122-99-6Relevant articles and documents
Zirconium complexes with pendant aryloxy groups attached to the metallocene moiety by ethyl or hexyl spacers
Cho, Won Seok,Kim, So Han,Kim, Da Jung,Mun, Sang-Deok,Kim, Ran,Go, Min Jeong,Park, Myung Hwan,Kim, Min,Lee, Junseong,Kim, Youngjo
, p. 205 - 212 (2014)
Four zirconium complexes with pendant aryloxy groups attached to the metallocene moiety by ethyl or hexyl spacers have been synthesized and characterized by spectroscopic methods and HR-MS or elemental analysis. The solid state structure of bis[{6-(2,6-dimethylphenoxy)hexyl}cyclopentadienyl] zirconium dichloride was determined by single crystal X-ray diffraction. The prepared complexes were tested as catalyst precursors in the polymerization of ethylene upon activation with MAO. The results showed a marked effect of the spacer length on the catalytic activity, while only a minor effect of the substitution on the aryl group, which affected its steric properties.
2-(1-naphthyloxy)ethylamines with enhanced affinity for human 5-HT(1Dβ) (h5-HT(1B)) serotonin receptors
Ismaiel,Dukat,Law,Kamboj,Fan,Lee,Mazzocco,Buekschkens,Teitler,Pierson,Glennon
, p. 4415 - 4419 (1997)
Although the β-adrenergic antagonist propanolol (1) binds at rodent 5- HT(1B) serotonin receptors, it displays low affinity (K(i) > 10 000 nM) for its species homologue 5-HT(1DB) (i.e., h5-HT(1B)) receptors. The structure of propanolol was systematically modified in an attempt to enhance its affinity for the latter population of receptors. Removal of the alkyl hydroxyl group, shortening of the O-alkyl chain from three to two methylene groups, and variation of the terminal amine substituent resulted in compounds, such as N- monomethyl-2-(1-naphthyloxy)-ethylamine (11; K(i) = 26 nM), that display significantly higher h5-HT(1B) affinity than propanolol. Compound 11 was shown to bind equally well at human 5-HT(1Dα) (h5-HT(1D) receptors (K(i) = 34 nM) and was further demonstrated to possess h5-HT(1B) agonist character in an adenylate cyclase assay. It would appear that such (aryloxy)alkylamines may represent a novel class of 5-HT(1D) receptor agonists.
Carbonates as reactants for the production of fine chemicals: The synthesis of 2-phenoxyethanol
Ziosi,Tabanelli,Fornasari,Cocchi,Cavani,Righi
, p. 4386 - 4395 (2014)
The solventless and heterogeneously catalysed synthesis of 2-phenoxyethanol (ethylene glycol monophenyl ether) via the reaction between phenol and ethylene carbonate was investigated using Na-mordenite catalysts as an alternative to the industrial process using ethylene oxide and homogeneous basic conditions. Under specific reaction conditions, it was possible to obtain total selectivity to phenoxyethanol at up to 75% phenol conversion and 82% selectivity at total phenol conversion in 5-7 hours of reaction time and using a moderate excess of ethylene carbonate. The main by-product was the linear carbonate of phenoxyethanol, bis(2-phenoxyethyl)carbonate (selectivity 15%), which could then be converted to phenoxyethanol by reacting with phenol in basic medium with 100% yield; so overall, the phenoxyethanol yield was as high as 97%. With a stoichiometric feed of phenol and ethylene carbonate, the maximum conversion of phenol was just 60%, still with 100% selectivity to phenoxyethanol. An autocatalytic phenomenon was also observed due to the higher basicity of 2-phenoxyethanol compared to phenol, which overlapped the Na-catalyzed activation of phenol. Starting from a commercial Na-mordenite, which showed significant deactivation, and by applying a post-treatment aimed at the reduction of microporosity, it was possible to minimize both the deactivation and Na leaching while keeping the selectivity enhancement effect shown by the mordenite structure.
