Mini Review of Sulfur Heterocyclization from π-Electron Deficient Quinones via Charge-Transfer Interaction

Abstract

This survey is mainly concerned with selected reactions of 2,3-dichloro-1,4-naphthoquinone (DHNQ), 3,4,5,6-tetrachloro-1,2-benzoquinone (o-CHL), 2,3,5,6-tetrachloro-1,4-benzoquinone (p-CHL), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as π-deficient quinones that are used or offer potential use for sulfur heterocyclic synthesis. Reaction of various donors with the π-deficient quinones are studied, especially those via charge-transfer complex formation.     

Chemiluminescence assay for quinones based on generation of reactive oxygen species through the redox cycle of quinone

A sensitive and selective chemiluminescence assay for the determination of quinones was developed. The method was based on generation of reactive oxygen species through the redox reaction between quinone and dithiothreitol as reductant, and then the generated reactive oxygen was detected by luminol chemiluminescence. The chemiluminescence was intense, long-lived, and proportional to quinone concentration. It is concluded that superoxide anion was involved in the proposed chemiluminescence reaction because the chemiluminescence intensity was decreased only in the presence of superoxide dismutase. Among the tested quinones, the chemiluminescence was observed from 9,10-phenanthrenequinone, 1,2-naphthoquinone, and 1,4-naphthoquinone, whereas it was not observed from 9,10-anthraquinone and 1,4-benzoquinone. The chemiluminescence property was greatly different according to the structure of quinones. The chemiluminescence was also observed for biologically important quinones such as ubiquinone. Therefore, a simple and rapid assay for ubiquinone in pharmaceutical preparation was developed based on the proposed chemiluminescence reaction. The detection limit (blank + 3SD) of ubiquinone was 0.05 μM (9 ng/assay) with an analysis time of 30 s per sample. The developed assay allowed the direct determination of ubiquinone in pharmaceutical preparation without any purification procedure. Figure Chemiluminescence generated through the redox cycle of quinone     

Photoreactions of p-quinones with dimethyl sulfide and dimethyl sulfoxide in aqueous acetonitrile. goerner@mpi-muelheim.mpg.de

The effects of dimethyl sulfide (DMS) and dimethyl sulfoxide (DMSO) on the photoreactions of 1,4-benzoquinone (BQ), 1,4-naphthoquinone (NQ), 9,10-anthraquinone (AQ) and several derivatives in acetonitrile/water were studied. The observed triplet state of the quinones is quenched and the rate constant is close to the diffusion-controlled limit for reactions of most quinones with DMS and lower with DMSO. Semiquinone radical anions (Q*-) produced by electron transfer from sulfur to the triplet quinone were detected. For both DMS and DMSO the yield of Q*- is similar, being generally low for BQ and NQ, substantial for AQ and largest for chloranil. The specific quencher concentrations and the effects of quinone structure and redox potentials on the time-resolved photochemical properties are discussed.     

Infrared laser desorption/vacuum ultraviolet photoionization mass spectrometry of petroleum saturates: a new experimental approach for the analysis of heavy oils

A novel method combining infrared (IR) laser desorption with tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (LD/VUV PIMS) is applied to characterize a number of petroleum saturates samples from Lungu atmospheric residue (LGAR) under different treatment procedures. The mass spectra of these saturates are well resolved with even masses as the dominant ions and are clearly sample‐dependent. In order to assess the ability of IR LD/VUV PIMS to determine the average molecular weight of heavy oils, the dependence of the measured molecular weight distributions on the VUV ionization photon energies is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Structural analysis of naphthoquinone protein adducts with liquid chromatography/tandem mass spectrometry and the scoring algorithm for spectral analysis (SALSA)

The relative reactivities of various naphthoquinone isomers (1,4-, 1,2- and 2-methyl-1,4-naphthoquinone) to two test proteins, apomyoglobin and human hemoglobin, were evaluated via liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). The structural characterization of the resulting adducts was also obtained by LC/ESI-MS analysis of the intact proteins. The reactive sites of apomyoglobin and human hemoglobin with 1,4-naphthoquinone and 1,2-naphthoquinone were also identified through characterization of adducted tryptic peptides by use of high-pressure liquid chromatography/electrospray ionization with tandem mass spectrometry (HPLC/ESI-MS/MS), TurboSEQUEST, and the scoring algorithm for spectral analysis (SALSA). Four adducted peptides, which were formed by nucleophilic addition of a lysine amino acid residue to 1,4-naphthoquinone, were also identified, as was an adducted peptide from incubation of 1,2-naphthoquinone with apomyoglobin. In the case of incubation of human hemoglobin with the two naphthoquinones, two adducted peptides were identified from the N-terminal valine modification of the alpha and beta chains of human hemoglobin. The adducted protein formation may imply that naphthalene produces its in vivo toxicity through 1,2- and 1,4-naphthoquinone metabolites reacting with biomolecular proteins.     

