Acid catalyzed multiple chain termination by quinone monoanilide in oxidizing hydrocarbons

A novel ternary system that causes multiple chain termination in oxidizing hydrocarbons is suggested. The system involvesN-phenylquinone imine, hydrogen peroxide, and citric acid. The inhibiting effect of the system is studied for the initiated oxidation of methyl oleate and ethylbenzene. The rate of the inhibiting oxidation of the hydrocarbon is proportional to the initiation rate and inversely proportional to the product of the concentrations of quinone imine, hydrogen peroxide, and the acid. The mechanism proposed involves the protonation of quinone imine, the abstraction of an H atom from quinone imine by the peroxyl radical, the reduction of the resulting radical cation by hydrogen peroxide to form the semiquinone radical, and the reaction of the latter with RO₂.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 79–82, January, 1995.     

Catalytic Asymmetric Diels–Alder Reaction of Quinone Imine Ketals: A Site‐Divergent Approach

The catalytic asymmetric Diels–Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl‐substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels–Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3‐alkyl quinone imine ketals from the inherently favored unsubstituted C?C bond to the disfavored alkyl‐substituted C?C bond.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-sulfonyl-1,4-benzoquinone imines with enamines

N-Sulfonyl derivatives of 1,4-benzoquinone imine reacted with enamines to give 1,4-addition products and products of their subsequent cyclization, substituted 5-aminobenzofurans and 5-aminoindoles, depending on the solvent nature, electron-withdrawing power of the substituent on the quinone imine nitrogen atom, and enamine structure. The presence of strong electron-withdrawing trifluoromethanesulfonyl group on the quinone imine nitrogen atom favors formation of 1,4-addition products and benzofuran derivatives.     

Reaction of some N-substituted 1,4-benzoquinone imines with sodium arenesulfinates

N-Arylsulfonyl, N-aroyl, and N-[arylsulfonylimino(phenyl)methyl] derivatives of 1,4-benzoquinone imine reacted with sodium arenesulfinates to give 1,4-, 1,6-, and 6,1-addition products which were formed according to two concurrent paths: direct nucleophilic addition of arenesulfinate anion to neutral quinone imine molecule and radical ion addition of arenesulfinate radical to radical anion derived from quinone imine.     

Mechanism of autoreduction of bis(4-methoxyphenyl)-oxoammonium perchlorate in aqueous alkali

Autoreduction of bis(4-methoxyphenyl)oxoammonium perchlorate in aqueous alkali follows a mechanism different from that generally accepted for diaryloxoammonium salts. Bis(4-methoxyphenyl)-oxoammonium cation undergoes hydrolysis to the corresponding quinone imine oxide and methanol, the latter gives rise to methoxide ion which reduces the oxoammonium cation to intermediate bis(4-methoxyphenyl)-hydroxylamine. The reaction of bis(4-methoxyphenyl)hydroxylamine with the initial cation yields bis-(4-methoxyphenyl)nitroxyl, and the quinone imine oxide undergoes disproportionation to N-(4-methoxyphenyl)-1,4-benzoquinone imine and oxidation products.     

Unique feature of chain reactions of thiols with quinone imines: thiols as reactants and simultaneously catalysts at the rate-determining step of chain propagation

The isomerization of radical adducts, formed due to the addition of thiyl radicals to the cyclohexadiene ring of quinone imine, to phenoxyl and aromatic aminyl radicals is considered by quantum chemical methods (DFT/PBE and CCSD). Isomerization via the intramolecular transfer of the highly mobile H atom of the C—H bond to the O or N atoms from the position of PhS? radical addition to the cyclohexadiene ring of quinone imine cannot virtually occur because of the high activation energy comparable or even exceeding the C—H bond dissociation energy. An alternative bimolecular mechanism involving the thiol molecule, which is inserted into the transition state thus extending it to be favorable for the reaction to occur, was proposed. After the reaction, the thiol is regenerated, i.e., acts as both the reactant and catalyst of the chain reaction of quinone imine with thiol. The reasons for the high rate of the H atom transfer via this mechanism are considered.     

On the presence of branching in polyaniline chains

The synthesis of polyaniline via the oxidation of aniline with ammonium bisulfate in water and formic acid was monitored potentiometrically by following the yield and changes in the electric conductivity of the polymer. Three basic stages of the process were determined, including the buildup of oligomeric quinone imines, chain propagation via aniline addition of quinone imine groups, and postpolymerization. The oligomeric intermediate products, substituted quinone imines, were isolated. On the basis of IR and NMR data, the presence of tri-and tetrasubstituted aromatic groups and phenazine structural units in the polyaniline chain was revealed.     

