Urea and Thiourea H‑Bond Donating Catalysts
for Ring-Opening Polymerization: Mechanistic Insights via (Non)linear
Free Energy Relationships
Version 2 2018-04-13, 18:52
Version 1 2018-04-13, 18:49
Posted on 2018-04-13 - 18:52
Hammett-style
free energy studies of (thio)urea/MTBD mediated ring-opening
polymerization (ROP) of δ-valerolactone reveal the complicated
interplay of reagents that give rise to catalysis through one of two
mechanisms. The operative mechanism depends most greatly on the solvent,
where polar solvents favor a (thio)imidate mechanism and nonpolar
solvents favor a classic H-bond mediated ROP. Data suggest that the
transition state is only adequately modeled with ground state thiourea–monomer
interactions in the H-bonding pathway, and elusive urea/reagent ground
state binding interactions may be irrelevant and, hence, not worth
pursuing. However, neither relationship is robust enough to be predictive
in the absence of other data. Isotope effects suggest that the base/alcohol
binding event is directly observable in the ROP kinetics. New opportunities
for catalysis emerge, and a reason for the observed mechanism change
is proposed.
CITE THIS COLLECTION
DataCite
3 Biotech
3D Printing in Medicine
3D Research
3D-Printed Materials and Systems
4OR
AAPG Bulletin
AAPS Open
AAPS PharmSciTech
Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg
ABI Technik (German)
Academic Medicine
Academic Pediatrics
Academic Psychiatry
Academic Questions
Academy of Management Discoveries
Academy of Management Journal
Academy of Management Learning and Education
Academy of Management Perspectives
Academy of Management Proceedings
Academy of Management Review
Pothupitiya, Jinal
U.; Hewawasam, Rukshika S.; Kiesewetter, Matthew K. (2018). Urea and Thiourea H‑Bond Donating Catalysts
for Ring-Opening Polymerization: Mechanistic Insights via (Non)linear
Free Energy Relationships. ACS Publications. Collection. https://doi.org/10.1021/acs.macromol.8b00321
or
Select your citation style and then place your mouse over the citation text to select it.