Total synthesis of (+/-)-4'-demethylmacrophyllol, a naturally occurring compound

The naturally occurring compound 4'-Demethylmacrophyllol (1), 8-Hydroxy-3-(4-hydroxy-3,5-dimethoxy-phenyl)-isochroman-1-one, was synthesized starting from 4-benzyloxy-3,5-dimethoxybenzaldehyde (3) and a phosphonium salt (2) in four steps with an overall yield of 44%. This is the first report on the total synthesis of 4'-demethylmacrophyllol (1). The structures of compounds were determined by NMR and MS and elemental analysis techniques.     

Chain extension of ketonic resins

Chain extensions of cyclohexanone-formaldehyde (CF) and acetophenone-formaldehyde (AF) resins via their hydroxyl groups were studied. The chain extension was regulated by the ratio of hydroxyl groups/reactive reagents. Dimethyl dichlorosilane, phosphorus oxychloride, toluene-2, 4-diisocyanate, phthalic anhydride, tetrahydro phthalic anhydride, trimellitic anhydride, 4, 4'-oxydiphthalic anhydride were used as chain extender reagent. It has been shown that solubilites, melting point and molecular weight of extended resins depended upon the characteristics of chain extender reagents.     

Infrared borescopic characterization of corona and conventional ignition for lean/dilute combustion in heavy-duty natural-gas engines

Natural gas (NG) is attractive for heavy-duty (HD) engines for reasons of cost stability, emissions, and fuel security. NG requires forced ignition, but conventional gasoline-engine ignition systems are not optimized for NG and are challenged to ignite mixtures that are lean or diluted with exhaust-gas recirculation (EGR). NG ignition is particularly difficult in large-bore engines, where it is more challenging to complete combustion in the time available. High-speed infrared (IR) in-cylinder imaging and image-derived quantitative metrics were used to compare two ignition systems in terms of the early flame-kernel development and cycle-to-cycle variability (CCV) in a heavy-duty, natural-gas-fueled engine that had been modified to enable exhaust-gas recirculation and to provide optical access via borescopes. Imaging in the near IR and short-wavelength IR yielded strong signals from the water emission lines, which acted as a proxy for flame front and burned-gas regions while obviating image intensification (which can reduce spatial resolution). The ignition systems studied were a conventional system and a high-frequency corona system. The air/fuel mixtures investigated included stoichiometric without dilution and lean with EGR. The corona system produced five separate elongated, irregularly shaped, nonequilibrium-plasma streamers, leading to immediate formation of five spatially distinct wrinkled flame kernels around each streamer. Compared to the conventional spark ignition, which produces a single flame kernel that exhibits an initial laminar growth regime before wrinkling, corona ignition's early achievement of higher flame surface areas significantly shortened the ignition delay, resulting in reduced overall combustion duration and CCV for each mixture. Additionally, although the lean, dilute mixture produced higher CCV than the stoichiometric, minimally diluted mixture with both igniters, the mixtures ignited by the corona system suffered less than those ignited by the conventional system. Image-based measurements of CCV agreed with those based on in-cylinder pressure.     

A simple technique for constructing exact solutions to nonlinear differential equations with conformable fractional derivative

The modified simple equation method is an interesting technique to find new and more general exact solutions to the fractional differential equations in nonlinear sciences. In this paper, the method is applied to construct exact solutions of (2+1)-dimensional conformable time-fractional Zoomeron equation and the conformable space-time fractional EW equation.     

The construction of a DC high voltage precision divider

A precise DC high-voltage divider was designed and constructed for use as a standard. The ratio of the divider for precise measurement must be known accurately independent of voltage and time. The changes in total resistance of a divider with voltage and time should be considered before design and construction. The divider consists of 100 wire-wound resistors with a total resistance of about 100 MΩ as the high-voltage arm and one wire-wound resistor with resistance of 100 kΩ as the low-voltage arm. The high voltage and ground electrodes were designed to prevent electric field concentration and corona formation at high voltages. A current measuring instrument with 6.5 digit resolution was developed to allow comparison of entering and existing currents for detection of current leakage. Considering the sources of error, a relative uncertainty of 66 ppm (parts per million) was obtained with coverage factor k = 2 for the constructed DC high-voltage divider.     

