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1.
We synthesized a series of n‐alkylthiomethyl‐substituted polystyrenes (#T‐PS, # = 4, 8, 12, and 16) and n‐alkylsulfonylmethyl‐substituted polystyrenes (#S‐PS, # = 4, 8, 12, and 16), where # is the number of carbon atoms in the n‐alkyl side group of the polymers, using polymer analogous reactions to investigate their liquid crystal (LC) alignment properties. In general, the LC cell fabricated using the polymer film having a longer n‐alkyl side group, a thioether linkage group, and a higher molar content of n‐alkyl side group showed homeotropic LC alignment behavior with a pretilt angle of about 90°. The homeotropic alignment behavior was well correlated with the surface energy of the polymer films; when the positive dielectric anisotropic LC (ZLI‐5900‐000 from Merck) and negative dielectric anisotropic LC (MLC‐7026‐000 from Merck) were used to fabricate the LC cells, homeotropic alignment was observed when the surface energy values of the polymer were smaller than about 25 and 32 mJ/m2, respectively. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
2.
Gary E. Martin Kirill A. Blinov R. Thomas Williamson 《Magnetic resonance in chemistry : MRC》2013,51(5):299-307
Unsymmetrical and generalized indirect covariance processing methods provide a means of mathematically combining pairs of 2D NMR spectra that share a common frequency domain to facilitate the extraction of correlation information. Previous reports have focused on the combination of HSQC spectra with 1,1‐, 1,n‐, and inverted 1JCC 1,n‐ADEQUATE spectra to afford carbon–carbon correlation spectra that allow the extraction of direct (1JCC), long‐range (nJCC, where n ≥ 2), and 1JCC‐edited long‐range correlation data, respectively. Covariance processing of HMBC and 1,1‐ADEQUATE spectra has also recently been reported, allowing convenient, high‐sensitivity access to nJCC correlation data equivalent to the much lower sensitivity n,1‐ADEQUATE experiment. Furthermore, HMBC‐1,1‐ADEQUATE correlations are observed in the F1 frequency domain at the intrinsic chemical shift of the 13C resonance in question rather than at the double‐quantum frequency of the pair of correlated carbons, as visualized by the n,1, and m,n‐ADEQUATE experiments, greatly simplifying data interpretation. In an extension of previous work, the covariance processing of HMBC and 1,n‐ADEQUATE spectra is now reported. The resulting HMBC‐1,n‐ADEQUATE spectrum affords long‐range carbon–carbon correlation data equivalent to the very low sensitivity m,n‐ADEQUATE experiment. In addition to the significantly higher sensitivity of the covariance calculated spectrum, correlations in the HMBC‐1,n‐ADEQUATE spectrum are again detected at the intrinsic 13C chemical shifts of the correlated carbons rather than at the double‐quantum frequency of the pair of correlated carbons. HMBC‐1,n‐ADEQUATE spectra can provide correlations ranging from diagonal (0JCC or diagonal correlations) to 4JCC under normal circumstances to as much as 6JCC in rare instances. The experiment affords the potential means of establishing the structures of severely proton‐deficient molecules. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
We prepared the benzoxazole derivatives bearing the (thio) phosphoryl moiety by addition reactions of 2‐hydrazionbenzoxazole with isothiocyanato (thio) phosphates and characterized their structures by elementary analysis and 1H NMR and IR spectral data. From the results of biological activity screening, we found that these compounds possess some herbicidal, and plant growth regulator activities, and especially good fungicidal activity against Puccinia recondita. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:151–155, 2001 相似文献
4.
Sergey P. Ivonin Tetjana E. Terikovska Alexandra A. Chaikovskaya Anatoliy P. Marchenko Georgiy N. Koydan Alexander M. Pinchuk Andrew A. Tolmachev 《Heteroatom Chemistry》1999,10(3):213-221
The phosphorylation of N‐methylpyrrole with phosphorus (III) halides has been studied. Migration of the dibromophosphino group from the second to the third position of N‐methylpyrrole, leading to the 3‐dibromophosphine, has been found. Methods for the synthesis of 2,4‐bisphosphorylated pyrroles have been developed. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10:213–221, 1999 相似文献
5.
