New and highly efficient synthesis of 3-substituted 1-hydroxybenz[g]isoquinoline-5,10-diones

A new and efficient strategy for the synthesis of 3-substituted 1-hydroxybenz[g]isoquinoline-5,10-diones by reaction of 2-methoxycarbonyl-1,4-naphthoquinone with different pyridinium salts under Kröhnke conditions is disclosed. This one-step reaction was found to be dependent on the substitution pattern of the aromatic nucleus in the pyridinium salts.     

Multistage thermal decomposition in films of cadmium chloride-doped PVA–PVP polymeric blend

Several reports exist on the use of natural-oil-based materials as rejuvenators to restore the properties of aged binders—more specifically, regarding their ability to enhance the binders’ low-temperature properties and to reduce their stiffness. Rejuvenators are typically made of low molecular weight constituents which could easily volatilize and thus render the rejuvenated binder thermally unstable. Hence, the study of the thermal stability of rejuvenated binders is of paramount importance. In this research, a binder with a performance grade (PG) of PG58-28 modified with a soybean-derived rejuvenator at 12% by mass is added to an extracted reclaimed asphalt pavement (RAP) binder at a ratio of 1:5 resulting in a rejuvenator dosage rate of 2% by total mass of binder. The PG of the rejuvenated RAP binder is determined using both dynamic shear rheometer and bending beam rheometer. The thermal stability of the rejuvenator and the binders is verified using thermogravimetric analysis (TG). The rejuvenator shows good thermal stability up to a temperature of 302 °C. The RAP binder containing the rejuvenator shows similar thermal stability to the unrejuvenated RAP binder. The evolved gases from the TG analysis are analyzed using Fourier transform infrared (FTIR) to chemically characterize the rejuvenator and the binders. The FTIR spectrum of the rejuvenator reveals characteristic peaks. The intensity of these peaks serves as an indication of the rate of mass loss of the rejuvenator within the rejuvenated RAP binder.     

Nouveaux modeles polysilicies a partir d'indoles,du benzothiophene et du benzofuranne

Direct polysilylation of bicyclic heterosubstrates was performed without (in the case of indole or its N-methyl or N-trimethylsilyl derivatives) or with (benzothiophene, benzofuranne) ring-opening. Hexasilylation from benzothiophene occurred with desulfurization.     

Investigation of redox properties of different PtSn/Al2O3 catalysts.

Alumina-supported Sn and PtSn particles are studied by 119Sn M?ssbauer spectroscopy after oxidation and reduction under various conditions. The observed species of Sn(IV), Sn(II) and Sn(0) are grouped in several categories, each being characterised by distinct structural properties. Tin phases in contact with the support or with platinum are identified. The results are used to establish a model describing the phase transformations occurring in PtSn particles under oxidising or reducing conditions. Particular attention is paid to the reduction/reoxidation mechanisms governing H2/O2 double titrations. An increased reactivity of tin towards oxygen, induced by the contact with platinum, is demonstrated. It is shown that tin contributes to the oxygen uptake VO1 of a first titration cycle by platinum-catalysed transformation of Sn(II) into an oxometallic phase Pt(x)Sn(O). The oxygen titre VO2 of a second cycle is due to O2 chemisorption on platinum only.     

An AM1 and DFT-AM1 computational study of methyl phenylpropiolate addition to 1-phenyl-3,4-dimethylphosphole

The transition state structures for the addition of maleic acid anhydride and methyl phenylpropiolate to 1-phenyl-3,4-dimethylphosphole were generated with the AM1 semiempirical method. The competitive transition state structures for 1,5-phenyl rearrangement in 1-phenyl-3,4-dimethylphosphole was also optimized with AM1. The energies were evaluated with the SVWN and Becke3LYP DFT methods using a 6-31G(d) basis set. The reaction outcome based on the evaluated energies were discussed and compared with experimental observations.     

Guttiferone BL with antibacterial activity from the fruits of Allanblackia gabonensis

Allanblackia genus, an endless source of bioactive compounds, was investigated for its antibacterial properties. The chemical study of the methanol extract from the fruits of Allanblackia gabonensis resulted in the isolation of the undescribed guttiferone BL (1) along with the known kaempferol (2), morelloflavone (3), morelloflavone 7″-O-β-D-glucopyranoside (4), β-sitosterol 3-O-β-D-glucopyranoside and β-sitosterol. Their structures were determined using spectrometry and spectroscopic techniques. The antibacterial activity was evaluated against five Gram-negative and two Gram-positive strains using a broth micro-dilution method. Compounds displayed low to significant activity against the tested bacterial strains with MICs ranging from 8 to 512 μg/mL. Morelloflavone (3) presented significant activity against E. coli ATCC8739 (MIC = 8 μg/mL) while guttiferone BL (1) exhibited low activity (MICs = 256–512 μg/mL) against all the tested strains. The crude extract also had moderate to significant activity against the tested bacterial strains.     

Flexible access to 2,3,5,6-tetrasubstituted dehydropiperidines by Ni- or Co-catalyzed site-selective cross-coupling using Vilsmeier-Haack-derived α-chloro-β-formyltetrahydropyridines

A flexible and cost-effective method for the highly functional group-compatible and site-selective cross-coupling of readily affordable α-chloro-β-formyltetrahydropyridines has been developed, under nickel or cobalt catalysis, leading to the rapid synthesis of 2,3,5,6-tetrasubstituted dehydropiperidines bearing α-amino allylic stereocenters. Cobalt-catalyzed reductive cross-coupling of chloro enaminals with electronically-diverse bromostyrenes as coupling partners proceeds in good yields and with high E/Z selectivity to afford Diels-Alder-suitable cross-conjugated 1,3-dienes.     

Determination of the Kinetic and Thermodynamic Parameters of Adsorption Processes by a Volume Step Thermal Method

A volume step method measuring the pressure and the adsorbent temperature of an adsorbent-adsorbate system has been developped. It is shown that this method allows the determination of all the relevant parameters of an adsorption process, kinetic as well as thermodynamic in case of Linear Driving Force mass transfer. The method for determining the parameters can be extended to the case of diffusive mass transfer if the mass transfer kinetics is faster than the heat transfer kinetics. An example is given, showing the determination of the diffusion coefficient of carbon dioxide in NaX zeolite pellets and the change of the diffusion coefficient and of the isosteric heat of adsorption when the adsorbent is not fully dehydrated.     

Legendre’s Necessary Condition for Fractional Bolza Functionals with Mixed Initial/Final Constraints

Journal of Optimization Theory and Applications - The present work was primarily motivated by our findings in the literature of some flaws within the proof of the second-order Legendre necessary...