A Density Functional Theory Study on the Ring-Opening Polymerization of D-Lactide Catalyzed by a Bifunctional-Thiourea Catalyst

2009 ◽  
Vol 62 (2) ◽  
pp. 157 ◽  
Author(s):  
Rong-Xiu Zhu ◽  
Ruo-Xi Wang ◽  
Dong-Ju Zhang ◽  
Cheng-Bu Liu
Keyword(s):  
Density Functional Theory ◽  
Ring Opening ◽  
Density Functional ◽  
Population Analysis ◽  
Density Functional Theory Calculations ◽  
Ring Opening Polymerization ◽  
Acyl Transfer ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Elimination Pathway

The thiourea-catalyzed methanolysis of d-lactide, a model system for the initiation and propagation of the organocatalyzed ring-opening polymerization (ROP) of lactide, has been studied by performing density functional theory calculations. Both the catalyzed and uncatalyzed reactions are explored along two possible pathways: one involves the stepwise addition–elimination pathway and the other is related to the concerted pathway. It is found that the reaction without the presence of the catalyst is difficult because the barrier involved is as high as 176 kJ mol–1. With the aid of a thiourea catalyst, the barrier is reduced to 88 kJ mol–1 with a preference for the stepwise addition–elimination mechanism over the concerted one. The role of the catalyst has been rationalized by analyzing the frontier molecular orbital interactions between the catalyst and substrates and by performing natural population analysis. Finally, another mechanism involving acyl transfer is discussed for the thiourea-catalyzed ROP.

scholarly journals Rationalizing the Reactivity of Mixed Allyl Rare-Earth Borohydride Complexes with DFT Studies

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 820
Author(s):  
Sami Fadlallah ◽  
Jashvini Jothieswaran ◽  
Iker Del Rosal ◽  
Laurent Maron ◽  
Fanny Bonnet ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Rare Earth ◽  
Ring Opening ◽  
Density Functional ◽  
Ring Opening Polymerization ◽  
Polymerization Reaction ◽  
Experimental Investigations ◽  
Dft Studies ◽  
Functional Theory ◽  
Activation Barriers

The reactivity of rare-earth complexes RE(BH4)2(C3H5)(THF)x (RE = La, Nd, Sm, Y, Sc) toward the Ring-Opening Polymerization (ROP) of ε-caprolactone (ε-CL) was rationalized by Density Functional Theory (DFT) calculations. Even if the polymerization reaction can be initiated by both RE-(BH4) and RE-allyl bonds, experimental investigations have shown that the initiation via the borohydride ligand was favored, as no allyl group could be detected at the chain-end of the resulting polymers. DFT studies could confirm these observations, as it was highlighted that even if the activation barriers are both accessible, the allyl group is not active for the ROP of ε-CL due to the formation of a highly stable intermediate that disfavors the subsequent ring-opening.

scholarly journals Spectroscopic Examination using Density Functional Theory Calculations on 3-chloro-5-methoxyphenol

2020 ◽  
Vol 8 (4S4) ◽  
pp. 113-118
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Density Functional Theory Calculations ◽  
Nbo Analysis ◽  
Computational Method ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Charge Delocalization ◽  
Raman Spectral Data

The complete vibrational assignment of 3-chloro-5-methoxyphenol (CMOP) has been identified by the observed IR and Raman spectral data and vibrational frequencies were calculated by density functional theory method. The ability of the computational method for describing the vibrational modes can be understood by comparing experimental and theoretical spectra. Besides, frontier molecular orbital, Mulliken’s charge analyses and molecular electrostatic potential (MEP) surfaces have been computed. The natural bond orbital (NBO) analysis has been studied to analyze the charge delocalization and molecular hyperconjugative interactions

scholarly journals Density Functional Theory Studies on the Synthesis of Poly(α-Amino Acid)s Via the Amine-Mediated Ring Opening Polymerizations of N-Carboxyanhydrides and N-Thiocarboxyanhydrides

2021 ◽  
Vol 9 ◽  
Author(s):  
Tianwen Bai ◽  
Botuo Zheng ◽  
Jun Ling
Keyword(s):  
Density Functional Theory ◽  
Amino Acid ◽  
Ring Opening ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
The Past

To synthesize well-defined poly (α-amino acid)s (PAAs), ring opening polymerizations (ROP) of cyclic monomers of α-amino acid N-carboxyanhydrides (NCAs) and N-thiocarboxyanhydrides (NTAs) are most widely used. In this mini-review, we summarize the mechanism details of the monomer preparation and ROP. The present study used density functional theory calculations to reveal the mechanisms together with experimental phenomena in the past decades. Detailed discussion includes normal amine mechanism and the selectivity of the initiators bearing various nucleophilic groups.

Mechanistic insights into the ring-opening of biomass derived lactones

RSC Advances ◽  
2016 ◽  
Vol 6 (16) ◽  
pp. 12932-12942 ◽  
Author(s):  
Shelaka Gupta ◽  
Rishabh Arora ◽  
Nishant Sinha ◽  
Md. Imteyaz Alam ◽  
M. Ali Haider
Keyword(s):  
Density Functional Theory ◽  
Ring Opening ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Ring Opening Reactions ◽  
Oxocarbenium Ion ◽  
Acid Catalyzed

Density functional theory calculations suggest the formation of an oxocarbenium ion intermediate in acid catalyzed ring-opening reactions of biomass derived lactones, which may play an important role in determining it's reactivity.

scholarly journals Density functional theoretical studies on the ring-opening polymerization mechanism of oxetane cation series compounds

RSC Advances ◽  
2017 ◽  
Vol 7 (78) ◽  
pp. 49626-49632
Author(s):  
Hai-Xia Wang ◽  
Min Pu ◽  
Yu-Cheng Ding
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Ring Opening ◽  
Density Functional ◽  
Ring Opening Polymerization ◽  
Basis Set ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Polymerization Mechanism

The mechanism of ring-opening polymerization of oxetane cation series compounds was investigated using the B3LYP and MP2 methods of density functional theory andab initiomethods, at the basis set levels of 6-31G(d,p) and 6-311++G(d,p).

Is a Non-Transition Element Nitride Ferromagnet Ever Achievable? Indication of the N-N Pairing Instability

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1525-1531 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition Element ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The enthalpy of four polymorphs of CaN has been scrutinized at 0 and 100 GPa using density functional theory calculations. It is shown that structures of diamagnetic calcium diazenide (Ca2N2) are preferred over the cubic ferromagnetic polymorph (CaN) postulated before, both at 0 and 100 GPa.

Sign in / Sign up

Export Citation Format

Share Document