Decoration of multi-walled carbon nanotubes with NiO nanoparticles and investigation on their catalytic activity to synthesize pyrimidinone heterocycles

A supported carbon material is shown to be a highly efficient, eco-friendly and recyclable solid acid catalyst for the Biginelli reaction of aldehyde, β-ketoester and urea or thiourea under microwave irradiation in the absence of solvent. This method offers significant advantages such as efficiency, the excellent yield, avoidance of the organic solvents, mild reaction conditions, easy separation and simple operation. In addition, because of employing microwave as heating source and reducing use of organic solvents, this novel method emerges as a green-approach leading to less harmful residues. Furthermore, a mechanism was proposed to rationalize the reaction and the role of NiO–MWCNTs was also investigated in these transformations.     

PPh3-catalyzed Mannich reaction: a facile one-pot synthesis of β-amino carbonyl compounds under solvent-free conditions at room temperature

Research on Chemical Intermediates - PPh3 was used as an efficient catalyst for the one-pot three-component Mannich reactions of acetophenone with different aromatic amines and aromatic aldehydes...     

Generalized (Jordan) left derivations on rings associated with an element of rings

In this paper, we introduce a new notion of generalized (Jordan) left derivation on rings as follows: let R be a ring, an additive mapping F : R → R is called a generalized (resp. Jordan) left derivation if there exists an element w ∈ R such that F(xy) = xF(y) + yF(x) + yxw (resp. F(x ²) = 2xF(x) + x ² w) for all x, y ∈ R. Then, some related properties and results on generalized (Jordan) left derivation of square closed Lie ideals are obtained.     

Development of colorimetric sensor array for discrimination of herbal medicine

Today, traditional systems of medicines (such as herbal distillates) become important resources for providing healthcare benefits. The ability to discriminate among closely similar herbal products is critical to ensure their efficacy. This article proposes a pattern-based recognition approach for the rapid discrimination of herbal distillates using a low-cost and sensitive colorimetric sensor array composed of 25 indicators. The color changes of the sensor exposed to the vapor of the herbal distillates can be monitored easily with an ordinary flatbed scanner. The digital representation of the array response was analyzed with hierarchical clustering analysis (HCA) and principal component analysis (PCA). Using new variable selection strategy, 6 indicators among the 25 employed indicators were selected as discriminant elements of the array. So, a complete discrimination (with 100% accuracy) of 46 herbal distillates was achieved. The proposed sensor represented a better resolution when analytes were placed in an oven at 85 °C for 45 min. This colorimetric sensor array demonstrates excellent potential for quality assurance/control applications of herbal distillates.     

Iodine‐Catalyzed Synthesis of Spiro[1,3,4‐benzotriazepine‐2,3′‐indole]‐2′,5(1H,1′H)‐diones under Mild Conditions

The I₂‐catalyzed preparation of spiro[1,3,4‐benzotriazepine‐2,3′‐indole]‐2′,5(1H,1′H)‐diones from 2‐aminobenzohydrazide and isatins in MeCN at room temperature in good‐to‐excellent yields is described. The structure of 3 was corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS data). A plausible mechanism for this type of reaction is proposed (Scheme 2).     

Substituted six-membered ring carbenes: the effects of amino and cyclopropyl groups through DFT calculations

DFT calculations are employed to compare and contrast six-membered ring carbenes including 1,3-dimethyltetrahydropyrimidin-2-ylidene (1a), 1-methyl-3-cyclopropyltetrahydropyridine-2-ylidene (2a), and 1,3-dicyclopropylcyclohexane-2-ylidene (3a) as well as their unsaturated analogues 1b, 2b, 3b, and 2c. The amino groups exert singlet-triplet energy separation (?E_s−t) of 60.9 kcal/mol to 1a while cyclopropyls induce a ?E_s−t of 14.8 kcal/mol to 3a. The simultaneous presence of amino and cyclopropyl in 2a leads to a ?E_s−t of 43.3 kcal/mol. Unsaturation slightly increases the ?E_s−t of 1a and 3a but not that of 2a. Our thermodynamic, kinetic, and reactivity results are compared with those of synthetic five-membered ring N-heterocyclic carbenes.     

Kinetics and mechanism of the reaction of novel low spin Fe(II)-azo amino acid complexes with hydrogen peroxide in aqueous solutions and in aqua-methanol binary mixtures

Kinetics of Fe(II)-azo complexes derived from amino acids (DL-phenylalanine, DL-tryptophane, histidine and alanine) and p-nitroso aromatic substituted amines (N,N-dimethylamino-4-nitrosoaniline and N,N-dimethylamino-4-nitrosoaniline) with hydrogen peroxide in the aqueous solutions and under pseudo-first order conditions have been studied. The reaction exhibits two-stage kinetics. The reaction mechanism was proposed and discussed in terms of complex structure, pH and nature of the medium. The activation parameters and pK _a values were evaluated and correlated with the structural effects of the complexes.     

Novel four-component route to the synthesis of spiro[indoline-3,4′-pyridine]-3′-carboxylate derivatives

An effective route to spiro[indoline-3,4′-pyridine]-3′-carboxylate derivatives is described. This involves reaction of isatin, 1-phenyl-2-(1,1,1-triphenyl-λ⁵-phosphanylidene)-1-ethanone, and benzylamine derivatives or aliphatic amines in the presence of alkyl acetoacetate (1,3-dicarbonyl compounds) in dry methanol under reflux conditions. The reactive 1:1 enaminone, which is obtained from the addition of the amine to 1,3-dicarbonyl compound, adds to the α,β-unsaturated ketone, which is formed from the reaction of isatin and 1-phenyl-2-(1,1,1-triphenyl-λ⁵-phosphanylidene)-1-ethanone, to produce the alkyl 1′-benzyl-2′-methyl-2-oxo-6′-phenyl-1′H-spiro[indoline-3,4′-pyridine]-3′-carboxylate derivatives in excellent yields.