A one-pot synthesis (yields over 50%) of methyl and ethyl esters from aldehydes (and the corresponding alcohol), using aromatic nitrocompounds as oxidizing agents under the catalytic action of cyanide ion or of a conjugate base of a thiazolium ion, is described. A variety of by-products (α-hydroxybenzylidenaniline) (16), α-methoxybenzylidenaniline (21), α-cyanobenzylidenaniline (27), N1-hydroxy-N1,N2-diphenylbenzamidine (28), and others) have been identified. 相似文献
Oxidative cyclization of morusin (I) by using one-electron transfer oxidizing agents (manganese dioxide, silver oxide) afforded morusin hydroperoxide (II). A similar reaction was carried out in the presence of 2,4,6-tri-t-butylphenol, a radical quencher, to give compounds (IV, V, VI and VII) coupled with the 2,4,6-tri-t-butylphenoxy radical. On the basis of above results, the possible mechanism of this oxidative cyclization was discussed. In addition, morusin hydroperoxide (II) was also obtained by photo-sensitized oxidation of morusin (I) in the presence of sensitizers (Rose Bengal, hematoporphyrin). To elucidate the reaction mechanism similar reactions were carried out in the presence of radical quencher (2,4,6-tri-t-butylphenol) or singlet oxygen quencher (triethylenediamine). From these results, the possible mechanism of the formation of morusin hydroperoxide (II) from morusin (I) was discussed. 相似文献
Reactions of peridazines (1H-1,2-diazaphenalenes) with electron-donor reagents (quinones, potassium ferrocyanide) involve multistage oxidative transformations resulting in products of dimarization and (or) dehydration. 相似文献
Oxidative coupling of 1-alkyl(benzyl)-4-(γ-pyridyl)-1,2,5,6-tetrahydropyridines with acetone in the presence of KMnO4 follows two pathways and yields both 1-R-2-(acetylmethylene)tetrahydropyridines and 1-R-3,4-dihydroxypiperidin-2-ones. When
acetonitrile is used instead of acetone, the reaction under similar conditions occurs as selective ketodihydroxylation of
the starting piperideines yielding 1-R-3,4-dihydroxy-4-(γ-pyridyl)piperidin-2-ones. The molecular and crystal structures of
one of these products (R=Et) was studied by X-ray diffraction analysis.
For part 4, see Ref. 1
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2020–2023, November, 1997. 相似文献
The behaviour of 2,4,5-triphenylpyrrole and 2-(p-tolyl)-4,5-diphenylpyrrole under oxidation conditions with dichromate has been investigated. The several reaction products obtained were separated by column cliromatography. In addition to products previously obtained using other oxidizing agents (2), additional products were isolated, namely, the 2,3′-dimers IIIa.b and related oxygenated products Va,b and VIa,b. Their structures were assigned by means of elemental analyses, chemical behaviour and spectroscopic data (ir, uv, nmr andms). 相似文献
Russian Journal of Organic Chemistry - The reaction of trifluoromethanesulfonamide with trifluoro-N-(prop-2-yn-1-yl)methanesulfonamide in the system t-BuOCl–NaI afforded... 相似文献
The influence of temperature (75-100°C), ammonia concentration in solution (1-5%), and oxygen pressure (1-8 MPa) on the yield of the target product (insoluble residue) and nitrogen content in this product in treatment of pine bark with oxygen in aqueous ammonia (oxidative ammonolysis) was studied. The resulting samples were tested in agriculture as nitrogen-containing fertilizers. 相似文献
