A Simple and Practical Method for the Oxidation of Thiols to Disulfides at Mild Conditions Without Solvents

Abstract

A green, straightforward, and novel method for the oxidation of thiols to the corresponding disulfides is reported using hydrogen peroxide catalyzed by tetrabutylammonium iodide (TBAI) without solvents at room temperature. The corresponding disulfides were obtained with excellent yields and short reaction times.     

Cellulose Sulfuric Acid: An Efficient Biodegradable and Recyclable Solid Acid Catalyst for the Synthesis of 1-Oxo-hexahydroxanthene

A series of 1-oxo-hexahydroxanthene derivatives was synthesized at room temperature in solid state from substituted salicylaldehydes and substituted 1,3-hexanediones in the presence of a catalytic amount of cellulose sulfuric acid. The results showed that the reaction performed under solid-state conditions was benign to the environment, with higher yields and more convenient workup.

氯化铜参与的制备对称二硫化合物的新方法

报道了在正丁基锂和氯化铜条件下氧化硫醇生成对称的二硫化合物的新方法.所实施的十个例子都具有很高的产率.     

A Novel Application of N‐Bromosaccharin as a Chemoselective and Efficient Oxidative Reagent for Oxidation of Thiols to Disulfides under Microwave Irradiation

Chemoselective oxidation of thiols to their corresponding disulfides with N‐bromosaccharin in a very short time and with high yields in dichloromathane under microwave irradiation conditions are described.     

Xanthan Sulfuric Acid: An Efficient and Recyclable Solid Acid Catalyst for Pechmann Condensation

In this report, substituted coumarins are formed via Pechmann condensation using various substituted phenols and ethyl acetoacetates in the presence of xanthan sulfuric acid as a solid acid catalyst under solvent-free conditions. This method is very simple, cost-effective, and has shorter reaction times, and the catalyst could be reused.     

Trimethylphenylammonium Tribromide as a New and Efficient Oxidizing Agent for the Oxidative Coupling of Thiols into Disulfides and Chemoselective Oxidation of Sulfides into Sulfoxides

Abstract

Trimethylphenylammonium tribromide has been introduced as a versatile and new oxidizing agent for the preparation of disulfides and sulfoxides from thiols and sulfides, respectively. The reaction progress is simple, and proceeds under mild and homogenous conditions in ambient temperature.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT      

A Modified and Practical Synthetic Route to Indazoles and Pyrazoles Using Tungstate Sulfuric Acid

Tungstate sulfuric acid‐catalyzed Knorr reaction have been used as a simple, rapid, atom economic and green method for the synthesis of indazole and pyrazole derivatives based on the condensation of hydrazine derivatives and ß‐dicarbonyl compounds under solvent‐free conditions. It was found that the catalyst could be recovered and reused without significant loss of its activity. The use of this method provides a novel and improved modification of Knorr synthesis in terms of clean reaction profile, use of a safe catalyst and solvent‐free conditions.     

Silica Sulfuric Acid as an Inexpensive and Recyclable Solid Acid Catalyzed Efficient Synthesis of Quinolines

Summary. Silica sulfuric acid as an inexpensive and recyclable solid acid efficiently catalyzes the Fridedl?nder synthesis of quinolines through a condensation reaction of a 2-aminoaryl ketone with an activated α-CH acid compound under solvent-free conditions in high yields at 100°C.     

Silica Sulfuric Acid as an Efficient Reagent for the Synthesis of Symmetrical Ethers Under Mild and Heterogeneous Conditions

A mild and efficient method for the synthesis of symmetrical ethers using silica sulfuric acid is reported. All reactions are performed under compeletly heterogeneous conditions in good to high yields.     

Cellulose Sulfuric Acid: Novel and Efficient Biodegradable and Recyclable Acid Catalyst for the Solid-State Synthesis of Thiadiazolo Benzimidazoles

An efficient method for the synthesis of 2-substituted benzimidazoles has been developed. In this method, benzo[c][1,2,5]thiadiazole-4,5-diamine was condensed with different aldehydes in the presence of cellulose sulfuric acid under solvent-free conditions by simple physical grinding of reactants using a mortar and pestle at room temperature. The methodology is mild, high-yielding, and green, and the catalyst could be easily recycled.     

An Efficient and Selective Solid State Oxidation of Thiols to Disulfides with Quinolinium Fluorochromate on Silica Gel

Summary. Various kinds of aliphatic (cyclic and acyclic), aromatic, and heterocyclic thiols are converted into the corresponding disulfides by quinolinium fluorochromate (QFC) on silica-gel in excellent yields. Selective oxidation of thiols in the presence of sulfides is also achieved under solid phase conditions.     

