the SO2−• radical anion prove that the electron transfer to CF3Br takes place at a reduction potential of the mediator between −0.9 and −1.0 V which prevents the transfer of a second electron to CF3• and the generation of CF3− [199]. Therefore electrochemical reduction in the

Synthetic incorporation of Nile Blue into DNA using 2′-deoxyriboside substitutes: Representative comparison of (R)- and (S)-aminopropanediol as an acyclic linker

• Daniel Lachmann,
• Sina Berndl,
• Otto S. Wolfbeis and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2010, 6, No. 13, doi:10.3762/bjoc.6.13

• , DNA2C), or both (DNA2G). It becomes clear from a rough estimation of the excited state potential for the Nile Blue dye that guanine oxidation by an photoinduced electron transfer causes the fluorescence quenching. If the singlet–singlet transition energy E00 = 1.9 eV is added to the reduction potential

Prediction of reduction potentials from calculated electron affinities for metal-salen compounds

• Sarah B. Bateni,
• Kellie R. England,
• Anthony T. Galatti,
• Handeep Kaur,
• Victor A. Mendiola,
• Alexander R. Mitchell,
• Michael H. Vu,
• Benjamin F. Gherman and
• James A. Miranda

Beilstein J. Org. Chem. 2009, 5, No. 82, doi:10.3762/bjoc.5.82

• could be used to predict the reduction potentials of a variety of metal-salen compounds, an important class of coordination compounds used in synthetic organic electrochemistry as electrocatalysts. Keywords: density functional theory; electron affinity; metal-salen; reduction potential; Introduction

• evidence for the formation of a Ni(II)-salen radical anion during electrolysis was later put forth by Peters and co-workers [6]. In mediated ERC, while Ni(II)-salen (reduction potential or Epc = −2.1 V vs. Ag/AgNO3) is an effective electrochemical mediator, the analogous Co(II)-salen (Epc = −1.6 V vs. Ag

• /AgNO3) fails to promote cyclization. Direct ERC (unmediated) occurs at a reduction potential of −2.7 V vs. Ag/AgNO3. It was concluded that the 1.1 V thermodynamic barrier was too large to allow electron transfer to occur from the reduced form of the Co(II)-salen to the substrate [4]. We sought to

New diarylmethanofullerene derivatives and their properties for organic thin- film solar cells

• Daisuke Sukeguchi,
• Surya Prakash Singh,
• Mamidi Ramesh Reddy,
• Hideyuki Yoshiyama,
• Rakesh A. Afre,
• Yasuhiko Hayashi,
• Hiroki Inukai,
• Tetsuo Soga,
• Shuichi Nakamura,
• Norio Shibata and
• Takeshi Toru

Beilstein J. Org. Chem. 2009, 5, No. 7, doi:10.3762/bjoc.5.7

• [19]. These first reduction potential data showed that the diarylmethanofullerene derivatives can be a better electron acceptor than PCBM [27]. Photovoltaic Devices A series of solar cells was fabricated with P3HT as the electron-donor and diarylmethanofullerene derivatives as the electron-acceptor

• the higher Voc value [20][27][29][30][31]. More negative first reduction potentials of the methoxy-substituted PCBM derivatives in comparison with that of PCBM have been shown to be well correlated to the Voc values of the solar cells [20]. On the other hand, the first reduction potential of 1a is

• less negative than that of PCBM (Table 1). In addition, a higher Voc value was shown for the P3HT-1a cell. The tris(octyloxy)phenyl- and (octyloxy)phenyl-substituted methanofullerenes 1b and 1c with less negative first reduction potential also showed enhanced Voc values. The electron-donating (octyloxy

Synthesis and redox behavior of new ferrocene- π-extended- dithiafulvalenes: An approach for anticipated organic conductors

• Abdelwareth A. O. Sarhan,
• Omar F. Mohammed and
• Taeko Izumi

Beilstein J. Org. Chem. 2009, 5, No. 6, doi:10.3762/bjoc.5.6

• cyclic voltammetry at ambient temperature on a Pt working electrode, using TBAP as the supporting electrolyte. The CV exhibited good donor properties, showing a one-electron quasireversible oxidation potential. The oxidation potential values, and to a larger extent the reduction potential values, are

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• reaction; would the analogous chemistry be seen with TDAE where no sulfur atoms are present? The experiments were of heightened interest because of the recent report by Andrieux and Pinson [60] on the standard reduction potential of the phenyl radical (formed by electrochemical reduction of the

Effect of transannular interaction on the redox- potentials in a series of bicyclic quinones

• Grigoriy Sereda,
• Jesse Van Heukelom,
• Miles Koppang,
• Sudha Ramreddy and
• Nicole Collins

Beilstein J. Org. Chem. 2006, 2, No. 26, doi:10.1186/1860-5397-2-26

• activity. However, attempts to directly relate the reduction potentials of substituted triptycene-quinones to the electronic effects of substituents are often unsuccessful. Thus, the negative shift of the reduction potential, caused by two methoxy-groups at the 5,8-positions (compound 2), was surprisingly

• difference may fall below the threshold that would warrant sufficient concentrations of the conformation B to account for the experimental redox-potential of 2. Yamamura and co-authors [3] also noticed that the reduction potential of the quinone 2 was higher than expected from the electronic effects of the

• (Epox) where (Eo' = 1/2(Epred + Epox) [11]. In order to check our process, we measured the first reduction potential of p-benzoquinone to be -0.507 V, which is exactly the same as the value reported in the literature [3]. The cyclic voltammograms (CV) for p-benzoquinone and the quinone 3 are presented