Search results for "Reaction"
showing 10 items of 6134 documents
The mechanism of formation of 3H,9H-Pyrano[3,4-b]indol-3-ones from 3-indolalkanoic acids
1991
The mechanism of the formation of 1-methyl-3H,9H-pyrano[3,4-b]indol-3-one (4) from the corresponding 3-indolacetic acid 1 is discussed. The suggested mechanism is substantiated by the isolation of a stable intermediate 2 and its transformations in the presence of acetic anhydride and/or Lewis acids.
Novel acrylamido monomers with higher hydrophilicity and improved hydrolytic stability: I. Synthetic route and product characterization.
1996
The novel acrylamido monomer reported by our group (N-acryloylaminoethoxyethanol, AAEE; Chiari et al., Electrophoresis 1994, 15, 177-186), found to combine high hydrophilicity with extraordinary resistance to alkaline hydrolysis, has come under closer scrutiny due to unexpected and random autopolymerization while stored as a 1/1 v/v water solution at 4 degrees C (possibly due to a greater oxidability of the ether group). We have additionally found a unique degradation pathway of the monomer, called "1-6 H-transfer", by which the C1 (on the double bond site), by constantly ramming against the C6, next to the ether oxygen (O7, which in fact favors the transfer of the hydrogen atom by C1), pro…
Reactive thiol-ene emulsion-templated porous polymers incorporating pentafluorophenyl acrylate
2013
Abstract Highly porous polymers (polyHIPEs) incorporating activated esters have been prepared by photopolymerisation of high internal phase emulsions (HIPEs) containing pentafluorophenyl acrylate (PFPA) in the monomer phase. The resulting materials have nominal porosity of 80% and a well-defined, interconnected pore morphology with average pore diameters ranging from 30 to 50 μm. PFPA could be added at up to 50 wt% of the monomer phase without destabilising the HIPE noticeably, however analysis of the polyHIPE materials revealed that only around half of this was incorporated into the final porous materials. The pentafluorophenyl groups were shown to be reactive towards a range of amines (tr…
Synthesis of pentafluorophenyl(meth)acrylate polymers: New precursor polymers for the synthesis of multifunctional materials
2005
Pentafluorophenyl acrylate and -methacrylate were polymerized using AIBN as a thermal initiator. The obtained polymers were soluble polymeric active esters that could be used for the preparation of multifunctional polymers. The reactivity of poly(pentafluorophenylacrylate) and poly(pentafluorophenylmethacrylate) towards primary and secondary amines, as well as alcohols was investigated in a quantitative way. Both poly(active esters) reacted satisfactorily with aliphatic primary and secondary amines but only low conversion was found in the case of aromatic amines. Conversions of only 30% were reached when poly(pentafluorophenylacrylate) was treated with one equivalent of alcohol under base c…
Versatile Responsive Surfaces via Hybrid Polymers Containing Acetal Side Groups
2009
Two hybrid polymers, poly(methylsilsesquioxane)-poly(2,2-diethoxyethyl acrylate) and poly-(methylsilsesquioxane)-poly(1,3-dioxolan-2-ylmethyl acrylate), were synthesized and used for preparation of stable surface coatings. Their acetal side groups could be functionalized via solution-dipping with different primary amines and hydroxylamines after acidic deprotection and thus allowed for flexible modification of the surface hydrophilicity. Functionalization with a thermo-responsive polymer resulted in a thermo-responsive surface with temperature-dependent contact angles. Further, the two types of acetals showed different stability toward acidic treatment and could be addressed independently.
ChemInform Abstract: Dihydrooxazine Oxides as Key Intermediates in Organocatalytic Michael Additions of Aldehydes to Nitroalkenes.
2013
Pause and play: dihydrooxazine oxides are stable intermediates that are protonated directly, without the intermediacy of the zwitterions, in organocatalytic Michael additions of aldehydes and nitroalkenes (see scheme, R=alkyl). Protonation of these species explains both the role of the acid co-catalyst in these reactions, and the observed stereochemistry when the reaction is conducted with α-alkylnitroalkenes.
Addition von Phosphor‐Nucleophilen an Benzothiet
1991
Addition Reactions of Phosphorus Nucleophiles to Benzothiete Trialkyl phosphites 4 add to the o-quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement – related to the Arbuzov reaction – can be avoided in a two-step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a–d form 2:1 adducts, namely the 12- to 15-membered heterocyclic compounds 17a – d. An intramolecular rearrangement in a 1:1 adduct is only obse…
Endgruppenuntersuchungen an isotaktischen Polystyrolen. VII. Mitt. über die stereospezifische Polymerisation von Styrol mit alkaliorganischen Verbind…
1963
Durch Polymerisation von Styrol mit optisch aktivem 2-Methylbutylnatrium oder -lithium konnen Polystyrole hergestellt werden, welche die Ebene des polarisierten Lichtes drehen; der gemessene Drehwert entspricht bei nicht zu hochmolekularen Polymeren einer 2-Methylbutylgruppe pro Makromolekul. Bei der Suche nach einer ungesattigten Endgruppe konnten weder mit einer infrarotspektroskopischen Kompensationsmethode noch durch eine Anlagerungsreaktion eines Siloxanmonohydrids Doppelbindungen in mit 2-Methylbutylnatrium hergestellten Polystyrolen nachgewiesen werden. Aus der Bestimmung der wachsenden Polystyrolmolekule mit Hilfe von MICHLERS Keton als Abbruchsreagenz ergibt sich, das der groste Te…
Glycidyl methacrylate derivatization of α,β-poly(N-hydroxyethyl)-dl-aspartamide and α,β-polyasparthydrazide
1997
Abstract α,β-Poly(N-hydroxyethyl)- dl -aspartamide (PHEA) and α,β-polyasparthydrazide (PAHy) are two synthetic macromolecules having many potential applications in the field of biomedical sciences. This paper describes the functionalization of PHEA and PAHy with glycidyl methacrylate (GMA), in order to introduce pendant double bonds in their chains. Derivatized PHEA and PAHy (samples PHG and PAG, respectively) at various GMA content have been obtained and characterized. It has been shown that the derivatization reaction can be controlled by varying some parameters as solvent, catalyst, pH, GMA concentration and reaction time. As expected, PAHy reacted more rapidly and more extensively than …
Unsaturated carboxylic acid dienolates. Addition to substituted cyclohexanones. Inverted kinetic and thermodynamic stereoselectivities.
1987
Abstract Addition of the lithium dienolate derived from crotonic acid to monosubstituted cyclohexanones occurs through the α and γ carbon atoms of the dienolate in the cold and on heating, respectively. For any regioselectivity, equatorial approach is found under kinetic conditions, but equilibration favours products from axial attack and selectivity may be inverted.