The reactivity of N‐heterocyclic carbenes (NHCs) and cyclic alkyl amino carbenes (cAACs) with arylboronate esters is reported. The reaction with NHCs leads to the reversible formation of thermally stable Lewis acid/base adducts Ar‐B(OR)2⋅NHC ( Add1 – Add6 ). Addition of cAACMe to the catecholboronate esters 4‐R‐C6H4‐Bcat (R=Me, OMe) also afforded the adducts 4‐R‐C6H4Bcat⋅cAACMe ( Add7 , R=Me and Add8 , R=OMe), which react further at room temperature to give the cAACMe ring‐expanded products RER1 and RER2 . The boronate esters Ar‐B(OR)2 of pinacol, neopentylglycol, and ethyleneglycol react with cAAC at RT via reversible B−C oxidative addition to the carbene carbon atom to afford cAACMe(B{OR}2)(Ar) ( BCA1 – BCA6 ). NMR studies of cAACMe(Bneop)(4‐Me‐C6H4) ( BCA4 ) demonstrate the reversible nature of this oxidative addition process. 相似文献
Metal(III)-polypyridine complexes [M(NN)(3)](3+) (M = Ru or Fe; NN = bipyridine (bpy), phenanthroline (phen), or 4,7-dimethylphenanthroline (Me(2)-phen)) oxidize the nitrosylpentaaquachromium(III) ion, [Cr(aq)NO](2+), with an overall 4:1 stoichiometry, 4 [Ru(bpy)(3)](3+) + [Cr(aq)NO](2+) + 2 H(2)O --> 4 [Ru(bpy)(3)](2+) + [Cr(aq)](3+) + NO(3)(-) + 4 H(+). The kinetics follow a mixed second-order rate law, -d[[M(NN)(3)](3+)]/dt = nk[[M(NN)(3)](3+)][[Cr(aq)NO](2+)], in which k represents the rate constant for the initial one-electron transfer step, and n = 2-4 depending on reaction conditions and relative rates of the first and subsequent steps. With [Cr(aq)NO](2+) in excess, the values of nk are 283 M(-1) s(-1) ([Ru(bpy)(3)](3+)), 7.4 ([Ru(Me(2)-phen)(3)](3+)), and 5.8 ([Fe(phen)(3)](3+)). In the proposed mechanism, the one-electron oxidation of [Cr(aq)NO](2+) releases NO, which is further oxidized to nitrite, k = 1.04x10(6) M(-1) s(-1), 6.17x10(4), and 1.12x10(4) with the three respective oxidants. Further oxidation yields the observed nitrate. The kinetics of the first step show a strong correlation with thermodynamic driving force. Parallels were drawn with oxidative homolysis of a superoxochromium(III) ion, [Cr(aq)OO](2+), to gain insight into relative oxidizability of coordinated NO and O(2), and to address the question of the "oxidation state" of coordinated NO in [Cr(aq)NO](2+). 相似文献
Oxidative polymerization of p-phenylenediamine in a hydrochloric acid solution yields not a polyquinoxaline polymer as described in the literature but a modified poly(1,4-benzoquinonediimine-N,N′-diyl-1,4-phenylene) analogous to polyaniline known as pernigraniline. A new scheme of oxidative polymerization of p-phenylenediamine was suggested. 相似文献
The oxidative coupling of a mixture of 1-methoxy-7-methyl-4,5-naphthylenediol and 4-methoxy-7-methyl-1,5-naphthylenediol using lead(IV) oxide gives the symmetrical bisnaphthalene indigos diosindigo A and diosindigo B together with the corresponding unsymmetrical isomer. Oxidation of the first two by nitric acid gives the binaphthyldiquinones mamegakinone and biramentaceone, respectively; the third gives the unsymmetrical diquinone rotundiquinone. Similar oxidations of related naphthylenediols are described. 相似文献
At temperatures near 650°C and residence times ofca. 3 s, the homogeneous oxidative dehydrogenation (OXD) of propane to propylene and ethylene approached oxygen limiting conditions, even when the reactor was filled with quartz chips. The addition of catalysts that are known to be effective in the OXD of ethane slightly increased the reaction rate, but the selectivities at a given conversion level were the same as those that were achieved in the homogeneous reaction. 相似文献
We report the use of a previously intractable nucleophile, anisole, in an oxidative "cross-dehydrogenative coupling" (CDC) reaction with the cyclic ether isochroman, as well as derivatives of both components. Metal catalysis was required for the reaction to proceed efficiently, and the reaction is highly sensitive to modification of either coupling partner but is able to produce a range of novel compounds via what is a synthetic alternative to the traditional oxa-Pictet-Spengler reaction. 相似文献