Bulk Free‐Radical Copolymerization of n‐Butyl Acrylate and n‐Butyl Methacrylate: Reactivity Ratio Estimation
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The reactivity ratios for the bulk free‐radical copolymerization of n‐butyl acrylate (BA)/n‐butyl methacrylate (BMA) are estimated at 80 °C. By performing a series of low conversion runs including replicate runs, the reactivity ratios are estimated as rBA = 0.460 and rBMA = 2.008. Runs to high conversions are then conducted at three different feed compositions (fBMA = 0.2, 0.5, and 0.8) to validate the reactivity ratios. The composition data from the high conversion experiments show good agreement with the estimated reactivity ratios in the integrated form of the Mayo–Lewis model. The molecular weight, gel content, and glass transition temperature of BA/BMA copolymers are also determined.
6.
《Journal of computational chemistry》2018,39(8):424-437
The focal‐point analysis (FPA) technique is used for the definitive characterization of conformational interconversion parameters, including activation energy barriers, activation free energies, and kinetic rate coefficients at 298 K, of two n‐alkanes, n‐butane, and n‐pentane, yielding the first complete analysis of their interconversion kinetics. The FPA implementation developed in this study is based on geometry optimizations and harmonic frequency computations carried out with density functional theory methods and single‐point energy computations up to the CCSD(T) level of electronic structure theory using atom‐centered Gaussian basis sets as large as cc‐pV5Z. The anharmonic vibrational computations are carried out, at the MP2/6‐31G* level of theory. Reflecting the convergence behavior of the Gibbs free‐energy terms and the interconversion parameters, well‐defined uncertainties, mostly neglected in previous theoretical studies, are provided. Finally, the effect of these uncertainties on the concentrations of the conformers of n‐butane and n‐pentane is examined via a global Monte–Carlo uncertainty analysis. © 2017 Wiley Periodicals, Inc. 相似文献
7.
The kinetics and mechanism of the reaction of chlorine atoms with n‐butanal and n‐pentanal have been investigated in a 142‐L reaction cell coupled to a Fourier transform infrared (FTIR) spectrometer at 298 ± 2 K and at 800 ± 3 Torr. The rate coefficients for Cl + n‐butanal and Cl + n‐pentanal were measured using the relative rate technique with isopropanol and ethene as the reference compounds. The yield of acyl radicals was determined by measuring yields of acid chloride and carbon monoxide products from the reaction of Cl + aldehyde in the absence of oxygen. The rate coefficients for Cl + n‐butanal and Cl + n‐pentanal are (1.63 ± 0.59) × 10?10 cm3 molecule?1 s? 1 and (2.37 ± 0.82) × 10?10 cm3 molecule?1 s?1, respectively. The yields of acyl radicals from the reactions are 0.66 ± 0.04 for n‐butanal and 0.45 ± 0.04 for n‐pentanal. Under ambient conditions, the acyl radicals generated will react almost exclusively with oxygen. Mechanistic implications of these measurements are discussed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 133–141, 2009 相似文献
8.
Efstathios Gavrielatos Giorgos Athanasellis Olga Igglessi‐Markopoulou 《Journal of heterocyclic chemistry》2002,39(1):185-188
The synthesis of a series of optically active N‐acetyl butenoates 3–5 is described using a facile methodology. These butenoates undergo cyclization to the corresponding N‐acetyl‐2‐alkyl‐pyrrolin‐4‐ones 6,7 retaining their stereochemical integrity. The structure of the newly synthesized compounds has been elucidated through 1H‐13C NMR, IR spectroscopy and their enantiomeric excesses have been measured by chiral HPLC analysis. 相似文献
9.
