Search results for "Chloroform"
showing 10 items of 414 documents
Synthesis of polyvinyl acetate-graft-poly-2-oxazolines
1994
Poly(vinyl acetate-co-vinyl chloroformate) (1) was synthesized via phosgenation of poly(vinyl acetate-co-vinyl alcohol). It was shown that (1) is capable of initiating the polymerization of 2-phenyl-2-oxazoline and 2-methyl-2-oxazoline, when the counter ion is exchanged using potassium iodide. Polyvinyl acetate-graft-poly-2-phenyl-2-oxazoline and polyvinyl acetate-graft-poly-2-methyl-2-oxazoline are obtained in the grafting reaction.
Facile laser-assisted synthesis of inorganic nanoparticles covered by a carbon shell with tunable luminescence
2015
We report a one-step strategy at ambient conditions for the production of hybrid inorganic core–carbon shell nanoparticles by means of pulsed laser ablation of inorganic targets (LiNbO3, Au, and Si) in hydrocarbon liquids such as toluene and chloroform. The core of these spherical nanoparticles consists of the target material, whereas the shells are carbon structures (multilayer graphite-type carbon and amorphous carbon), which are formed due to the thermal decomposition of the organic liquid in contact with hot inorganic nanoparticles ejected from the bulk target. These carbon shells emit photoluminescence in the blue-green spectral region and the obtained luminescence, in which the lumine…
Branched polymers starting from ethylene-vinyl acetate copolymers
1995
Abstract Polyethylene-graft-poly-2-phenyl-2-oxazoline, polyethylene-graft-poly-2-methyl-2-oxazoline and polyethylenegraft-poly(ethylene oxide) were prepared using poly(ethylene-co-vinyl chloroformate) as macroinitiator or polyfunctional precursor. The vinyl acetate groups of ethylene-vinyl acetate copolymer were hydrolyzed, the corresponding alcohol functions were converted into chloroformate, which in turn was used for grafting of oxazolines. Comb-like polymers with hydrophilic poly(ethylene oxide) grafts with definite length were synthesized as well. The resulting graft copolymers were characterized by GPC, IR, and 1 H-NMR spectroscopy and differential scanning calorimetry.
Enhancing reactivity of carbonyl compounds via hydrogen-bond formation. A DFT study of the hetero-Diels-Alder reaction between butadiene derivative a…
2003
To examine how hydrogen-bond (HB) formation involving chloroform solvent molecules influences the chemical reactivity of ketones, the hetero-Diels-Alder reaction of N,N-dimethyl-1-amino-3-methoxy-1,3-butadiene and acetone has been studied by using density functional theory (DFT) at the B3LYP/6-31G level. The effects of the chloroform on the activation energies have been modeled by means of discrete-continuum models. In the gas phase, the formation of specific HB between acetone and one and two chloroform molecules decreases the activation barriers from 19.3 to 13.6 and 8.5 kcal/mol, respectively. Inclusion of solvent effects by means of combined discrete and polarizable continuum models yie…
ChemInform Abstract: Novel Prolinamide-Supported Polystyrene as Highly Stereoselective and Recyclable Organocatalyst for the Aldol Reaction.
2008
A new prolinamide derivative anchored to a polystyrene support has been straightforwardly prepared and employed as heterogeneous catalyst in the direct asymmetric aldol reaction with good results in terms of yield and stereoselectivity. The optimal reaction conditions were found when a 1:2 (v/v) water/chloroform mixture was used. This mixture was the best compromise between the good swelling properties of chloroform and the formation of a concentrated organic phase due to the presence of water. Noticeably, the enantioselectivities obtained employing acetone as ketone were, to the best of our knowledge, the highest achieved with a supported proline derivative. This catalyst can be easily rec…
ChemInform Abstract: Reaction of Diphenyldiazomethane with N-Methyloxy- and N-Ethyloxycarbonyl-N-(2,2,2-trichloroethylidene)amines.
2010
Reaction of the title imines with diphenyldiazomethane gives a Δ3-1,3,4-triazoline, which leads, after loss of dinitrogen, to a transient azomethine ylide. Subsequent elimination of ethyl or methyl chloroformate gives the unexpected 1,1-diphenyl-4,4-dichloro-2-aza-1,3-butadiene.
