Intramolecular cyclization of beta,beta-difluorostyrenes bearing an iminomethyl or a diazenyl group at the ortho position: synthesis of 3-fluorinated isoquinoline and cinnoline derivatives

o-Formyl-substituted beta,beta-difluorostyrenes readily react with NH(2)OH.HCl or NH(4)OAc to afford 3-fluoroisoquinoline derivatives in good yield via (i) the formation of the corresponding oximes or imines and (ii) subsequent intramolecular replacement of a vinylic fluorine by the sp(2) nitrogen of the iminomethyl group (HON=CH- or HN=CH-). Beta,beta-Difluorostyrenes bearing an o-diazenyl group (HN=N-), generated by reduction of the corresponding diazonium ions, undergo a similar substitution to afford 3-fluorinated cinnolines.     

Specific interaction between polyethylenimine and azo dyes carrying hydroxyl groups

The binding of acid azo dyes having phenolic hydroxyl groups such as orange I ( I ), orange II ( II ), chrome violet ( III ), 4-hydroxyazobenzene-4′-sulfonate ( IV ), and 2,4-dihydroxyazobenzene-4′-sulfonate ( V ) by polyethylenimine was studied by equilibrium dialysis and spectroscopic methods. The results obtained indicate that dyes ( III ) and ( V ) with two OH groups are bound much more strongly than dyes ( I ), ( II ), and ( IV ) with one OH group. Also polyethylenimine is far superior to any other polymers which have been examined, including bovine serum albumin, polyvinylpyrrolidone, and poly-L -lysine, in its ability to form complexes with these dyes ( III ) and ( V ). The OH groups involved participate preferentially in complex formation with polyethylenimine. The unusual affinity of polyethylenimine for the dyes carrying OH groups is discussed.     

Thermal stability of phthalate esters: Effect of substituents on the β-carbon atom

In order to clarify the mechanism conferring heat resistance on phthalate esters, those with a substituent on the β-carbon atom, such as bis(2-aminobutyl) phthalate, bis(2-nitrobutyl) phthalate, bis(2,4-diphenylbutyl) phthalate and dineopentyl phthalate, were synthesized and their thermal stabilities were studied by thermogravimetry and differential thermal analysis. The analytical results for these phthalate esters were compared with those for dibutyl phthalate, with a straight alkyl chain. As the temperatures required for a 3% weight loss of phthalate esters with a substituent, an electron-donating group (amino group) or an electron-accepting group (nitro group) on the β-carbon atom move to the higher end of the range, the effect of the adjacent group was recognized. The presence of a phenyl group in phthalate esters considerably improved the heat resistance. It is considered that the high heat resistance of bis(2,4-diphenylbutyl) phthalate is due to the obstruction of the planar configuration for cis elimination by the phenyl group and hindrance by the phenyl group of the formation of the six-membered cyclic transition state owing to the interaction between non-bondable molecules.     

Highly Pure Synthesis,Spectral Assignments,and Two‐Photon Properties of Cruciform Porphyrin Pentamers Fused with Benzene Units

Tetrameric porphyrin formation of 2‐hydroxymethylpyrrole fused with porphyrins through a bicyclo[2.2.2]octadiene unit gave bicyclo[2.2.2]octadiene‐fused porphyrin pentamers. Thermal conversion of the pentamers gave fully π‐conjugated cruciform porphyrin pentamers fused with benzene units in quantitative yields. UV/Vis spectra of fully π‐conjugated porphyrin pentamers showed one very strong Q absorption and were quite different from those of usual porphyrins. From TD‐DFT calculations, the HOMO level is 0.49 eV higher than the HOMO?1 level. The LUMO and LUMO+1 levels are very close and are lower by more than 0.27 eV than those of other unoccupied MOs. The strong Q absorption was interpreted as two mutually orthogonal single‐electron transitions (683 nm: 86 %, HOMO→LUMO; 680 nm: 86 %, HOMO→LUMO+1). The two‐photon absorption (TPA) cross section value (σ⁽²⁾) of the benzene‐fused porphyrin pentamer was estimated to be 3900 GM at 1500 nm, which is strongly correlated with a cruciform molecular structure with multidirectional π‐conjugation pathways.     