Oxygenated compounds such as ethers and alcohols are used as gasoline additives and industrial solvents. However, despite their widespread use, the atmospheric reaction mechanisms of some of these compounds are unknown. This study examines the ·OH‐initiated gas‐phase removal mechanisms of ethyl‐n‐butyl ether (ENBE) and di‐n‐butyl ether (DNBE) utilizing gas chromatography–mass spectrometry techniques. The primary products and molar yields from the hydroxyl‐radical–initiated photooxidation of ENBE in the presence of nitric oxide were acetaldehyde (0.173 ± 0.012), ethyl formate (0.219 ± 0.033), butyraldehyde (0.076 ± 0.004), butyl formate (0.241 ± 0.009), butyl acetate (0.032 ± 0.001), and ethyl butyrate (0.0044 ± 0.0006). From the calculated molar yields, approximately 45.5% of the reacted carbon were recovered. The primary products and molar yields from the DNBE and hydroxyl radical reaction in the presence of nitric oxide were propionaldehyde (0.379 ± 0.022), butyraldehyde (0.119 ± 0.003), butyl formate (0.410 ± 0.009), and butyl butyrate (0.019 ± 0.001). Approximately 47.7% of the reacted DNBE were recovered. The chemical mechanisms are presented to explain the formation of these products. In addition, the importance of the isomerization and nitrate/nitrite formation pathways in the reactions of large ethers are discussed. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 328–341, 2001 相似文献
10.
Andrzej Malankiewicz Ewa Michalik Andrzej Kowalski 《Journal of heterocyclic chemistry》2003,40(2):201-206
The 1H and 13C nmr spectra of the rotational isomers 3a and 3b of 6‐N‐methyl‐N‐formylaminomefhyl)‐thioquinanthrene were completely assigned with a combination of 1D and 2D nmr techniques. The key‐parts of this methodology were long‐range proton‐carbon correlations and NOE experiments with N‐methyl‐N‐formylaminomethyl substituent. The X‐ray study of 4‐methyl‐2‐N‐methyl‐N‐formylaminomethyl)quinoline 4a as well as 1H and 13C nmr spectra show that N‐methyl‐N‐formylaminomethyl substituent in 4a and 4b has a different steric arrangement than the same substituent in 3a and 3b . 相似文献
11.
Jan Fbry Ivana Císaov Jan Kroupa 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e359-e360
n‐Propylammonium dihydrogenphosphate, C3H7NH3+·H2PO4?, crystals are ferroelastic at room temperature. The phase transition into the prototypic phase takes place at approximately 378 K. All atoms except two H atoms are linked by the lost symmetry operations derived from the prototypic space group P2/b21/n21/a. Each of these two different H atoms is involved in an asymmetric hydrogen bond between an oxygen pair. Ferroelastic switching is concomitant with jumps of these H atoms from the donor to the acceptor O atoms. The compound belongs to the structural family of n‐alkylammonium dihydrogenphosphate and in particular to the structure type of pentylammonium dihydrogenphosphate, which differs by localization of alternating layers from the rest of the known alkylammonium dihydrogenphosphates. The crystal was slightly twinned; the proportion of the minor domain was approximately 3.5%. 相似文献
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Duringthelasttwodecades ,peoplehavepaidmuchinterestinthechemistryofself assembledmonolayers(SAMs) ,whichshowspowerfulapplicationsinthefieldsofbiosensorsandtailoredsurfaces .Particularly ,twotypesofSAMs ,i.e .,thiols/thiolatesongoldandsilanesonsiliceoussurface… 相似文献
15.
Roman V. Tsyshevsky Guzel G. Garifzianova Alexander G. Shamov Grigorii M. Khrapkovskii 《International journal of quantum chemistry》2009,109(2):196-201
The quantum chemical calculations at the different levels of theory were performed with the target being to determine the vibration frequencies and to estimate the barriers to internal rotations of n‐pentane molecules. In connection with the observed losses of CH3 and CH4 from the n‐pentane in gas phase, the calculations at the B3LYP level of theory with the 6‐31G(d) basis set were used to study the ground‐state potential energy surface of the n‐pentane. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 相似文献
16.
R. Fournet F. Battin‐Leclerc P. A. Glaude B. Judenherc V. Warth G. M. Cme G. Scacchi A. Ristori G. Pengloan P. Dagaut M. Cathonnet 《国际化学动力学杂志》2001,33(10):574-586
Since n‐hexadecane or cetane is a reference fuel for the estimation of cetane numbers in diesel engines, a detailed chemical model of its gas‐phase oxidation and combustion will help to enhance diesel performance and reduce the emission of pollutants at their outlet. However, until recently the gas‐phase reactions of n‐hexadecane had not been experimentally studied, prohibiting a validation of oxidation models which could be written. This paper presents a modeling study of the oxidation of n‐hexadecane based on experiments performed in a jet‐stirred reactor, at temperatures ranging from 1000 to 1250 K, 1‐atm pressure, a constant mean residence time of 0.07 s, and high degree of nitrogen dilution (0.03 mol% of fuel) for equivalence ratios equal to 0.5, 1, and 1.5. A detailed kinetic mechanism was automatically generated by using the computer package (EXGAS) developed in Nancy. The long linear chain of this alkane necessitates the use of a detailed secondary mechanism for the consumption of the alkenes formed as a result of primary parent fuel decomposition. This high‐temperature mechanism includes 1787 reactions and 265 species, featuring satisfactory agreement for both the consumption of reactants and the formation of products. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 574–586, 2001 相似文献
17.
