Syndiotactic‐specific radical polymerization of <i>N</i>,<i>N</i>‐dimethylacrylamide in the presence of tartrates: A proposed mechanism for the polymerization

Hirano, Tomohiro; Masuda, Shuhei; Nasu, Shou; Ute, Koichi; Sato, Tsuneyuki

doi:10.1002/pola.23226

Cited by 22 publications

(27 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…S6 †). The r diad content reached up to 65% in THF, which is comparable to the highest r diad content of 69% reported to date for radically prepared poly (DMAAm)s. 58 On the other hand, LiOTf exhibited a different effect to that of LiNTf 2 and LiCl, in that it gave syndiotactic-Scheme 2 Relationship between the stoichiometry of the DMAAm-Li + complex and the stereospecificity of the DMAAm polymerization. In contrast, LiCl induced syndiotactic specificity in CH 3 CN and THF, whereas LiNTf 2 induced isotactic specificity under the same conditions (Table 3, runs 21 and 23).…”

Section: Relationship Between Complex Structure and Stereospecificitymentioning

confidence: 59%

Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

et al. 2015

Self Cite

View full text Add to dashboard Cite

The radical polymerization of N,N-dimethylacrylamide (DMAAm) has been investigated in the presence of several alkali metal salts, including lithium bis(trifluoromethanesulfonyl)imide (LiNTf 2 ). The addition of an alkali metal salt led to a significant increase in the yield and molecular weight of the resulting polymer.NMR analysis of mixtures of DMAAm and LiNTf 2 suggested that DMAAm was being activated by the coordination of Li + to its CvO group. Electron spin resonance analysis of the DMAAm polymerization in the presence of LiNTf 2 suggested that the propagating radical was being stabilized by Li + through a single-electron lithium bond, because a signal for the propagating radical of the acrylamide derivatives was observed for the first time in solution when LiNTf 2 was added. Based on these results, we have proposed a mechanism for this polymerization, where the propagation steps occur between a lithium ionstabilized propagating radical and a lithium ion-activated incoming monomer. Furthermore, polymers with a wide range of stereoregularities, such as isotactic, syndiotactic and heterotactic systems, were successfully prepared using this method by carefully selecting the appropriate combination of solvent and alkali metal salt. † Electronic supplementary information (ESI) available: Dependence of polymer yield on the added amount of LiNTf 2 in toluene, additional 1 H NMR spectra of the main-chain methylene groups of the poly(DMAAm)s prepared in this study and changes in the chemical shifts of DMAAm in the presence of MNTf 2 . See View Article Online a [Monomer] 0 = 1.0 mol L −1 , [MAIB] 0 = 1.0 × 10 −2 mol L −1 , [alkali metal salts] 0 = 1.0 mol L −1 . b Determined from 1 H NMR signals. c Determined by SEC (PMMA standards). d Alkali metal salt was not completely dissolved. e Polymer precipitated during polymerization reaction. Polymer Chemistry PaperThis journal is

show abstract

Section: Relationship Between Complex Structure and Stereospecificitymentioning

confidence: 59%

Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…Hirano et al . 27–29 proposed a mechanism for the syndiotactic‐specific radical polymerization of poly(N‐isopropylacrylamide) in the presence of hexamethylphosphoramide. This mechanism was adapted to explain the influence of AES on the PMMA tacticity (Figure 5).…”

Section: Resultsmentioning

confidence: 99%

“…Thus, steric hindrance of the AES would limit approach via pathway “b” of the next incoming monomer. As a result, syndiotactic‐specificity was induced 27…”

Section: Resultsmentioning

confidence: 99%

Natural Compounds against Alzheimer’s Disease: Molecular Recognition of Aβ1–42 Peptide by Salvia sclareoides Extract and its Major Component, Rosmarinic Acid, as Investigated by NMR

Airoldi

Sironi

Dias

et al. 2013

Chemistry An Asian Journal

View full text Add to dashboard Cite

Amyloid peptides, Aβ1-40 and Aβ1-42, represent major molecular targets to develop potential drugs and diagnostic tools for Alzheimer's Disease (AD). In fact, oligomeric and fibrillar aggregates generated by these peptides are amongst the principal components of amyloid plaques found post mortem in patients suffering from AD. Rosmarinic acid has been demonstrated to be effective in preventing the aggregation of amyloid peptides in vitro and to delay the progression of the disease in animal models. Nevertheless, no information is available about its molecular mechanism of action. Herein, we report the NMR characterization of the interaction of Salvia sclareoides extract and that of its major component, rosmarinic acid, with Aβ1-42 peptide, whose oligomers have been described as the most toxic Aβ species in vivo. Our data shed light on the structural determinants of rosmarinic acid-Aβ1-42 oligomers interaction, thus allowing the elucidation of its mechanism of action. They also provide important information for the rational design of new compounds with higher affinity for Aβ peptides to generate new anti-amyloidogenic molecules and/or molecular tools for the specific targeting of amyloid aggregates in vivo. In addition, we identified methyl caffeate, another natural compound present in different plants and human diet, as a good ligand of Aβ1-42 oligomers, which also shows anti-amyloidogenic activity. Finally, we demonstrated the possibility to exploit STD-NMR and trNOESY experiments to screen extracts from natural sources for the presence of Aβ peptide ligands.

show abstract

“…We have reported that radical polymerization of vinyl monomers with amide groups, such as acrylamide derivatives and N ‐vinylacetamide, can be moderately well controlled by utilizing hydrogen bonding interaction 2–8. For example, complex formation of N ‐isopropylacrylamide (NIPAAm) with hexamethylphosphoramide (HMPA) or alkyl alcohol (ROH) such as 3‐methyl‐3‐pentanol (3Me3PenOH) gave syndiotactic polymers.…”

Section: Introductionmentioning

confidence: 99%

Stereospecific radical polymerization of N‐tert‐butoxycarbonylacrylamide in the presence of fluorinated alcohols

Hirano

Yamaoka

Miyazaki

et al. 2010

J. Polym. Sci. A Polym. Chem.

Self Cite

View full text Add to dashboard Cite

Radical polymerization of N-tert-butoxycarbonylacrylamide (NBocAAm) in toluene at low temperatures in the presence of the fluorinated alcohols, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, and nonafluoro-tert-butanol, afforded atactic, heterotactic, and syndiotactic polymers, respectively. NMR analysis revealed that the fluorinated alcohols formed hydrogen bonding-assisted complexes with NBocAAm, with different structures. The difference in the structures of the complexes was responsible for the differences in the induced stereospecificities. Based on the structures of the complexes between NBocAAm and the fluorinated alcohols, mechanisms for the three kinds of stereospecific radical polymerizations are proposed. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5718-5726, 2010

show abstract

Syndiotactic‐specific radical polymerization of N,N‐dimethylacrylamide in the presence of tartrates: A proposed mechanism for the polymerization

Cited by 22 publications

References 55 publications

Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

Natural Compounds against Alzheimer’s Disease: Molecular Recognition of Aβ1–42 Peptide by Salvia sclareoides Extract and its Major Component, Rosmarinic Acid, as Investigated by NMR

Stereospecific radical polymerization of N‐tert‐butoxycarbonylacrylamide in the presence of fluorinated alcohols

Contact Info

Product

Resources

About