Andrzej Sobkowiak

Rzeszów University of Technology · Faculty of Chemistry

The use of dioxygen as an oxidant in fine chemicals production is an emerging problem in chemistry for environmental and economical reasons. In acetonitrile, the [(N4Py)FeII]2+ complex, [N4Py—N,N-bis(2-pyridylmethyl)-N-(bis-2-pyridylmethyl)amine] in the presence of the substrate activates dioxygen for the oxygenation of cyclohexene and limonene. Cy...

[(salen)FeIII]+MeCN complex is a useful catalyst for cyclohexene oxidation with dioxygen. As the main products, ketone and alcohol are formed. In acetonitrile, [(salen)FeII]MeCN is rapidly oxidized by dioxygen, forming iron(III) species. Voltammetric electroreduction of the [(salen)FeIII]+MeCN complex in the presence of dioxygen causes the increase...

Iron complexes are particularly interesting as catalyst systems over the other transition metals (including noble metals) due to iron’s high natural abundance and mediation in important biological processes, therefore making them non-toxic, cost-effective, and biocompatible. Both homogeneous and heterogeneous catalysis mediated by iron as a transit...

Inspired by tea stains, a plant polyphenolic‐based macroinitiator is prepared for the first time by partial modification of tannic acid (TA) with 2‐bromoisobutyryl bromide. In accordance with the “grafting from” methodology, a naturally occurring star‐like polymer with a polar gallotannin core and a hydrophobic poly(n‐butyl acrylate) side arms is s...

Spontaneity criteria for processes with useful (especially electrical) work have been discussed based on total differentials of thermodynamic functions. Reaction Gibbs energy (ΔrG) and electrochemical reaction Gibbs energy (ΔrG̃) have been juxtaposed. Three-dimensional graphs showing the dependencies of ΔrG̃ on the extent of reaction (ξ) and the ce...

The flavonoid-based macroinitiator was received for the first time by the transesterification reaction of quercetin with 2-bromoisobutyryl bromide. In accordance with the "grafting from" strategy, a naturally-occurring star-like polymer with a polar 3,3',4',5,6-pentahydroxyflavone core and hydrophobic poly(tert-butyl acrylate) (PtBA) side arms was...

Experimental section including NMR spectra, first-order kinetic plot, GPC traces, preparative electrolysis and CV results.

The efficiency of the vanadyl(IV)acetylacetonate (1)–catalyzed oxidation of cyclohexane by hydrogen peroxide in acetonitrile increased in the presence of oxalic acid (2). The addition of 2 leads to the substitution of acac ligands by oxalate resulting in formation of vanadyl(IV)oxalate (3). That promotes the formation of cyclohexanol, cyclohexanone...

Study the mild cyclohexane oxygenation using vanadyl(IV)acetylacetonate as the starting catalyst and H2O2 as the oxidant has shown that oxalic acid as activator alters the products ratio, increases yield and catalyst turnover number. According to the instrumental (ESI-MS, NMR, EPR, UV–vis, GC, pH, titrimetric) investigations both the parental VO(ac...

Poly(ethylene oxide)-block-poly(butyl acrylate) copolymers were prepared via simplified electrochemically mediated atom transfer radical polymerization (seATRP) utilizing only 1 ppm of CuII complex, which is the limit of a successful well-controlled polymerization. The presented seATRP system works under potentiostatic and galvanostatic conditions....

This review covers both fundamental aspects and applications of electrochemically mediated atom transfer radical polymerization (eATRP). eATRP setup is discussed in detail, together with the advantages and limitations of this technique. All relevant parameters that can influence eATRP outcome are evaluated (e.g. applied current and potential, stirr...

Poly(butyl acrylate) homopolymers were prepared via electrochemically mediated atom transfer radical polymerization (eATRP) using only 10 ppm concentration of Cu(II) complex catalyst, lower than commonly reported 50-400 ppm. The results of chromatographic analysis (GPC) indicate that the formation of polyacrylates proceeded via ATRP mechanism. 1H N...

