Ruthenium(II)-NHC-catalyzed (NHC = perhydrobenzimidazol-2-ylidene) alkylation of amines using the hydrogen borrowing methodology under solvent-free conditions

Transition Metal Chemistry - New ruthenium(II) complexes with N-heterocyclic carbene ligand were synthesized by transmetalation reactions between silver(I) N-heterocyclic carbene complexes and...     

Strength and ultrasonic properties of cemented paste backfill

This paper presents the strength (UCS) and ultrasonic pulse velocity (UPV) properties of cemented paste backfill (CPB) produced from two different mill tailings (Tailings T1 and T2). A total of 240 CPB samples with diameter × height of 5 × 10 cm and 10 × 20 cm prepared at different binder dosages (5–7 wt.%) and water-to-cement ratios (3.97–5.10) were subjected to the UPV and UCS tests at 7, 14, 28 and 56-days of curing periods. UCS and UPV of CPB samples increased with increasing the binder dosage and reducing the w/c ratio irrespective of the sample size and tailings type. CPB samples with a diameter × height of 5 × 10 cm were observed to produce consistently higher (up to 1.69-fold) UCSs than those of 10 × 20 cm CPB samples at all binder dosages and w/c ratios. However, at the corresponding binder dosages and w/c ratios, the maximum variation of UPV between the CPB samples of 5 × 10 cm and 10 × 20 cm was only 7.45%. Using the method of least squares regression, the UCS values were correlated with the UPV values for CPB samples of 10 × 20 cm in size. A linear relation with a high correlation coefficient appeared to exist between the UCS and UPV for CPB samples. These findings suggest that the UPV is essentially independent of the sample size. In this regard, the UPV test can be suitably exploited for the rapid estimation of the strength and quality of CPB samples even using small samples with concomitant benefits of reducing sample size.     

Development of Kinetic Mechanism for the Esterification of Acrylic Acid with Hexanol Catalyzed by Ion‐Exchange Resin

The heterogeneous esterification reaction of acrylic acid with hexanol over three different cation‐exchange resins, Amberlyst 131, Amberlyst 15, and Dowex 50Wx‐400, was investigated. Surface area, pore volume, average pore diameter, and acid capacity analyses were carried out for these three catalysts. Amberlyst 131 gave the highest conversion, and therefore, further experiments were performed catalyzed by Amberlyst 131. The absence of external and internal mass transfer resistances was investigated for the esterification of acrylic acid with hexanol. Experiments showed that the reaction is controlled by chemical step rather than external and internal mass transfer steps. The effects of temperature, catalyst loading, and alcohol to acid molar ratio on the conversion of acrylic acid were determined. The activation energy and kinetic and adsorption constants were determined according to the Langmuir–Hinshelwood–Hougen–Watson mechanism.     

Synthesis of N'-[4'-Benzo(15-Crown-5)]-4-Tolylaminoglyoxime and N'-[4'-Benzo(15-Crown-5)]-4-Chlorophenylaminoglyoxime and Their Complexes with Copper (II), Nickel (II) and Cobalt (II)

N'-[4'-benzo(15-crown-5)]-4-tolylaminoglyoxime (H₂L¹),the sodium chloride salt of H₂L¹ (H₂L¹...NaCl),N'-[4'-benzo(15-crown-5)]-4-chlorophenylaminoglyoxime(H₂L²) and the sodium chloride salt of H₂L² (H₂L²...NaCl)have been prepared from p-chlorophenylchloroglyoxime,p-tolylchloroglyoxime, 4'-aminobenzo[15-crown-5] and sodiumbicarbonate or sodium bicarbonate and sodium chloride. Nickel (II),cobalt (II) and copper (II) complexes of H₂L and H₂L...NaClhave a metal-ligand ratio of 1 : 2 and the ligand coordinatesthrough the two N atoms, as do most of the vic-dioximes. Their IR spectra and elemental analyses are given, together with¹H NMR spectra of the ligands.     

N‐Cyclo­hexyl‐2‐[5‐(4‐pyridyl)‐4‐(p‐tolyl)‐4H‐1,2,4‐triazol‐3‐yl­sulfanyl]­acetamide dihydrate

In the title compound, C₂₂H₂₅N₅OS·2H₂O, the mol­ecules are stacked in columns running along the b axis. In this arrangemant, the mol­ecules are linked to each other by a combination of one two‐centre N—H⋯O hydrogen bond and four two‐centre O—H⋯O hydrogen bonds containing two types of ring motif, viz.R₄⁴(10) and R₃³(11). In the crystal structure, centrosymmetric π–π inter­actions between the triazole rings, with a distance of 3.691 (2) Å between the ring centroids, also affect the packing of the mol­ecules.     

Synthesis of four new vic-dioximes and their nickel(II), cobalt(II), copper(II) and cadmium(II) complexes

Four unsymmetrical vic-dioximes: [L¹H₂] N-(4-butylphenyl)amino-amphi-glyoxime, [L²H₂] N-(4-butylphenyl)amino-anti-glyoxime, [L³H₂] N-(4-phenylazophenyl)amino-amphi-glyoxime and [L⁴H₂] N-(4-phenylazophenyl)amino-anti-glyoxime have been prepared from amphi-chloroglyoxime, anti-chloroglyoxime, 4-butylaniline and 4-(phenylazo)aniline respectively. The complexes of these vic-dioximes with Ni^II, Co^II, Cu^II and Cd^II ions have been investigated. All are insoluble in common solvents. Their i.r. spectra and elemental analyses are given, together with mass and ¹H-n.m.r. spectra of the ligands.     

Antioxidant and cytotoxic properties of some new dipeptide-indole conjugates

In this study, 10 new indole-dipeptide conjugates were synthesized, and their anticancer activity was determined against on A2780 (ovarian cancer cell line) and MCF-7 (breast cancer cell line) cells. Among compounds, 5 and 10 showed better activity against A2780 cell lines than the standard drug docatexel at 0.1 and 1 μM concentrations, while only compound 5 showed better activity than docatexel, the MCF-7 cell line at 0.1 and 1 μM concentrations. The antioxidant potencies of the compounds were low in both the DPPH and iron reducing power methods tested when compared to standard antioxidants used in this work.     

Self-dual Yang-Mills fields in eight dimensions

Strongly self-dual Yang-Mills fields in even-dimensional spaces are characterised by a set of constraints on the eigenvalues of the Yang-Mills fieldsF . We derive a topological bound on R⁸, , wherep1 is the first Pontryagin class of the SO(n) Yang-Mills bundle, andk is a constant. Strongly self-dual Yang-Mills fields realise the lower bound.