Presence Of Wet SiO2 Research Articles

Mukaiyama reagent/NaNO2/wet SiO2 as a mild and heterogeneous reagent system for the N-nitrosation of amines and preparation of azides from hydrazines

The combination of the Mukaiyama reagent and sodium nitrite in the presence of wet SiO2 was found to be an effective system for the conversion of amines into N-nitrosamines and hydrazines into azides. The heterogeneous reaction proceeded in good to excellent yields and possesses advantages such as the use of non-hazardous reagents, and simple reaction work-up.

Facile N-Nitrosation of Secondary Amines Using Poly(N,N'-dibromo-Nethylene- benzene-1,3-disulfonamide)and N,N,N',N'-tetrabromobenzene- 1,3-disulfonamide/NaNO<sub>2</sub> Under Mild Conditions

In this research project, a combination of poly(N,N'-dibromo-N-ethylene-benzene-1,3-disulfonamide) [PBBS] and/or(N,N,N',N'-tetrabromobenzene-1,3-disulfonamide) [TBBDA] with sodium nitrite in the presence of wet SiO2 (50% w/w) was used as an efficient nitrosating agent for the conversion of secondary amines to their corresponding nitroso compounds. N-Nitrosation reaction has been performed in dichloromethane at room temperature under mild and heterogeneous conditions. The reaction is operationally simple and corresponding products were achieved in good to excellent yields. Keywords: Poly (N, N'-Dibromo-N-ethylene-benzene-1, 3-disulfonamide) [PBBS], N, N, N', N'-tetrabromobenzene-1, 3-disulfonamide [TBBDA], N-Nitrosation, N-Nitrosamines, Sodium nitrite, Wet SiO2

Oxidative aromatization of novel tetrahydrochromeno[4,3-b]quinolines using silica sulfuric acid/NaNO2

A combination of silica sulfuric acid and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidative aromatization of novel Tetrahydrochromeno[4,3-b]quinolines to their corresponding pyridine derivatives under reflux and heterogeneous conditions in high yields.

ChemInform Abstract: Selective Conversion of C=N Bonds to Their Corresponding Carbonyl Compounds by the Tribromoisocyanuric Acid/Wet SiO2 System as a Novel Reagent.

AbstractTribromoisocyanuric acid in the presence of wet SiO2 is a suitable reagent for the regeneration of carbonyl compounds from oximes, semicarbazones, azines, and Schiff bases under mild conditions.

Cu(NO3)2 · 3 H2O as an Efficient Reagent for the Chemoselective Trimethylsilylation of Primary Alcohols and Oxidation of Trimethylsilyl Ethers

Cu(NO3)2 · 3 H2O can be used as an efficient reagent for the chemoselective trimethylsilylation of primary benzylic and aliphatic alcohols with hexamethyldisilazane (HMDS). This reagent is also able to oxidize the obtained trimethylsilyl ethers to the corresponding carbonyl compounds in the presence of wet SiO2 and KBr. In this study, all reactions are performed in the absence of a solvent and good-to-high yields are obtained.

Metal-free catalytic oxidation of urazoles under mild and heterogeneous conditions via combination of ammonium nitrate and catalytic amounts of silica sulfuric acid

Highly efficient production of 4-substituted-1,2,4-triazole-3,5-diones from urazole derivatives using ammonium nitrate and silica sulfuric acid (SiO2-OSO3H), as a cheap and nontoxic catalyst, in the presence of wet SiO2 (50% w/w) under mild and heterogeneous conditions is reported. The process presented here is operationally simple, environmentally benign and produces high yield.

ChemInform Abstract: An Efficient Method for the Oxidation of Hantzsch 1,4-Dihydropyridines to Their Corresponding Pyridine Derivatives under Mild and Heterogeneous Conditions.

Abstract A combination of oxalic acid dihydrate and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives at room temperature with excellent yields.

ChemInform Abstract: An Efficient Method for N-Nitrosation of Secondary Amines under Mild and Heterogeneous Conditions.

Abstract A combination of inorganic acidic salts or silica gel supported inorganic acids and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of secondary amines to their corresponding nitroso drivatives under mild and heterogeneous conditions in moderate to excellent yields. Mg(HSO4)2 and NaHSO4 are superior to all the aforementioned reagents in convenience, yield and purity of the isolated nitrosoamines.

Catalytic oxidation of sulfides to sulfoxides using aluminium hydrogen sulfate, sodium nitrite and catalytic amounts of metal bromide

A catalytic, chemoselective and environmentally friendly procedure for the oxidation of sulfides is described. A wide range of aliphatic or aromatic sulfides were successfully oxidized to the corresponding sulfoxides using NaNO2, Al(HSO4)3 and a catalytic amount of KBr or NaBr in the presence of wet SiO2 (50% w/w) in CH3CN under heterogeneous conditions in moderate to high yields.

