bluuebunny/crossref_metadata_2025_split huggingface dataset:
General Approach for Template‐Directed Synthesis of Macroheterocycles by Ring‐Closing Metathesis (RCM)
Authors: Chuchuryukin Alexey V. , Chase Preston A. , Dijkstra Harm P. , Suijkerbuijk Bart M. J. M. , Mills Allison M. , Spek Anthony L. , van Klink Gerard P. M. , van Koten Gerard 
Published: February 2005

AbstractA general method to prepare macroheterocycles is reported in which a rigid symmetric platinated tris‐pincer tricationic complex (3) is used as a template. The system uses bisolefin functionalized pyridine ligands (1, 2) which selectively bind to the three platinum centers of the template resulting in pre‐organization of the olefinic tails. By subjecting these pre‐organized complexes (4) to olefin metathesis reaction conditions, the olefinic tails were interconnected affording several macroheterocycles of different compositions and sizes. Various pyridines with different substitution patterns (2,6‐ and 3,5‐disubstituted) and different olefinic tails (aliphatic, polyether, and styryl) were synthesized and used in the cyclization reactions, showing the diversity of this method. It was found that only the use of 2,6‐disubstituted pyridines resulted in the formation of the desired macrocycles while 3,5‐difunctionalized pyridines gave only pyridinophane formation. Furthermore, the length of the olefinic tails needs to be at least eleven atoms (C or O) in order to suppress oligomerization in favor of macrocycle formation. Yields of up to 70% of the macrocycles were obtained using the first‐generation [Cl2(Cy3P)2RuCHPh] or second‐generation [Cl2(Cy3P)(IMes)RuCHPh] Grubbs' catalysts. Reactions of the platinated pincer pyridines with Schrock Mo‐based metathesis catalysts results in exclusive olefin isomerization and no productive metathesis. The generated macrocycles (hosts) could effectively be separated from the template by addition of aqueous sodium chloride and reattached to the (recycled) template (guest). The X‐ray structure determination of host‐guest complex10is the definite proof for this reattachment and the perfect cyclic structure of the macrocycle.
[Zinc‐Diamine]‐Catalyzed Hydrosilylation of Ketones in Methanol. New Developments and Mechanistic Insights
Authors: Bette Virginie , Mortreux André , Savoia Diego , Carpentier Jean‐François 
Published: February 2005

AbstractThe Zn‐promoted direct reduction of various ketones, including alkyl aryl ketones, α‐ and β‐keto esters, α‐ and β‐keto amides, into the corresponding alcohols with polymethylhydrosiloxane (PMHS) in protic conditions is reported. The reaction proceeds chemoselectively under smooth conditions, with simple catalyst combinations based on a zinc precursor [ZnEt2, Zn(OMe)2, Zn(OH)2] and a 1,2‐diamine ligand, e.g., N,N′‐dibenzylethylenediamine (dbea). The reaction rates are significantly faster than under aprotic conditions. For β‐keto esters and amides, the use of an excess of PMHS is required. Moderate enantioselectivities (ee up to 55%) have been obtained using a variety of enantiopure diamine ligands. Two mechanisms are proposed for the new catalytic reaction, on the basis of the synthesis of [(diamine)Zn(alkoxide)2] complexes which are models of the possible reaction intermediates and a study of their activity.
Heterogenization of Organometallic Molybdenum Complexes with Siloxane Functional Groups and their Catalytic Application
Authors: Sakthivel Ayyamperumal , Zhao Jin , Hanzlik Marianne , Chiang Anthony S. T. , Herrmann Wolfgang A. , Kühn Fritz E. 
Published: February 2005