The Diels-Alder reactions of quinone imine ketals: a versatile synthesis of highly substituted 5-methoxyindoles

[reaction: see text]. N-benzoylated quinone imine ketals undergo smooth cycloadditions in a [4 + 2] sense to yield the expected cycloadducts. The crude cycloadducts, when subjected to a short series of simple transformations, produce synthetically useful quantities of 5-methoxyindoles in excellent overall yields.     

Structural and spectral studies of a 1-N(4)-substituted thiosemicarbazone derived from 2-hydroxy-1,4-naphthaquinone

2-Hydroxy-1,4-naphthaquinone reacted with N(4)-ethylthiosemicarbazide in basic solution forms the 1-thiosemicarbazone. The crystal structure shows that the 2-hydroxy hydrogen is shifted to the remaining quinone oxygen resulting in the formation of a dimer due to intermolecular hydrogen bonding from each hydroxy group to the other molecule's quinone oxygen. Intramolecular hydrogen bonding occurs between the amide NH and the imine thiosemicarbazone moiety, as well as between the hydrazinic NH and the quinone oxygen. This new compound's IR, UV and ¹H NMR spectra are included.     

Reinvestigation of the reaction of n-2-methyl-9-hydroxyellipticinium acetate with adenosine and methanol.

Reaction of the quinone imine obtained by oxidation of 9-hydroxyellipticine derivatives with adenosine and methanol has been reinvestigated and the structures of the adducts established.     

Substituent effects on the polycondensation of quinones with aromatic amines to form poly(quinone imine)s

The effect of alkyl groups on the polycondensation of aromatic diamines and quinones to form poly(quinone imine)s was investigated. Models were synthesized under standard conditions: 1 equiv of quinone was reacted with 2 equiv of aniline in the presence of titanium tetrachloride and 1,4‐diazabicyclo[2.2.2]octane. Only modest yields of diimines were obtained when alkyl substituents were introduced. Likewise, alkyl substituents were harmful in the polycondensation of both anthraquinones and benzoquinones with aromatic diamines. As for fluorine substituents, model reactions with either 1,5‐difluoroanthraquinone or 1,4‐difluoroanthraquinone with aniline proceeded in high yields. These model compounds for aromatic poly(quinone imine)s were characterized with ¹H NMR spectroscopy, ¹⁹F NMR spectroscopy, variable‐temperature ¹H NMR spectroscopy, and X‐ray crystal structure determination. Polymers of the difluoroanthraquinones with aromatic diamines were obtained in high yields, although not in high molecular weights, and no stereocontrol was found. Both p‐benzoquinones and anthraquinones were used as monomers in these polymerizations, and a fundamental difference in reactivity was observed. With the former, the polymerization behaved as a classical polycondensation and demanded exact reagent equivalence. With the anthraquinones, however, the polymerization proceeded by a condensation chain polymerization and was much more forgiving. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 43–54, 2002     

聚苯胺的质子酸掺杂机制的研究

木文用FT-IR、ESR、XPS等研究了聚苯胺的质子酸掺杂机制。结果表明聚苯胺掺杂时的质子化反应优先发生在分子链中的醌亚胺结构单元的氮原子上,并产生了分子内氧化还原反应而形成阳离子自由基。质子所带的电荷由于共轭作用能较好地离域到邻近苯环及对位氮原子上。     

Molecular complexes and solvation interactions in the reaction of quinone imines with thiols

This study aims to investigate the role of complexation between reagents and the role of solvation of reagents by solvents in the kinetics of chain reactions of quinone imines with thiols. The thermodynamic characteristics of the complexation of quinone imines with thiophenol in CCl₄, chlorobenzene, and ethanol, as well as of the complexation of quinone imines and thiophenol with these solvents were calculated by quantum chemical methods (DFT calculations at the PBE/cc-pVDZ level of theory) and in terms of the additive-multiplicative model. Both approaches give consistent results. The formation of molecular complexes in quinone imine–thiphenol systems is accompanied by a 10–30 kJ mol^–1 decrease in enthalpy and has only a slight effect on the reaction mechanism.     

Total syntheses of clausamines A-C and clausevatine D

The first total syntheses of clausamines A-C and clausevatine D are reported. The key step involves a Diels-Alder reaction between an imine quinone and cyclic diene, allowing for the subsequent construction of the carbazole core in a regiospecific manner. Stereochemistry of the natural products is also discussed.     

