Carbon-13 spectra of some tetrahydropyridines. The structure of the tetrahydropyridines from 3,5-lutidine 1-oxide and mercaptans in acetic anhydride

The reaction of 3,5-lutidine 1-oxide ( 1 ) with t-butyl mereaptan in acetic anhydride, with or without triethylamine, was reinvestigated. There was obtained 2-t-butylthio-3,.5-lutidine as the major product, a small quantity of 3-(t-bulylthio)methyl-5-picoline, 1-acetyl-2,3-diacetoxy-3,5-dirnethyl-6-t-butylthio-1,2,3,6-tetrahydropyridine (which represents a structure revision) and l-acetyl-2,6-dihydroxy-3-t-butylthio-3,5-dimethyl-1,2,3,6-tetrahydropyridine. A similar reaction of 1 with 1-adamantyl mercaptan furnished 2-(l-adamantylthio)-3,5-lutidine and 1-acetyl-2,3-diacetoxy-3,5-dimethyl-6-(1-adamantylthio)-1,2,3,6-tetrahydropyridine. The structures of these new tetrahydropyridines were established primarily by carbon-13 nmr spectra.     

A new differential scanning calorimetry based approach for the characterization of peracid resin

Differential scanning calorimetry was used to trace the heat of decomposition of the peracid groups (ΔH_d) in the oxidized EVA-g-AA resin. From the correlation between ΔH_d and the oxidation capacity measured by iodometry, it was found that 35 ± 5 cal of energy evolved per miliequivalent of peracid group decomposed. The ΔH_d values are also useful in finding the optimum condition for oxidation of acid groups and can be used to investigate the distribution of active peracid groups across the matrix. The stability and the activation energy of decomposition of grafted type peracid resin were also studied, where the activation energy of decomposition was calculated to be 13.4 kcal/mol.     

Preparation of Enamines Catalyzed by Lewis Acids in the Presence of Solid Supports

A simple and effective preparation of enamines from bulky ketones and secondary amines has been achieved with the aid of Lewis acid on various solid supports. The optimized yields were higher than those obtained without the solid support. Factors affecting the yield and regioselectivity of these reactions were also studied. Evidence showed that the reaction proceeded simultaneously in solution and on the solid support.     

聚丙烯微孔膜的等离子体接枝聚合改性

利用拉伸时的晶型转变致孔特性,从β晶相聚丙烯经单向或双向拉伸制得了新型聚丙烯微孔膜、用等离子体接枝聚合技术接上了亲水性聚合物如聚丙烯酸、聚丙烯腈等。研究了等离子体处理时间、单体性质对得到的亲水膜的亲水性、离子/溶质渗透性的影响。发现接枝聚丙烯酸的双向拉伸膜对Na~+、Mg~(++),尿素有较大的渗透性,并具有优良的形状稳定性。     

3,4′-二甲氧基莰菲醇的合成

以间苯三醛和茄香醛为原料,经Ｈｏｅｓｃｈ－Ｈｏｕｂｅｎ反应,羟基保护、缩合、Ａｌｇａｒ－Ｆｌｙｎｎ－Ｏｙａｍａｄｅ反应、甲基化、等６步反应合成了３,４′－二甲氧基莰菲醇。     

Intrinsic thermal stability and quenching recovery of thin-film superconductors with thermal boundary resistance

The stability behaviour of a thin-film superconductor under a localized release of thermal disturbance is investigated. Two-dimensional conjugate film/substrate conduction equation with anisotropic thermal conductivity of the film, and Joule heat are employed to investigate effects of substrate and thermal properties on the intrinsic stability and quenching recovery. To consider the thermal boundary resistance between film and substrate, an interfacial-layer model (ILM) with very low diffusivity and an acoustic mismatch model (AMM) are employed. Results show that the thermal boundary resistance influences strongly the intrinsic stability. Thermal boundary resistance increases intrinsic stability if the thermal conductivity of the substrate or the disturbance energy is large. Higher Biot numbers and thermal conductivity ratios of film to substrate in longitudinal direction influence stability favorably. We demonstrate also that operation of a film/substrate system, such as YBCO/MgO, is either intrinsically stable or irrecoverably unstable.The authors wish to express their sincere appreciation to Dr. R. C. Chen for his invaluable advice and suggestions during the course of this paper. This research was supported by the National Science Council of the R. O. C. through grant NSC 83-0401-E-009-006. The computations were performed on the IBM ES/9000 at the National Center For High-Performance Computing.