Dynamic nuclear polarization experiments were performed to study the solutions of the stable free radical α,γ‐Bisdiphenylene‐β‐phenyl allyl complex with benzene (1∶1) in some highly fluorinated aliphatic and aromatic solvents. In solutions examined in this study, the Overhauser effect, which normally arises due to both dipolar and scalar interactions between the unpaired electrons of the free radical molecules and fluorine nuclei of solvent molecules occurs mainly. 1‐Iodotridecafluorohexane, 2,2,3,4,4,4‐Hexafluoro‐1‐butanol, N‐methyl‐bis‐trifluoroacetamide, hexafluoroacetylacetone, octafluorotoluene, and hexafluorobenzene were used as the solvents. The experiments were performed at a low field double resonance NMR spectrometer, which operates at 1.53 mT. The NMR enhancements depend on competition between intermolecular magnetic interactions. The measurements were performed at four different temperatures to test the dipolar and the scalar part of the coupling between the fluorine nucleus (19F) and the unpaired electron. It was found that the dipolar interactions are more effective for the aliphatic solvents, while the scalar interactions are more effective for the aromatics. The nuclear‐electron coupling parameter varies between 0.018 and 0.157 in all aliphatic solvents and between ?0.063 and ?0.035 in aromatic solvents. 相似文献
The oligomers having the blue photoluminescence and conductivities of 5 × 10–7–7.4 × 10–4 S m–1 after doping by iodine are extracted successfully from coal tar pitches which were dealt with by the air oxidization method at 350°C. Meanwhile, it is observed that extracted materials have the blue photoluminescence with the fluorescence quantum yield of 7–10.2%. In these cases, we used the solutions of toluene and pyridine to extract these functional materials from coal tar pitches. Consequently, we consider these extracted materials showing the advantages in the application of fabricating the electronic devices, because it can decrease the production cost remarkably than use of the materials obtained by general organic synthesis methods. Finally, this research also can provide the one of beneficial references for solving the serious problem of overproduction of coal tar pitches in China. The oligomers having the blue photoluminescence and conductivities of 5 × 10–7–7.4 × 10–4 S m–1 after doping by iodine are extracted successfully from coal tar pitches which were dealt with by the air oxidization method at 350°C. Meanwhile, it is observed that extracted materials have the blue photoluminescence with the fluorescence quantum yield of 7–10.2%. In these cases, we used the solutions of toluene and pyridine to extract these functional materials from coal tar pitches. Consequently, we consider these extracted materials showing the advantages in the application of fabricating the electronic devices, because it can decrease the production cost remarkably than use of the materials obtained by general organic synthesis methods. Finally, this research also can provide the one of beneficial references for solving the serious problem of overproduction of coal tar pitches in China. 相似文献
Flash pyrolysis of raw and tetralin treated coal samples were carried out in nitrogen atmosphere. Two representative coal samples from Lakhra coalmines labeled Lakhra‐3 (L3) and Lakhra‐6B (L6B) were pyrolyzed in their raw state and after treatment with tetralin. Initial experiments were carried out at 700 °C with 2 milligrams of 80 mesh size samples. The main hydrocarbon products detected from both samples were methane, ethylene, ethane, propane, butane, pentane, benzene, toluene and xylene (BTX). The ratio of the total hydrocarbon yield from L3 and L6B raw samples is 1:1.49, respectively, while the relative yield of aliphatic C1‐C5 straight chain products to BTX are 7.65:5.49. Theses differences in product yields clearly indicate the compositional variation between the two samples. The total hydrocarbon yield (C1‐C5 +BTX) of tetralin swollen L3 coal and L6B coal was larger than the raw coal at all temperatures, and larger by 50.6% and 32.6%, respectively, at 700 °C. The treatment of coal samples has a more pronounced effect on BTX yield than C1‐C5 aliphatic hydrocarbons. BTX yield of tetralin treated L3 coals at 700 °C was 3.5 times higher while for L6B coal the BTX yield was 2.1 times higher than the raw samples. These significant increases in hydrocarbons yields can be explain in terms of the suppression of the cross‐linking reactions of coal fragments due to the penetration of tetralin in to the micropores of coal, as well as the effective H radicals transfer from tetralin to coal fragments during pyrolysis. 相似文献
Summary: The photografting of methacrylic acid (MAA) onto high‐density polyethylene (HDPE) initiated by butanone, pentan‐3‐one, and heptan‐3‐one is presented. These aliphatic ketones can act as photoinitiators for photografting when they are a component of a suitable solvent mixture with water and ethanol. It is possible that the photoinitiation effect of the aliphatic ketone is induced by the hydrogen bond formed between it and water.
