Acetonitrile anthraquinone

Solvent Effects. The conversion of dihydroanthracene could be increased by adding water to the pyridine solvent (Table III). An 86% conversion to anthraquinone was obtained when 95% aqueous pyridine was used as the solvent. Furthermore, methanol could be substituted for the water with equivalent results. Other solvents were tried in place of pyridine (Table IV). The data indicate that 95% aqueous pyridine gave the best yields, although aniline gave nearly similar results. When acetonitrile and dimethylformamide were used, the large amounts of unreacted starting material indicate that these solvents may have deactivated the base by undergoing a hydrolysis reaction. 

V in both methanol and acetonitrile. These values, combined with the doping density and the band gap of 1.12 eV for p-Si places the conduction band edge in methanol and acetonitrile at -0.85V (vs SCE). The supraband edqe redox couples chosen for the two electrolytes were 1,3 dimethoxy-4-nitrobenzene (8,=-l -0V vs SCE)for methanol, and 1 nitronaphthalene (E0=-l. 08), 1, 2 dichloro 4-nitrobenzene (E0= -0.95), and anthraquinone (Eo=-0.95) for acetonitrile. These redox couples lie from 0.IV to 0.24V above the conduction band edge of p-Si, and hence, in the conventional model, could not be photoreduced by p-Si. 

Figure 3. Photoreduction on p-Si or redox couples with redox potentials lying above the conduction band edge as determined by dark flat-band potential measurements. (a) Photoreduction of 1,3 dimethoxy-4-nitrobenzene in methanol (E0 = —1.0V vs. SCE) (b) photoreduction of anthraquinone in acetonitrile (E0 = —0.95 V vs. SCE) Ec for p-Si in both cases in the dark is —0.85 V vs. SCE (------------------------------) dark (---) light (5).

Figure 5. Current-voltage curve for anthraquinone (400 mw/cmz) in acetonitrile...

Anthraquinone photosensitised irradiation of tertiary N-allylamines in the presence of aP-unsaturated esters gives good yields of lactams. Using pyrex-filtered output (X>290 nm) from a 450 W medium pressure Hanovia lamp, for example, A-allylpiperidine and methyl methacrylate reacted in acetonitrile to give a 2 3 diastereomeric mixture (2S, 9S 2R, 95) of the indolizidone 1. 

This study evaluated the impurity profile of untreated water from a textile plant in Portugal [35]. The organic material was concentrated by extraction from 11 of water into dichloromethane and HPLC-NMR and HPLC-MS experiments were carried out using a reverse-phase separation with an acetonitrile/ D2O gradient elution with H NMR spectroscopic observation at 600 MHz. For the HPLC-NMR studies, the samples were further fractionated into two pools according to their HPLC retention times. The HPLC-NMR studies were carried out in the stop-flow mode and the combination of NMR and MS results yielded the identification or tentative identification of 14 compounds, comprising mainly surfactants, anthraquinone dyes and nonylphenol-related molecules. 

Fig. 24 Pulsed irradiation of a homogenous solution of anthraquinone 31a, in acetonitrile (c = 8.9x10 mol dm"3), at room temperature. Working potential (a) -800 mV,...

Fig. 12a—e. H CIDNP spectra of diethylvinylamine observed during the reaction of (a) anthraquinone with triethylamine, (b) benzoquinone with triethylamine in acetone-d6, (c) benzoquinone with triethylamine in acetonitrile-d3. Traces (d) and (e) show theoretical spectra calculated for the exclusive involvement of the aminoalkyl radical and of the aminium radical ion, respectively. The change from emission (trace a) to enhanced absorption (trace c) for the doublets near 6.0 ppm indicates an increasing involvement of the aminium radical ion [178]... 

In addition to quinone reduction and hydroquinone oxidation, electrode reactions of many organic compounds are also inner-sphere. In these charge transfer is accompanied by profound transformation of the organic molecules. Some reactions are complicated by reactant and/or product adsorption. Anodic oxidation of chlorpro-mazine [54], ascorbic acid [127], anthraquinone-2,6-disulfonate [128], amines [129], phenol, and isopropanol [130] have been investigated. The latter reaction can be used for purification of wastewater. The cyclic voltammogram for cathodic reduction of fullerene Cm in acetonitrile solution exhibits 5 current peaks corresponding to different redox steps [131]. 

Issaq and McNitt [585] published a computer program for peak recognition on the basis of peak areas. They investigated the reproducibility of the area of some well-separated peaks for three solutes (anthraquinone, methyl anthraquinone and ethyl anthraquinone) in the 10 solvents used for their optimization procedure. The solvents included binary, ternary and quaternary mixtures of water with methanol, acetonitrile and THF. The areas were found to be reproducible within about 2 percent. The wavelength used for the UV detector in this study was not reported. 

FIGURE 9.5 Polarity-dependent polarization patterns in photosensitized hydrogen abstractions from triethylamine DH (sensitizer A, 9,10-anthraquinone). For the formulas, see Chart 9.3. Shown are the signals of the olehnic a and P protons of the product N, A-di ethyl vinylamine, V-a (6.05ppm) and V-P (3.45ppm), as functions of the relative permittivity e (given at the right). Top, pure acetonitrile-fi 3 bottom, pure chloroform-fi 3 other traces, mixtures of these two solvents. All spectra were normalized with respect of the absolute amplitude of V-a. Further explanation, see text. 