Photoionization and Pyrolysis of a 1,4‐Azaborinine: Retro‐Hydroboration in the Cation and Identification of Novel Organoboron Ring Systems

The photoionization and dissociative photoionization of 1,4‐di‐tert‐butyl‐1,4‐azaborinine by means of synchrotron radiation and threshold photoelectron photoion coincidence spectroscopy is reported. The ionization energy of the compound was determined to be 7.89 eV. Several low‐lying electronically excited states in the cation were identified. The various pathways for dissociative photoionization were modeled by statistical theory, and appearance energies AE_0K were obtained. The loss of isobutene in a retro‐hydroboration reaction is the dominant pathway, which proceeds with a reverse barrier. Pyrolysis of the parent compound in a chemical reactor leads to the generation of several yet unobserved boron compounds. The ionization energies of the C₄H₆BN isomers 1,2‐ and 1,4‐dihydro‐1,4‐azaborinine and the C₃H₆BN isomer 1,2‐dihydro‐1,3‐azaborole were determined from threshold photoelectron spectra.     

α-甲氧基萘的电子转移光氧化反应

近年来芳烃和杂环化合物的电子转移光氧化反应受到日益的注意^[1-5]。电子转移光氧化反应不仅可应用于很多对¹O₂为惰性的烯烃和芳烃^[1-7],而且对某些¹O₂活性化合物,也可给出与¹O₂反应不同的产物。     

Electronic absorption spectra of amino substituted anthraquinones and their interpretation using the ZINDO/S and AM1 methods

Electronic absorption spectra of 1,2-diamino-9,10-anthraquinone (12DAAQ), 1,4-diamino-9,10-anthraquinone (14DAAQ), 1,5-diamino-9,10-anthraquinone (15DAAQ), and 2,6-diamino-9,10-anthraquinone (26DAAQ) are investigated. Molecular geometries of the amino anthraquinones in the ground state are optimized using the semiempirical ZINDO/1 and AM1 methods without imposing any symmetry constraints. The ground state geometries of all the molecular systems are found to be planar. For interpretation of the spectra, ZINDO/S-CI and AM1-CI calculations employing singly excited configuration using the completely optimized geometry are carried out. Such calculations on the electronic spectra of amino anthraquinones are carried out for the first time. On the basis of these calculations, the assignment of the spectra are successfully made.     

Anomalous behavior in the two-step reduction of quinones in acetonitrile

The electrochemical reduction of eight quinones, 9,10-anthraquinone (1), duroquinone (2), 2,6-di-tert-butyl-1,4-benzoquinone (3), 2,6-dimethoxy-1,4-benzoquinone (4), 9,10-phenanthrenequinone (5), tetrachloro-1,2-benzoquinone (6), tetrabromo-1,2-benzoquinone (7) and 3,5-di-tert-butyl-1,2-benzoquinone (8), have been studied in acetonitrile. In every case it was found that cyclic voltammograms differed in significant ways from those expected for simple stepwise reduction of the quinone to its radical anion and dianion. The various types of deviations for the eight quinones have been cataloged and some speculation is offered concerning their origins.     

1,2-和1,4-萘醌248 nm激光光解的瞬态吸收光谱研究

利用纳秒级激光光解动态吸收光谱装置,研究了1,2-和1,4-萘醌中性水溶液的瞬态吸收光谱.发现1,2-萘醌及1,4-萘醌被光电离后形成的阳离子自由基在380nm均有最大吸收,但1,4-萘醌阳离子自由基在衰变过程中又形成了两种新的活性粒子,它们的最大吸收分别位于410和580nm,分析表明:410nm属于1,4-萘醌脱氢自由基的吸收,而580nm很可能归属由于电子转移而形成的瞬态产物.进一步研究发现,1,2-萘醌在中性水溶液中能被248nm激光单光子电离.     

Size dependence of inner-shell autoionization lines in mercury clusters

Inner-shell photoionization spectra of Hg_n clusters (n8) have been obtained with a molecular beam experiment using synchrotron radiation from the VUV storage ring at Orsay. The photoionization spectra exhibit two strong autoionization resonances which are red-shifted with increasing cluster size. The present results are compared with solid-state experimental data which indicate that the clusters (Hg₈) do not yet have metallic character.     

