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61.
Jardim IC Maldaner L Lourenço J Fioravanti LM Collins CH 《Journal of separation science》2010,33(19):2917-2929
At the present time, more complex analyses of apolar compounds with similar chemical structures or of polar compounds, especially basic ones, having diverse properties require more selective stationary phases having better stabilities. This paper describes several new stationary phases with directed selectivities that were prepared by immobilizing two different phenyl group-containing siloxanes and a trifluoropropyl-containing siloxane onto chromatographic silica and, in the case of the fluorinated siloxane, onto zirconized silica, using thermal treatment or microware radiation. The chromatographic properties and stabilities of these new phases were determined and several applications were evaluated. The phenyl-containing phases showed excellent characteristics related to the separation of several different types of aromatic compounds while the fluorinated phases, which present a more polar character, revealed selectivity for the separation of positional isomers as well as for a mixture of basic pharmaceuticals. Stability tests indicate that immobilization of the polysiloxanes increases column lifetimes by making the stationary phases less susceptible to dissolution, while the phases immobilized with microwave radiation were somewhat more stable than those immobilized by thermal treatments. 相似文献
62.
Paul G. Stevenson Arianne Soliven Gary R. Dennis Ross A. Shalliker 《Journal of separation science》2009,32(22):3880-3889
C1 and phenyl-type stationary phases were assessed in terms of their environmental impact on separations using as test solutes polycyclic aromatic hydrocarbons. Methanol (MeOH) and acetonitrile (ACN) mobile-phase gradients were employed. These stationary phases were examined to determine if different physical and chemical properties possessed by these surfaces decreased the organic solvent consumption, and yet maintained peak capacity. The cumulative energy demand (CED) was used to gauge the environmental impact of the separations. The separation of the polycyclic aromatic hydrocarbon test mixture using current methodologies (i.e. a C18/ACN combination) had a CED of 1.13 MJ-eq, and a peak capacity of 27 peaks (resolving 7 of 12 peak pairs with Rs>1). In comparison, a butyl phenyl stationary phase with a methanol mobile phase had a peak capacity of 26, but with a CED of 0.670 MJ-eq. Monolithic columns containing C18 and C1 phases were also tested. A monolithic C18 column with MeOH had the lowest CED at 0.675 MJ-eq, a peak capacity of 28 peaks and good resolving power (resolving ten peak pairs with Rs>1), suggesting that this is a viable option with respect to reducing environmental impact for these types of analyses. 相似文献
63.
Michael I. Bruce Prof. Dr. Natasha N. Zaitseva Brian W. Skelton Allan H. White 《无机化学与普通化学杂志》2010,636(6):1075-1077
The reaction between Ru(C≡CH)(dppe)Cp* and Co3(μ3‐CBr)(CO)9 in the presence of Pd(PPh3)4/CuI afforded dark red Co3{μ3‐CC(O)C≡C[Ru(dppe)Cp*]}(CO)8(PPh3), whose formation may involve attack of the Ru‐ethynyl fragment on an intermediate cluster‐bound CCO ligand; abstraction of PPh3 from the palladium catalyst also occurs. 相似文献
64.
Two new compounds identified as methyl derivatives of phenyl naphthalenedicarboxylic acid and phenyl naphthalenecarboxylic acid linked to a phenylphenalene unit were isolated from the extract of Eichhornia crassipes (water hyacinth). The structures have been determined on the basis of spectroscopic analyses, mainly using 2D NMR techniques. 相似文献
65.
Some new 3,5‐diphenyl and 1,3,5‐triphenyl‐2‐pyrazolines derivatives were synthesized by reacting 1,3‐diphenyl‐2‐propen‐1‐ones with hydrazine hydrates and phenyl hydrazine in ethanol. The structural elucidation of the compounds was performed by IR, 1H NMR and elemental analysis. All examined compounds showed appreciable antibacterial activity. 相似文献
66.
67.
G.K.Surya Prakash 《Journal of fluorine chemistry》2004,125(4):595-601
Chlorodifluoromethanesulfonic acid (1) was prepared using a new procedure starting from perchloromercaptan, which is readily obtained from chlorination of CS2. Modified Swarts reaction transformed N,N-diethyl trichloromethanesulfenamide into N,N-diethyl chlorodifluoromethanesulfenamide, and the latter species was further oxidized and hydrolyzed into chlorodifluoromethanesulfonic acid. The preparations of other two new α,α-difluoroalkanesulfonic acids, phenyl difluoromethanesulfonic acid (2) and 2-phenyl-1,1,2,2,-tetrafluoroethanesulfonic acid (3), are also disclosed. The acids 2 and 3 are stable in the forms of sodium (lithium) salts or in aqueous solutions; however, the pure forms of 2 and 3 can readily undergo defluorinations. 1-3 and their salts have potential applications as superacid catalysts and lithium battery electrolytes. 相似文献
68.