Oxidative treatment of anion 11 (obtained by deprotonation of 6,6-dimethylpentafulvene 10 , Scheme 3) with CuCl2 gives a very complex mixture of coupling products 13 (18%), 14 (16%), 15 (36%), 16 (5%), and 17 (6%) (Scheme 4 and Table 2). These results show that the reactive intermediate obtained by oxidation of 11 (which is believed to be the fulvenyl radical 12 ) has several reactive sites. According to the experiments, reactivity is decreasing in the series C(7) > C(2)/C(3) > C(5) > C(1)/C(4) (Table 2), while simple frontier-orbital considerations would suggest the sequence C(7) > C(5) > C(2)/C(3) > C(1)/C(4). The results suggest that SOMO-SOMO interaction of the approaching fulvenyl radicals 12 is the central effect governing regioselectivity and product distribution, while Coulomb and steric interactions are secondary effects (Table 4). 相似文献
Summary: The first π‐conjugated poly(thioketene dimer) was synthesized via the homopolymerization of a silylthioketene dimer by a chemical oxidation‐reduction process. The polymerization of trimethylsilylthioketene dimer in the presence of FeCl3 (in CHCl3 at 70 °C for 24 h) gave the corresponding doped poly(thioketene dimer). After treatment of the doped polymer with an aqueous solution of ammonia, the neutral poly(thioketene dimer) was obtained with an incidental desilylation. The polymer obtained was soluble in DMF and DMSO. From gel permeation chromatographic analysis (DMF, polystyrene standards), the number‐average molecular weight of the polymer was found to be 7 460. The polymer showed low oxidation potentials derived from the thioketene dimer unit. An effective extension of the π‐conjugation was observed in the polymer.
Synthesis of π‐conjugated poly(thioketene dimer). 相似文献
Previous studies have shown that oxidative lime pretreatment is an effective delignification method that improves the enzymatic
digestibility of many biomass feedstocks. The purpose of this work is to determine the recommended oxidative lime pretreatment
conditions (reaction temperature, time, pressure, and lime loading) for Alamo switchgrass (Panicum virgatum). Enzymatic hydrolysis of glucan and xylan was used to determine the performance of the 52 studied pretreatment conditions.
The recommended condition (110°C, 6.89 bar O2, 240 min, 0.248 g Ca(OH)2/g biomass) achieved glucan and xylan overall yields (grams of sugar hydrolyzed/100 g sugar in raw biomass, 15 filter paper
units (FPU)/g raw glucan) of 85.9 and 52.2, respectively. In addition, some glucan oligomers (2.6 g glucan recovered/100 g
glucan in raw biomass) and significant levels of xylan oligomers (26.0 g xylan recovered/100 g xylan in raw biomass) were
recovered from the pretreatment liquor. Combining a decrystallization technique (ball milling) with oxidative lime pretreatment
further improved the overall glucan yield to 90.0 (7 FPU/g raw glucan). 相似文献
As a normal attribute of aerobic life, structural damage to organic compounds of a wide variety (DNA, proteins, carbohydrates and lipids) may occur as a consequence of oxidative reactions. Oxidative damage inflicted by reactive oxygen species has been called “oxidative stress”. Biological systems contain powerful enzymatic and nonenzymatic antioxidant systems, and oxidative stress denotes a shift in the prooxidant/antioxidant balance in favor of the former. Diverse biological processes such as inflammation, carcinogenesis, ageing, radiation damage and photobiological effects appear to involve reactive oxygen species. This field of research provides new perspectives in biochemical pharmacology, toxicology, radiation biochemistry as well as pathophysiology. 相似文献