Search results for "Alkyl"
showing 10 items of 928 documents
Phosphororganische Verbindungen, 68. Darstellung und Eigenschaften von Tetrakis(diphenylphosphin)‐nickel(0)
1971
Die Titelsubstanz 1 wurde durch Einwirkung von Diphenylphosphin auf Bis-π-allyl-nickel, Tetrakis(triphenylphosphin)-nickel(0) (2), Nickelpulver oder Nickel(II)-bromid dargestellt. Ihre Struktur wurde durch Zerewitinoff-Bestimmung, IR- und NMR-Spektren abgesichert. Eine Alkylierung von metalliertem 1 gelang nicht. Organic Phosphorus Compounds, 68. Preparation and Properties of Tetrakis(diphenylphosphine)nickel(0) The title compound, 1, was prepared by reacting of diphenylphosphine with bis(π-allyl)nickel, tetrakis(triphenylphosphine)nickel(0) (2), nickel-powder, or nickel(II) bromide. The structure of 1 was elucidated by Zerewitinoff method, i. r. and n. m. r. spectra. The alkylation of meta…
ChemInform Abstract: Gold(I)-Catalyzed Intermolecular Oxyarylation of Alkynes: Unexpected Regiochemistry in the Alkylation of Arenes.
2010
The reaction between acetylenes and sulfoxides, studied as a test case for gold-catalyzed intermolecular addition, provides the oxyarylation compounds 3 in good yields. Unpredictably, in all cases a single regioisomer arising from the electrophilic aromatic alkylation at the position adjacent to the sulfur atom is obtained instead of the expected Friedel−Crafts regioisomer. A new concerted mechanism based on DFT calculations is proposed to account for the products in this intermolecular gold(I)-catalyzed reaction.
A kinetic study of the basic hydrolysis of 2-phenylethyl nitrite in the presence of borate buffer and β-cyclodextrin
2002
The kinetics of the hydrolysis of 2-phenylethyl nitrite have been studied in basic aqueous solutions (borate buffer) in the absence and presence of β-cyclodextrin. The observed kinetic trends show that the hydrolysis reaction consists of at least three subsequent processes. The first is a fast acid-base reaction between the boron atom of boric acid and oxygen atom of the alkyl nitrite. The second one should be the nucleophilic attack of hydroxyl ion on the alkyl nitrite. The last process could be referred to as a combination of transfer of hydrogen acid to a water molecule followed by ruptures of nitrogen-oxygen and boron-oxygen bonds. The effect of β- cyclodextrin on each process is also d…
On the effect of the nature of counterions on the self-assembly of polyoxyethylene alkyl ether carboxylic acids
2020
In this contribution, we investigate the effect of the type of counterion on the properties of dilute solutions of polyoxyethylene alkyl ether carboxylic acids. Two different surfactants, presenting an oleic acid alkyl chain and on-average five and nine ethylene oxide units, and terminated by a weakly anionic carboxymethyl group were studied. The surfactants were gradually ionized with sodium hydroxide, arginine, and choline hydroxide. The solutions properties were probed by light scattering, electrophoretic mobility, density and sound velocity measurements, as well as by small-angle neutron scattering. To our initial surprise, no specific effect arising from the nature of the counterion co…
Synthesis, characterization and antimicrobial activity of palladium(II) complexes with some alkyl derivates of thiosalicylic acids: Crystal structure…
2012
Abstract S-Alkyl (R = benzyl, methyl, ethyl, propyl and butyl) derivatives of thiosalicylic acid and the corresponding palladium(II) complexes were prepared and their structures were proposed on the basis of infrared, 1H and 13C NMR spectroscopy. The cis geometrical configurations of the isolated complexes were proposed on the basis of an X-ray structural study of the bis(S-benzyl-thiosalicylate)–palladium(II), [Pd(S-bz-thiosal)2] complex. Antimicrobial activity of the tested compounds was evaluated by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) in relation to 26 species of microorganisms. The tested ligands, with a few exceptions, sho…
Divergent reactivity of nucleophilic 1-bora-7a-azaindenide anions
2017
The reactions of 1-bora-7a-azaindenide anions, prepared in moderate to excellent yields by reduction of the appropriate 1-bora-7a-azaindenyl chlorides with KC8 in THF, with alkyl halides and carbon dioxide were studied. With alkyl halides (CH2Cl2, CH3I and BrCH(D)CH(D)tBu), the anions behave as boron anions, alkylating the boron centre via a classic SN2 mechanism. This was established with DFT methods and via experiments utilizing the neo-hexyl stereoprobe BrCH(D)CH(D)tBu. These reactions were in part driven by a re-aromatization of the six membered pyridyl ring upon formation of the product. Conversely, in the reaction of the 1-bora-7a-azaindenide anions with CO2, a novel carboxylation of …
Thieme Chemistry Journals Awardees – Where Are They Now? Molybdenum(V)-Mediated Synthesis of Nonsymmetric Diaryl and Aryl Alkyl Chalcogenides
2017
Oxidative chalcogenation reaction using molybdenum(V) reagents provides fast access to a wide range of nonsymmetric aryl sulfides and selenides. The established protocol is tolerated by a variety of labile functions, protecting groups, and aromatic heterocycles. In particular, when labile moieties are present, the use of molybdenum(V) reagents provides superior yields compared to other oxidants.
Friedel-Crafts catalytic alkylations using rare earth-based mineral supports
1998
Abstract Rare earth halides supported on mineral supports (K10 montmorillonite and silica) were investigated as catalysts for Friedel-Crafts alkylations. This project concerns the replacement of the widely used Lewis acid AlCl3 in Friedel-Crafts reactions by environmentally friendly catalysts in that they circumvent the production of aluminum waste. The catalytic activity of these heterogeneous catalysts was established in a series of alkylations of aromatic compounds.
Synthesis of alkyl-5,8-dimethyl-6-phenyl-5,6-dihydropyrazolo[3,4-f] [1,2,3,5]tetrazepin-4(3H)-ones of pharmaceutical interest
2006
The multistep synthesis of two pyrazolo[3,4-f][1,2,3,5]tetrazepin-4(3H)-one derivatives, a new class of fused 1,2,3,5-tetrazepinones with potential antiproliferative activity, has been carried out. Owing to the instability of the above compounds, the last step of the synthesis was performed at -5/0 degrees C. The obtained tetrazepinones, when allowed to stand at r.t. for 24 h, afforded quantitatively 1-phenyl-3,6-dimethylpyrazolo [3,4-d][1,2,3] triazole.
Liquid Phase Micro-Extraction of Linear Alkylbenzene Sulfonate Anionic Surfactants in Aqueous Samples
2011
Hollow fiber liquid phase micro-extraction (LPME) of linear alkylbenzene sulfonates (LAS) from aqueous samples was studied. Ion pair extraction of C10, C11, C12 and C13 homologues was facilitated with trihexylamine as ion-pairing agent, using di-n-hexylether as solvent for the supported liquid membrane (SLM). Effects of extraction time, acceptor buffer concentration, stirring speed, sample volume, NaCl and humic acids were studied. At 10–50 µg L−1 linear R2-coefficients were 0.99 for C10 and C11 and 0.96 for C12. RSD was typically ~15%. Three observations were especially made. Firstly, LPME for these analytes was unusually slow with maximum enrichment observed after 15–24 h (depending on sa…