An amidoalkylation of PCl3 or its organic derivatives in acetic acid solution takes place because equilibrium between AcOH and exist, leading to hydroxychlorophosphines. Those last compounds undergo an amidoalkylation like other nucleophiles. Based on these data, it was shown that an amidoalkylation reaction is usual for all phosphorus compounds with the R2P(O)H system and provides derivatives with the functions. The scope and limitation of these reactions are discussed. 相似文献
d-N.M.R.-Investigations of the Restricted Rotation at the Bonding Increment. IX. Restricted Rotation about Partial Double Bonds in Nucleo-substituted Phenyl-β-dimethylaminovinyl-thioketones Due to resonance stabilization restricted rotations about partial and double bonds have been observed in some substituted phenyl-β-dimethylaminovinyl-thioketones 2. The free enthalpies of activation have been determined by means of d-n.m.r.-spectroscopy in dependence on the properties of the p-phenyl substituents and the solvent. The measured ΔG≠-values depend on the σ-substituent constants and on the ET-values of solvent polarity linearly. Substituents with electron-withdrawing properties and solvents with increasing polarity enhance the free enthalpies of activation of the restricted rotation. 相似文献
The arithmetic means of wave numbers of symmetric and antisymmetric CO stretching vibrations measured in tetrachloro- and trichloromethane of 31 substituted maleinimides were correlated with Taft inductive σ* substituent constants. The series of N-phenyl and N-(4-methylphenyl) derivatives exhibit normal i.e. positive values of slope of vs σ* correlations. In series of substituted N-methylmaleinimides (and probably also in maleinimides) the negative values of slope of vs σ* correlations indicate a reversed substituent effect on the CO stretching vibration. The mechanism of transmission of substituent effects in maleinimidee system is discussed considering the results of above mentioned observations. 相似文献
From poly(alkylene terephthalates) (n = 2, 3, 4) with intrinsic viscosities of 0.75–0.80 dl/g the cyclic oligomers with x = 2, 3, 4 were extracted and analysed by gel permeation chromatography. For comparison with the experimental equilibrium contents of cyclic oligomers the molar cyclization constants Kx were calculated according to Jacobson and Stockmayer. To describe the statistical conformations of the corresponding open chain molecules (end-to-end distances) the rotational isomeric state model of Flory and Williams was used. 相似文献
Electosynthesis of N-Substituted DL-Arylglycineesters and 1,2-Diarylamino-1,2-diarylethanes by Cathodic Reduction of Azomethines in the Presence of Carbon Dioxide The electroreduction of the N-arylidene-arylamines 1–12 in CO2-saturated solvents of low proton availability as DMF at markedly more positive potentials than carbon dioxide end up in carboxylating the C-atom and hydrogenating the nitrogen of the double bond. The resulting N-arylsubstituted DL-arylglycines and traces of carbamates may be isolated as esters, adding ethylchloride during the electrolysis. A competing pathway of the electrocarboxylation is the C C-hydrodimerisation and the hydrogenation of the double bond, whose importance increases with the water content of the solvent. Based on cyclic-voltametric evidence and product analysis the mechanism of the reductive electrocarboxylation reaction is discussed in terms of nucleophilic attack of the azomethine anion radical on a proton or CO2. 相似文献
The rates of reduction of some CoIII pentaamine complexes by HINA·, and , HNA·, radicals were measured. It was found that HNA· is more reactive than HINA·. The redox potential for the couple HINA·/HINA+ was calculated, E° = 0.80 ± 0.02 V. In the presence of large excess of NA, a catalytic enhancement in the reduction of CoIII(NH3)5 NA and CoIII(NH3)5 Pyridine by Eu2+ was observed. The difference in the mechanism of reduction of CoIII(NH3)5 X by Eu2+ where X = NA or INA is discussed. The redox potential of the HNA·/HNA+ couple was estimated, 0.80 < E° < 1.1 V. 相似文献
Trimethylammoniumhydroxypropyl (TMAHP)–cellulose in 10 anionic forms (F?, Cl?, Br?, I?, HSO, NO, OH?, HCO, H2PO, CH3COO?) was prepared, and the influence of each anion on thermal degradation in inert atmosphere was studied. With the help of dynamic and isothermal thermogravimetry (TG) it was found that H2PO ions had the greatest retarding effect on TMAHP–cellulose degradation. From the values of rate constants it can be seen that all ionic forms of TMAHP–cellulose have the starting rate of thermal degradation greater than unmodified cellulose. The calculated values of activation energy of thermal degradation for different ionic forms are decreasing in following sequence: H2PO > F? > NO > I? > Br? > HCO > Cl? > HSO > OH? > unmodified cellulose > CH3COO?. From the results of pyrolyse measurements in combination with gas chromatography and mass spectrometry (Py–GC–MS) it follows that the products of the elimination of quarternary ammonium salts are trimethylamine, 3-hydroxy-2-propanone, and, in the case of OH? form, water. In all other ionic forms the third product is the corresponding acid. 相似文献