Electrochemical cholesterylation of various sugars with cholesteryl diphenylphosphate was studied. The reaction afforded mono-, di-, tri-, and tetra-cholesterylated products using equivalent amounts of the reagent. The reactions turned out to be completely stereoselective with respect to both sugar and steroid but only partially regioselective – pr...

The electrochemically mediated atom transfer radical polymerisation (eATRP) of n-butyl acrylate was investigated under a variety of catalyst concentrations. Poly(n-butyl acry late)- block-polyurethane-block-poly (n-butyl acrylate) copolymers were prepared via electrochemically mediated atom transfer radical polymerisation (eATRP) using only 7 × 10–...

Cyclodextrin-based star polymers were synthesized using functionalized β-cyclodextrin (β-CD) core, and n-butyl acrylate (BA) as hydrophobic arms. The β-CD core macroinitiator was prepared by the transesterification reaction of β-CD with 2-bromoisobutyryl bromide. The core-first method was chosen as the synthetic strategy as it allows good control o...

A 5 mM limonene sample was oxidized with O-2 on complex MOO or Fe(II) catalysts into a closed vessel with vol. of 22 mL at the catalyst-to-limonene ratio 0.5, 1, 10 and 15. The reaction was carried out at 23 degrees C for 24 h. The reaction products were analyzed by gas chromatog. to det. the main components (1,2-limonene oxide, carvone and carveol...

Poly(ethylene oxide)-block-poly(methyl methacrylate) amphiphilic copolymers were prepared via electrochemically mediated atom transfer radical polymerization (eATRP) utilizing only 50 ppm of CuII complex, rather than previously reported concentrations of catalyst of ca. 1,000-30,000 ppm. The copolymers were also prepared via a simplified electroche...

Indirect cholesterol electrochemical oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and afford...

3α,5α-Cyclocholestan-6β-yl alkyl and aryl ethers were proved to be efficient cholesteryl donors in the electrochemical synthesis of glycoconjugates. 3α,5α-Cyclocholestan-6β-ol (i-cholesterol) and its tert-butyldimethylsilyl ether can also be used for this purpose. The i-cholesterol derivatives show similar reactivities to those of previously studie...

Several derivatives of cholesterol and other 3β-hydroxy-Δ(5)-steroids were prepared and tested as sterol donors in electrochemical reactions with sugar alcohols. The reactions afforded glycoconjugates with sugar linked to a steroid moiety by an ether bond. Readily available sterol diphenylphosphates yielding up to 54% of the desired glycoconjugate...

Vanadyl(IV)-acetylacetonate-catalyzed oxidation of cyclohexane with H(2)O(2), at 40 degrees C under air atmosphere, has been studied in the presence of small quantities of oxalic acid. The process efficiency is increased by this additive and depends on the nature of the solvent (MeCN >= MeOH > Me(2)CO >= 2-PrOH > EtOH). The relationships between th...

A new protocol for the effective oxidation of cyclohexane in acetonitrile at 40°C and atmospheric pressure into cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide using hydrogen peroxide as the oxidant, vanadyl(IV)-acetylacetonate as the catalyst, oxalic acid and glyoxal as additives is presented with some reaction mechanism proposals.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A new electrochemical glycosylation method is presented. According to the method cholesterol and other 3beta-hydroxy-Delta(5)-steroids can be selectively transformed to glycosides using non-activated sugars. The method is also useful for the synthesis of glycoconjugates with sugar linked to a steroid moiety by an ether bond.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Manganese(II) complexes {[MnII(bpy)2 2+]MeCN} in acetonitrile activate dioxygen for the oxidation of limonene to produce mainly carvone, carveol, limonene oxide, and perillaldehyde. The reaction efficiencies after 24h reaction time are approximately 5-times higher than those obtained for analogous iron(II) complexes. However, the 5h long induction...

The peculiarity of H2O2 cleavage catalyzed with cobalt(II)acetylacetonate has been studied by the method of inhibitors in different hydrophilic solvents. As established, physical-chemical properties of reaction medium can significantly affect the rate of peroxide decomposition and catalyst oxidation as well.