Interactions of guanine and guanosine hydrates with quinones: a laser flash photolysis and magnetic field effect study

Laser flash photolysis and an external magnetic field have been used to study the interaction of two quinone molecules, namely, 9,10-anthraquinone (AQ) and 2-methyl 1,4-naphthoquinone, commonly known as menadione (MQ), with one of the DNA bases, guanine (G) and its nucleoside guanosine hydrate (dG). In organic homogeneous medium, it has been observed that G undergoes a predominant hydrogen (H) abstraction reaction with both the quinones while dG supports photoinduced electron transfer (PET) along with H abstraction. On the other hand, in SDS medium, G supports PET with AQ but not with MQ. However, behavior of dG remains unperturbed toward AQ and MQ with the change in medium. All of these observations have been explained on the basis of stabilization of radical ion pair and difference in size of the quinones, which can affect the distance of approach among the interacting molecules.     

Electrogenerated chemiluminescence of 9,10-diphenylanthracene, rubrene, and anthracene in fluorinated aromatic solvents

The electrogenerated chemiluminescence (ECL) of 9,10-diphenylanthracene (DPA), rubrene, and anthracene has been studied in fluorinated aromatic solvents. Mixed annihilation ECL between aromatic luminophores and quinones was observed in solvent systems containing acetonitrile and either benzene, benzotrifluoride, 3-fluorobenzotrifluoride, or 1,3-bis(trifluoromethyl)benzene. Increases in ECL efficiency (phi ecl, photons generated per redox event) correlated with decreasing solvent polarity when 1,4-benzoquinone was used as a nonemitting ECL partner. However, opposite results were observed using 1,4-naphthaoquinone (NQ) as a nonemitting partner. phi ecl also correlated with radical anion stability of NQ in these solvent systems, as indicated by reverse/forward current ratios ( I r/ I f), suggesting noncovalent interactions between the solvent and the nonemitting ECL partner. Specifically, the reaction of an aromatic luminophore with 1,4-naphthoquinone in acetonitrile/benzotrifluoride showed a 1.03-1.63-fold increases in ECL efficiency over that of acetonitrile/benzene. Slight blue shifts ( approximately 3 nm) in photoluminescence and ECL emissions were seen as solvent polarity increased. Reaction enthalpies of each system were estimated using half-wave potentials of oxidation and reduction and were found to correlate well with emission energy.     

Thermal decomposition of polypropylene by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry

The application of synchrotron vacuum ultraviolet (VUV) photoionization combined with molecular-beam mass spectrometry, also called synchrotron VUV photoionization mass spectrometry (SVUV-PIMS), in the research of the thermal decomposition of polypropylene (PP) was studied, and some main pyrolysis products formed at different photon energies have been identified. Using SVUV-PIMS, some isomers can be distinguished, which are much helpful for further understanding of the thermal decomposition of PP.     

Direct identification of propargyl radical in combustion flames by vacuum ultraviolet photoionization mass spectrometry

We have developed an effusive laser photodissociation radical source, aiming for the production of vibrationally relaxed radicals. Employing this radical source, we have measured the vacuum ultraviolet (VUV) photoionization efficiency (PIE) spectrum of the propargyl radical (C(3)H(3)) formed by the 193 nm excimer laser photodissociation of propargyl chloride in the energy range of 8.5-9.9 eV using high-resolution (energy bandwidth = 1 meV) multibunch synchrotron radiation. The VUV-PIE spectrum of C(3)H(3) thus obtained is found to exhibit pronounced autoionization features, which are tentatively assigned as members of two vibrational progressions of C(3)H(3) in excited autoionizing Rydberg states. The ionization energy (IE = 8.674 +/- 0.001 eV) of C(3)H(3) determined by a small steplike feature resolved at the photoionization onset of the VUV-PIE spectrum is in excellent agreement with the IE value reported in a previous pulsed field ionization-photoelectron study. We have also calculated the Franck-Condon factors (FCFs) for the photoionization transitions C(3)H(3) (+)(X;nu(i),i = 1-12)<--C(3)H(3)(X). The comparison between the pattern of FCFs and the autoionization peaks resolved in the VUV-PIE spectrum of C(3)H(3) points to the conclusion that the resonance-enhanced autoionization mechanism is most likely responsible for the observation of pronounced autoionization features. We also present here the VUV-PIE spectra for the mass 39 ions observed in the VUV synchrotron-based photoionization mass spectrometric sampling of several premixed flames. The excellent agreement of the IE value and the pattern of autoionizing features of the VUV-PIE spectra observed in the photodissociation and flames studies has provided an unambiguous identification of the propargyl radical as an important intermediate in the premixed combustion flames. The discrepancy found between the PIE spectra obtained in flames and photodissociation at energies above the IE(C(3)H(3)) suggests that the PIE spectra obtained in flames might have contributions from the photoionization of vibrationally excited C(3)H(3) and/or the dissociative photoionization processes involving larger hydrocarbon species formed in flames.     