Different values are reported in the literature for the intrinsic birefringence of the crystalline (Δn) and the amorphous (Δn) phases in nylon 6. Mostly, these values have either been determined by extrapolation (and then it is assumed that Δn = Δn) or calculated theoretically. In this study, intrinsic birefringence values Δn and Δn for nylon 6 were determined using the Samuels two-phase model which correlates sonic modulus with structural parameters. Three series of fiber samples were used: (1) isotropic samples of different degrees of crystallinity for estimation of E and E moduli at two temperatures. The following modulus values were obtained: 1.62 × 109 and 6.66 × 109 N/m2 for 28.5°C, and 1.81 × 109 and 6.71 × 109 N/m2 for ?20°C; (2) anisotropic, amorphous fiber samples for estimation of Δn = 0.076 and E = 1.63 × 109 N/m2 at 28.5°C; (3) semicrystalline samples of various draw ratios for estimations of Δn = 0.089 and Δn = 0.078. All measurements were carried out with carefully dried samples to avoid erroneous results caused by moisture. 相似文献
Oxidative coupling of methane over a La2O3/CaO catalyst was investigated in laboratory-scale fluidized-bed reactors (ID = 5 and 7 cm) in the following range of reaction conditions: T = 700 – 880°C, P = 41 – 72 kPa and P = 6 – 29 kPa. The maximum C2+ selectivity and yield amounted to 73.8% (T = 800°C, X = 13.1%, Y = 9.7%) and 16.0% (T = 840°C, X = 34.0%, S = 47.2%), respectively. Axial gas concentration profiles revealed that C2+ selectivity was not only influenced by oxidative consecutive reactions, but also by steam reforming of ethylene. When diluting the catalytic bed (mcat = 145 g) with quartz (m = 200 and 400 g), a slight decrease of the selectivity (1–2%) was observed. The dilution of the feed gas with nitrogen only led to only a small increase (< 2%) of the C2+ selectivity. 相似文献
The Catalysis of the Co-Oxidation of cis-Oct-4-ene and n-Butyric Aldehyde The co-oxidation of cis-oct-4-ene and n-butyric aldehyde in the absence of catalysts, or in the presence of molybdenum and Co(acac)3, resp., was studied in dependence on the aldehyde/olefin ratio, on the temperature and other reaction conditions. Under the same conditions, the noncatalyzed co-oxidation converted 50%, the MoO2(acac)2-catalyzed one 68%, and the Co(acac)3-catalyzed one 40% of the reacted olefin into the epoxide. The cis/trans-epoxide ratio in the molybdenum-catalyzed co-oxidation was nearly 2 independent of the aldehyde/olefin ratio. In the non-catalyzed co-oxidation the cis/trans-epoxide ratio depends linearly on the aldehyde/olefin ratio (cis/trans E. = 0,58 + 0,90 n/n). From these dependences we can conclude that the homolytic mechanism of epoxide formation decreases and the polar mechanism (Priležaev-reaction) increases with increasing aldehyde/olefin ratio. Optimization of the epoxide yields according to a Box-Hunter experimental plan gave the following reaction conditions to yield 95% epoxide based on reacted olefin: 70°C, ΔnS/n = 0,49, n/n = 3,5 · 10−3, n/n = 0,53. The co-oxidation in the presence of other molybdenum catalysts of the chloro-nitrosyl-complex type and of the carbonyl-complex type as well as the co-oxidation with other aldehydes were studied, too. 相似文献
Thiolated starches with a degree of substitution of 0.01–0.6 were obtained by pyrolysis of starch dithiobis(thioformates) followed by saponification. The pyrolytic decomposition of dithiobis(thioformates) followed two pathways: (1) to thionocarbonate , carbon disulfide, and sulfur, and (2) to dithiocarbonate , carbonyl sulfide, and sulfur. Only the second pathway affords thiolation. Thiol groups were determined by Ellman's reagent, by sulfur analyses, and, following acetylation, by the ratio of O-acetyl versus S-acetyl absorption in nuclear magnetic resonance spectra. The poly-saccharides cellulose, dextran, and xylan were thiolated by the same procedure. 相似文献
The modification of ε-caprolactam oligomers with ethylene oxide was studied. The reaction was carried out in a solution of oligoamides with gaseous ethylene oxide in the presence of sulfuric acid as a catalyst at 60°C and atmospheric pressure. The product, obtained in that way can be presented by the following formula: where R1 and R2 are alkyl groups. 相似文献
Summary: It is well known that the weight‐average molecular weight ( ) is strictly dependent on conversion in step‐growth polymerizations performed in batch and that the is very sensitive to impurities and molar imbalance. This makes the work of controlling a non trivial job. In this paper a new methodology is introduced for in‐line monitoring and control of conversion and of polyurethanes produced in solution step‐growth polymerizations, based on near‐infrared spectroscopy (NIRS) and torquemetry. A calibration model based on the PLS method is obtained and validated for monomer conversion, while the weight‐average molecular weight is monitored indirectly with the relative shear signal provided by the agitator. Control procedures are then proposed and implemented experimentally to avoid gelation and allow for maximization of . The proposed monitoring and control procedures can also be applied to other step growth polymerizations.