高频燃烧红外分析法测定混凝土中的硫含量

采用高频红外碳硫仪快速测定混凝土中的硫含量.通过试验确定了适宜的分析条件:以水泥标准物质校正仪器,以铁屑、钨粒加锡粒为助熔剂,称样量为0.03～0.2g.用该法对4种混凝土样品进行测定,测定结果与化学法测定结果相吻合,5次测定结果的相对标准偏差不大于4%,精密度较为理想.     

高频燃烧红外吸收法测定铅精矿中的硫

利用高频燃烧红外吸收碳硫仪测定铅精矿中的硫含量。低硫含量(S<5%)铅精矿样品直接称样测定;高硫含量(S>5%)铅精矿样品添加稀释剂后称样测定。对样品称样量、助熔剂类型及用量等条件进行了研究,获得最佳分析条件。通过空白实验测得方法检出限为0.0010%,利用铅精矿有证标准物质进行精密度和准确度验证,方法的标准偏差在0.295%~1.3%之间,结果表明该方法精密度高、准确度好,能够满足铅精矿中硫含量的快速准确测定。     

高频燃烧–红外吸收法测定石墨及其制品中的硫含量

建立高频燃烧–红外吸收法测定石墨及其制品中的硫含量。结合高频红外碳硫分析仪器特点,试验确定了方法的实验条件:试样粉碎至2.5 mm以下颗粒状,所有试样均为干燥状态,称样量控制在0.200 0~0.300 0 g之间,助熔剂为纯铁和钨粒,助熔剂添加顺序为纯铁+样品+钨粒。采用该方法对石墨标准样品进行测定,测定结果与标准值相符合,测定结果的相对标准偏差为0.86%~1.96%(n=10)。该法可用于石墨及其制品中硫含量的测定。     

管式炉直接燃烧-红外吸收光谱法同时测定硅铁中碳和硫量

提出了管式炉直接燃烧-红外吸收光谱法测定硅铁中碳、硫含量的方法。对试验条件进行了优化,选择氧化铜(1.5g)为助熔剂,样品称样量为0.2～0.3g,碳和硫的分析时间为60s。方法的检出限为硫0.001%,碳0.004%。分析了标准样品(BH1917-1)进行准确度及精密度试验,测定结果与认定值相符,碳和硫测定值的相对标准偏差(n=10)分别小于4%和8%。     

高频红外碳硫分析仪测定土壤、粘土中的硫

应用高频红外碳硫分析仪测定土壤、粘土中的硫含量,对助熔剂的选择、分析时间、吹氧流量及称样量等分析条件进行优化后对标准样品中的硫含量进行测定,测定结果均在标准值范围内。土壤样品测定结果的相对标准偏差为5.10%(n=8),粘土样品测定结果的相对标准偏差为5.51%(n=8)。该方法对实际样品的测定结果与硫酸钡重量法测定结果相吻合。     

高频红外碳硫仪测定区域地球化学样品中的硫

高频红外碳硫仪由于便捷高效,常应用于区域地球化学样品中硫的分析检测。本文采用高频红外碳硫仪测定低中高含量的硫,以纯铁屑、锡粒和钨粒为助熔剂,对样品称样量、助熔剂的种类、加入顺序和用量等因素进行探讨,确定了最佳分析岩石、土壤和水系沉积物中硫含量的条件,并且用国家一级标准物质验证了该方法的准确度和精密度。结果表明,当样品和助熔剂的加入顺序和质量分别为：0.05 g样品、0.5 g铁助熔剂、1.7 g钨粒时,土壤和水系沉积物中硫的测定结果最稳定,岩石标准样品额外的加入0.5 g锡改善样品流动性,提高分析准确度。该方法的相对标准偏差（RSD）小于6%（n= 12）,相对误差绝对值小于8%。此方法具有操作简单、高效、稳定性好的特点,适合于大批量区域地球化学样品中硫的检测。     

高温燃烧碘量法测定萤石中的总硫

建立高温燃烧碘量法测定萤石中总硫含量的方法。采用铜粉为助熔剂与萤石样品混合,以氧气为载气,萤石样品在高温燃烧管式炉中于1 200℃加热燃烧,将萤石样品中的硫转化为二氧化硫,以酸性碘化钾–淀粉溶液吸收二氧化硫,用碘酸钾标准溶液滴定。实验条件:氧气流量为1.5～2.2 L/min;称样质量为500 mg;铜粉用量为1 000 mg。在选定的实验条件下,总硫测定结果的相对标准偏差为2.1%～2.8%(n=11),方法的加标回收率为98.0%～103.5%。该方法准确、快速、简便、检测成本低,可用于萤石中总硫含量的测定。     

微波消解-电感耦合等离子体质谱测定口红中铅的方法研究

建立了微波消解-电感耦合等离子体质谱准确测定口红中铅的方法.考察了不同混合酸对样品消解的效果.由HNO3+HF+H2O2组成的混合酸对称样量小于0.2 g的口红样品具有很好的消解效果;分别测定了霜类化妆品标准物质中的Pb元素和两种口红样品,验证了方法的准确度和精密度(＜3.0%).     

高频燃烧红外吸收光谱法测定仲钨酸铵(APT)中微量硫

对高频燃烧红外吸收光谱法测定仲钨酸铵(APT)中的微量硫含量进行了研究。依据仲钨酸铵的材料性质和高频燃烧红外吸收光谱分析方法的分析特点,分别针对样品的前处理、样品称样量、助熔剂的选择及用量、校准物质的选择等做了条件实验。最终得出最佳的实验条件是称取1g仲钨酸铵样品,进行一定的前处理,再加入0.3g纯铁和1.5g钨助熔剂。按照最佳实验方法,对仲钨酸铵中微量硫含量进行测定,结果的相对标准偏差(RSD,n=5)小于8%,加标回收率为98%~109%。     

高频燃烧红外吸收光谱法测定铪合金中碳

通过对称样量、助熔剂、最短分析时间和比较器水平、分析功率等条件进行了优化选择,建立了高频燃烧红外碳硫分析仪对铪合金中碳含量的分析方法。确定采用称样量为0.4g,助熔剂选择为Fe+Sn+W=0.5g+0.1g+1.3g,最短分析时间为45s,比较器水平为1,分析功率选择100%的条件对铪合金中碳含量进行测定。方法用于测定铪合金实际样品中碳的相对标准偏差(RSD)为5.0%,加标回收率为99%～102%。方法重复性好,准确度高,在实际操作中切实可行。     

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.