Asymmetric functionalization was achieved in the two dendrimers 60 and 61, which contain two branches terminated with electron-donor TTF units and one branch terminated with electron-acceptor anthraquinone (AQ) units [131]. Cyclic voltammetric investigation in acetonitrile showed that each of these electroactive units are noninteracting, giving rise to two waves on oxidation (due to TTF) and to two waves on reduction (due to AQ). The number of electrons exchanged in each of... 

Me R = Br, R = H) by various donors in viscous soJventa are decreased by a factor of <2 in a 0.34 T magnetic field and pressure is reported to accelerate the photoreduction of p-benzoquinone in SOS and CTAB micelles in Aerosol OT reversed micelles, the reaction is retarded.The yield of anthraquinone-2-sulphonate radical anion (AQS) generated by irradiation of AQS in aqueous acetonitrile containing propan-2-oJ has been found to depend on the water concentration and to follow Perrin s equation.Complexation of aryl alkyl ketones with /3-cyclodextrin leads to changes in the ratio of the products of elimination and cyclisation which result from reaction of the... 

Figure 11. Time-resolved CIDNP spectra in a system described by the mechanism of Chart VI photoreaction of the acceptor anthraquinone 12 (8 x 10-4 M) with the donor /V,/V-dimethylaniline 13 (3.2 x 10 4M) in acetonitrile-d,. Experimental parameters T — 257 K, excitation wavelength 343 nm. Shown is the dependence of the signal I of the dimethylamino protons (marked with in the formula) on the delay time f0 between laser flash and acquisition pulse. [Adapted from ref. [86a] with permission. Copyright 1990 Elsevier Science Publishers B.V.]...

In all the articles the anthraquinones of Rubia tinctorum were (quantitatively) measured through determination of their ultraviolet (UV) absorbance at 254 nm [51,57,58,63,66,71,84], 280 nm [46,47,66] or at visible wavelengths more specific for anthraquinones such as 430 nm [50], 480 nm [58] or 500 nm [58]. The eluents used for the HPLC separation of the glycosides generally consisted of mixtures of water and acetonitrile or water and methanol [4]. Most research groups added some acid to suppress tailing of the anthraquinone peaks [51]. In Table (3) the HPLC systems used for the separation of anthraquinones of Rubia tinctorum are described. 

Figure Bl.16.9. Background-free, pseudo-steady-state CIDNP spectra observed in the photoreaction of triethylamine with different sensitizers ((a), anthraquinone (b), xanthone, CIDNP net effect (c), xanthone, CIDNP multiplet effect, amplitudes multiplied by 1.75 relative to the centre trace) in acetonitrile-d3. The structural formulae of the most important products bearing polarizations (1, regenerated starting material 2, N,N-diethylvinylamine 3, combination product of amine and sensitizer) are given at the top R denotes the sensitizer moiety. The polarized resonances of these products are assigned in the spectra. Reprinted from [21).

Hypervalent iodine species were demonstrated to have a pronounced catalytic effect on the metalloporphyrin-mediated oxygenations of aromatic hydrocarbons [93]. In particular, the oxidation of anthracene (114) to anthraquinone (115) with Oxone readily occurs at room temperature in aqueous acetonitrile in the presence of 5-20 mol% of iodobenzene and 5 mol% of a water-soluble iron(llI)-porphyrin complex (116) (Scheme 4.57) [93]. 2-ferf-Butylanthracene and phenanthrene also can be oxygenated under similar conditions in the presence of 50 mol% of iodobenzene. The oxidation of styrene in the presence of 20 mol% of iodobenzene leads to a mixture of products of epoxidation and cleavage of the double bond. Partially hydrogenated aromatic hydrocarbons (e.g., 9,10-dihydroanthracene, 1,2,3,4-tetrahydronaphthalene... 

S. R. Belding, J. G. Limon-Petersen, E. J. P. Dickinson, and R. G. Compton. Voltammetry in the absence of excess supporting electrolyte offers extra kinetic and mechanistic insights Comproportionation of anthraquinone and the anthraquinone dianion in acetonitrile, Angew. Chem. Int. Ed. 49, 9242-9245 (2010). 

Polynuclear aromatics without alkyl chains are electron-rich systems which rapidly react with Ce(IV) in aqueous THF. Anthracene gives a 61% yield of anthraquinone, yields of quinones are lower with naphthalene or phenanthrene (71). Very good yields of quinones are obtained when dihydroxy aromatics are treated with CAN a few minutes at room temperature in aqueous acetonitrile (72) (eq. 46 ). 

In the paper [74] oxidation of ferrocene and anthracene in acetonitrile and dichloromethane was successfully studied using the NPV technique at 5 pm Pt disc microelectrodes. The pulse widths were very short (5 to 20 ps) combined with the waiting times of duration 25 ps. Besides NPV also RPV has been applied. The resulting NP and RP waves for the oxidation of 9,10-anthraquinone are demonstrated in Fig. 28. The model of quasi-reversible charge transfer was fitted and parameters of both processes (k , and E1/2) were estimated. The results show that NP and RP voltammetric experiments retain the advantages over fast CV method even at pulse times as short as 5 ps. They provide effective discrimination against the double-layer charging current as well. 

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