Oxone as a Mild,Inexpensive, and Environmentally Benign Oxidant for the α-Thiocyanation of Ketones

An efficient and direct approach for the α-thiocyanation of ketones with α-hydrogens has been developed using ammonium thiocyanate as a thiocyanating agent and oxone as an oxidant in methanol.     

Direct α-thiocyanation of carbonyl and β-dicarbonyl compounds using potassium peroxydisulfate-copper(II)

A convenient approach for the direct α-thiocyanation of carbonyl and β-dicarbonyl compounds has been developed using ammonium thiocyanate as the thiocyanating agent and potassium peroxydisulfate as the oxidant in the presence of a catalytic amount of copper(II) sulfate in aqueous acetonitrile. The catalyst and oxidizing agent used in the reaction are inexpensive and provide good to excellent yields.     

在NaCl和SCN~-存在下浮选铜(Ⅱ)间接测定十六烷基三甲基溴化铵

研究了NaCl和NH4SCN浮选Cu(Ⅱ)间接测定十六烷基三甲基溴化铵的新方法。在水溶液中,Cu(Ⅱ)与SCN-和CTMAB缔合生成沉淀,在NaCl存在下,此沉淀被浮选。实验表明,Cu(Ⅱ)的浮选率与CTMAB的量在3.6~54.7 mg/L范围内呈良好的线性关系。CTMAB的检出限为1.8μg/mL。方法已用于合成水样和自来水中CTMAB的测定。     

A reactant promoted solvent free synthesis of 3,4-dihydropyrimidin-2(1H)-thione analogues using ammonium thiocyanate

This is the first-time ammonium thiocyanate (NH₄SCN) has been used as a self-promoting reactant for the synthesis of 3,4-dihydropyrimidin-2(1H)-thiones. This report describes a greener, efficient and economic protocol for one pot three-component synthesis of Biginelli compounds using various aldehydes, β-ketoesters and ammonium thiocyanate. Ammonium thiocyanate being a weak acid, accelerate the rate of reaction to obtain Biginelli compounds in solvent-free condition at 110 °C. The key advantages of the present method are high yields, short reaction time, solvent free condition, easy workup and ability to tolerate a variety of functional groups. Ammonium thiocyanate is readily available, cheaper, safer and industrial acceptable material which gives economical as well as ecological rewards to the present method.     

Calculated phase diagrams for cellulose/ammonia/ammonium thiocyanate solutions in comparison to experimental results

Flory's lattice theory for rigid rod molecules and Kuhn chains is used to calculate phase diagrams for cellulose/ammonia/ammonium thiocyanate solutions. Persistence length values measured by light scattering and reported previously are used as rod length values. Variations in the phase diagram based on varying rod length/solvent composition and cellulose molecular weight are explored. Spinodal curves are calculated in a region of the phase diagram predicting phase separation between two anisotropic solutions. Finally, calculated phase diagrams are compared to published data for the system. Discrepancies between theory and data may be accounted for by soft interactions between cellulose molecules and solvent which are not incorporated into the lattice theory.     

Synthesis of bis-indolylmethanes catalyzed by oxone

Oxone (3.5 mol%) was found to be an effective catalyst for the condensation reactions of indoles with aldehydes to afford bis-indolylmethanes in good to excellent yields within 10–30 min. The method is simple and economic. The catalyst is found to be recyclable.     

Regioselective and high-yielding bromination of aromatic compounds using hexamethylenetetramine-bromine

A regioselective and highly efficient method for bromination of aromatic compounds in the presence of a stoichiometric amount of hexamethylenetetramine-bromine (HMTAB) as an efficient reagent in dichloromethane is reported. The selectivity depends on the temperature and nature of the substituent on the substrate. The reactivity of this reagent was increased by supporting it to silica gel for bromination of less activated compounds.     

Regioselective ring-opening of aziridines with potassium thiocyanate and thiols using sulfated zirconia as a heterogeneous recyclable catalyst

Ring-opening of aziridines with potassium thiocyanate and thiols has efficiently been carried out at room temperature in the presence of sulfated zirconia to give the corresponding β-aminothiocyanates and β-aminosulfides, respectively, in high yields within 2 h and with high regioselectivity. The catalyst, a solid acid, functions under heterogeneous conditions.     

A convenient one-pot synthesis of 3,5-diarylisoxazoles via oxidative cyclisation using catalytic CuBr2 and oxone

A facile one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones and hydroxylamine hydrochloride is reported. The reaction is efficiently promoted by catalytic CuBr₂ and Oxone to afford the desired products mostly in high yields and in relatively short time. The mild nature of the synthesis and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.     

Simple and regioselective oxyiodination of aromatic compounds with ammonium iodide and Oxone

A simple method for the iodination of aromatic compounds using NH₄I as the iodine source and Oxone^® as the oxidant is described.     

Transition-metal-free regioselective thiocyanation of phenols,anilines and heterocycles

An expedient direct and regioselective thiocyanation of phenols, anilines and heterocycles is described. Transformation is realized via the direct CH functionalization under transition metal free conditions at ambient temperature in excellent yields. Method proved to be monoselective and variety of functional groups tolerated the reaction conditions. The practicality of the protocol is demonstrated in gram scale synthesis of a precursor of PPAR δ agonist in excellent yield.     

A novel amination of aromatic and heteroaromatic compounds

Vinyl azides act as NH⁺₂ equivalents in reaction with aromatic or heteroaromatic lithium derivatives thus providing a direct method for amination of such compounds.     