Abstractη5‐CpMo(CO)3R complexes containing siloxane functional groups [(CH2)3Si(OMe)3 or (CH2)Si(OEt)3] attached to either the cyclopentadiene ligand or directly to Mo were grafted on the mesoporous materials MCM‐41 and MCM‐48 by reaction of the OR (R=Me, Et) moieties in the silane ligand and surface silanol groups (Si‐OH). For the sake of comparison mesoporous materials modified with silane groups were reacted with Na+[CpMo(CO)3]−. The XRD, N2 adsorption‐desorption, and TEM analyses provide strong evidence that the mesoporous structure of the supporting material retains its long‐range ordering throughout the grafting process, despite significant reductions in surface area, pore volume and pore size. The appearance of strong IR bands around 2016 and 1956 cm−1 on the grafted samples also shows that the η5‐CpMo(CO)3R complexes have been successfully grafted. Elemental analysis reveals that the grafted samples contain 0.3–3.5 wt % Mo. 29Si CP MAS‐NMR spectra give clear evidence for a reduction in the numbers of the Q3 and Q2 sites. The formation of new peaks around −49.8, −57.9, and −66.2 ppm (T1, T2, and T3) indicates esterification of silanol groups by the alkoxy groups of the silane ligand. Both the in situ and ex situ prepared samples show good catalytic activity for the epoxidation of cyclooctene.
Room Temperature Liquid Salts of Cr and Mo as Self‐Supported Oxidants
Authors: Noguera Gladys , Mostany Jorge , Agrifoglio Giuseppe , Dorta Romano 
Published: February 2005

AbstractRoom temperature liquid salts of Cr and Mo were synthesized and fully characterized including cyclic voltammetry of the neat Mo salt. These liquid salts were used as self‐supported reagents for the oxidation of alcohols (under solvent‐free and biphasic conditions) and their potential for biphasic self‐supported catalytic applications was demonstrated.
Convenient and Inexpensive Synthesis of (1R,2R)‐ trans‐1‐Amino‐6‐nitroindan‐2‐ol
Authors: Kozhushkov Sergei I. , Yufit Dmitrii S. , de Meijere Armin 
Published: February 2005

AbstractRacemic trans‐1‐amino‐6‐nitroindan‐2‐ol (rac‐1) has been prepared in five steps from inexpensive indene (7) in 96% overall yield. The key step was a direct nitration of the known trans‐1‐aminoindan‐2‐ol (rac‐9) which gave sulfuric acid mono‐(rac‐trans‐1‐amino‐6‐nitroindan‐2‐yl) ester (rac‐10) in quantitative yield. The latter was quantitatively converted into rac‐1 by treatment with aqueous 6 N HCl and then ammonia solutions. The same transformations of (1R,2R)‐9 [prepared by deracemization of rac‐9 with (−)‐dibenzoyl‐L‐tartaric acid (DBT)] proceeded without loss of the optical activity. Deracemization of rac‐1 applying (+)‐(S)‐L‐mandelic acid (MA) furnished (1R,2R)‐1 and (1S,2S)‐1 in 34 and 17% yield, respectively, with e.e. ≥ 98 and 97.6%, respectively. Procedures for recycling of the chiral auxiliaries DBT and MA are also described. The structures of key intermediates were confirmed by X‐ray crystal structure analysis.
A General and Efficient Method for the Synthesis of Silyl‐Protected Arenethiols from Aryl Halides or Triflates
Authors: Kreis Michael , Bräse Stefan 
Published: February 2005

AbstractAn improved palladium‐catalyzed synthesis of silyl‐protected arenethiols has been developed. This method is particularly useful because of its experimental simplicity, high generality and high level of functional group toleration. The first synthesis of enantiomerically pure [2.2]paracyclophane‐4‐thiol was realized employing this method.
Synthesis of (all‐rac)‐α‐Tocopherol in Supercritical Carbon Dioxide: Tuning of the Product Selectivity in Batch and Continuous‐Flow Reactors
Authors: Kokubo Yoshiaki , Hasegawa Aiko , Kuwata Shigeki , Ishihara Kazuaki , Yamamoto Hisashi , Ikariya Takao 
Published: February 2005