It has been found that cholesterol undergoes direct electrochemical oxidation on platinum electrode in dichloromethane. Voltammetric measurements show that the process is controlled by the rate of electron transfer and the height of the oxidation peak is linear vs. concentration of cholesterol. Preparative electrolysis with separated cathodic and a...

Labile iron(II) and iron(III) complexes {[FeII(bpy)22+]solv and [FeIII(bpy)23+]solv} in acetonitrile activate dioxygen for the oxidation of limonene to produce mainly carvone, carveol, limonene oxide, and perillaldehyde. Iron(III) complex is reduced by the substrate to iron(II) one, which activates dioxygen. Probably the catalyst interacts with sub...

Electrooxidation of tigogenin acetate afforded two products: 3β-acetoxy-16β-hydroxy-23,24-dinor-5α-cholanoic acid lactone (2) and 20-epitigogenin acetate (3). The structure of the latter compound was confirmed by an X-ray analysis. The tentative mechanism of reaction is proposed.

It has been found that hydrogen peroxide can act as an oxidant and as a reductant of transition metal complexes in acetonitrile. Therefore, the examples of catalytic currents of oxidants and reductants has been described. In the case of Co(acac)3 both the types of catalytic currents are present in a single cyclic-voltammetric scan.

IntroductionActivation of Hydrogen PeroxldeActivation of DioxygenConclusions

It has been found that cholesterol undergoes direct electrochemical oxidation on platinum electrode in glacial acetic acid containing sodium perchlorate and sodium acetate as supporting electrolytes. Voltammetric measurements show that the process is controlled by the rate of electron transfer and the height of the oxidation peak is linear vs. conc...

It has been found that tert-butyl hydroperoxide is analogous to hydrogen peroxide with respect to their reactivity towards iron(II) and iron(III). In water iron(II) is oxidized by tert-butyl hydroperoxide, whereas in acetonitrile iron(III) is reduced by tert-butyl hydroperoxide. The last reaction when performed by cyclic-voltammetry is an example o...

Labile iron complexes (e.g., [FeIII(bpy)2]MeCN3+, [FeII(bpy)2]MeCN2+, [FeIII(H2O)6]MeCN3+, and [FeII(H2O)6]MeCN2+) in base-free acetonitrile activate dioxygen for the direct oxygenation of N,N- and N-alkylated amines to form N-dealkylated products and corresponding aldehydes. N,N-dimethylaniline (DMA) is oxidized to N-methylaniline (MA) and formald...

Simple iron(III) salts activate hydrogen peroxide to oxidize 2-methylnaphthalene to 2-methyl-1-naphthol in glacial acetic acid. 2-Methyl-1-naphthol is then oxidized to 2-methyl-1,4-naphthoquinone by hydrogen peroxide without influence of the catalyst. This is in contrast to the previous reports, which excluded the formation of 2-methyl-1-naphthol a...

It has been found that in acetonitrile, in contrast to water, iron(III) is reduced by hydrogen peroxide, according to 2:1 stoichiometry. The reaction when performed by cyclic-voltammetry is an example of electrochemical catalytic processes of reductants. For the [Fe(III)]/[HOOH] ratios greater than 1, 1mol of dioxygen is produced from 1mol of hydro...

In concentrated sulfuric acid–glacial acetic acid solvent benzene is oxidized to poly(para-phenylene) (PPP) if the concentration of glacial acetic acid is less than 40vol.%. Depending on the potential applied the chains containing 11–18 monomer units are formed. PPP forms quasi-reversible redox system, which is deactivated if oxidized at potentials...

Labile iron complexes [e.g., [FeIII(bpy)2]aq3+, [FeII(bpy)2]aq2+, [FeIII(H2O)6]aq3+ and [FeII(H2O)6]aq2+ in base-free acetonitrile activate dioxygen for the direct oxygenation of cyclohexene [to ketone, alcohol, and epoxide; , c-C6H9OH, c-C6H10-epoxide] and related unsaturated hydrocarbons with allylic carbon centers. For example, the combination o...