Synthesis of photoreactive polyimide having indan structure

Polyimide containing an indan unit and alkyl moiety with a high molecular weight was prepared from 5,7‐diamino‐1,1,4,6‐tetramethylindan and 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride. This polyimide was amorphous and soluble in common organic solvents, such as tetrahydrofuran, chloroform, and cyclopentanone. Thermogravimetry of the polyimide showed good thermal stability, indicating that a 10% weight loss of the polyimide was observed at 500 °C in nitrogen. The glass‐transition temperature of the polyimide was not observed by DSC measurement between room temperature and 400 °C at a heating rate of 10 °C/min (Apparatus: DSC3100 MAC Science Co., Ltd.). Transparency of the polyimide at 365 nm was 80%. The polyimide acted as a photosensitive resist of negative type by UV radiation. The resist had a sensitivity of 31 mJ/cm² and a contrast of 2.3 when it was developed with cyclopentanone at room temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 423–428, 2002     

Synthesis and properties of 1,3,5-benzene periodic mesoporous organosilica (PMO): novel aromatic PMO with three point attachments and unique thermal transformations

A new aromatic periodic mesoporous organosilica material containing benzene functional groups that are symmetrically integrated with three silicon atoms in an organosilica mesoporous framework is reported. The material has a high surface area, well-ordered mesoporous structure and thermally stable framework aromatic groups. The functional aromatic moieties were observed to undergo sequential thermal transformation from a three to two and then to a one point attachment within the framework upon continuous thermolysis under air before eventually being converted to periodic mesoporous silica devoid of aromatic groups at high temperatures and longer pyrolysis times. The mesoporosity of the material was characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and nitrogen porosimetry, whereas the presence and transformation of the aromatic groups in the walls of the materials were characterized by solid-state NMR spectroscopy, mass spectrometry, and thermogravimetric analysis. The attachment of a benzene ring symmetrically onto three siloxanes of the framework was used advantageously as a cross-linker to enhance the thermal stability of the organic group. Some of these properties are investigated in comparison with other aromatic PMOs that have only two point attachments and an amorphous phenylsilica gel that has only one point attachment. The successful synthesis of the first aromatic PMO with its organic group attached within the framework through more than two points is an important step toward the synthesis of PMOs having organic groups with more complex and multiple attachments within the framework.     

Assay of cholesterol 7 alpha-hydroxylase utilizing a silica cartridge column and 5 alpha-cholestane-3 beta, 7 beta-diol as an internal standard

A simplified and accurate assay of cholesterol 7 alpha-hydroxylase activity using 5 alpha-cholestane-3 beta,7 beta-diol as an internal standard is described. Endogenous microsomal cholesterol was used as the substrate. Following incubation and addition of the internal standard, lipids extracted from the incubation mixture were applied to Bond-Elut silica cartridge columns. 7 alpha-Hydroxycholesterol, 7 beta-hydroxycholesterol, 7-ketocholesterol and the internal standard were quantitatively recovered by eluting the column with 6 ml of benzene-ethyl acetate (2:3, v/v) after removal of cholesterol with 6 ml of benzene-ethyl acetate (9:1, v/v). After trimethylsilylation, the mass of 7 alpha-hydroxycholesterol was determined by capillary gas chromatography with selected-ion monitoring. The method permits a faster, easier and more sensitive determination of the activity of cholesterol 7 alpha-hydroxylase in small samples.     

Invisible photochromism of diarylethene derivatives

Diarylethene derivatives with oxidized thiophene rings shift their absorption band to a shorter wavelength in the UV region upon photocyclization; no color change was observed during the photochromic reaction, and the invisible photochromism is advantageous for devices used under room light.     

Pilot-Scale Experiment for Simultaneous Dioxin and NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Removal from Garbage Incinerator Emissions Using the Pulse Corona Induced Plasma Chemical Process

A pilot-scale pulse corona induced plasma chemical process (PPCP) reactor for controlling gas-phase dioxins and NO _x simultaneously is installed in a garbage incineration plant. The flow rate of the sampled flue gas is 5,000 Nm³/h (N: standard state) in maximum at the PPCP reactor, which consists of 22 wire-cylinder electrodes and is energized by a 50 kW nanosecond pulse high voltage generator. With an applied plasma energy density of 2.9–6.1 Wh/Nm³, the decomposition efficiency for dioxins is 75–84% based on TEQ (toxic equivalents); the conversion efficiency of NO to NO₂ is ~93% at maximum. The flue gas treated by the PPCP reactor is introduced at a rate of 50 Nm³/h to a wet-type chemical reactor, which uses an aqueous solution of sodium sulfite (Na₂SO₃). More than 90% of NO _x is reduced to nitrogen, with negligible byproducts such as NO₂ ⁻ or NO₃ ⁻ ions left in the solution.