Inclusive production of the meson in hadronic decays of the Z boson

The inclusive production rate of the ρ^±(770) vector meson in hadronic Z decays is measured with the ALEPH detector at the LEP collider. A total of 3.2 million hadronic events are selected from data recorded between 1991 and 1995. Decays of ρ^±→π⁰+π^± are reconstructed for x_E>0.05 and x_p>0.05 where x_p=p_ρ/p_beam and x_E=E_ρ/E_beam. The average ρ^± multiplicity per hadronic event is evaluated to be N(ρ^±)=2.59±0.03±0.15±0.04 where the first error is statistical and the second systematic. The third error is from the uncertainty in the extrapolation to x_p=x_E=0. The rates and differential cross-section are compared with Monte Carlo model predictions and OPAL measurements. Residual Bose–Einstein correlations are found to be an important component in the analysis.     

N‐Cinnamo­ylsaccharin

The title compound [systematic name: 2‐cinnamoyl‐1,2‐benzisothiazol‐3(2H)‐one 1,1‐dioxide], C₁₆H₁₁NO₄S, contains both saccharin and cinnamo­yl groups. The mol­ecule is approximately planar in the solid state, and adjacent mol­ecules are connected by C—H·O and C—H·π(phen­yl) inter­actions. In the C—H·π inter­action, the C·CgA distance is 3.916 (4) Å (CgA is the non‐fused benzene ring centroid) and the C—H·π angle is 156 (2)°. A feature of the mol­ecular geometry is the narrow C—S—N angle of 92.51 (9)° in the five‐membered ring. This angle relieves strain from the ring and makes it possible for the whole saccharin group to become quite planar.     

trans‐Bis­[N‐(2‐hydroxy­ethyl)­ethyl­ene­di­amine‐κ2N,N′]­bis­(iso­thio­cyanato‐κN)­nickel(II)

The crystal structure of the title compound, [Ni(NCS)₂(C₄H₁₂N₂O)₂], has two crystallographically independent half‐mol­ecules in the asymmetric unit, with each Ni atom residing on a centre of symmetry. The two mol­ecules exhibit similar coordination geometry but display differences with regard to other structural features. Each Ni^II centre is octahedrally coordinated by two mutually trans chelating hydroxy­ethyl­ethyl­ene­di­amine ligands and two mutually trans iso­thio­cyanate ions. The two independent mol­ecules form chains through different types of non‐covalent interactions. In the case of one of the mol­ecules, only NCS and free OH groups participate in hydrogen bonding, while in the chain based on the second mol­ecule, the NCS, NH, NH₂ and free OH groups are involved in intermolecular hydrogen bonding. The two chains interact with one another through hydrogen bonding, forming planar sheets. The third packing direction is mediated only by van der Waals interactions.     

Bis(1,10‐phenanthroline‐κ2N,N′)(squarato‐κO)copper(II) trihydrate

The title mononuclear [Cu(sq)(phen)₂]·3H₂O complex [sq is squarate (C₄O₄) and phen is 1,10‐phenanthroline (C₁₂H₈N₂)] has been synthesized and the structure consists of a neutral mononuclear [Cu(sq)(phen)₂] unit and three solvate water mol­ecules. The Cu^II ion has distorted square‐pyramidal coordination geometry, comprised of one carboxyl­ate O atom from a monodentate squarate ligand and four N atoms from two chelating phen ligands. An extensive three‐dimensional network of OW—H⋯O/OW hydrogen bonds, face‐to‐face π–­π interactions between the 1,10‐phenanthroline aromatic rings and a weak π–ring interaction are responsible for crystal stabilization.     

4‐[(2‐Chloro­phenyl)­diazenyl]‐6‐methoxy‐2‐{[tris­(hydroxy­methyl)­methyl]­amino­methyl­ene}cyclo­hexa‐3,5‐dien‐1(2H)‐one

The structure of the title compound, C₁₈H₂₀ClN₃O₅, displays the characteristic features of azo­benzene derivatives. Intramolecular N—H⋯O, weak intramolecular C—H⋯O, and intermolecular O—H⋯O and C—H⋯O interactions influence the conformation of the mol­ecules and the crystal packing. Intermolecular hydrogen bonds link the mol­ecules into infinite chains, and the title compound adopts the keto–amine tautomeric form. The azo­benzene moiety of the mol­ecule has a trans configuration. The mol­ecule is not planar, and the dihedral angle between the two phenyl rings is 35.6 (2)°.