Abstractα‐Tocopherol was synthesized using a condensation reaction of 2,3,6‐trimethylhydroquinone with isophytol in supercritical CO2 using batch and continuous–flow reactors. In the batch reaction catalyzed by a fluorinated molecular catalyst bearing strong Brønsted acidity, C6F5CHTf2 (Tf=SO2CF3), an increase in the CO2 pressure causes a marked increase in the product selectivity for α‐tocopherol, albeit with a slight decrease in the product yield. The solubility measurements by extraction experiments and the supercritical fluid NMR (scNMR) indicate that the homogeneous and non‐polar reaction phase in scCO2 is crucial to obtain α‐tocopherol with high selectivity. A continuous flow scCO2 process for the condensation reaction can be performed with a strong acid resin, Amberlyst 15, as a solid acid catalyst to give the desired product with high selectivity.
Organic Base‐Mediated Condensation of Pyridinecarboxaldehydes to Azachalcones
Authors: Downs Laura E. , Wolfe Derek M. , Schreiner Peter R. 
Published: February 2005

AbstractA DBU‐mediated aldol condensation‐dehydration sequence has been used to prepare a series of synthetically important substituted 2‐ and 3‐azachalcones. Michael products that typically accompany this sequence with inorganic bases were not observed in this protocol of high practical value.
Asymmetric Synthesis of Acyclic Amines Through Zr‐ and Hf‐Catalyzed Enantioselective Alkylzinc Reagents to Imines
Authors: Akullian Laura C. , Porter James R. , Traverse John F. , Snapper Marc L. , Hoveyda Amir H. 
Published: February 2005

AbstractReadily available chiral amino acid‐based ligands are used in metal‐catalyzed additions of alkylzinc reagents to various aromatic and aliphatic imines; the desired amine products are formed efficiently and in high levels of optical purity. In cases where the more Lewis acidic Zr salts afford lower efficiency, Hf‐based catalysts deliver significantly higher yields with similar enantioselectivities. Critical structural features of the N‐activating groups as well as the optimal chiral ligands are discussed. A mechanistic working model is presented to rationalize the existing data and to serve as a predictive tool.
Influence of mass transfer in distillation: Feasibility and design
Authors: Baur R. , Krishna R. , Taylor R. 
Published: February 2005

AbstractThe influence is considered of mass transfer on distillation column design. The column design equations incorporating mass‐transfer effects are similar to the conventional design equations and are as easy to solve numerically. Mass‐transfer effects do not influence pinch‐point curves and pitchfork distillation boundaries. Mass transfer does, however, change the composition trajectories, which might thus cross the pinch‐point curves. Inclusion of mass transfer in the design equations allows us to estimate the actual number of stages (or the column height). The curvature of composition trajectories may have a significant impact on the total number of stages and on the feed stage location. Mass‐transfer effects do not influence the minimum reflux for columns involving a very sharp split. However, and contrary to previous reports, mass‐transfer effects may strongly affect the minimum reflux for less than very sharp separations. Mass‐transfer effects should be taken into consideration when trace components are a concern. A feasible design based on residue curve maps might be rejected by a design method based on mass transfer. More important, however, the converse also is true. © 2005 American Institute of Chemical Engineers AIChE J, 51: 854–866, 2005
Mass and heat transfer modeling of a physical vapor deposition effusion source
Authors: Junker S. Tobias , Birkmire Robert W. , Doyle Francis J. 
Published: February 2005

AbstractThe effusion sources modeled in this article are part of a continuous process for production of thin‐film photovoltaic modules. Industrial production requires tight control of the vapor flow rates during long run times. A dynamic model is developed to provide physical insight, facilitate simulation studies, and to be incorporated into model‐based control schemes. Prediction of the vapor flow rate requires both the mass and energy balance to be solved. Model parameters are estimated based on literature and experimental data, and the entire model is shown to be consistent with independent experimental data. © 2005 American Institute of Chemical Engineers AIChE J, 51: 878–894, 2005
Multiscale models of sweep gas and porous support effects on zeolite membranes
Authors: Skoulidas Anastasios I. , Sholl David S. 
Published: February 2005

