Search results for "Reaction"

Üuber die kationische polymerisation von äthylensulfid, initiiert durch SO3

1971

SO3 verursacht eine heftige Polymerisation von Athylensulfid in wasserfreien, inerten organischen Losungsmitteln. Die kinetischen Daten, die chemische Analyse der Endgruppen und die IR-spektroskopische Untersuchung des Polymerisats sprechen gegen eine Cokatalyse und fur einen direkten zwitterionischen Initiierungsschritt unter Bildung von Die kationischen aktiven Zentren werden rasch durch Reaktion mit den Sulfidgruppen des Oligomeren unter Bildung nicht wachstumsfahiger, acyclischer Sulfoniumionen desaktiviert; dadurch bleiben die kinetischen Kettenlangen klein, und es entsteht ein verzweigtes oder vernetztes, unlosliches Produkt. SO3 is a vigorous initiator of the cationic polymerization …

ChemInform Abstract: Synthesis of a Fullerene Derivative of Benzo(18)crown-6 by Diels-Alder Reaction: Complexation Ability, Amphiphilic Properties, a…

2010

A fullerene derivative 1 of benzo[18]crown-6 was obtained by Diels-Alder addition of fullerene[60](C60) to the ortho-quinodimethane prepared in situ from 4,5-bis(bromomethyl)benzo[18]crown-6 (3) with Bu4NI in toluene. Extraction experiments show that the complexation of K+ ions strongly increases the solubility of 1 in protic solvents like MeOH. Using Langmuir-Blodgett techniques, monolayers of the highly amphiphilic fullerene-derived crown ether 1 and its K+ ion complex were prepared. An X-ray crystal structure was obtained from a benzene clathrate of comparison compound 2, synthesized by Diels-Alder reaction of C60 with the ortho-quinodimethane derived from 1,2-bis(bromomethyl)-4,5-dimeth…

I(py)2BF4, ein neues Reagens: allgemeine Methode für die 1,2-Iodfunktionalisierung von Olefinen

1985

ChemInform Abstract: First Evidence of Proline Acting as a Bifunctional Catalyst in the Baylis-Hillman Reaction Between Alkyl Vinyl Ketones and Aryl …

2008

Proline in the presence of sodium hydrogen carbonate has been found to be an effective catalyst for the Baylis–Hillman reaction between methyl or ethyl vinyl ketone and aryl aldehydes. Screening of several amine catalysts showed that an ionizable carboxylic function directly linked to the secondary amine catalyst plays an important role in the synthesis of the desired product in good yield. The data obtained has allowed us to suggest, for the first time, that proline, sarcosine, pipecolinic acid and homoproline may act as bifunctional catalysts via a bicyclic enaminolactone species as intermediate. Quantum-mechanical calculations (PM3/COSMO and ab initio 3-21G/COSMO) support this mechanism …

1977

Methacryloyloxyalkyltrimethylammonium chlorides (1a–c) with different alkyl chain lengths were synthesized and polymerized radically with 4,4′-azobis(4-cyanovalerianic acid) and K2S2O8 as initiators. With K2S2O8 as initiator, reaction orders of 0,5 and 1 with respect to initiator and monomer, were found. For the ionic monomers with longer alkyl chains the ratio of rate constants kp(2fkd/kt)0,5 was determined over a wide concentration range. It was found that with decreasing monomer concentration the ratio of rate constants increases, which is caused by a diminished termination rate because of an increased electrostatic repulsion of the ionic polymer radicals in dilute solution (increase of …

Polymere ester von säuren des phosphors, 6. Ringöffnende polymerisation cyclischer phosphite und phosphonite durch michaelis-arbuzov-reaktion.–Theori…

1977

The hypothesis of Harwood and Patel, suggesting for the polymerization of 2-phenyl-1,3,2-dioxaphospholane a type of insertion reaction to explain the formation of ethylenediphosphinic ester structures besides the normal 2-hydroxyethyl(phenyl)phosphonic ester structures is extended to similar monomers and its theoretical consequences are examined. It is shown that in such a system mutual transformations between ω-hydroxyalkyl-P-acid and alkylenedi(P-acid)structures should occur, establishing a dynamic equilibrium and leading to a sort of azeotropic polymer, in which only one unique composition is kinetically stable. Equations relating to different kinetic parameters are deduced.

Mechanismus und Reaktionswege der Xanthenylierung an ambidenten nukleophilen Arzneistoffen

1986

Am Beispiel der ambidenten nukleophilen Arzneistoffe 4-Aminobenzolsulfonamid (3), Indometacin (7) und Phenylbutazon (10) werden Aralkylierungen mit dem SN1-aktiven Reagens Xanthydrol (1) vorgestellt. Mechanism and Reaction Path of the Xanthenylation of Ambident Nucleophilic Drugs The aralkylation of ambident nucleophilic drugs, e.g. 4-aminobenzenesulfonamide (3), indometacine (7) and phenylbutazone (10), with SN1-active xanthydrol (1) is described.

ChemInform Abstract: Tandem Asymmetric Michael Reaction-Intramolecular Michael Addition. An Easy Entry to Chiral Fluorinated 1,4-Dihydropyridines.

2010

The sequential treatment of optically active sulfoxide (I) with fluorinated nitriles and alkyl propiolates affords (sulfinylmethyl)dihydropyridines of type (IV) as single diastereomers in most cases.

1992

A series of copolymers are synthesized by repetitive Diels-Alder polyaddition reaction of bifunctional cyclohepta-1,3,5-trienes with bifunctional 1,2,4-triazoline-3,5-diones. The copolymers of different bistriazolinediones with a bisdiene, or of different biscycloheptatrienes with a dienophile, have good solubility in CH2Cl2 and CHCl3, while the homopolymers are poorly soluble. The copolymers were characterized by standard analytical techniques to test the structural regularity of these systems. Due to the kinetic control, it is possible to apply copolymerization statistics to these systems. Based on a model study, it is concluded that alipatic and aromatic bistriazolinediones have the same…

FeCl3·6H2O-catalyzed Mukaiyama-aldol type reactions of enolizable aldehydes and acetals.

2014

Mukaiyama-aldol type reactions of acetals derived from enolizable aldehydes with FeCl3·6H2O, an eco-friendly, low-cost, and stable catalyst, lead to β-methoxycarbonyl compounds with nearly quantitative yields. The methodology is extended to the parent aldehydes as starting materials, leading to the corresponding aldols with lower yields, but efficiently. Different alkyl and aryl substituted acetals and aldehydes have been tested in the reaction with linear and cyclic silyl enol ethers. Reactions are carried out in an open air atmosphere, and additives are not required. Acetals can be considered activating groups of the carbonyl moiety rather than a protecting group in this type of FeCl3·6H2…