Ultrafast energy transfer in dansylated POPAM–eosin complexes
2006
Abstract Excitation energy transfer (EET) in dendritic host–guest complexes has been studied. Three generations G2, G3 and G4 of dansyl substituted poly(propyleneamine) dendrimers (POPAM) were complexed with a fluorescent dye eosin in chloroform solution. Arrival of excitation from dansyls to eosin was monitored by femtosecond transient absorption spectroscopy. EET rates from the dansyls to eosin(s) are characterised by two time constants 1 ps and 6 ps independent of dendrimer generation. Relaxation processes in eosin were clearly faster when complexed with dendrimer than in solution. As several eosins are bound to G3 and G4 dendrimers, besides host–guest interaction, also eosin–eosin inter…
Bedeutung von Assoziationsphänomenen quartärer Oniumverbindungen in der organischen Phase für den Ablauf phasentransferktalysierter Reaktionen
1980
Quartare Oniumsalze sind, wie dampfdruckosmometrische Messungen zeigen, in Benzol und Chloroform assoziiert [in Benzol starker (Faktor 4–15) als in Chloroform (Faktor 1.2 – 2.4)]. Im Homogen- und Zweiphasensystem laufen die Modellreaktionen (1) und (2) mit steigendem Assoziationsgrad schneller ab — langsamer im Zweiphasensystem wegen des Wassergehaltes der organischen Phase (Verminderung des Assoziationsgrades). Assoziationsphanomene sind offensichtlich fur die “Katalyse” im Zweiphasensystem wesentlich. Importance of Association Phenomena of Quaternary Onium Salts in the Organic Phase Responsible for the Course of Phase-Transfer-Catalysed Reactions As shown by vapour pressure osmometry quat…
N,N-Dimethylformamide Diethyl Acetal
2001
(1; R1 = Et, R2 = Me) [1188-33-6] C7H17NO2 (MW 147.25) InChI = 1S/C7H17NO2/c1-5-9-7(8(3)4)10-6-2/h7H,5-6H2,1-4H3 InChIKey = BWKAYBPLDRWMCJ-UHFFFAOYSA-N (2; R1 = Me, R2 = Me) [4637-24-5] C5H13NO2 (MW 119.19) InChI = 1S/C5H13NO2/c1-6(2)5(7-3)8-4/h5H,1-4H3 InChIKey = ZSXGLVDWWRXATF-UHFFFAOYSA-N (3; R1 = PhCH2, R2 = Me) [2016-04-8] C17H21NO2 (MW 271.39) InChI = 1S/C17H21NO2/c1-18(2)17(19-13-15-9-5-3-6-10-15)20-14-16-11-7-4-8-12-16/h3-12,17H,13-14H2,1-2H3 InChIKey = JFIKHFNGAURIIB-UHFFFAOYSA-N (4; R1 = Et, R2 = Et) [22630-13-3] C9H21NO2 (MW 175.31) InChI = 1S/C9H21NO2/c1-5-10(6-2)9(11-7-3)12-8-4/h9H,5-8H2,1-4H3 InChIKey = AYZXEGOJMRKZCV-UHFFFAOYSA-N (mild and selective reagents for alkylation, f…
Stufenweise darstellung eines cycloheptamers aus p-kresol, 4-tert-butylphenol und formaldehyd. Vergleich mit einem phenolischen, heptanuklearen kette…
1980
A phenolic cycloheptamer (11) and an analogous chain oligomer (10) with nearly the same structure were gained by stepwise syntheses. The cycloheptamer has a higher melting point and a better solubility in chloroform. In contrast to the chain oligomer his infrared spectrum indicates a stronger association of the hydroxyl groups which is not influenced by the solvent. The mass spectra announce a preferred statistical cleavage along the chain of compound 10 and a great stability of the ring of 11 which preferentially loses his substituents. The 1H NMR spectra confirm the constitutions of the chain (10) and ring compound (11). The cycloheptamer is distinguished by a ring inversion or a pseudoro…