AbstractExisting detailed models of gas permeation through zeolite membranes have focused on adsorption and diffusion within zeolite crystals. Practical zeolite membranes, however, are typically grown as thin films on porous supports and are often studied experimentally in the presence of a sweep gas in addition to the permeating species of interest. We have used a combination of atomically detailed and continuum models to examine the impact of sweep gases and porous supports on permeation of CH4 through silicalite membranes at room temperature. The adsorption and transport properties of the gas mixture inside the zeolite are treated using atomically detailed models, whereas transport in the porous support is treated using well‐validated continuum models. Our results indicate that the effect of He as a sweep gas on unsupported membranes is minor. In many cases, the use of a porous support when no sweep gas is present also has only negligible effects compared to that of an unsupported membrane. When a sweep gas and a porous support are present, however, strong deviations from the permeation properties of an equivalent unsupported membrane with no sweep gas can occur, and these effects can depend strongly on whether the support faces the feed or permeate side of the process. These observations are related to existing experimental studies of gas permeation through zeolite membranes. © 2005 American Institute of Chemical Engineers AIChE J, 51: 867–877,2005
Rapid generation of composition profiles for reactive and extractive cascades
Authors: Chin James , Lee Jae W. 
Published: February 2005

AbstractA quick method for estimating composition profiles for reactive and extractive cascades in a double‐feed column without stage calculations is presented. This profile estimation is based on the feasibility and pinch point analyses. The trajectories of pinch points are determined with material balance equations and phase and reaction equilibrium data. From these pinch point trajectories, the ranges of feasible external reflux ratios and required entrainer flow rates are calculated for a given reaction extent and product purity. Then, for given external reflux ratios, heat balance constraints are imposed to determine the positions of pinch points. Finally, using the internal reflux ratios of these pinch points, manifolds of possible composition profiles are generated. Composition profiles of a reactive/extractive cascade can lie in the section of the reaction equilibrium surface where the internal reflux ratio of a saddle pinch is between the upper and lower bounds of the internal reflux ratio. © 2005 American Institute of Chemical Engineers AIChE J, 51: 922–930, 2005
Crystallographic report: Crystal and molecular structure of Ph3GeO2CC4H3O
Authors: Yin Han‐Dong , Wang Chuan‐Hua 
Published: February 2005

AbstractThe germanium atom in the title compound is in a distorted tetrahedral geometry defined by an oxygen donor, derived from an effectively monodentate carboxylate ligand, and three ipso‐carbon atoms from the phenyl substituents. Copyright © 2005 John Wiley & Sons, Ltd.
Crystallographic report: Hydroxytrimethylarsonium iodide, [Me3AsOH]I
Authors: Patrick Brian O. , Sun Hongsui , Fricke Michael W. , Cullen William R. 
Published: February 2005

AbstractHydroxytrimethylarsonium iodide, [Me3AsOH]I, was obtained from the reaction of Me2AsI and MeI in strong basic aqueous solution. The arsenic atom, lying on a mirror plane, is surrounded by one OH and three Me groups, forming a tetrahedral centre. Copyright © 2005 John Wiley & Sons, Ltd.
Crystallographic report: Dimethyl‐2‐phenylethan‐2‐olamine cyanoborane
Authors: Takrouri Khuloud , Shalom Eli , Goldberg Israel , Katzhendler Jehoshua , Srebnik Morris 
Published: February 2005

AbstractThe structure of the title compound reveals the geometry around the boron atom to be tetrahedral, and the BCN moiety has a bent geometry. Copyright © 2005 John Wiley & Sons, Ltd.
Crystallographic report: Dipyridium mercaptoacetotrichlorophenylstannate
Authors: Zhong Gui‐Yun , Song Hai‐Bin , Sun Li‐Juan , Xie Qing‐Lan 
Published: February 2005

AbstractThe tin atom in the anion of [C5H5NH]2[PhSn(SCH2COO)Cl3] is six‐coordinated within an octahedral geometry defined by a CCl3OS donor set; the cations and anion interact via hydrogen bonds. Copyright © 2005 John Wiley & Sons, Ltd.
Crystallographic report: Chloro[1,3‐bis[2‐[2‐[(4‐methoxybenzyl) amino]ethylamino]]‐2‐propanol]zinc(II) chloride hydrate, [(C23H36N4O3)ZnCl]Cl·H2O
Authors: Liu Xueting , Xie Yongshu , Liu Qingliang 
Published: February 2005

