Catalytic Oxidative Conversion from Naphthol to 2-Hydroxy-1, 4-naphthoquinone over Iron Porphyrin Catalysts by Molecular Oxygen in an Alkaline 2-Propanol Solution

In an alkaline 2-propanol solution with 5,10,15,20-tetra(4-methoxyl phenyl) porphyrin iron chloride(TOMPPFeCl) as a catalyst and oxygen as a cheap green oxidant, 2-naphthol was conversed to 2-hydroxy-\{1,4-naphthoquinone(HNQ)\} with a yield of 62.17% and a selectivity of 100%, and the conversion number of TMOPPFeCl catalyst was 8.32/min. The catalytic oxidation products were characterized by means of UV-Vis, IR, GC-MS, ~ 1H NMR and melting point determination. In this catalytic oxidation, the catalytic activity of TMOPPFeCl was researched in detail and the reacting conditions were optimized. A possible reaction mechanism is summarized based on in situ EPR determination.

Magnetic Field Effects on Photoreduction Reaction of 2-Methyl-1,4-Naphthoquinone in Brij 35 Micellar Solution with Additional Radical

A study was made of magnetic field effects (MFEs) on the photoreduction reaction of 2-methyl-1,4-naphthoqui- none (MNQ) in Brij 35 micellar solution containing 4-lauroylamino-TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) radical (L-R) under magnetic fields below 1.75 T by a nanosecond laser flash photolysis technique. The triplet MNQ mainly underwent the hydrogen abstraction from Brij 35 molecule to give a radical pair. The escaped radical yield increased with magnetic fields from 0 to 0.62 T and then saturated from 0.62 to 1.75 T. MFEs for both sys-tems can be explained by the relaxation mechanism. However, it was supposed that additional radical, L-R affected the MFEs mainly through enhancing the spin-spin interactions of radical pairs. The effect of the micelle size on MFEs of the studying system was also discussed.

Electron Transfer Reaction Between Desoxyadenosine and Triplet 2-Methyl-1,4-naphthaquinone:A Laser Photolysis Study

Introduction Electron transfer oxidation of DNA by triplet artificial photonuclease reveals a bright prospect of its application in biology and medicine. Both molecular orbital calculation and laser experiments have indicated that the homo guanine sequence should be the final localization site of photoexcited hole via long range migration within DNA. However, the direct observation of the produced ion pairs of biomolecules especially the stabilized radical cation DNA or its components is hampered by the overwhelming transient absorption of protonated radical anion of photosensitizers, such as 2-methyl-1,4-naphthaguinonel （MQ）.

Catalytic Conversion of 2-Naphthol to 2-Hydroxy-1,4-naphthoquinone Under Mild Conditions

2-Hydroxy-1,4-naphthaquinone (HNQ) was selectively synthesized from catalytic oxidation of 2-naphthol by molecular oxygen over tetra(4-methoxyl-phenyl)porphyrinate iron(III) chloride (TMOPPFeCl) catalyst in an alkali methanol solution under mild conditions. The influences of solvents, temperature, time, as well as amounts of cata-lysts and alkali were studied. The quantitative data show that 32.9% of 2-naphthol (0.093 mol/dm3) was catalyti-cally converted to HNQ with the selectivity of 100% at 323 K for 9 h over TMOPPFeCl catalyst (2.54×10-4 mol/dm3) in alkali media (30 mL of methanol containing 2.5 mol/dm3 of NaOH) by flowing molecular oxygen (flowing rate of 45 mL/min).

Synthesis,Characterization,X-ray Crystal Structure and Safener Activity of Chiral 2-(3-Methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl)-2-oxoethyl Acetate

The new title compound, chiral 2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）- 2-oxoethyl acetate, has been synthesized via reduction, cyclization and acylation reaction. The structure of the product has been confirmed by IR, 1H NMR, 13C NMR, LC-MS （ESI） and single-crystal X-ray diffraction. （R）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate crystallizes in monoclinic, space group P21/c with a = 11.867（2）, b = 8.4087（2）, c = 14.325（6） A^°, β = 117.59（2）°, Z = 4, V = 1266.9（6） A^°3, Dc = 1.307 g/cm^3, F（000） = 528, μ（MoKα） = 0.097 mm-1, R = 0.0453 and wR = 0.1237; （S）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate belongs to the triclinic system, space group P with a = 8.2647（17）, b = 8.7034（17）, c = 9.5479（19） A^°, α = 105.33（3）, β = 100.95（3）, γ = 105.14（3）°, Z = 2, V = 614.1（2） A^°3, Dc = 1.348 g/cm^3, F（000） = 264, μ（MoKα） = 0.10 mm-1, R = 0.0613 and wR = 0.1037. Both of the molecules prefer to form crystal packing through C–H…O hydrogen bonds.

An environmentally friendly synthesis of 1,4-dihydropyrano[2,3-c]pyrazole derivatives catalyzed by tungstate sulfuric acid

An efficient three-component synthesis of 6-amino-4-aryl-5-cyano-3-metriyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazoles via a reaction between 3-methyl-1-phenyl-2-pyrazolin-5-one,aromatic aldehydes and malononitrile using tungstate sulfuric acid as a catalyst was described.Mild conditions,good to excellent yields,easily available catalyst and easy work-up are the key features of this method.