Metal-free catalytic oxidation of sulfides to sulfoxides with ammonium nitrate, ammonium hydrogen sulfate and ammonium bromide as catalyst

A general and metal-free catalytic oxidation of aliphatic and aromatic sulfides to their corresponding sulfoxides via combination of ammonium nitrate (NH4NO3), supported ammonium hydrogen sulfate on silica gel (NH4HSO4-SiO2) and a catalytic amount of ammonium bromide (NH4Br) in the presence of wet SiO2 (50%, w/w) has been investigated. The reactions were carried out heterogeneously and selectively in short reaction times in CH2Cl2 at room temperature. This protocol is mild and efficient compared to other reported methods.

1,3-Dibromo-5,5-dimethylhydantoin or N-bromosuccinimide as efficient reagents for chemoselective deprotection of 1,1-diacetates under solvent-free conditions

A simple and efficient method is reported for rapid chemoselective transformation of 1,1-diacetates to the parent aldehydes using 1,3-dibromo-5,5-dimethylhy- dantoin or N-bromosuccinimide in the presence of wet SiO2 (50%, w/w) as solid support under solvent-free con- ditions at room temperature. This procedure has valuable advantages, for example short reaction times, simple work- up, high yields of products, absence of solvent, and use of commercially available and non-toxic reagents.

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

AbstractHighly 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.

Aluminum nitrate and silica sulfuric acid as efficient nitrating media for the mononitration of phenols under mild and heterogeneous conditions

A variety of phenol derivatives were successfully nitrated via combination of Al(NO3)3·9H2O and silica sulfuric acid in the presence of wet SiO2 (50% w/w) in dichloromethane at room temperature with moderate-to-good yields.

An Efficient Catalytic Procedure for the Selective Oxidation of Sulfides to Sulfoxides by Citric Acid/Al(NO3)3.9H2O/MBr Under Mild and Heterogeneous Conditions

AbstractA wide range of aliphatic or aromatic sulfides are selectively oxidized to the corresponding sulfoxides using Al(NO3)3.9H2O, citric acid and a catalytic amount of KBr or NaBr in the presence of wet SiO2 (50% w/w)in CH2Cl2 under mild and heterogeneous conditions in good to high yields.

Catalytic oxidation of sulfides to sulfoxides using sodium perborate and/or sodium percarbonate and silica sulfuric acid in the presence of KBr

Abstract Chemoselective catalytic oxidation of sulfides has been developed. A variety of aliphatic and aromatic sulfides are subjected to the sulfoxidation reaction by treatment of sodium perborate (SPB) and/or sodium percarbonate (SPC), silica sulfuric acid (SSA) and catalytic amounts of KBr in the presence of wet SiO2 (50% w/w) in dichloromethane at room temperature with moderate to good yields.

Chemoselective N-nitrosation of secondary amines under heterogeneous and mild conditions via in situ generation of HNO 2

A wide variety of secondary amines are chemoselectively subjected to N-nitrosation reaction with treatment of citric acid and NaNO 2 in the presence of wet SiO 2 (50%, w/w) in dichloromethane at room temperatture under heterogeneous conditions. The N-nitrosation method is very simple and products can be easily isolated with good to high yields.

Aluminium Nitrate/Silica Sulfuric Acid/Bromide Ion: As an Effective and Catalytic Oxidizing Media for the Selective Oxidation of Sulfides to Sulfoxides

AbstractVarious types of sulfides are chemoselectively oxidized to the corresponding sulfoxides by treatment of Al(NO3)3.9H2O, silica sulfuric acid and a catalytic amount of NaBr in the presence of wet SiO2 (50% w/w) in CH2Cl2 at room temperature. The catalytic oxidation procedure is very simple and the products are easily isolated in good yields.

Ferric nitrate in the presence of catalytic amounts of KBr or NaBr: an efficient and homoselective catalytic media for the selective oxidation of sulfides to sulfoxides

A mild, efficient, and highly selective oxidation method of sulfides to sulfoxides using Fe(NO3)3·9H2O and catalytic amounts of KBr or NaBr in the presence of wet SiO2 (50% w/w) has been developed. A variety of aliphatic and aromatic sulfides were selectively oxidized at room temperature in good to excellent yields.

Selective and efficient oxidation of sulfides to sulfoxides using ammonium cerium (IV) nitrate in the presence of a catalytic amount of KBr or NaBr

A wide range of aliphatic or aromatic sulfides are selectively oxidized to the corresponding sulfoxides using ammonium cerium (IV) nitrate (CAN) and a catalytic amount of KBr or NaBr in the presence of wet SiO2 in CH2Cl2 under heterogeneous conditions in moderate to high yields.

Molybdatophosphoric Acid/NaNO2/Wet SiO2 as an Efficient System for the Aromatization of 1,2‐Dihydroquinolines under Mild and Heterogeneous Conditions

A combination of molybdatophosphoric acid and NaNO2 in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of 1,2‐dihydroquinolines to their corresponding quinoline derivatives in dichlomethane at room temperature with excellent yields.