Preparation and structure investigation of novel Schiff bases using spectroscopic, thermal analyses and molecular orbital calculations and studying their biological activities
Zayed, Ehab M.,Zayed,El-Desawy
, p. 155 - 164 (2015)
Two novel Schiff's bases (EB1 and L1) as new macrocyclic compounds were prepared via condensation reactions between bisaldehyde (2,2′-(ethane-1,2- diylbis(oxy))dibenzaldehyde): firstly with hydrazine carbothioamide to give (EB1), secondly with 4,6-diaminopyrimidine-2-thiol to give (L1). EB1 has a general formula C18H20N6O2S 2 of mole mass = 416.520, and IUPAC name ((N,N′Z,N,N′E)- N,N′-(((ethane1,2diylbis(oxy))bis(2,1phenylene))bis(methanylylidene)) bis(1hydrazinylmethanethioamide). L1 has a general formula C20H 16N4O2S of mole mass = 376.10; and IUPAC name 1,2-bis(2-vinylphenoxy)ethane4,6-diaminopyrimidine-2-thiol). The structures of the compounds obtained were characterized based on elemental analysis, FT-IR and 1H NMR spectra, mass, and thermogravimetric analysis (TG, DTG). The activation thermodynamic parameters, such as, ΔE*, ΔH*, ΔS* and ΔG * were calculated from the TG curves using Coats-Redfern method. It is important to investigate their structures to know the active groups and weak bond responsible for their biological activities. The obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculation using PM3 procedure, on the neutral and positively charged forms of these novel Schiff bases. Therefore, comparison between MS and TA helps in selection of the proper pathway representing the decomposition of these compounds to give indication about their structures and consequently their biological activities. Their biological activities have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillissubtilies and Staphylococcus aurous bacteria in order to assess their antimicrobial potential.
Olefin oxidative cleavage and dioxetane formation using triethylsilyl hydrotrioxide: Applications to preparation of potent antimalarial 1,2,4-trioxanes
Posner,Oh,Milhous
, p. 4235 - 4238 (1991)
Oxidative cleavage of alkenyl esters and ethers using Et3SiOOOH was found to be easier than oxidative cleavage of hydrocarbon alkenes, and Et3SiOOOH was successfully applied to very short syntheses of new, simple, and potent antimalarial trioxanes 6 and 8.
Development of effective bidentate diphosphine ligands of ruthenium catalysts toward practical hydrogenation of carboxylic acids
Saito, Susumu,Wen, Ke,Yoshioka, Shota
, p. 1510 - 1524 (2021/06/18)
Hydrogenation of carboxylic acids (CAs) to alcohols represents one of the most ideal reduction methods for utilizing abundant CAs as alternative carbon and energy sources. However, systematic studies on the effects of metal-to-ligand relationships on the catalytic activity of metal complex catalysts are scarce. We previously demonstrated a rational methodology for CA hydrogenation, in which CA-derived cationic metal carboxylate [(PP)M(OCOR)]+ (M = Ru and Re; P = one P coordination) served as the catalyst prototype for CA self-induced CA hydrogenation. Herein, we report systematic trial- and-error studies on how we could achieve higher catalytic activity by modifying the structure of bidentate diphosphine (PP) ligands of molecular Ru catalysts. Carbon chains connecting two P atoms as well as Ar groups substituted on the P atoms of PP ligands were intensively varied, and the induction of active Ru catalysts from precatalyst Ru(acac)3 was surveyed extensively. As a result, the activity and durability of the (PP)Ru catalyst substantially increased compared to those of other molecular Ru catalyst systems, including our original Ru catalysts. The results validate our approach for improving the catalyst performance, which would benefit further advancement of CA self-induced CA hydrogenation.
Electrophotocatalytic C?H Heterofunctionalization of Arenes
Huang, He,Lambert, Tristan H.
supporting information, p. 11163 - 11167 (2021/04/19)
The electrophotocatalytic heterofunctionalization of arenes is described. Using 2,3-dichloro-5,6-dicyanoquinone (DDQ) under a mild electrochemical potential with visible-light irradiation, arenes undergo oxidant-free hydroxylation, alkoxylation, and amination with high chemoselectivity. In addition to batch reactions, an electrophotocatalytic recirculating flow process is demonstrated, enabling the conversion of benzene to phenol on a gram scale.
