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91.
综述了环己酮肟在发烟硫酸条件下液相重排生成己内酰胺的相关新工艺、新设备及新技术,并对其进行了概括和分析. 相似文献
92.
Grigor B. Bantchev Kenneth M. Doll Girma Biresaw Karl E. Vermillion 《Journal of the American Oil Chemists' Society》2014,91(12):2117-2123
Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2‐ethylhexanol, benzyl alcohol, in the presence of Brønsted acid catalyst, were investigated. Products, not reported in prior studies of similar reactions, were found. These were furan fatty acid alkyl esters (FFE, mixture of alkyl 8‐(5‐hexyl‐2‐furyl) octanoate and alkyl 9‐(5‐pentyl‐2‐furyl)nonanoate) which were unambiguously identified by means of GC–MS and two‐dimensional NMR. Evidence suggests that the FFE are formed by an acid‐catalyzed rearrangement of the epoxidized linoleates. The FFE were formed in presence of all four alcohols tested and in the presence of either sulfuric acid or Amberlyst 15 catalyst. Yields of up to 13 %, as quantified by GC and NMR spectroscopies, were observed. 相似文献
93.
Zhengshen Wang Huaiji Zheng Juan Yang Xingang Xie Xuegong She 《Advanced Synthesis \u0026amp; Catalysis》2015,357(9):2082-2088
An effective synthesis of structurally diverse pyrroline derivatives has been accomplished by a gold(I)‐catalyzed tandem 1,3‐acyloxy rearrangement/intramolecular azacylization reaction of γ‐amino‐substituted propargylic esters in good to excellent chemical yields (52–98%). The reaction proceeds under extremely mild conditions and has also demonstrated its potential in a concise formal synthesis of (±)‐aphanorphine with a catalyst loading as low as 0.5 mol% to provide the key intermediate 5‐(4‐methoxybenzyl)‐1‐tosyl‐2,5‐dihydro‐1H‐pyrrol‐3‐yl pivalate on a gram scale.
94.
T. R. HOPKINS 《Software》1996,26(8):967-982
We use knot count and path count metrics to identify which routines in the Level 1 basic linear algebra subroutines (BLAS) might benefit from code restructuring. We then consider how logical restructuring and the improvements in the facilities available from successive versions of Fortran have allowed us to improve the complexity of the code as measured by knot count, path count and cyclomatic complexity, and the user interface of one of the identified routines which computes the Euclidean norm of a vector. With these reductions in complexity we hope that we have contributed to improvements in the maintainability and clarity of the code. Software complexity metrics and the control graph are used to quantify and provide a visual guide to the quality of the software, and the performance of two Fortran code restructuring tools is reported. Finally, we give some indication of the cost of the extra numerical robustness offered by the BLAS routine over the use of new Fortran 90 intrinsic functions. 相似文献
95.
96.
Software engineers have tacitly assumed that there exists a link between coverage and reliability. An argument is presented which leads to an inverse logarithmic relationship which depends upon the structure of the software and on a parameter called the strength of the coverage metric. The relationship is developed by considering reliability as a function of an idealized coverage metric and then interpreting the result for a range of actual coverage metrics. 相似文献
97.
以2-苄基吡啶氮氧化物和三氟乙酸酐为原料,通过“一锅三步法”(串联“酰化、[3,3]σ重排和水解”反应)合成了关键药理活性中间体苯基-2-吡啶基甲醇,并对反应条件进行了优化。结果表明:当n(2-苄基吡啶氮氧化物):n(三氟乙酸酐)=1 : 1.2、N, N-二异丙基乙胺(DIPEA)为碱、甲苯为反应溶剂,室温反应6小时,经硅胶柱层析分离即可得到苯基-2-吡啶基甲醇,收率为81.0%。产物经1H NMR,13C NMR 和HRMS进行结构表征。本文以原子经济学的理念首次实现了由2-苄基吡啶氮氧化物到苯基-2-吡啶基甲醇的直接转化。 相似文献
98.
99.
Dongsen Mao Guanzhong Lu Qingling Chen Zaiku Xie Yuxian Zhang 《Catalysis Letters》2001,77(1-3):119-124
A series of boria catalysts supported on titania–zirconia mixed oxide (B2O3/TiO2–ZrO2) with different boria loadings (8–20 wt%) were prepared and characterized by X-ray diffraction, adsorption of nitrogen, 11B magic angle spinning (MAS) NMR measurements and temperature-programmed desorption (TPD) of ammonia. The catalytic performance of B2O3/TiO2–ZrO2 for vapor-phase Beckmann rearrangement of cyclohexanone oxime to -caprolactam was studied at 300°C. It was found that the lactam selectivity increased with increasing of boria loading, whereas a maximum oxime conversion was obtained at the boria loading of 12 wt%. The acid sites of medium strength on the surface of the catalyst play an important role in the selective formation of lactam. 相似文献
100.