HgO/I2 as an Efficient Reagent for the Oxidative Aromatization of Hantzsch 1-NH, 4-Dihydropyridines under Mild and Heterogeneous Conditions

A variety of Hantzsch 1-NH, 4-dihydropyridines were efficiently aromatized to the corresponding pyridine derivatives by treatment with HgO/I2 reagent in dichloromethane under mild and  heterogeneous conditions in good to excellent yields at room temperature. The products were separated by simple filtration and evaporation of the solvent.KEYWORDS: HgO/I2, Hantzsch 1,4-dihydropyridine, aromatization, heterogeneous

Ultrasound-assisted catalytic synthesis of acyclic imides in the presence of p-toluenesulfonic acid under solvent free conditions

A rapid and convenient preparation of acyclic imides by the reaction of aliphatic and aromatic nitriles with acyclic carboxylic anhydride in the presence of catalytic amounts of p-toluenesulfonic acid under thermal or ultrasonic conditions is reported. The advantages of this procedure are moderate reaction times, good to excellent yields, use of inexpensive and ecofriendly catalyst. The reaction of nitriles with aliphatic anhydrides proceeds in thermal conditions, while by the use of ultrasound irradiations these reactions get accelerated

{2-[2-(Ethyl­amino)ethyl­imino­meth­yl]-5-methoxy­phenolato}thio­cyanato­nickel(II)

In the title mononuclear nickel(II) complex, [Ni(C12H17N2O2)(NCS)], the metal atom is four-coordinated in a tetra­hedrally distorted square-planar geometry by the phenolate O atom, the imine N atom and the amine N atom of the Schiff base ligand and by the N atom of a thio­cyanate ligand. In the crystal structure, centrosymmetrically related mol­ecules are linked into dimers through inter­molecular N—H⋯O hydrogen bonds. These dimers are further connected by inter­molecular C—H⋯S hydrogen bonds, forming chains running parallel to [101]

{5-Meth­oxy-2-[(2-morpholinoethyl)­iminometh­yl]phenolato}(thio­cyanato-κN)­nickel(II)

In the mononuclear title complex, [Ni(C14H19N2O3)(NCS)], the nickel(II) atom is four-coordinated in a square-planar geometry by the O and N atoms of the tridentate Schiff base ligand and by the N atom of a thio­cyanate ligand. The crystal structure is stabilized by inter­molecular C—H⋯S and C—H⋯O hydrogen bonds, forming a three-dimensional network

Highly selective and sensitive determination of copper ion by two novel optical sensors

AbstractNew optical sensors for the determination of copper ion by incorporation of 1,1′-(4-nitro-1,2-phenylene)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-lidene)dinaphthalen-2-ol(L1), 1,1′-2,2′-(1,2-phenylene)bis(ethene-2,1-diyl)dinaphthalen-2-ol 1(L2), dibutylphthalate (DBP) and sodium tetraphenylborate (Na-TPB) to the plasticized polyvinyl chloride matrices were prepared. The tendency of both ionophores (L2 and L1) as chromoionophore was significantly enhanced by the addition of DBP to the membrane. The proposed sensors benefit from advantages such as high stability, reproducibility and relatively long lifetime, good selectivity for Cu2+ ion determination over a large number of alkali, alkaline earth, transition and heavy metal ions. At optimum values of membrane compositions and experimental conditions, both sensors’ response was linear over a concentration range of 7.98×10−6 to 1.31×10−4molL−1 and 1.99×10−6 to 5.12×10−5molL−1 for L2 and L1, respectively. Sensor detection limit based on the definition that the concentration of the sample leads to a signal equal to the blank signal plus three times of its standard deviation was found to be 3.99×10−7 and 5.88×10−7molL−1 for L2 and L1, respectively. The response time of the optodes (defined as the time required reaching the 90% of the peak signal) was found to be 5–8min for L2 and 20–25min for L1 based sensor. The proposed optical sensors were applied successfully for the determination of Cu2+ ion content in water samples