Several manganese (III) complexes (MnIIILx) in combination with tert-butyl hydroperoxide (t-BuOOH) activate dioxygen (O2) to oxygenate cyclohexene (c-C6H10) to its ketone, alcohol, and epoxide. The product profiles depend on the ligand and solvent matrix. With picolinate (PA), bipyridine (bpy), or triphenylphosphine oxide (OPPh3) as the ligand in p...

Cyclic-voltammetric measurements show that 2-methylnaphthalene-1,4-diacetate is electrochemically oxidized on glassy-carbon electrode in glacial acetic acid at +1.45V vs SCE. The process is irreversible and diffusion controlled. Preparative controlled-potential electrolysis indicates that 2-methyl-1,4-naphthoquinone is a sole product. The material...

Examples of a variety of redox equations. Keywords (Audience): High School / Introductory Chemistry

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Electrochemical oxidation of cyclohexane to cyclohexanone has been studied in the FeII-FeIV and FeIII-FeV manifolds. In the former manifold, the presence of chloride ion diverts, by radical chemistry, ketone formation to cyclohexyl chloride synthesis. In contrast, in the latter manifold, only cyclohexanone is produced by non-radical chemistry. Diph...

Iron complexes [Fe-II(OPPh(3))(4)(2+), Fe-II(bpy)(2),(2+), Fe-II(OH2)(6)(2+), and (FeCl3)-Cl-III] catalytically activate 1:1 HOOH/HCl combinations for the efficient chlorohydroxylation of olefins. The reactive intermediate 7 is not HOCl, but appears to be formed via a Fenton process Fe(II)L(x)(2+) reversible arrow (B) [L(x)(+)Fe(II)OOH(BH+)] (1) --...

The combination of Fe-II(DPAH)(2) (DPAH(2) = 2,6-dicarboxypyridine) and O-2 in a 2:1 pyridine/acetic acid solution results in a rapid autoxidation to produce HOOH and Fe-III(DPA)(DPAH) (k(1), 1.8 +/- 0.5 M(-1) s(-1)). The resultant HOOH reacts with excess Fe-II(DPAH)(2) via a nucleophilic addition to give a Fenton reagent [(DPAH)(2)(FeOOH)-Fe---O-I...

In acetonitrile/pyridine bis(bipyridine)copper(I) [Cu[sup I](bpy)[sub 2][sup +]] activates HOOH and t-BuOOH for the selective ketonization of methylenic carbons. With 5 mM Cu[sup I](bpy)[sub 2][sup +]/100 mM HOOH(Bu) the conversion efficiencies [product per 2HOOH(Bu)] for c-C[sub 6]H[sub 12] are 31% (HOOH) and 59% (t-BuOOH, argon atmosphere) and fo...

The combination of FeII(DPAH)2 (DPAH2 = 2,6-dicarboxyl pyridine) and O2 in a 2:1 pyridine/acetic acid solution results in a rapid autoxidation to produce HOOH and FeIII(DPA)(DPAH) (k1, 1.8±0.5 M-1s-1). The resultant HOOH reacts with excess FeII(DPAH)2 via a nucleophilic addition to give a Fenton reagent [(DPAH)2-FeIIOOH + pyH+] (1) that reacts with...

In pyridine/acetic acid solvent FeII(PA)2 (PA =picolinate) and FeII(DPA) (DPA = 2,6-dicarboxylato-pyridine) catalyze hydrogen peroxide for the selective ketonization of methylenic carbons, and the dioxygenation of arylolefins to aldehydes. Analogous chemistry is facilitated by related cobalt complexes and solvent systems. With the py2(HOAc) solvent...