A.Charis R. Croft 《Journal of organometallic chemistry》2003,683(1):120-130
Chloride ligand substitution reactions of tert-butyl- and arylimido-titanium complexes supported by the pendant arm functionalised N-trimethylsilyl benzamidinate ligand Me3SiNC(Ph)NCH2CH2CH2NMe2 are described. Reaction of previously-described [Ti(NtBu){Me3SiNC(Ph)NCH2CH2CH2NMe2}Cl] (1) with PhLi afforded thermally sensitive [Ti(NtBu){Me3SiNC(Ph)NCH2CH2CH2NMe2}Ph] (2). The corresponding reaction of 1 with MeLi afforded [Ti(NtBu){Me3SiNC(Ph)NCH2CH2CH2NMe2}Me] (3) detected by 1H-NMR spectroscopy but this compound could not be isolated. Reaction of 1 with LiCH2SiMe3 gave a complex mixture, but with LiN(SiMe3)2 and LiO-2,6-C6H3Me2 the compounds [Ti(NtBu){Me3SiNC(Ph)NCH2CH2CH2NMe2}X] (X=N(SiMe3)2 (4) or O-2,6-C6H3Me2 (5)) were isolated. The X-ray structure of 5 was determined. Reaction of the homologous compound [Ti(NtBu){Me3SiNC(Ph)NCH2CH2NMe2}Cl] (6) (containing a 2-carbon atom chain in the pendant arm) with MeLi or PhLi were unsuccessful although the aryloxide compound [Ti(NtBu){Me3SiNC(Ph)NCH2CH2NMe2}(O-2,6-C6H3Me2)] (7) could be isolated from the reaction of 6 with LiO-2,6-C6H3Me2. Reaction of the 3-carbon pendant arm arylimido compound [Ti(N-2,6-C6H3Me2){Me3SiNC(Ph)NCH2CH2CH2NMe2}Cl] (8) with MeLi afforded thermally sensitive [Ti(N-2,6-C6H3Me2){Me3SiNC(Ph)NCH2CH2CH2NMe2}Me] (9), and although the analogous phenyl homologue was elusive, the aryloxide derivative [Ti(N-2,6-C6H3Me2){Me3SiNC(Ph)NCH2CH2CH2NMe2}(O-2,6-C6H3Me2)] (10) was successfully isolated and structurally characterised. Comparison of the X-ray structures of 5 and 10 show unexpectedly large differences between the TiNR and TiOAr bond lengths in the two compounds. 相似文献
69.
苯丙酮酸是合成苯丙氨酸的重要中间体 ,也是重要的动物新陈代谢产物 ,在生物化学和药物学上都有广泛的用途 .例如 ,在泌尿系统疾病的治疗中 ,摄入苯丙酮酸盐 ,可以在酶的作用下 ,结合体内过多的氨生成苯丙氨酸 ,从而降低血氨浓度 ,防止氨中毒 .合成苯丙酮酸的氯化苄双羰化方法应用较广 ,催化剂一般采用钴的配合物如八羰基二钴等 .这种方法一步完成 ,工艺简单 ,产品易分离、收率高 ,与传统的合成方法相比具有很大的优势 [1] .但催化剂八羰基二钴价格比较高 ,且在空气中不稳定 [2 ] .若能实现催化剂的回收再利用 ,对于实现苯丙酮酸的工业化生… 相似文献
70.
Zbigniew Grobelny Andrzej Stolarzewicz Adalbert Maercker Wolfgang Demuth 《Journal of organometallic chemistry》1999,590(2):321-157
A new mechanism of the reaction of K−, K+(15-crown-5)2 with phenyl glycidyl ether is presented. The linear ether bond is attacked only to a small extent, if at all. As the main reaction path the oxirane bond in the β-position is cleaved, followed by the γ-elimination of potassium phenoxide and the formation of potassium cyclopropoxide. Crown ether ring opening also occurs in reactions with organometallic intermediates. 相似文献