N-溴代丁二酰亚胺滴定法测定铁矿石中铁

铁矿石经盐酸溶解后,用Ｈ２Ｏ２氧化,使Ｆｅ＾２＋氧化成Ｆｅ＾３＋。加入过量的ＶＣ还原Ｆｅ＾３＋,剩余ＶＣ用ＮＢＳＭ滴定。方便简便,快速,终点敏锐,精了,准确度高,ＲＳＤ≤０．３％,相对误差〈０．４％,并可选择性地滴定矿石中的三价铁。     

THE EXCITED STATES AND VIBRATIONAL FREQUENCIES OF Bli_2~e（e＝0，＋1，－1）CLUSTERS

ＴＨＥＥＸＣＩＴＥＤＳＴＡＴＥＳＡＮＤＶＩＢＲＡＴＩＯＮＡＬＦＲＥＱＵＥＮＣＩＥＳＯＦＢｌｉ：（ｅ＝０，＋１，－１）ＣＬＵＳＴＥＲＳＴＨＥＥＸＣＩＴＥＤＳＴＡＴＥＳＡＮＤＶＩＢＲＡＴＩＯＮＡＬＦＲＥＱＵＥＮＣＩＥＳＯＦＢｌｉ：（ｅ＝０，＋１，－１）Ｃ...     

Eu^3＋,Bi^3＋Me2Y8（SiO4）6O2中的发光特性与取代格位

在紫外光激发下，Ｅｕ＾３＋和Ｂｉ＾３＋在Ｍｅ２Ｙ８（ＳｉＯ４）６Ｏ２基质（Ｍｅ＝Ｍｇ，Ｚｎ，Ｃａ，Ｓｒ）中分别发射红光（＾５Ｄ０－＾７Ｆ２）和蓝光（＾３Ｐ１－＾１Ｓ０）．Ｅｕ＾３＋发光的红橙比随着激发波长和Ｍｅ＾２＋的不同而变化。荧光拉曼光谱表明，Ｅｕ＾３＋在四种基质中同时占据了４ｆ格位和６ｈ格位。依据Ｂｉ＾３＋发光的Ｓｔｏｋｅｓ位移推断，当Ｍｅ＝Ｃａ，Ｚｎ时，Ｂｉ＾３＋主要占据４ｆ格位，而当Ｍｅ     

STRUCTURAL MODIFICATION OF 11－ISOPROPYLIDENE endo－TRICYCLO［6．2．1．0~（2，7）］UNDECA－4， 9－DIENE－3，6－DIONE TO IMPROVE THE STABILITY

ＳＴＲＵＣＴＵＲＡＬＭＯＤＩＦＩＣＡＴＩＯＮＯＦ１１－ＩＳＯＰＲＯＰＹＬＩＤＥＮＥｅｎｄｏ－ＴＲＩＣＹＣＬＯ［６．２．１．０￣（２，７）］ＵＮＤＥＣＡ－４，９－ＤＩＥＮＥ－３，６－ＤＩＯＮＥＴＯＩＭＰＲＯＶＥＴＨＥＳＴＡＢＩＬＩＴＹ￥ＸｉａｏＰｅｉＧ...     

硫代苹果酸作为络合滴定掩蔽剂的研究

本系统地研究了硫代苹果在络合滴定中的掩蔽性能，发现它在ｐＨ１．５～１０可作为Ｓｎ＾４＋、Ｓｂ＾３＋、Ｔｂ＾３＋、Ｂｉ＾３＋、Ｃｕ＾２＋、Ｈｇ＾２＋和Ａｇ＾＋等的掩蔽剂（在ｐＨ２～３．５还可掩蔽Ｆｅ＾３＋）。掩蔽上述离子后，可在ｐＨ２．５～３用Ｔｈ＾４＋回滴ＥＤＴＡ，在ｐＨ５～６用ＥＤＴＡ滴定Ｚｎ＾２＋或Ｙｂ＾３＋等，或在ｐＨ１０用ＥＤＴＡ滴定Ｍｇ＾２＋、Ｃａ＾２＋、Ｍｇ＾２＋＋Ｃａ＾２＋和Ｍｎ＾     