Photoionization Mass Spectrometry: A Useful Method to Evaluate the Pyrolysis Process of Glycoside Flavor Precursor

The thermal decomposition behavior and the pyrolysis products of benzyl‐2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranoside (BGLU) were studied with synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry at temperatures of 300, 500 and 700 °C at 0.062 Pa. Several pyrolysis products and intermediates were identified by the measurement of photoionization mass spectra at different photon energies. The results indicated that the primary decomposition reaction was the cleavage of O‐glycosidic bond of the glycoside at low temperature, proven by the discoveries of benzyloxy radical (m/z = 107) and glycon radical (m/z = 331) in mass spectra. As pyrolysis temperature increased from 300 to 700 °C, two possible pyrolytic modes were observed. This work reported an application of synchrotron VUV photoionization mass spectrometry in the study of the thermal decomposition of glycoside flavor precursor, which was expected to help understand the thermal decomposition mechanism of this type of compound. The possibility of this glycoside to be used as a flavor precursor in high temperature process was evaluated.     

Reactions of Ketene Acetals V The Reaction with p-Benzoquinone Dihalides

2- or 3-Halonaphthoquinones are known to react with ketene dialkyl acetals and to yield 1,3-dialkoxyanthraquinones^2,3. Various p-benzoquinones on the other hand have given only 2-alkoxy-benzofurans². 3-Chloro-5,7-dimethoxy-1,4-naphthoquinone (4) and 1,3,6,8-tetramethoxyanthraquinone (10), important intermediates for the synthesis of naturally occurring quinones, have now been obtained under analogous conditions using p-benzoquinone dihalides (trans-5,6-dihalo 2-cyclohexene 1,4-diones). Compound 4 does not appear to have been described but is readily converted to 3,5,7-trimethoxy-1,4-naphthoquinone (7) and regiospecifically³ to 1,3,6,8-tetramethoxyanthraquinone. Although the yields obtained in the reactions of ketene acetals with quinone dihalides are low, compounds 7 and 10 have only been prepared until now by tedious means involving a large number of steps^4–8, or by the degradation of natural products^9,10.     

Quinone—cyanide reactions: their use for the determination of quinones and cyanide

Both quinones and cyanide can be determined in the μg—ng ml^-1 range by measuring the fluorescence of the addition products produced. The yield is low (except for the 2-sulfonic acid of 1,4-naphthoquinone) in aqueous solution and 1:1 DMSO:water is the recommended medium for determinations of quinones. The 2-sulfonic acid of 1,4-naphthoquinone permits the determination of trace amounts of cyanide in aqueous solution; there are few interferences.     

Tunable single-photon ionization TOF mass spectrometry using laser-produced plasma as the table-top VUV light source

Here we report on a laser plasma-based tunable VUV photoionization time-of-flight (TOF) mass spectrometer conceived mainly to study complex gaseous mixtures. Ionizing photons at tunable vacuum UV (VUV) wavelengths are generated by a gas-target laser-produced plasma, spectrally dispersed in the range 100–160 nm and efficiently focused onto a sample molecular beam. As a test case, we studied the exhaust gas of a four-stroke moped, a typical example of a complex gaseous mixture. Due to the VUV “soft” ionization, the mass spectra are less congested and more easily interpretable. Substituted benzene derivatives are found to give the most intense signals. Several aliphatic hydrocarbons are also detected. The use of tunable VUV radiation allowed the investigation of the contribution of isomers in the mass spectrum from the onset and shape of the photoionization efficiency spectra. Semiquantitative analysis was performed using known literature data detailing the photoionization cross sections. Our findings suggest that using combined data on the mass/photoionization efficiency spectra may be very helpful for a comprehensive analysis of complex gaseous mixtures.     

A thermal decomposition study of polymers by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry

The thermal decomposition of polymers (poly(vinyl chloride) (PVC) and polystyrene (PS)) has been studied with synchrotron VUV photoionization mass spectrometry at low pressure. Pyrolysis products formed at different temperatures have been identified by the measurement of photoionization mass spectra at different photon energies. The experimental results demonstrate the variation of the pyrolysis product pool of PVC at different temperatures, dividing the thermal decomposition process into two stages: the low‐temperature stage to form HCl and benzene, and the high‐temperature stage to form numerous large aromatic hydrocarbons. For the thermal decomposition of PS, four reaction categories are determined. This work reports a new application of synchrotron VUV photoionization mass spectrometry in the study of the thermal decomposition of polymers, and demonstrates its good performance in product analysis, which is expected to help understand the thermal decomposition mechanism of PVC, PS and other synthesized polymers. Copyright © 2009 John Wiley & Sons, Ltd.