Hydrazinolysis of 4-acyl and 4-ethoxycarbonyl-3H-imidazo[1,5-b]-pyridazine-5,7-(6H)diones: 8-Oxo-1,4,7,8-tetrahydropyridazino-[4,5-c]pyridazine, 8-oxo-7,8-dihydropyridazino[4,5-c]pyridazine and 5,8-dioxo-1,4,5,6,7,8-hexahydropyridazino[4,5-c]pyridazine derivatives

Reaction of 4-acyl-3H-imidazo[1,5-b]pyridazine-5,7-(6H)diones with hydrazine hydrate gave 3R-5R′-8-oxo-1,4,7,8-tetrahydropyridazino[4,5-c]pyridazine together with 3R-5R′-8-oxo-7,8-dihydropyridazino[4,5-c]pyridazine derivatives. Their structures were assigned by means of elemental analyses and spectroscopic data (ir, uv, nmr and ms). The conclusive structural elucidation involved the fact that 2R-4-ethoxycarbonyl-3H-imidazo[1,5-b]pyridazine-5,7-(6H)-diones treated with hydrazine hydrate afforded 3R-5,8-dioxo-1,4,5,6,7,8-hexahydropyridazino-[4,5-c]pyridazine which, upon dehydrogenation, gave products previously reported in the literature.     

N‐(2‐Carboxy­benzoyl)‐l‐leucine methyl ester

The title compound (with the systematic name 2‐{[(1S)‐1‐(methoxy­carbonyl)‐3‐methyl­butyl]amino­carbonyl}benzoic acid), C₁₅H₁₉NO₅, crystallizes in the monoclinic space group P2₁, with two independent mol­ecules per asymmetric unit. The most notable difference between the two mol­ecules is in the dihedral angles between the planes of the carboxyl group and the benzene ring, which are 3.5 (3) and 25.7 (1)°. This difference may account for the fact that two competing reactions are observed in aqueous solution, namely cyclization to form the imide N‐phthaloyl­leucine and hydrolysis of N‐(2‐carboxy­benzoyl)‐l ‐leucine methyl ester to phthalic acid and leucine.     

Complexation of phosphine ligands with peracetylated beta-cyclodextrin in supercritical carbon dioxide: spectroscopic determination of equilibrium constants

The interaction between peracetylated beta-cyclodextrin and several triphenyl phosphine derivatives was studied in supercritical carbon dioxide (scCO2) by UV-visible spectroscopy. The equilibrium constant for a 1:1 complexation reaction was obtained from titration spectra and calculated using two established mathematical models. The values of the equilibrium constants are 1-3 orders of magnitude smaller than those obtained in aqueous solution with analogous phosphines. This is likely due to the absence in scCO2 of the hydrophobic effect, which is replaced by a corresponding, but weaker, CO2-phobic effect. The largest value of Kf was found for complexes of diphenyl(4-adamantylphenyl)phosphine, which is rationalized on the basis of the excellent fit of the phosphine in the cyclodextrin cavity, leading to enhanced host-guest van der Waals interactions. This study can be considered the first step toward the comprehension of the complexation thermodynamics of modified cyclodextrins soluble in scCO2.     

Comparing the <Emphasis Type="Italic">ℤ</Emphasis><Subscript>2</Subscript>-Graded Identities of Two Minimal Superalgebras with the Same Superexponent

Let F be a field of characteristic zero. We study two minimal superalgebras A and B having the same superexponent but such that T ₂ (A) ? T ₂ (B), thus providing the first example of a minimal superalgebra generating a non minimal supervariety. We compare the structures and codimension sequences of A and B.     

Analysis of a microfluidic device for diffusion coefficient determination of high molecular weight solutes detectable in the visible spectrum

The European Physical Journal E - We performed ground-based experiments on the sample polystyrene–toluene–cyclohexane in order to complement the experimental activities in microgravity...     

Utilization of poly(vinylchloride) and poly(vinylidenefluoride) as macroinitiators for ATRP polymerization of hydroxyethyl methacrylate: Electroanalytical and graft‐copolymerization studies

The utilization of poly(vinylchloride) (PVC) and poly(vinylidenefluoride) (PVDF) as macroinitiators for atom transfer radical polymerization (ATRP) of hydroxyethyl methacrylate (HEMA) was studied performing electroanalytical investigations and “grafting from” experiments to evaluate the potential modification of such commercial polymers by ATRP. The study was performed changing various operating parameters such as the nature of the copper salt, the ligand, the solvent, the temperature, and the reaction time. Electroanalytical data suggest that PVC can be easily activated by both CuCl/Tris(2‐pyridylmethyl)amine (TPMA) and CuCl/Tris[2‐(dimethylamino)ethyl]amine (Me₆TREN), two catalytic systems widely adopted for ATRP reactions, in a wide range of operating conditions. PVDF is more difficult to be activated, due to the higher strength of the C? F bond. In particular, the utilization of high temperature and of a more reductant redox couple such as Cu(I)Me₆TREN/Cu(II)Me₆TREN was needed to achieve a significant degree of grafting. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2524–2536