Sodium dodecyl sulfate coated γ-alumina support modified by a new Schiff base for solid phase extraction and flame-AAS determination of lead and copper ions

A simple and fast approach for solid phase extraction is herein described, and used to determine trace amounts of Pb2+ and Cu2+ metal ions. The solid phase support is sodium dodecyl sulfate (SDS)-coated γ-alumina modified with bis(2-hydroxy acetophenone)-1,6-hexanediimine (BHAH) ligand. The adsorbed ions were stripped from the solid phase by 6 mL of 4 M nitric acid as eluent. The eluting solution was analyzed by flame atomic absorption spectrometry (FAAS). The sorption recovery of metal ions was investigated with regard to the effects of pH, amount of ligand, γ-alumina and surfactant and the amount and type of eluent. Complexation of BHAH with Pb2+ or Cu2+ ions was examined via spectrophotometry using the HypSpec program. The detection limit for Cu2+ was 7.9 µg L-1 with a relative standard deviation of 1.67%, while that for Pb2+ was 6.4 µg L-1 with a relative standard deviation of 1.64%. A preconcentration factor of 100 was achieved for these ions. The method was successfully applied to determine analyte concentrations in samples of liver, parsley, cabbage, and water

{N,N′-Bis[(E)-3-phenyl­prop-2-en-1-yl­idene]propane-1,3-diamine-κ2 N,N′]dichloridocobalt(II)

The CoII atom in the title monomeric Schiff base complex, [CoCl2(C21H22N2)], is bonded to two Cl atoms and to two N atoms of the Schiff base ligand N,N′-bis­[(E)-3-phenyl­prop-2-en-1-yl­idene]propane-1,3-diamine in a distorted tetra­hedral geometry. The mol­ecule has an idealised mirror symmetry, but is not located on a crystallographic mirror plane

2,2′-[(Propane-1,3-diyldinitrilo)bis­(phenyl­methyl­idyne)]diphenol

In the title mol­ecule, C29H26N2O2, there are two strong intra­molecular O—H⋯N hydrogen bonds involving the hydr­oxy and imine groups, forming S(6) ring motifs. The dihedral angles between adjacent phenyl rings and phenol-containing planes are 85.27 (19) and 91.38 (18)°. In the crystal structure, weak inter­molecular C—H⋯O hydrogen bonds connect mol­ecules into a two-dimensional network

Disulfides – Effective radical generators for flame retardancy of polypropylene

The potential of thirteen aliphatic, aromatic, thiuram and heterocyclic substituted organic disulfide derivatives of the general formula R-S-S-R’ as a new group of halogen-free flame retardants (FR) for polypropylene films have been investigated. According to DIN 4102-1 standard ignitibility test, for the first time it has been demonstrated that many of the disulfides alone can effectively provide flame retardancy and self-extinguishing properties to polypropylene (PP) films at already very low concentrations of 0.5 wt%. In an effort to elucidate the mechanism of the thermal decomposition of disulfide derivatives the fragmentation patterns of the evolved gases from a thermogravimetric analyzer (TGA) have been analyzed by simultaneous mass spectrometry (MS) and Fourier transform infrared spectrometry (FTIR). The main decomposition products initiated by homolytic scission of the S-S bond and/or scission of the C-S bond were identified as thiols, aliphatic and aromatic hydrocarbons, isothiocyanates (depending on the disulfide structures) with further evolution of elemental sulfur and sulfur dioxide at temperatures of above 300 oC and 450 oC, respectively. Based on this preliminary study, we have shown that disulfides represented by e.g. diphenyl disulfide (1), 5,5'-dithiobis(2-nitrobenzoic acid) (2), bis(1-phenyl-1H-tetrazol-5yl)-disulfide (4), 2-bisbenzothiazole-2,2′-disulfide (6) and N,N-dithiobis-(phtalimide) (10) constitute a new halogen-free family of additives for flame retarding of polypropylene