Shaune McFarlane Robert McDonald Jonathan G. C. Veinot 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(12):o671-o673
The title compound, C29H42, crystallizes from the melt as a triclinic crystal. The unit cell contains three crystallographically independent molecules. The three fluorene ring systems are oriented such that two non‐equivalent ring systems related by a roto‐translation are separated by a third ring system oriented orthogonally to them. The octyl chains of all three molecules are perpendicular to the fluorene ring system and force a 7.4 Å separation between the two coplanar molecules, thereby preventing molecular π‐stacking. 相似文献
18.
Ashish Kadam Thomas Karbowiak Andree Voilley Jean‐Pierre Bellat Olivier Vitrac Frederic Debeaufort 《Journal of Polymer Science.Polymer Physics》2014,52(19):1252-1258
Sorption properties of pure n‐hexane vapor in amorphous polystyrene (PS) were studied at 298 K by thermogravimetry under controlled vapor pressure. Two sorption–desorption cycles were performed by varying the relative pressure between 0 and 0.91. Mixing of PS with n‐hexane resulted in a strong plasticization, which was evidenced by quite significant depression in the glass transition temperature of the polymer as shown by differential scanning calorimetry. Maximum quantity of n‐hexane sorbed in the PS at 298 K and at a pressure close to saturation was about 12.4 wt %. The thermogravimetry yielded an isotherm with a strong hysteresis loop, explanation of which was hypothesized with the help of (a) Flory–Huggins sorption model extended by Vrentas, (b) analysis in terms of modification in the glass transition temperature of the n‐hexane/PS system as a function of sorbed quantity, and (c) change in total volume of the system. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1252–1258 相似文献
19.
L. A. Schwegler C. Meyer‐Pundsack M. Mller 《Journal of polymer science. Part A, Polymer chemistry》2000,38(13):2306-2318
Poly(dipentylsilylene) copolymers containing n‐pentyl‐n‐oct‐7‐enylsilane units were prepared by reductive coupling of the corresponding dichlorosilanes. Linear high molecular weight and some crosslinked polymer were obtained. The soluble products exhibited optical and thermal properties like poly(dipentylsilylene). Differential scanning calorimetry was used to investigate crystallization and to monitor thermal crosslinking. Vinyl functionalized side chains were hydrosilylated with dipentylsilane and dimethylchlorosilane and crosslinked via the side chains. Hydrosilylation with di‐n‐pentyl(trimethylsiloxypropyl)silane led to a partial hydroxy functionalization of the polysilylene and enabled anionic PEO grafting of the poly(dipentylsilylene). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2306–2318, 2000 相似文献
20.
Jan Fbry Radmila Krupkov Ivana Císaov 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):403-405
n‐Heptylammonium dihydrogenarsenate, (C7H18N)[As(O)2(OH)2] (C7ADA), is ferroelastic at room temperature and isostructural with n‐heptylammonium dihydrogenphosphate (C7ADP). In contrast to the other known n‐alkylammonium dihydrogenphosphates (CnADP) and dihydrogenarsenates (CnADA), two independent anions in the present structure are substantially disordered (~88 and ~12%, respectively). There are strong hydrogen bonds between the dihydrogenarsenates themselves, and moderate hydrogen bonds between the dihydrogenarsenates and the n‐alkylammonium groups. The hydrogen‐bond distances correspond well to those observed in the dihydrogenphosphates. There are two H atoms in the structure which are involved in asymmetric hydrogen bonds between respective oxygen pairs. These H atoms jump from the donor to the acceptor O atoms during ferroelastic switching. 相似文献