AbstractThe zinc(II) center in the molecule of [(C23H36N4O3)ZnCl]Cl·H2O is coordinated by four nitrogen atoms of HL (1,3‐bis[2‐[2‐[(4‐methoxybenzyl) amino]ethylamino]]‐2‐propanol) and one chloro anion. The coordination moieties are connected by hydrogen bonds to form a one‐dimensional structure. Copyright © 2005 John Wiley & Sons, Ltd.
µ2‐Diiodotetrakis(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)dicadmium(II) bis[triiodo(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)cadmate(II)] dihydrate
Authors: Yang Yang‐Yi , Szeto Lap , Ouyang Gang‐Feng , Huang Zhong‐Qi , Wong Wing‐Tak , Weng Ng Seik 
Published: February 2005

AbstractThere are two types of Cd in the title compound, the six‐coordinated Cd atom in the cation is in a distorted octahedral geometry while the four‐coordinated Cd in the anion shows a distorted tetrahedral geometry. Copyright © 2005 John Wiley & Sons, Ltd.
Diiodobis(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)cadmium(II)
Authors: Yang Yang‐Yi , Huang Zhong‐Qi , Chen Xiao‐Ming , Wong Wing‐Tak , Ng Seik Weng 
Published: February 2005

AbstractThe Cd atom in Cd(Hmmi)2I2 is five‐coordinate with a trigonal bipyramidal geometry in which the apical sites are occupied by I and O atoms. Copyright © 2005 John Wiley & Sons, Ltd.
Bis[tris(cyclohexyl)tin] azide hydroxide, (Cy3Sn)2N3(OH): X‐ray structure determination and comparison with analogous compounds
Authors: Alan Howie R. , Wardell James L. , Wardell Solange M. S. V. 
Published: February 2005

AbstractThe structure of bis[tris(cyclohexyl)tin] azide hydroxide, (Cy3Sn)2N3(OH) (1), contains infinite chains of molecules linked by regularly alternating and µ2 bridging azide and hydroxide groups that create trigonal bipyramidal tin centres. The bridges, with SnN 2.436(11) and 2.385(11) Å and SnO 2.199(8) and 2.197(8) Å, are relatively symmetrical. This structure is similar to that of catena bis(trimethyltin) azide hydroxide, (Me3Sn)2N3(OH) (2). In the structure of 1, each terminal nitrogen atom of the azide is bonded to a different tin atom (1,3 or α,γ bridge formation). In the structure of 2, however, only one nitrogen atom of each azide is involved in bridging and bonds to two different tin atoms (1,1 or α,α bridge formation). In this case, the remaining terminal nitrogen atoms act as acceptors for OHN hydrogen bonds that link the chains to form infinite sheets. It appears then, from these two examples, that in such compounds the size of the organic species bonded to tin can affect the azide bridging mode and also the packing of the polymeric chains Copyright © 2005 John Wiley & Sons, Ltd.
The germanium(II) ate complex [Ph3PiPr][Ge(OCOMe)3]: the first structurally characterized compound containing a discrete [E14(II)O3](−) (E14(II) = Si, Ge, Sn or Pb) anion
Authors: Khrustalev Victor N. , Antipin Mikhail Yu. , Zemlyansky Nikolay N. , Borisova Irina V. , Ustynyuk Yuri A. , Lunin Valery V. , Izod Keith 
Published: February 2005

AbstractAn X‐ray diffraction study reveals an unusual structure of the new thermally stable germanium(II) ate complex [Ph3PiPr][Ge(OAc)3] (4) containing a discrete [Ge(OAc)3](−) anion containing monodentate acetate ligands with a trigonal pyramidal germanium centre. Copyright © 2005 John Wiley & Sons, Ltd.
Comparison of mild extraction procedures for determination of arsenic compounds in different parts of pepper plants (Capsicum annum, L.)
Authors: Száková Jiřina , Tlustoš Pavel , Goessler Walter , Pavlíková Daniela , Balík Jiří 
Published: February 2005

