甲烷中微量噻吩气体标准物质研制

研制了甲烷中噻吩气体标准物质。以高纯噻吩、高纯甲烷为原材料，包装容器为4 L内壁经抛光处理的铝合金瓶，通过微量转移与常规相结合的方法完成了甲烷中微量噻吩气体标准物质制备。利用气相色谱法对标准物质进行了均匀性检验及稳定性考察。F检验和回归曲线法实验结果表明，该气体标准物质在压力为0.5～10 MPa范围内，均匀性良好，在常温条件下保存12个月稳定。采用称量法对该气体标准物质进行了定值，并对定值、均匀性和稳定性引入的不确定度进行了评定，该系列甲烷中微量噻吩气体标准物质标称摩尔分数为1.00～10.0μmol/mol，定值结果的相对扩展不确定度为2%(k=2)。     

重量法配气的称量数学模型及其不确定度评定

对重量法制备气体标准物质中充入气体质量的计算方法进行了研究,建立了基于单盘电子天平的钢瓶称量方法,并建立了系统的数学模型和不确定度评价方法。为重量法制备气体标准物质提供一种简单、实用和精确的钢瓶称量方法和气体加入质量的计算方法。     

氮中多元标准混合气体的制备

研究用重量法制备氮中多元标准混合气体，对其制备原理、制备装置、气体称量装置，制备过程以及组分气体纯度的分析方法进行了介绍。分析了重量法制备氮中多元标准混合气体定值不确定度的来源，其定值的扩展不确定度小于3％。     

高准确度氮中微量一氧化碳气体标准物质的研制

本文介绍了利用微量气体转移技术制备含量为1μmol·mol-1的氮中微量一氧化碳气体标准物质的过程,建立了利用气相色谱仪高准确度分析微量一氧化碳的方法。研制的氮中微量一氧化碳标准物质的扩展不确定度为0.5%(k=2),并通过参加国际比对验证了研制标准物质的准确性。     

氦离子化气相色谱仪校准用混合物中甲烷气体标准物质研制

介绍氦中甲烷气体标准物质的制备方法.以超纯氦气和高纯甲烷为原料,采用称量法制备特性值为10μmol/mol的氦中甲烷气体标准物质.采用气相色谱法(DID检测器)对制备的标准物质进行均匀性、稳定性检验,并对定值结果的不确定度进行评定.研制的气体标准物质均匀性和稳定性良好,有效期为12个月,相对扩展不确定度为2％(k=2)...     

二氧化碳中一氧化氮气体标准物质研制

研制二氧化碳中一氧化氮气体标准物质。以高纯二氧化碳和一氧化氮气体标准物质为原料,采用称量法制备二氧化碳中一氧化氮气体标准物质,用气体分析仪对制备的标准物质浓度进行检测,并对该标准物质定值结果的不确定度进行评定。研制的二氧化碳中一氧化氮气体标准物质中一氧化氮的浓度为5,25,50 μmol/mol,相对扩展不确定度为3.0% (k=2)。该气体标准物质具有良好的均匀性和稳定性,可用于食品级二氧化碳分析方法的确认和评价。     

氦气分析用杂质成分气体标准物质研制

采用称量法研制了氦气中微量氖、氢、氧、氮、甲烷、二氧化碳和一氧化碳7种杂质成分气体标准物质,介绍了称量法制备技术、稀释气中相关杂质的定量等过程,并分别用F检验和回归曲线法对研制的气体标准物质进行了均匀性和稳定性检验。结果表明,研制的氦气分析用杂质成分气体标准物质具有良好的均匀性和稳定性,气体标准物质定值结果为10μmol/mol,定值结果的相对扩展不确定度为1%(k=2)。     

氮中二氧化氮气体标准物质的研制

采用称量法制备并计算定值,研制(10～5000)μmol.mol-1氮中二氧化氮气体标准物质。考察了气体标准物质随贮存时间和钢瓶压力变化的稳定性,将制备的气体标准物质与GBW 08180进行比对验证,结果表明研制的气体标准物质定值的扩展不确定度优于3%(k=3),有效期限为12个月。     

氮气中六氟化硫气体标准物质的研制

建立了制备氮气中六氟化硫气体标准物质的方法。以称量法制备气体标准物质并计算定值,采用气相色谱法对制备的气体标准物质的均匀性和稳定性进行考察。将所制备的标准物质与中国计量院提供的氮气中六氟化硫气体标准物质进行比对分析验证,确保了气体标准物质量值的准确可靠。结果表明,所研制的浓度为10μL/L的氮气中六氟化硫气体标准物质定值的扩展不确定度为2%,贮存有效期为1年,完全能够满足电力部门仪表的检定与校准要求。     

等离子体发射检测器在检测高纯氦气中微量氖气的应用

采用等离子发射检测器(PED)和氦离子放电检测器(DID)对重量法制备的氦气中微量氖气进行了检测,对比了微量氖气在两种检测器上的灵敏度和重复性。结果显示,PED对氖气的检测灵敏度较高,氖气含量在0.03~0.3μmol/mol范围与响应值呈良好的线性关系,r2=1.000,检测限小于1 nmol/mol,测定结果的相对偏差小于2%(n=6)。利用大气压离子质谱仪对检测限测试结果进行了验证。采用等离子发射检测器检测氦气中微量氖气的方法,可以降低微量氖气标准物质的定值不确定度,为研制高准确度微量氖气标准物质奠定基础。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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%).