ChemInform Abstract: EQUILIBRIUM ACIDITIES OF CARBON ACIDS. VI. ESTABLISHMENT OF AN ABSOLUTE SCALE E OF ACIDITIES IN DIMETHYL SULFOXIDE SOLUTION

Matthews, Walter S.; Bares, Joseph E.; Bartmess, John E.; Bordwell, F. G.; Cornforth, Frederick J.; Drucker, George E.; Margolin, Z.; McCallum, Robert J.; McCollum, Gregory J.; Vanier, Noel R.

doi:10.1002/chin.197607074

Cited by 14 publications

(16 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, we measured the pK a values of 8b (19.2 ± 0.2 in DMSO) and 8c (19.9 ± 0.3 in DMSO) by using the spectrophotometric method of overlapping indicators developed by Schreiner 39 and Bordwell. 40 These pK a values support that both activity and M w /M n decrease with decreasing pK a . In contrast, the N-substituted oxindole 8d (pK a = 18.5 in DMSO), devoid of the N−H group, exhibited low activity and produced PLA with a broad dispersity (Table 1, entry 17); this result supports our hypothesis of the importance of Brønsted base/ Lewis acid cooperativity (Scheme 1d).…”

Section: ■ Results and Discussionsupporting

confidence: 58%

Fast and Controlled Ring-Opening Polymerization of Cyclic Esters by Alkoxides and Cyclic Amides

2018

View full text Add to dashboard Cite

Ring-opening polymerization is a powerful method for the synthesis of biodegradable and biorenewable polyesters. In this contribution, we report that the combination of alkali alkoxides and commercially available cyclic amides catalyzes fast and controlled ring-opening polymerization of l-lactide. The constrained cis CN bond in the imidate catalyst is critical for achieving high catalytic activity. By optimizing the basicity of the catalyst, a good balance between activity and control (M w/M n < 1.1) is realized. A high amide/initiator ratio is essential for producing narrow dispersities and inhibiting transesterification.

show abstract

Section: ■ Results and Discussionsupporting

confidence: 58%

Fast and Controlled Ring-Opening Polymerization of Cyclic Esters by Alkoxides and Cyclic Amides

2018

View full text Add to dashboard Cite

show abstract

“…It is generally observed that the pK a values in water are lower than in other polar but aprotic solvents such as DMSO solvent by about 1−2 pK units. 56 In our calculation, the pK a of IH in water is lower than the pK a of the structurally similar acid PhN(Bz)OH in DMSO (pK a(DMSO) = 23.8) by ∼1.5 pK unit. 57 Therefore, the calculated pK a of 22.3 of IH is in the expected range.…”

Section: Resultsmentioning

confidence: 52%

Is Indolinonic Hydroxylamine a Promising Artificial Antioxidant?

Bay

Nam

et al. 2019

J. Phys. Chem. B

View full text Add to dashboard Cite

Indolinonic hydroxylamine (IH) is a new-generation artificial antioxidant that, due to its ability to fractionate into apolar environments, is considered for prevention against lipid peroxidation. For this reason, it is important to understand, and compare, its activity in polar and nonpolar environments. In this study, the antioxidant activity of IH has been evaluated against HO• and HOO• radicals in water and, for a lipid-mimetic environment, pentyl ethanoate solvent, using kinetic calculations. It was found that the overall reaction rate constant of the HO• radical scavenging is more than 7 times higher in aqueous (8.98 × 109 M–1 s–1) than in apolar (1.22 × 109 M–1 s–1) media. However, HOO• scavenging was 35 times faster in apolar media (1.00 × 105 M–1 s–1 vs 2.80 × 103 M–1 s–1). In a lipid environment, the HAT mechanism was favored for the antioxidant activity for both radical species, whereas in aqueous solution the SET mechanism defined the HO• scavenging, while HAT described the HOO• scavenging. IH was shown to be one of the most active antioxidants in lipid environment, an essential characteristic for the protection of biological systems.

show abstract

“…Some of them have comparable values of the acidity constant with the most acidic phenols. 71,72 However, it should be remembered that in the process of proton transfer in the excited state the key role belongs not to acidity and basicity, but photoacidity and photobasicity. Photoacids and photobases are organic dyes which become stronger acids and stronger bases (pH-jump) in the electronic excited-state.…”

Section: Selection Of Potential Candidates For Excited State Intramolmentioning

confidence: 99%

Acidic C–H Bond as a Proton Donor in Excited State Intramolecular Proton Transfer Reactions

Stasyuk

Cyrański

Gryko

et al. 2015

J. Chem. Theory Comput.

View full text Add to dashboard Cite

An unprecedented type of excited state intramolecular proton transfer in a series of benzo[h]quinoline (BHQ) derivatives substituted at position 10 with strong CH acid character is described using density functional theory/time-dependent density functional theory computational approaches with a hybrid functional and the 6-311++G(d,p) triple-ξ quality basis set. Our results show that for 10-malononitrile-substituted BHQ (2CNBHQ) the excited state intramolecular proton transfer C-H···N reaction is a barrierless process. Calculations also reveal that the reaction profiles of the 4-amino-substituted 2CNBHQ show a large dependence on the polarity of the environment.

show abstract

ChemInform Abstract: EQUILIBRIUM ACIDITIES OF CARBON ACIDS. VI. ESTABLISHMENT OF AN ABSOLUTE SCALE E OF ACIDITIES IN DIMETHYL SULFOXIDE SOLUTION

Cited by 14 publications

References 1 publication

Fast and Controlled Ring-Opening Polymerization of Cyclic Esters by Alkoxides and Cyclic Amides

Fast and Controlled Ring-Opening Polymerization of Cyclic Esters by Alkoxides and Cyclic Amides

Is Indolinonic Hydroxylamine a Promising Artificial Antioxidant?

Acidic C–H Bond as a Proton Donor in Excited State Intramolecular Proton Transfer Reactions

Contact Info

Product

Resources

About