fulltext.study @t Gmail

Room-temperature polymerization of β-pinene by niobium and tantalum halides

Paper ID Volume ID Publish Year Pages File Format Full-Text
55172 47042 2012 6 PDF Available
Title
Room-temperature polymerization of β-pinene by niobium and tantalum halides
Abstract

The easily accessible niobium pentahalides NbX5 (X = F, 1a; X = Cl, 1b; X = Br, 1c) and the tantalum TaF5 (2a) were applied for the first time as effective catalysts for the synthesis of poly-β-pinene at room temperature, adopting low catalyst content (0.6 mM). 1H NMR analyses indicated that the produced β-pinene polymers were structurally identical to that formed by conventional cationic Lewis acid initiators. Niobium pentachloride gave low molecular weight (Mn = 1200–1600) polymer with high conversion degree. The effects of the main reaction parameters (i.e. solvent, temperature, catalyst concentration, time and eventual co-catalysts) on the NbCl5-promoted polymerization were investigated. Polymerization quenching with methanol resulted in the incorporation of a methoxy-end group into the polymer chain, thus confirming a cationic mechanism. On the other hand, NbI5, TaCl5, the carbamato-complexes M(O2CNEt2)5 (M = Nb, Ta) and the mononuclear adducts NbX5L [X = Cl, L = MeCN, Ph2CO or (NMe2)2CO; X = F, L = EtOH] were not active in β-pinene polymerization.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (62 K)Download as PowerPoint slideHighlights► Niobium halides are effective catalysts for cationic β-pinene polymerization. ► Good performances can be obtained at room temperature. ► Tantalum derivatives are less efficient than niobium ones.

Keywords
β-Pinene; Cationic polymerization; Lewis acids; Niobium halides; Tantalum halides
First Page Preview
Room-temperature polymerization of β-pinene by niobium and tantalum halides
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 192, Issue 1, 30 September 2012, Pages 177–182
Authors
, , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us