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克拉霉素在不同条件下水解,分别生成3-羟基克拉霉素(2)和3-羟基-8,9,10,11-二脱水-9,12-半缩酮克拉霉素(3),用乙酸酐保护2的C(2’)-OH得到2’-乙酰基-3-羟基克拉霉素(4),用N-氯代琥珀酰亚胺(NCS)氧化4的C(3)-OH合成了2’-乙酰基-3-氧代克拉霉素(5),采用MS,IR,^1H NMR,^13C NMR等对这些化合物进行了表征.用X射线单晶衍射法测定了化合物2和5的晶体结构,其均属于正交晶系,P212121空间群.化合物2的晶胞参数a=1.3657(3)nm,b=1.4783(3)nm,c=1.6510(3)nm,Z=4,V=3.3332(12)nm^3,Dc=1.175g/cm^3,F(000)=1288,/t=0.087mm^-1;化合物5的晶胞参数a=1.5124(3)nm,b=1.5247(3)nm,c=1.5288(3)nm,Z=4,V=3.5254(12)nm^3,Dc=1.187g/cm^3,F(000)=1368.0,μ=0.088mm^-1. 相似文献
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用AlI3作还原剂,还原二茂铁磺酰氯得到二硫二茂铁。通过元素分析,IR, ^1H NMR和^13C NMR对化合物进行了表征。用X射线单晶衍射法测定了该化合物的晶 体结构。结果表明,晶体属单斜晶系,P21空间群,a=0.61881(4)nm,b=0.3232 (9)nm,c=1.39056(11)nm,β=94.179(3)°,V=0.85593(12)nm^3,Dc=1. 628g/cm^3,μ=1.870mm^-1,F(000)=444,Z=2,R1=0.027,ωR2=0.0678。 相似文献
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TiO2/SnO2复合光催化剂的制备及光催化降解敌敌畏 总被引:7,自引:0,他引:7
合成了直链醚-组氨酸Schiff碱(四甘醇醛缩双组氨酸Schiff碱)及其稀土配合物,以元素分析、红外光谱、热重、磁化率等确定配合物组成为Ln3(H2L)2(NO3)9(Ln=La,Nd,Gd,Er,Yb;L=C20H26N6O7),采用交叉极化结合魔角旋转技术(CP/MAS)和消除旋转边带技术(TOSS),获得固体高分辨^13C NMR谱,见到-COO^-的^13C谱峰分裂等新信息。结合液体^1H NMR谱等,对L-组氨酸中咪唑基的配位进行了研究,以EPR波谱探讨了配合物的晶体场强等特性。观察到Er配合物对超氧阴离自由基的清除有一定效果。 相似文献
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采用现代核磁共振技术,通过分析给药肝、肾损伤模型化合物异硫氰酸α-萘酯(灌胃150mg/kg体重)和二溴乙胺氢溴酸盐(腹腔注射250mg/kg体重)24h内Wistar大鼠尿液的^1H NMR谱,由尿液中内源性代谢物浓度变化研究了肝、肾模型毒物在大鼠体内的急性毒性。首次利用模式识别技术中的二阶段聚类分析方法解析大鼠尿液^1H NMR谱确定了模型化合物尿液^1H NMR标记物。结果表明,应用核磁共振和二阶段聚类分析相结合的方法,可提供模型化合物毒性比较清楚的认识。该方法也可用于金属化合物、中药及其它药物的毒性分类和预测研究以及建议各类靶向毒性的NMR标记物。 相似文献
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The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted
indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator
model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was
established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing
analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997. 相似文献
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Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared. 相似文献
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Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position. 相似文献
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Stepkowska E. T. Perez-Rodriguez J. L. Jimenez de Haro M. C. Sayagues M. J. 《Journal of Thermal Analysis and Calorimetry》2002,69(1):187-204
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
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The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations
were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples
were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of
hematite Fe2O3. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the
best fitting experimental data.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6. 相似文献
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