Oxidation of Thiols Using K 2 S 2 O 8 in Ionic Liquid

A green, straightforward, and novel method for oxidation of thiols to the corresponding disulfides is reported using K ₂ S ₂ O₈ in the ionic liquid 1-butyl-3-methylimidazolium bromide [(bmim)Br] at 65–70°C. The corresponding disulfides were obtained in excellent yield and short reaction time.     

Copper nanoparticles supported on 2‐methoxy‐1‐phenylethanone‐functionalized MCM‐41: An efficient and recyclable catalyst for one‐pot three‐component C–S coupling reaction of aryl halides with benzyl bromide and thiourea

An environmentally friendly copper‐based catalyst supported on 2‐methoxy‐1‐phenylethanone‐functionalized MCM‐41 was prepared and characterized by Fourier transform‐infrared, transmission electron microscopy, field emission‐scanning electron microscopy, X‐ray diffraction and inductively coupled plasma techniques. The catalyst was applied for the one‐pot three‐component C–S coupling reactions of aryl halides with benzyl bromide and thiourea under aerobic conditions to afford the corresponding coupled products in good yields in water. The catalyst could be recovered and recycled five times. These results prove 2‐methoxy‐1‐phenylethanone‐functionalized MCM‐41 supported Cu (II) complex was not leached during the reaction. Also it shows the correct heterogeneous nature of the catalyst.     

Supported Bismuth(III) Nitrate on Silica Sulfuric Acid as Useful Reagent for Nitration of Aromatic Compounds under Solvent-Free Conditions

A number of aromatic compounds were nitrated to the corresponding nitroaromatic derivatives with the use of supported bismuth(III) nitrate on silica sulfuric acid under solvent-free conditions.     

Synthesis of 1,2,4,5-tetrasubstituted imidazoles and 2,4,5,6-tetrasubstituted pyrimidines: three-component,the one-pot reaction of arylamidines,malononitrile, and arylglyoxals or aryl aldehydes

A highly efficient one-pot synthesis of the 1,2,4,5-tetrasubstituted imidazoles and 2,4,5,6-tetrasubstituted pyrimidines through an arylamidine, malononitrile, and carbonyl compound by using Et₃N in CH₃CN at reflux conditions was developed. The nature of the carbonyl compounds were different; when the carbonyl compound was arylglyoxal or aryl aldehyde, 1,2,4,5-tetrasubstituted imidazole and 2,4,5,6-tetrasubstituted pyrimidine were achieved respectively.     

Selective oxidation of alcohols over copper zirconium phosphate

The catalytic activity of copper zirconium phosphate (ZPCu) in the selective oxidation of alcohols to their corresponding ketones or aldehydes, using H₂O₂ as an oxidizing agent, was studied. The oxidation reaction was performed without any organic solvent, phase-transfer catalyst, or additive. Steric factors associated with the substrates influenced the reaction. The catalyst was characterized using X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. It was shown that the interlayer distance increased from 0.74 to 0.80 nm and the crystallinity was reduced after Cu²⁺ intercalation into the layers. This catalyst can be recovered and reused three times without significant loss of activity and selectivity.     

三(羟甲基)氨基甲烷改性SiO_2固载钯纳米粒子:合成、表征及其催化Heck偶联反应活性（英文）

The preparation of supported Pd nanoparticles on Tris(tris(hydroxymethyl)aminomethane)‐ modi‐fied Si O2 gel and their catalytic application in Heck coupling are investigated. The catalyst was char‐acterized using a combination of X‐ray diffraction, transmission electron microscopy, field‐emission scanning electron microscopy, and scanning electron microscopy/energy‐dispersive X‐ray spec‐troscopy. The supported Pd nanoparticles were found to be a highly active and reusable catalyst for the Heck reaction at a low Pd loading(0.02 mol%) because of stabilization by the Tris moieties. Several reaction parameters, including the type and amount of solvent, base, and temperature, were evaluated. The heterogeneity of the catalytic system was investigated using different approaches, and showed that slight Pd leaching into the reaction solution occurred under the reaction condi‐tions. Despite this metal leaching, the catalyst can be reused seven times without significant loss of its activity.     

Simple and Facile Tetrahydropyranylation of Alcohols by use of Catalytic Amounts of Benzyltriphenylphosphonium Tribromide

An efficient and mild system for protection of a variety of alcohols with 3,4‐dihydro‐2H‐pyran (DHP) in the presence of catalytic amounts of benzyltriphenylphosphonium tribromide (BTPTB) (1) gives the corresponding tetrahydropyan ethers (ROTHP) in dichloromethane. The experimental procedure is simple, and the products are straightforwardly isolated in high to excellent yields.     

An Easy and Efficient Method for Cleavage of Carbon-Nitrogen Double Bonds Under Non-Aqueous and Neutral Conditions

1-Benzyl-4-aza-1-azoniabicyclo[2.2.2]octane periodate (BAABCP) (1), readily prepared as an orange solid from commercially available DABCO (1,4-diazabicyclo [2.2.2]octane, performs oxidation in anhydrous conditions. Under these conditions, the reagent converts phenylhydrazones, p-phenylhydrazones, semicarbazones, and β-keto sulfoxide hydrazones to the corresponding carbonyl compounds and β-keto sulfoxides respectively, the yields and enantioselectivity are excellent.     

Triphenylmethylphosphonium Dichromate: An Effective and Chemoselective Reagent for Oxidation of Benzylic Alcohols to the Corresponding Aldehydes and Ketones

An efficient and straightforward method for oxidation of the benzylic alcohols to the corresponding aldehydes and ketones has been accomplished using triphenylmethylphosphonium dichromate (MTPPD) under solvent-free conditions with high chemoselectivity. The reaction is fast with good yields and straightforward workup.