A De Novo Heterodimeric Due Ferri Protein Minimizes the Release of Reactive Intermediates in Dioxygen‐Dependent Oxidation

Metalloproteins utilize O₂ as an oxidant, and they often achieve a 4‐electron reduction without H₂O₂ or oxygen radical release. Several proteins have been designed to catalyze one or two‐electron oxidative chemistry, but the de novo design of a protein that catalyzes the net 4‐electron reduction of O₂ has not been reported yet. We report the construction of a diiron‐binding four‐helix bundle, made up of two different covalently linked α₂ monomers, through click chemistry. Surprisingly, the prototype protein, DF‐C1, showed a large divergence in its reactivity from earlier DFs (DF: due ferri, two iron). DFs release the quinone imine and free H₂O₂ in the oxidation of 4‐aminophenol in the presence of O₂, whereas Fe^III‐DF‐C1 sequesters the quinone imine into the active site, and catalyzes inside the scaffold an oxidative coupling between oxidized and reduced 4‐aminophenol. The asymmetry of the scaffold allowed a fine‐engineering of the substrate binding pocket, that ensures selectivity.     

Reaction of N-[aryl(benzylidene,phenoxy)acetyl]-1,4-benzoquinone imines with sodium 4-methylbenzenesulfinate

The reaction of N-[aryl(phenoxy, benzylidene)acetyl]-1,4-benzoquinone imines with sodium 4-methylbenzenesulfinates takes different addition patterns, depending on the LUMO energy and charge distribution over the quinoid ring of the initial quinone imine.     

Reaction of 4-[2-(arylmethylidene)hydrazinylidene]cyclohexa-2,5-dienones with aromatic amines

4-[2-(Arylmethylidene)hydrazinylidene]cyclohexa-2,5-dienones react with aromatic amines according to the 1,8-addition pattern with formation of N-aryl-N′-(4-oxocyclohexa-2,5-dien-1-ylidene)arenecarbohydrazonamides. The reaction is favored by increase of electron-donating power of the substituent in aromatic amine and electron-withdrawing power of the benzylidene fragment of quinone imine. A probable reaction scheme has been proposed.     

Kinetics and mechanism of the chain reaction between <Emphasis Type="Italic">N</Emphasis>-phenyl-1,4-benzoquinone monoimine and thiophenol

The kinetics of the reaction between N-phenyl-1,4-benzoquinone monoimine (quinone monoimine) and thiophenol is studied in chlorobenzene at 343 K. The reaction has the same mechanism proposed earlier for a similar reaction involving N,N'-diphenyl-1,4-benzoquinone diimine (quinone diimine). This mechanism has two paths: chain and nonchain. An important difference between the kinetics of the two reactions is the apparent reversible nature of the chain reaction in the quinone monoimine + thiophenol system. This nature reveals itself when the concentrations of thiophenol are comparable to or slightly higher than the concentrations of quinone imine. In light of this, kinetic research is conducted under conditions where the concentrations of thiophenol are significantly higher than those of quinone monoimine, allowing us to simplify the kinetic features and obtain interpretable data. The rate constants of the reaction’s elementary steps are estimated and found to be three to five times lower for the reaction involving quinone monoamine than for the one involving quinone diimine. Both reactions have relatively short chains whose lengths do not exceed several tens of units.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-sulfonyl derivatives of 1,4-benzoquinone monoimine with substituted hydrazines

Reaction direction of N-sulfonyl derivatives of 1,4-benzoquinone monoimine with substituted hydrazines depends on the redox potential of the quinone imine and on the basicity of the hydrazine. Aryl (alkyl)hydrazines of high basicity favor the reduction of quinone monoimine. In reactions with less basic aroylhydrazones N'-(4-oxocyclohexa-2,5-dienylidene)aroylhydrazides were obtained only from the alkylsubstituted in the quinoid ring N-sulfonyl derivatives possessing a lower redox potential.     

Intramolecular Aza‐Diels–Alder Reactions of ortho‐Quinone Methide Imines: Rapid,Catalytic, and Enantioselective Assembly of Benzannulated Quinolizidines

Aza‐Diels–Alder reactions (ADARs) are powerful processes that furnish N‐heterocycles in a straightforward fashion. Intramolecular variants offer the additional possibility of generating bi‐ and polycyclic systems with high stereoselectivity. We report herein a novel Brønsted acid catalyzed process in which ortho‐quinone methide imines tethered to the dienophile via the N substituent react in an intramolecular ADAR to form complex quinolizidines and oxazinoquinolines in a one‐step process. The reactions proceed under very mild conditions, with very good yields and good to very good diastereo‐ and enantioselectivities. Furthermore, the process was extended to a domino reaction that efficiently combines substrate synthesis, ortho‐quinone methide imine formation, and ADAR.