Pyrrole studies part 41. Reactivity of 3,4-diformyl-2,5-dimethylpyrrole with diaminoalkanes. An unusual formation of 2-azafulvenes

3,4-Diformyl-2,5-dimethylpyrrole (1) reacts with ,ω-diamino-alkanes, NH₂(CH₂)_nNH₂t' to form either the potentially tautomeric 2:2 macrocyclic adduct (7a) (8), when N = 2, or the potentially tautomeric 1:1 bicyclic adduct (18) (19), when N = 4, 5, 6, and 12. ¹H and ¹³C N.m.r. spectral data indicate that the 2-azafulvene structures predominate for both types of cycloadducts. Only polymeric material was obtained when N = 3.     

One-pot synthesis of 4,5-disubstituted 1,2,3-(NH)-triazoles by silica supported-zinc bromide in the aerobic condition

An efficient one-pot cross-coupling/1,3-dipolar cycloaddition sequence was developed for a convenient synthesis of 4,5-disubstituted-1,2,3-(NH)-triazoles, starting from various acid chlorides, terminal alkynes and sodium azide in the presence of silica supported-zinc bromide under aerobic conditions.     

Geometry of warped product pseudo-slant submanifolds of Kenmotsu manifolds

In this paper, we study pseudo-slant submanifolds and their warped products in Kenmotsu manifolds. We obtain the necessary conditions that a pseudoslant submanifold is locally a warped product and establish an inequality for the squared norm of the second fundamental form in terms of the warping function. The equality case is also considered.     

Developing an electro-thermal model to determine heat generation and thermal properties in a lithium-ion battery

Journal of Thermal Analysis and Calorimetry - Lithium-ion batteries should continuously be operated at the optimum temperature range $$\left( {15 \sim 40 \,^\circ C} \right)$$ for the best...     

One-pot synthesis of 1,2-disubstituted pyrrolo[2,3-b]quinoxalines via palladium-catalyzed heteroannulation in water

The reaction of N-alkyl-3-chloroquinoxaline-2-amines with 1-alkynes, catalyzed by Pd-Cu, in the presence of sodium lauryl sulfate as the surfactant in water, leads to the one-pot formation of 1,2-disubstituted pyrrolo[2,3-b]quinoxalines in good-to-high yields.     

Lipase mediated sequential resolution of aromatic β-hydroxy esters using fatty acid derivatives

The lipase-catalyzed kinetic resolution of a series of aromatic β-hydroxy esters in organic media has been investigated. Decanoic acid and its esters were successfully used as acyl donors for selective O-acylation. The regio- and enantioselective enzymatic hydrolysis of the decanoate moiety of the diesters was also investigated. The effects of water, reaction temperature, and solvent type, and also the influence of substrates structure on the catalytic behavior of potential commercially available lipases were studied. A novel procedure was developed for the efficient and highly stereoselective synthesis of both enantiomers of both novel and known target compounds.     

Nile Blue and Indigo Carmine organic dyes as corrosion inhibitor of mild steel in hydrochloric acid

The inhibiting behavior of Nile Blue and Indigo Carmine organic dyes on mild steel corrosion was evaluated in 1 M HCl solution, separately, by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques. Results show that the inhibition efficiency (%IE) increases with the increasing concentration of Indigo Carmine up to 9.65 × 10⁻⁰⁵ M (%IE ~ 98) and Nile Blue up to 1.08 × 10⁻⁰⁴ (%IE ~ 75–80). Good agreement was found between the results obtained from the different techniques used. Polarization curves indicate that the inhibition of the both inhibitors is of a mixed anodic–cathodic nature, and Langmuir isotherm is found to be an accurate isotherm describing the adsorption behavior. The inhibition mechanism of the inhibitors involves chemisorption interaction between the inhibitor and the mild steel. The inhibition efficiency for both inhibitors decreased by the rising temperature in the range of 25–55 °C, and these results verified the chemisorption behavior of both the inhibitors.     

The effect of co-electrodeposited ZrO<Subscript>2</Subscript> particles on the microstructure and corrosion resistance of Ni coatings

Pure Ni and Ni–ZrO₂ composite coatings were electroplated using a Watt’s bath containing different amounts of ZrO₂ to be co-deposited. Surface morphology and microstructure of the samples and particle distribution in the coatings were studied using optical microscope, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The results showed that the electroplated sample in the bath containing 90 g l⁻¹ ZrO₂ has the maximum particle content and the best particle distribution. Evaluation of microstructure and corrosion behavior demonstrated that with increasing ZrO₂ content in the coating, the corrosion potential shifted toward noble and positive values. This is probably due to diminishing of the metallic surface area exposed to the solution. Higher ZrO₂ contents in the coating results in lower corrosion current densities probably due to the changing of the microstructure from coarse-grained columnar to fine-grained granular structure. The results revealed that the electroplated sample in the bath containing 90 g l⁻¹ ZrO₂ has the best corrosion resistance.