A Convenient Method for the Aerobic Oxidation of Thiols to Disulfides

Thiols are oxidized to the corresponding disulfides using K⁺/CH ₃ CN system under ambient conditions in the presence of air. This system provides a convenient, rapid, and efficient aerobic oxidative for the syntheses of symmetrical disulfides.     

钨化合物催化过氧化氢氧化环己酮合成己二酸

在无相转移催化剂的条件下,用Na2WO4·2H2O 或 H7[P(W2O7)6]·xH2O为催化剂,30% H2O2可以将环己酮高产率地氧化成己二酸.钨催化剂用量、反应液酸度对反应结果有着重要的影响.当钨原子与环己酮的摩尔比为1.5%,反应初始液的pH值为1.0时,己二酸的得率可达82%;而且催化体系具有很好的可循环性.     

清洁催化氧化环己烯合成己二酸反应中酸性配体的作用

 以30％H2O2为氧源，研究了Na2WO4·2H2O催化氧化环己烯制己二\r\n酸反应中的配体效应．在大多数情况下，配体的酸性越强，目标产物己\r\n二酸的产率越高．尽管一些酚类配体、L（＋）抗坏血酸和8－羟基喹啉\r\n的酸性较弱，但己二酸的产率仍然很高．这表明影响目标产物产率的因\r\n素除配体的酸效应以外，还存在配体的配位效应．邻苯二酚和对苯二酚\r\n等酚类配体的实验结果表明，反应可能是通过络合催化反应机理完成的\r\n．对酸性配体用量及对反应动力学考察结果表明，反应过程中环氧化物\r\n水解为1，2－环己二醇是整个反应的控制步骤，反应体系的酸性起到决\r\n定性的作用．     

Tribromoisocyanuric Acid (TBCA) and Oxone®‐MX Systems as Oxidizing Agents: Oxidative Coupling of Thiols to Their Corresponding Disulfides under Mild and Heterogeneous Conditions

Tribromoisocyanuric acid (TBCA) and Oxone^®‐MX systems were used as effective oxidizing agents for the oxidation of thiols to their corresponding disulfides under mild conditions at room temperature with good to excellent yields.     

A Novel Method for Beckmann Rearrangement of Oximes with Silica Sulfuric Acid under Mild Condition

The conversion of ketoxime into corresponding amide, known as the Beckmann rearrangement, is a common method used in organic chemistry and is also a topic of current interest. It accomplishes both the cleavage of carbon-carbon bond and the formation of a carbon-nitrogen bond, and represents a powerful method particularly for manufacture ε-caprolactam in chemical industry. This reaction, however, generally requires high reaction temperature, strong Br?nsted acid and dehydrating media, causing …     

Tributylammonium Halochromates/silica Gel:Simple Reagents for Oxidative Coupling of Thiols to Symmetrical Disulfides

New orange solid tributylammonium halochromates, (C₄H₉)₃N⁺CrO₃X^?, TBAXC (X=F, Cl) are easily synthesized by the reaction of tributylammonium fluoride and chloride with CrO₃ in a 1:1 molar ratio in the presence of HF and HCl. Tributylammonium halochromates(VI) are versatile reagent for the effective and selective oxidation of organic substrates. Silica gel supported TBAFC and TBACC are versatile reagents for the effective and selective oxidation of organic substrates, in particular, thiols, under mild conditions. Considerable improvements are observed in the presence of the absorbent, making the work‐up much more convenient.     

Ethylenebis( N -methylimidazolium) Chlorochromate ( EBMICC ): An Efficient and Selective Reagent for the Oxidation of Thiols to Disulfides

Ethylenebis(N-methylimidazolium) chlorochromate was prepared by addition of N-methylimidazole to 1,2-dibromoethane to form the corresponding dibromide salt and subsequent treatment of this salt with CrO₃ in 6N HCl solution. It is a stable yellow-orange solid, which oxidized thiols to the corresponding disulfides at room temperature. Selective oxidation of thiols in the presence of sulfides and hydroxyl groups was also achieved with this reagent.     

A Novel Catalytic Method for the Oxidation of Sulfides to Sulfoxides with Silica Sulfuric Acid and Sodium Nitrite in the Presence of KBr and/or NaBr as Catalyst

Highly efficient selective oxidation of sulfides to sulfoxides by NaNO₂ and silica sulfuric acid catalyzed with KBr or NaBr has been reported. This oxidation was carried out in the presence of wet SiO₂ (50% w/w) in acetonitrile at room temperature with good to excellent yields.