The grafting of 2 M MAA in different ketone/water/ethanol (30/30/40) solvents. 相似文献
We have developed a high‐yielding synthesis of meso‐tetraalkylporphyrins, which previously have been obtained only in lower yields. By employing Montmorrilonite K10 as the acid catalyst and 3 Å molecular sieves as the dehydrating agent, yields that reached 70 % could be achieved with some aliphatic aldehydes. The free‐base porphyrins with decyl ( C10 ) or longer chains were imaged at the single‐molecule level at the solvent/surface interface. Highly oriented pyrolytic graphite (HOPG) was used as a π‐stacking surface, whereas 1‐phenyloctane and 1‐phenylnonane were used as solvents. An odd–even effect was observed from C13 to C16 . For C13 a single‐crystal X‐ray structure allowed an unprecedented insight into how packing from two dimensions is expanded into a three‐dimensional crystal lattice. 相似文献
The solvation structures of l ‐leucine (Leu) in aliphatic‐alcohol–water and fluorinated‐alcohol–water solvents are elucidated for various alcohol contents by using molecular dynamics (MD) simulations and IR, and 1H and 13C NMR spectroscopy. The aliphatic alcohols included methanol, ethanol, and 2‐propanol, whereas the fluorinated alcohols were 2,2,2‐trifluoroethanol and 1,1,1,3,3,3‐hexafluoro‐2‐propanol. The MD results show that the hydrophobic alkyl moiety of Leu is surrounded by the alkyl or fluoroalkyl groups of the alcohol molecules. In particular, TFE and HFIP significantly solvate the alkyl group of Leu. IR spectra reveal that the Leu C?H stretching vibration blueshifts in fluorinated alcohol solutions with increasing alcohol content, whereas the vibration redshifts in aliphatic alcohol solutions. When the C?H stretching vibration blueshifts in the fluorinated alcohol solutions, the hydrogen and carbon atoms of the Leu alkyl group are magnetically shielded. Consequently, TFE and HFIP molecules may solvate the Leu alkyl group through the blue‐shifting hydrogen bonds. 相似文献
2‐Pyridylsulfone‐ and fluoroalkylated group‐activated olefins underwent highly efficient diastereo‐ and enantioselective 1,3‐dipolar cycloadditions across various aromatic and aliphatic nitrones in the presence of a chiral NiII/bis(oxazoline) catalyst. The process was tuned by 4 Å molecular sieves, chiral bis(oxazoline) ligands, reaction solvents, and temperature. A wide array of optically pure fluoroalkylated isoxazolidines were obtained, thus facilitating the asymmetric synthesis of an enantioenriched α‐trifluoromethylated γ‐amino alcohol in gram‐scale and a trifluoromethylated derivative of 1,3‐oxazinan‐2‐one with potential pharmaceutical interest. A stereochemical model, based on the absolute configuration of one adduct and some control experiments, was postulated to account for the observed endo‐ and enantioselectivity. 相似文献
A new class of polyheterocycles, polybenzodipyrrolediones (PBP), has been synthesized successfully by the two-step polymerization of dibenzylidenebenzodifurandiones with aliphatic diamines. New bislactone monomers, 3,5-dibenzylidene-3,5-dihydro-1H,7H-benzo[1,2-c:4,5-c′]difuran-1,7-dione and 3,7-dibenzylidene-3,7-dihydro-1H,5H-benzo[1,2-c:4,5-c′]-difuran-1,5-dione, were synthesized from pyromellitic dianhydride and phenylacetic acid. The ring-opening polyaddition reaction of the bislactones with aliphatic diamines in a polar solvent afforded novel polyamides having inherent viscosities of 0.1–1.0 in quantitative yield. The solution polymerization was almost completed within several hours at 80°C, while it required approximately a week to its completion at room temperature. Dimethyl sulfoxide and N-methyl-2-pyrrolidone were preferred solvents for the polymerization. The open-chain polyamides were subsequently cyclodehydrated by heating at 240°C to give PBP having high molecular weight. The aliphatic PBP were soluble in hot polar solvents such as N-methyl-2-pyrrolidone, m-cresol, and nitrobenzene. They began to decompose at about 400°C in a nitrogen atmosphere as determined by thermogravimetric analysis. 相似文献
Abstract A new methacrylamide monomer, 4‐methacrylamidophenyl‐2′,3′‐benzostyryl ketone (MPBSK) having a free‐radical polymerizable group and a photocrosslinkable functional group, was synthesized by reacting 4‐(2′,3′‐benzocinnamoyl)aniline with methacryloyl chloride in the presence of triethyl amine. The monomer, MPBSK was polymerized in methyl ethyl ketone (MEK) at 70°C using benzoyl peroxide (BPO) as the initiator. The polymer was characterized by UV, IR, 1H‐NMR, and 13C‐NMR spectroscopy. The polymer was found to be soluble in several polar aprotic solvents and in chlorinated solvents but insoluble in aliphatic and aromatic hydrocarbons and in alcohols. The molecular weight data of the polymer as obtained from gel permeation chromatography suggests a higher tendency for chain termination by disproportionation than dimerization. The glass transition temperature of the polymer was determined by differential scanning calorimetry. Thermogravimetric analysis of the polymer carried out in air reveals that it possesses good thermal stability required of a negative photoresist. The photocrosslinking property of the polymer was investigated by irradiating the polymer solution with UV light in the presence and absence of triplet photosensitizers. The effect of the solvent on the rate of photocrosslinking of the polymer was also studied. 相似文献