Search results for "Anhydride"

Eine oligomeranaloge friessche umlagerung oligomerer 2-acetoxy-1,3-phenylenmethylene

1979

α-Hydro-ω-hydroxypoly(5-chloro-2-hydroxy-1,3-phenylenemethylene)s (1a, b), the oligomeric condensation products from 4-chloro-2,6-bis(hydroxymethyl)phenol and 4-chlorophenol with hydrochloric acid in 1,4-dioxane, could be completely dehalogenated at room temperature and atmospheric pressure with hydrogene/Raney-Ni. The resulting oligomers 2a, b were esterified with acetic anhydride, and the esters 3a, b were subjected to a oligomer analogous Fries rearrangement to form the linear α-hydro-ω-hydroxypoly(5-acetyl-2-hydroxy-1,3-phenylenemethylene)s 4a and 4b. The characterization of the products was mainly done by spectroscopic methods.

New synthesis of condensed heterocycles from isoxazole derivatives VI. 2,5-Dimethyl-3-aeetyl-7-amino-1H-pyrrolo[3,2-b] pyridine

1978

A new synthesis of pyrrolo[3,2-b] pyridine starting with pyrrole ring is described. The procedure allows the synthesis of 4-azaindoles bearing a sensitive group at C-7. The nitration of 4b with nitric acid and acetic anhydride at −15° gave 5. The hydrogenation of 5 led to simultaneous reduction of N-hydroxy and nitro groups and to hydrogenolysis of the isoxazole nucleus, affording an appropriate chain of atoms to building up the pyrrolo[3,2-b] pyridine ring.

Propanephosphonic Acid Anhydride–Mediated Cyclodehydration of Maleic Acid Monoamides

2013

Abstract Propanephosphonic acid anhydride (T3P) has been proposed as a novel reagent for the preparation of maleic acid isoimides from the corresponding monoamides. A series of substituted aromatic and aliphatic isoimides have been prepared in good yields. The main advantage of this synthetic method is the use of environmentally benign, cost-efficient reagents and solvents, which are also safer to handle than the ones employed previously. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

Compositional analysis of styrene and maleic anhydride copolymerization: Complex model and penultimate model

1985

N-trifluoracetyl-nylon 66 als polymeres reagenz

1979

N-Trifluoroacetyl-Nylon 66 (2) obtained by the reaction of Nylon 66 (1) with trifluoroacetic anhydride is very suitable as a polymeric reagent for the trifluoroacetylation of amines and alcohols. The advantages of 2 compared with low molecular trifluoroacetylating reagents are discussed. The selectivity against different substituted anilines and against structurally isomeric secondary amines was studied intensively by kinetic measurements.

Crystal structure of 3-(tri-phenyl-phosphoranyl-idene)-2,5-di-hydro-furan-2,5-dione tetra-hydro-furan monosolvate.

2018

The title pseudo-polymorph of 3-(triphenylphosphoranylidene)-2,5-dihydrofuran-2,5-dione crystallizes with a tetrahydrofuran solvent molecule, viz. C22H17O3P·C4H8O. The succinic anhydride ring is approximately planar (r.m.s. deviation = 0.032 Å). The tetrahydrofuran molecule is disordered over two orientations about a pseudo-twofold axis with refined occupancy ratio 0.718 (4):0.282 (4). In the crystal, C—H...O hydrogen bonds link molecules of the dihydrofuran-2,5-dione derivative into chains parallel to the b axis and arranged into layers stacked along [100] alternating with hydrogen-bonded tetrahydrofuran layers.

Palladium-Catalyzed Hydroxycarbonylation of Aryl and Vinyl Bromides by Mixed Acetic Formic Anhydride

2006

The palladium-catalyzed hydroxycarbonylation of aryl and vinyl bromides in the presence of acetic anhydride and lithium formate as a carbon monoxide source has been developed. The combination of palladium(II) acetate with 1,1'-bis(diphenylphosphino)ferrocene (dppf) is an efficient catalytic system when the reaction is carried out at 120 °C.

Modeling optical constants from the absorption of organic thin films using a modified Lorentz oscillator model

2022

Optical constants of organic thin films can be evaluated using the Lorentz oscillator model (LOM) which fails to fit inhomogeneously broadened absorption of highly concentrated molecular films. In modified LOM (MLOM), the inhomogeneous broadening is implemented through a frequency-dependent adjustable broadening function. In this work, we evaluate the optical constants of rhodamine 6G doped poly-vinyl alcohol thin films with varying doping concentration (including also extensively high concentrations) using MLOM, which outperforms LOM by showing a better agreement with the experimental results. Our proposed method provides a way to accurately determine optical constants of isotropic organic…

Reaction of 4-acylaminomethylpyridine N-oxides with phenylbutazone in the presence of acetic anhydride

1987

Facile and efficient chemical functionalization of aliphatic polyesters by cross metathesis

2016

International audience; An effective preparation of new tailor-made macromolecular materials via a combination of two (atom-efficient) catalytic transformations is reported. First, new aliphatic polyesters with alternated composition have been prepared using a salen aluminum catalyst system. Next, the pendant vinyl moieties in those copolymers have been selectively transformed into various functional groups by metathesis in the presence of homogeneous Grubbs catalysts. The latter metathesis reaction has been optimized in terms of catalytic activity and selectivity, to define the conditions for an effective and safe procedure that does not affect the macromolecular architecture. All polymer …