月桂酸稀土复合热稳定剂对PVC热稳定作用的研究

合成了月桂酸镧/铈/钕,分别与硬脂酸钙、季戊四醇复配得到了硬质PVC用月桂酸稀土复合热稳定剂。采用刚果红法、转矩流变仪、动态力学谱仪等考察其对PVC热稳定性、流变性能、力学性能的影响,利用红外光谱初步探讨了其热稳定机制。结果表明:稀土复合热稳定剂中月桂酸镧(铈/钕)/硬脂酸钙/季戊四醇最佳比例为3∶1∶1;具有良好的热稳定性,静态、动态热稳定时间均达到为90和50 min以上;其加工性能和力学性能与铅盐体系相当,断裂伸长率明显高于铅盐体系。     

稀土PVC稳定剂的作用机制研究

稀土化合物可以作为聚氯乙烯稳定剂，硬脂酸稀土是稀土复合稳定剂的重要成分。本文通过研究PVC与硬脂酸镧及其它硬脂酸盐作用前后的红外光谱，探讨了硬脂酸盐对PVC的热稳定作用机制，发现了稀土化合物对PVC的特殊稳定机制，即改变PVC的构象和抑制脱氯化氢的作用，并对稀土稳定剂独特的协同作用做出了解释。     

某些稀土元素的薄层色谱分离和吸光光度法测定

本文研究以硅胶/淀粉/硝酸铵作固定相,用磷酸三丁酯/丁酮/乙酸乙酯/硝酸作展开剂的薄层色谱分离轻稀土元素,钇与钕元素。在硅胶/淀粉/硝酸铵为2.8/0.15/0.5,磷酸三丁酯/丁酮/乙酸乙酯/硝酸(1∶1)为24/45/13.5/2.4时、镧、铈、谱、钕、钐可以满意地分离;磷酸三丁酯/丁酮/乙酸乙酯/硝酸(1∶1)为18/45/13.5/2.4时,钇与钕比例在1∶1—100∶1时也可以满意地分离。应用偶氮氯膦Ⅲ吸光光度法测定分离后稀土元素,可用于轻稀土为主的稀土氧化物中镧、铈、镨、钕的分离及测定。应用本法分离及测定了独居石中镧、铈、镨、钕。     

山梨酸镧复合热稳定剂的制备及协同性能研究

以山梨酸, NaOH, La(NO_3)_3, Ca(NO_3)_2, Zn(NO_3)_2为原料,制备山梨酸镧、山梨酸钙和山梨酸锌热稳定剂,并通过机械共混,制备了复合稀土热稳定剂。采用刚果红试纸法和转矩流变法考察其协同效应,从中筛选出协同效果最好的复合稀土热稳定剂。通过红外光谱法探讨了复合稀土热稳定剂的热稳定机制。研究表明:山梨酸镧-硬脂酸钙的协同效果最好,最佳复配比例为1∶1,静态热稳定时间为56.25 min,动态热稳定时间为1709 s。山梨酸镧复合稀土热稳定剂主要通过吸收中和HCl和与不稳定的氯原子络合以抑制聚氯乙烯(PVC)脱HCl,从而起到稳定作用。     

高纯金属镨的电感耦合等离子体原子发射光谱分析

某些稀土杂质对高纯金属镨的冶炼与性质有很大影响,因此需建立准确可靠的分析方法。镨的ICP光谱极为复杂,本文除用乙醇预去溶进样方式以提高分析灵敏度外,还研究了基体用量和稀土元素间的光谱干扰和校正方法。得出当样品中稀土总浓度为5mg/mL时,可直接同时测定纯度>99.99%的高纯金属镨中的镧、铈、钕、钐和钇,测定下限分别为镧、钕和钐0.002%,铈0.003%,钇0.0005%;其相对标准偏差分别为2.2%,6.2%,3.6%,1.4%和     

磺胺醋酰稀土化合物的研究

在无水乙醇中制备了磺胺醋酰与镧、镨、钕、钐、铕和钆六种固态化合物。元素分析它们的组成为 NaLn(SA)_4·4H_2O(SA 为磺胺醋酰,Ln为镧、镨、钕、钐、铕和钇)。测定了化合物的溶解性和在无水乙醇,无水二甲基甲酰胺中的摩尔电导。从红外和紫外光谱推测,化合物的分子结构中含有O、O′配位螯合的络阴离子。对化合物作了X 光粉末衍射相分析和测定了热稳定性。     

脉冲激光热透镜光度法的研究Ⅰ.钕的测定

本文采用探测激光非聚焦型光学结构,用自装的热透镜实验装置,研究了溶液中Nd~(3+)的热透镜行为和影响热透镜效应的一些因素。用热透镜光度法直接分析了混合轻稀土氧化物样品中钕的含量。大量共存的镧、铈、镨不干扰测定。用1.8mJ/脉冲的加热激光能量,检出限为3.2×10~(-5)吸光度。     

稀土荧光素配合物的合成和电学性质

Bhobe利用稀土离子与荧光素直接反应,制备了配合物,并研究了它们的电学性质。本文采用了与之不同条件合成了镧、铈、镨、钕、钐、铕、钇等稀土的荧光素、二溴荧光素配合物,研究了它们的电阻率与温度的变化关系。 稀土荧光素配合物的制备是先取9.4克荧光素二钠盐于烧杯中,加入1.3克荧光素,在     

硬脂酸稀土对PVC热稳定效能的递变

研究了钪、钷外其他稀土金属硬脂酸皂对PVC热稳定作用. 结果表明 它们均属长期型热稳定剂, 与少量硬脂酸锌并用可有效改善其抑制PVC初期着色的效能;不同硬脂酸稀土与硬脂酸锌并用稳定的PVC具有相似的初期色相, 但中、长期热稳定性不同, 其中镧系金属皂的中、长期热稳定性随原子序数呈现明显的奇偶效应递变规律性;硬脂酸稀土具有类似于碱土金属皂的热稳定作用机制.     

稀土氧化物上SO2和NO的催化还原Ⅱ.用CO作还原剂的脱硫及反应机理

采用连续流动固定床石英反应器,在反应气体为1%SO2和2%CO, 流量为180 ml/min, 以及催化剂用量为0.5 g的条件下,考察了经活化处理的稀土系列氧化物对CO还原SO2的催化活性,探讨了空速、温度和水蒸气等因素对反应的影响.所研究的样品依据对SO2的转化能力可分为三组: 高活性的镧、镨、钕、钐、铕和钆氧化物; 低活性的铈、钬和铒氧化物; 无活性的铽和镝氧化物.在活性最高的钕和钐氧化物样品上, 450 ℃时SO2的转化率＞98%.反应过程中,活性相为稀土氧硫化物,反应遵从COS中间物机理.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.