Thermal Cyclization (thermal + cyclization)

Distribution by Scientific Domains

Selected Abstracts

Thermal Cyclization of N-[2-(2-Propenyl)-1-naphthyl]ketenimines: Intramolecular Diels,Alder Reaction versus [1,5] Hydrogen Migration.

CHEMINFORM, Issue 47 2005
Benzo[h]quinolines., Synthesis of Dibenz[b, h]acridines
No abstract is available for this article. [source]

ChemInform Abstract: Thermal Cyclization of ,-Hydroxyamides to Oxazolines.

CHEMINFORM, Issue 38 2001
Ratnasamy Somanathan
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

A positive-working photosensitive polyimide based on thermal cross-linking and acidolytic cleavage

Myung-Sup Jung
Abstract A novel positive-working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three-component PSPI was synthesized from 4,4,-oxydiphthalic anhydride and 2,2,-bis(3-amino-4-hydroxyphenyl)hexafluoropropane through ring-opening polymerization and subsequent thermal cyclization. 2,2,-bis(4-(2-(vinyloxy)ethoxy)phenyl)propane (BPA-DEVE) was used as a vinylether compound and diphenyliodonium 5-hydroxynaphthalene-1-sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA-DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA-DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 ,m in a 3.7-,m-thick film was obtained from the three-component PSPI. 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Microwave-assisted synthesis of quinolone derivatives and related compounds

Suhas Pednekar
The Gould-Jacob type of reaction for the synthesis of ethyl 5-ethyl-8-oxo-5,8-dihydro-[1,3]-dioxolo[4,5-g]quinoline-7-carboxylate 4 has been carried out conventionally by the condensation between N -ethyl-3,4-methylenedioxyaniline 1 and diethyl ethoxymethylenemalonate 2 gave the unsaturated ester 3 and thermal cyclization in refluxing diphenyl oxide gave quinolone ethyl ester 4 and the results obtained were compared with single step microwave irradiation under solvent free conditions for the synthesis of 4. The esters on basic hydrolysis formed free acid 5, which, upon treatment with thionyl chloride gave the acid chloride 6. Treatment of acid chloride with o -phenylenediamine, hydrazine hydrate, ammonia, urea, and thiourea gave the amides (7,11). CS2 treatment in presence of KOH on 8 gave 12. We prepared 7,12 derivatives by conventional as well as microwave irradiation. These compounds have been characterized on the basis of IR, 1H NMR, MS, and elemental analysis. All the compounds prepared herein were screened for their antibacterial activity. Compounds 4, 5 possess promising antibacterial activity and compound 8 showed significant antibacterial activity. J. Heterocyclic Chem., (2010). [source]

Preparation of polybenzoxazole fibers via electrospinning and postspun thermal cyclization of polyhydroxyamide

Steve Lien-Chung Hsu
Abstract Polybenzoxazole (PBO) fibers with a submicron diameter were successfully prepared by electrospinning its precursor, polyhydroxyamide (PHA), solutions to obtain the PHA fibers first, followed by appropriate thermal treatments for cyclization reaction. BisAPAF-IC PHA with two different molecular weights (MWs) were synthesized from a low temperature polymerization of 2,2,-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BisAPAF) and isophthaloyl chloride (IC). Using dimethylacetamide (DMAc) and tetrahydrofuran (THF), solvent effects on the electrospinnability of PHA solutions were investigated. For balancing the solution properties, it was found that DMAc/THF mixture with a weight ratio of 1/9 was the best cosolvent to prepare smooth PHA fibers; uniform PHA fibers with a diameter of 325,720 nm were obtained by using 20 wt % PHA/(DMAc/THF) solutions. For a fixed PHA concentration, solutions with a lower MW of PHA yielded thinner electrospun fibers under the same electrospinning condition. After obtaining the electrospun BisAPAF-IC PHA fibers, subsequent thermal cyclization up to 350 C produced the corresponding thermally stable BisAPAF-IC PBO fibers with a diameter of 305,645 nm. The structure of the precursor fibers and the fully cyclized fibers were characterized by FTIR. For the cyclized BisAPAF-IC PBO fibers, thermogravimetric analysis showed a 5% weight loss temperature at 523 C in nitrogen atmosphere. The interconnected fiber structure in the BisAPAF-IC PBO fiber mats was irrelevant to the curing process, but resulted from the jet merging during the whipping process as revealed by the high speed camera images. 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8159,8169, 2008 [source]