Search results for "Imide"

An AM1 study on π-facial selectivity in Diels-Alder reactions of 2-aza-1, 3-dienes with azodienophiles

1994

Abstract A theoretical study of the π-facial selectivity in Diels-Alder reactions of chloro derivatives of 2-aza-1,3-dienes with azodienophiles has been carried out using the semiempirical AM1 method. Three transition structures for the model reaction of the diene 3 with the dienophile 4 were located. The Diels-Alder reaction of the non-substituted 2-aza-1,3-diene 6 with the trans -diimide was studied. All transition structures located show an important asynchronicity and the calculations reveal the presence of stereoelectronic effects. The predicted stereoselectivity is in agreement with the experimental evidence.

1963

Es wird gezeigt, das sich e-Caprolactam mit wasserfreiem Bromwasserstoff kationisch polymerisieren last und die dabei gebildeten Polymeren die Struktur von N-(Poly-e-aminocaproyl)-caprolactamen besitzen. Die charakteristische Diacylimidstruktur wird IR-spektroskopisch, durch die Hydroxamsaurereaktion und durch alkoholytische Abspaltung des C-terminalen Lactamringes nachgewiesen. Oligomerengemische, die durch kurzzeitige Umsetzung molarer Mengen an Caprolactam und Initiator bei 175–200°C erhalten werden, konnen durch Hochspannungspapierelektrophorese in einheitliche Individuen aufgetrennt werden. Die Umsetzung mit Hydroxylamin fuhrt zu Oligo-e-aminocapronhydroxamsauren, die sich mit Hilfe au…

Toward an understanding of the acceleration of Diels-Alder reactions by a pseudo-intramolecular process achieved by molecular recognition. A DFT stud…

2007

The pseudo-intramolecular Diels−Alder (DA) reaction between a 2-substituted furan (1) and a N-maleimide derivative (2) has been analyzed using DFT methods. Formation of two hydrogen bonds between the appendages on furan and maleimide derivatives favors thermodynamically the formation of a molecular complex (MC1) through an efficient molecular recognition process. The large enthalpy stabilization associated with the molecular recognition overcomes the unfavorable activation entropy associated with the bimolecular process. As a consequence, the subsequent DA reaction is clearly accelerated through a pseudo-intramolecular process.

Density, Speed of Sound, Viscosity, and Excess Properties of Binary Mixtures Formed by Ethanol and Bis(trifluorosulfonyl)imide-Based Ionic Liquids

2015

In this work, viscosities, densities, and speeds of sound of three binary mixtures containing the ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [emim][NTf2], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][NTf2], and 1-hexyl-3-methylimidazo-lium bis(trifluoromethylsulfonyl)imide, [hmim][NTf2], mixed with ethanol were measured at atmospheric pressure in the range of (278.15 to 338.15) K, covering the entire range of compositions. From these experimental data, the excess isentropic compressibility and molar isentropic compressibility of pure components and mixtures have been calculated. Additionally, excess properties, such as viscosity dev…

Theoretical Analysis of the Excited States in Maleimide

2003

The electronic excited states of maleimide have been studied using multiconfigurational second-order perturbation theory in its multistate formulation (MS-CASPT2) and extended atomic natural orbita...

(3RS,1SR)-3-Bromo-3-(1-phenylpropyl)chroman-2,4-dione

2005

The title compound, C18H15BrO3, was obtained by bromination of phenprocoumone with N-bromo­succin­imide. The X-ray structure confirms an earlier proposal concerning the regioselectivity of the reaction to introduce the Br atom at the 3-position.

ChemInform Abstract: STRUKTUR-WIRKUNGS-BEZIEHUNGEN BEI ANALEPTICA VOM TYP DES NICETHAMIDS 3. MITT. SYNTHESE VON ANALOGEN DES 6-METHYL-NICETHAMIDS

1975

Als potentiell analeptisch wirksame Substanzen mit partiell fixierter funktioneller Gruppe werden strukturanaloge Amide, Imide und Lactame des 2-Methyl-nicethamids synthetisiert. Synthesis of 2-Methyl-Nicethamide Analogues. As potentially analeptically active substances with partially fixed functional groups, structural analogues of 2-methyl-nicethamide, in the form of amides, imides and lactams, are synthesized.

N-Bromosuccinimide, Its Properties and Reactions The Course of Substitution

1964

Synthesis and self-assembly of a PEGylated-graphene aerogel

2016

Abstract In the frame of this work, we present, for the first time, the synthesis and self-assembly of an aerogel built by graphene oxide-polyethylene glycol. The synthetic route involves at first the coupling of GO with an amino-terminated polyethylene glycol sample by carbodiimide in aqueous environment, and the subsequent conversion of the hydrogel achieved into an aerogel via freeze-drying. The 3D PEGylated graphene-based aerogel, characterized by spectroscopic, morphological, structural and mechanical analyses, displays an ultralight and highly porous (99.7%) network and possesses high mechanical properties together with a good biocompatibility.

Protein synthesis of the sponge Geodia cydonium: characterization of the system.

1974

Abstract The ribosomal population of the sponge Geodia cydonium has been examined. The monosomes have a sedimentation constant of 80 S, the sizes of the subunits are approximately 60 S and 45 S respectively. The polyribosomes contain up to 40 ribosomal units. Cell free protein synthesizing systems (cell homogenate as well as reconstituted system) have been prepared and characterized with respect to Mg2+, KCI and ATP concentrations, temperature, pH and time course of the reaction. In the cell-free system and in the cellular system the protein biosynthesis is inhibited by chloramphenicol. It is not affected by cycloheximide.