In acetonitrile the bis(pyridine)cobalt(II) complex [Co(II)(bpy)2](ClO4)2] activates dioxygen via the reversible formation of a mu-dioxygen complex. This complex dehydrogenates (oxidizes) N-methylanilines, benzyl alcohol, and aldehydes (with subsequent autoxidation). In the absence of substrate, the Co(II)(bPy)2(2+) complex reduces dioxygen via res...

In acetonitrile, diphenyldiselenide undergoes a reversible one-electron reduction, which is similar to the electrochemical behavior of O2.

In aprotic solvents the bis(picolinato)iron(II) [Fe(PA)2] and (2,6-pyridinedicarboxylato)iron(II) [Fe(DPA)] complexes react with hydrogen peroxide and with dioxygen to form a series of monooxygen and dioxygen intermediates and adducts [(PA)2FeOFe(PA)2 (1), (PA)2Fe(OO), (PA)2FeOFe(PA)2·HOOH (2), and their analogues with Fe(DPA)]. The electron-transf...

In pyridine/acetic acid solvent complexes such as (I) and its μ-oxo dimer (II) catalyze hydrogen peroxide for the selective ketonization of methylenic carbons and the dioxygenation of acetylenes to α-diketones and arylolefins to aldehydes; e.g. cyclohexane is transformed with 72% efficiency to give 95% cyclohexanone and 5% cyclohexanol.

In acetonitrile, diphenyl diselenide (PhSeSePh) undergoes a reversible one-electron reduction (-0.85 V vs SCE), which is similar to the electrochemical behavior of dioxygen. PhSeSePh facilitates the oxidation of water and hydroxide ion and the reduction of protons. In combination with HOOH, PhSeSePh is photocatalyzed and proton-catalyzed to form a...

In pyridine/acetic acid solvent bis(picolinato)iron(II) [Fe(PA)2], (2,6-dicarboxylatopyridine)iron(II) [Fe(DPA)], and their μ-oxo dimers [(PA)2FeOFe(PA)2 and (DPA)FeOFe(DPA)] catalyze hydrogen peroxide for the selective ketonization of methylenic carbons (>CH2 → C=O) and the dioxygenation of acetylenes to α-diketones and arylolefins to aldehydes. C...

The title reaction is demonstrated in the scheme for the example of cyclohexane (I).

It has been found that the polarographic catalytic current of the Fe(III)/H2O2 system shows inverse [H+] dependence. It can be accounted for by assuming that Fe(II) reacts not only with H2O2 but also with HO−2. The determined values of rate constants are about 54 and 1011 M−1 s−1, respectively.

The hydroxylation of benzene and phenol during oxygen electroreduction on mercury, lead, copper and silver electrodes in 0.1 M H2SO4 in the presence and absence of Fe2+ has been investigated. Evidence is presented that hydroxylation is possible in the absence of Fe2+. Further facts confirming that, in this case, hydroxyl radicals are the hydroxylat...

The polarographic method of determining rate constants of the hydroxyl radicals reactions has been worked out on the basis of the previously presented equation describing the value of the catalytic current of the Fe(III)H2O2 system with regard to hydroxylation.

The paper presents an ionite model of a mercury electrode covered with adsorbed organic ions, and points out that the kinetic current of protonation in the presence of ionic surfactants depends on the process of ion exchange with the participation of the so-called ionite layer formed during the adsorption of organic ions, which have long carbon cha...

On the basis of the reaction layer concept, the equation describing the value of ik/id has been introduced with regard to a few chemical reactions responsible for the occurrence of catalytic current. The value calculated have been compared with those obtained experimentally.

Beim Leiten eines O2-Stroms über eine Cu-Spirale in einem emulgiertes Benzol enthaltenden korrosiven Medium (0,lm H, SO4/0,lm H3 P04) wird das Benzol zunächst zu Phenol, weiter zu Hydrochinon und Brenzcatechin hydroxyliert.

Während der O2-Reduktion zu H2O2 an der Hg-Tropfelektrode in Gegenwart von oberflächenaktiven Stoffen werden im Polarogramm eine Adsorptions-(Vorstufe) und eine kinetische Stufe beobachtet.