铝与溴代二甲氨基苯基荧光酮的多元配合物的光度研究

本文研究了在表面活性剂存在性，铝与溴代二甲氨基苯基荧光酮的显色反应。在弱酸性介质中，Ａｌ＾３＋ＢＤＭＡＦ－ＣＴＭＡＢ三元配合物在水浴加热至７０℃－８０℃时形成，其最大吸收波长为５７７ｎｍ，Ａｌ＾３＋：ＢＤＭＡＦ＝１：２，表观摩尔吸光系数为１．３４×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，表观稳定常数为７．４×１０＾５。在ＰＨ９．５－１０．５的氨性缓冲介质中，Ａｌ＾３＋－Ｆ＾－－ＢＤＭＡＦ－非离子表面     

维脑路通与铜(Ⅱ)的配位化学研究

用单扫描极谱法研究了Ｃｕ＾２＋与维脑路通（ＶＥＮＯＲＵＴＯＮ,简称ＶＲＴ）形成配合物的条件和机理,在磷酸盐缓冲溶液中（ＰＨ７．０）,Ｃｕ＾２＋与维脑路通配位并产生１个不可逆还原波,其峰电位为－０．５５Ｖ（ｖｓ．ＳＣＥ）。配合物的摩尔组成比为Ｃｕ＾２＋,ＶＲＴ＝１：２,表观稳定常数为１．１＊１０＾１１。     

CONVERSION OF KETONES INTO1，1－DISUBSTITUTED－2，3，3－TRIFLUORO－2－PROPEN －1－OLSWITH1，1－DIBROMO－1，2，2，2－TETRLUORO ETHANE／MAGNESIUM REAGENT

ＣＯＮＶＥＲＳＩＯＮ　ＯＦ　ＫＥＴＯＮＥＳ　ＩＮＴＯ１，１－ＤＩＳＵＢＳＴＩＴＵＴＥＤ－２，３，３－ＴＲＩＦＬＵＯＲＯ－２－ＰＲＯＰＥＮ　－１－ＯＬＳＷＩＴＨ１，１－ＤＩＢＲＯＭＯ－１，２，２，２－ＴＥＴＲＬＵＯＲＯ　ＥＴＨＡＮＥ／ＭＡＧＮＥＳＩＵＭ...     

MCSCF AND VTST STUDIES OF THE REACTION CH(2~π)+H_2→CH_3

ＭＣＳＣＦＡＮＤＶＴＳＴＳＴＵＤＩＥＳＯＦＴＨＥＲＥＡＣＴＩＯＮＣＨ（２~π）＋Ｈ_２→ＣＨ_３￥ＳｉＹｕＭＡａｎｄＲｕｏＺｈｕａｎｇＬｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｅｄ．ＢｅｉｊｉｎｇｆｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１００?..     

稀土离子与NAD^＋和NAD—LDH相互作用的伏安行为研究

报道了稀土离子与ＮＡＤ＾＋和ＮＡＤ－ＬＤＨ相互作用的伏安行为，研究结果表明，稀土离子能够与ＮＡＤ＾＋发生作用，使ＮＡＤ＾＋在－０．９４Ｖ处的还原峰分裂为２个还原峰；ＮＡＤ＾＋和ＬＤＨ在汞电极上可形成络合物，络合物的还原峰在－１．１６Ｖ处，加５μｍｏｌ／ＬＬａ＾３＋，Ｃｅ＾３＋，Ｐｒ＾３＋，Ｅｕ＾３＋，Ｇｄ＾３＋，Ｄｙ＾３＋，Ｙｂ＾３＋和Ｌｕ＾３＋离子，能增大ＮＡＤ－ＬＤＨ络合物的解离常数约４０％～     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.