Luminescence-laser classification of heteroaromatic and aromatic compounds.

The luminescent and laser properties of heteroaromatic and aromatic compounds are reviewed and discussed on the basis of all possible mutual arrangements of singlet and triplet states. All heteroaromatic compounds are divided into five classes. It is shown that a heteroaromatic compound can only be an effective laser dye if it belongs to class V (a situation where the Tnpi* level lies at higher energy than the S1(pipi*) level). Moreover, it is shown that the energy interval between the Tnpi* and S1(pipi*) states must be no less than 1000 cm - since the rate constant of the non-radiative process S1(pipi*)[symbol in text]Tnpi*[symbol in text]T1(pipi*) is usually 100 times greater than the fluorescence rate constant. The classification is extended to compounds with orbitals of pi/,pi*, pi,nupi* and pi/,nupi* nature. Pure aromatic compounds, the spectral-luminescent properties of which are solely determined by transitions of pi-electrons (pi --> pi*), are also divided into five classes, depending on the mutual arrangement of the Sp(1La), Salpha(1Lb), Tp(3La) and Tbeta(3Bb) states. It is found that only aromatic compounds of classes IV and V can be effective scintillators and laser dyes. It is also shown that the energy interval Salpha-Sp (for class IV) and Tbeta-Sp (for class V) must be no less than 1000 cm(-1). To illustrate the classifications for heteroaromatic and aromatic compounds, 12 specifically chosen compounds were studied experimentally and quantum chemically. The quantum yields, gamma and decay times, tauf of fluorescence in aerated and non-deaerated ethanol or cyclohexane solutions were measured. The oscillator strength, f(e), fluorescence rate constant, k(f), natural lifetimes, tauT(0) and intersystem crossing rate constants, kST are calculated. The laser ability of each of the compounds studied is tested. The suggested classification schemes can be extremely useful in the quest for effective scintillators and laser dyes among hypothetical heteroaromatic and aromatic molecules, enabling evaluation of these properties for a particular compound using only quantum chemical simulations.     

The sulfonation of aromatic and heteroaromatic polycyclic compounds

Relative reactivities of a series of polycyclic carbo- and heteroaromatic compounds to sulfonation by sulfur trioxide in nitrobenzene are measured and discussed. The results show the following reactivity in decreasing order: indole, carbazole, pyrene, perylene, naphthalene, phenanthrene, benzene, benzothiophene, and dibenzothiophene.     

Osmotic and activity coefficients of ammonium thiocyanate in aqueous solution at 25°C

Osmotic and activity coefficients of ammonium thiocyanate in aqueous solution at 25°C have been determined by the isopiestic vapor pressure method. The activity coefficients do not agree with values reported previously but are consistent with trends shown by activity coefficients of ammonium chloride and bromide.     

Osmotic and activity coefficients of ammonium thiocyanate in aqueous solutions at 25°C

Osmotic and activity coefficients of ammonium thiocyanate determined by the isopiestic vapor pressure method are compared with the data recently reported by Covington and Matheson. Activity coefficients calculated using the Pitzer equation are now in much better agreement although a systematic difference is evident in the two sets of data.Comment to the paper by Covingtonet al. (see ref. 2).We thank Mr. P. Kordes for programming.     

Metal-free visible-light-promoted thiocyanation/cyclization cascade for the synthesis of thiocyanato-containing isoquinolinediones

A visible-light induced metal-free thiocyanate radical addition/intramolecular cyclization cascade reaction for the synthesis of thiocyanato-containing isoquinolinediones from N-alkyl-N-methacryloylbenzamides is described. The organic dye 9-mesityl-10-methylacridinium perchlorate (Acr⁺-Mes ClO₄⁻) is used as a photocatalyst, and cheap and readily available ammonium thiocyanate is used to provide thiocyanate radical by single-electron transfer pathway. The reaction completes the synthesis of CS and CC bonds in one pot with abundant molecular oxygen as the sole sacrificial reagent. The method is easy to implement, and 25 new compounds have been prepared in moderate to good yields under mild conditions. This is the first time that a thiocyanate group has been introduced into isoquinoline-1,3(2H,4H)-diones to construct highly functional drug-like molecules.     

硫氰酸铵-结晶紫-H2O 体系浮选分离钴

研究了硫氰酸铵-结晶紫-H2O 体系浮选分离 Co(Ⅱ)与 Ni(Ⅱ)、Fe(Ⅲ)、Mn(Ⅱ)、Al(Ⅲ)、Cd(Ⅱ) 等常见离子的方法及条件。当 NaCl 用量为 1 g,硫氰酸铵(0.1 mol/L)和结晶紫(1×10-3 mol/L)溶液用量分别为 1.5 mL 和 2.5 mL,总体积为 10 mL 时,控制 pH 1.0～2.0,即可实现 Co(Ⅱ) 与上述离子的分离。     

Oxidative bromination of ketones using ammonium bromide and oxone®

A highly efficient, environmentally safe and economic method for selective α-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and β-keto esters and α,α-dibromination of 1,3-diketones and β-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone® as an oxidant. The reaction proceeds at ambient temperature and yields range from moderate to excellent. Bromination of unsymmetrical ketones takes place at the less substituted α-position predominantly. Aromatisation of tetralones is also carried out with this reagent system.     

Thiocyanation of Aromatic and Heteroaromatic Compounds using Ammonium Thiocyanate and I2O5

Thiocyanation of indoles, pyrrols, and anilines has been efficiently achieved using ammonium thiocyanate as a thiocyanation agent and I₂O₅ as an oxidant.