AbstractEight extraction agents (water, methanol–water mixtures in various ratios, methanol, a 20 mmol l−1 ammonium phosphate buffer, and a methanol–phosphate buffer) were tested for the extraction of arsenic compounds from fruits, stems + leaves, and roots of pepper plants grown on soil containing 17.2 mg kg−1 of total arsenic. The arsenic compounds in the extracts were determined using high‐performance liquid chromatography–hydride generation inductively coupled plasma mass spectrometry. Whereas pure water was the most effective extraction agent for fruits (87 ± 3.3% extraction yield) and roots (96 ± 0.6% extraction yield), the 20 mM ammonium phosphate buffer at pH 6 extracted about 50% of the arsenic from stems + leaves. Decreasing extractability of the arsenic compounds was observed with increasing methanol concentrations for all parts of the pepper plant. In pepper fruits, arsenic(III), arsenic(V), and dimethylarsinic acid (DMA) were present (25%, 37%, and 39% respectively of the extractable arsenic). Arsenic(V) was the major compound in stems + leaves and roots (63% and 53% respectively), followed by arsenic(III) representing 33% and 42% respectively, and small amounts (not exceeding 5%) of DMA and methylarsonic acid were also detected. Hence, for a quantitative extraction of arsenic compounds from different plant tissues the extractant has to be optimized individually. Copyright © 2005 John Wiley & Sons, Ltd.
Crystallographic report: Trimethylaminedibromopropoxycarbonylborane
Authors: Shalom Eli , Takrouri Khuloud , Goldberg Israel , Katzhendler Jehoshua , Srebnik Morris 
Published: February 2005

AbstractThe conformation around the boron atom is nearly tetrahedral, with BrBBr bond angles of 109.14(19)° and slightly wider NBC bond angles up to 113.6(3)°. Copyright © 2005 John Wiley & Sons, Ltd.
Crystallographic report: Benzilate of diaquabis(ethylenediamine)copper(II) dihydrate and benzilate of aquabenzylatobis(ethylenediamine)copper(II)
Authors: Carballo Rosa , Covelo Berta , García‐Martínez Emilia , Vázquez‐López Ezequiel M. 
Published: February 2005

AbstractCompounds [Cu(en)2(OH2)2](HB)2· 2H2O (1) and [Cu(HB)(en)2(OH2)](HB) (2) (HB = benzilate; en = ethylenediamine) present the Cu(II) atom coordinated by different N4O2 donor sets, with 4 + 2 and 4 + 1 + 1 coordination geometries, respectively. In compound 1 the Cu(II) atom is located on a centre of inversion. Copyright © 2005 John Wiley & Sons, Ltd.
Crystallographic report: Bis{µ‐[O‐cyclopentyl(4‐methoxyphenyl) dithiophosphonato]1κ:S,2κ:S‐[O‐cyclopentyl(4‐methoxyphenyl)dithiophosphonato]1κ2S,S′} dizinc(II)
Authors: Karakus Mehmet , Yilmaz Hamza , Bulak Ece , Lönnecke Peter 
Published: February 2005

AbstractThe centrosymmetric [Zn2{CH3OC6H4P(OC5H9)S2}4], features an eight‐membered Zn2S4P2 ring as a result of two bidentate bridging thiolate ligands; the remaining ligands are chelating. Copyright © 2005 John Wiley & Sons, Ltd.
Trinuclear tin salicylaldoximate cluster‐catalyzed selective acylation of alcohols
Authors: Camacho‐Camacho Carlos , Biesemans Monique , Verbruggen Ingrid , Willem Rudolph 
Published: February 2005

AbstractThe reactivity and catalytic potential of the tin salicylaldoximate cluster [(Me2Sn)2(Me2SnO)(OCH3) (HONZO)(ONZO)] (1), with HONZOH = o‐HONCHC6H4OH, on the acylation reaction of various alcohols with ethyl acetate is reported. The catalyst is active toward primary and unhindered secondary alcohols, but inefficient toward tertiary and secondary bulky alcohols and phenols. A possible mechanism for the transesterification reaction catalyzed by 1, accounting for the influence of steric factors, is proposed. Copyright © 2005 John Wiley & Sons, Ltd.