The Relative Acidifying Influence of Oxygen and Sulfur Atoms on α-Hydrogen Atoms<sup>1</sup>

Brehm, Warren J.; Levenson, Theodore

doi:10.1021/ja01650a040

Cited by 31 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is has been shown that sulfur's ability to expand its octet can increase the acidity of an αhydrogen compared to when an oxygen takes the same position. 17,18 This effect can be observed in S4 where it displays a slightly higher headgroup-associated peak OD stretching frequency compared to S1 due to the ability of sulfur to expand its octet and therefore more readily accept additional electron density relative to oxygen. The trend of charge density was confirmed by computing the partial charge of the sulfonate group using DMol 3 DFT calculations.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The difference in charge density between S4 and S1 can be explained based on the differences between thioether and ether linkages. It is has been shown that sulfur’s ability to expand its octet can increase the acidity of an α-hydrogen compared to when an oxygen takes the same position. , This effect can be observed in S4 where it displays a slightly higher headgroup-associated peak OD stretching frequency compared to S1 due to the ability of sulfur to expand its octet and therefore more readily accept additional electron density relative to oxygen.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers

et al. 2017

View full text Add to dashboard Cite

The charge density and hydrogen bonding with water of five different polymer membranes functionalized with various sulfonate side-chain chemistries were investigated using Fourier transform infrared (FTIR) techniques and density functional theory (DFT) calculations. The peak position of the OD stretch of dilute HOD absorbed into the sulfonated poly(sulfone) membranes was studied using FTIR to compare the charge density of the sulfonate headgroup across the different samples, which can ultimately be related to the acidity of the proton-form sulfonate moieties. The OD peak was deconvoluted to determine the percentage of headgroup-associated, intermediate, and bulk water. DFT modeling was used to calculate the charge density of each headgroup and visualize how the chemistry of the headgroup influenced the conformation of the side-chain tether. FTIR-determined OD peak positions and charge density calculations demonstrated that a perflurosulfonate containing a thioether linkage produced the most acidic sulfonate headgroup. However, the amount of headgroup-associated water calculated for this side chain was low due to the unique cis conformation of the thioether side chain. The biperfluorosulfonate side chain had very low calculated headgroup-associated water due to its bulkiness and water molecules bridging the two sulfonates. These detailed insights on local hydration of sulfonate side chains will point towards new headgroup designs for advanced membranes.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Yellow liquid (128 mg, 90%); IR (neat) ν max 2142 (diazo), 1687, 1365, 752, 642 cm –1 ; 1 H NMR (400 MHz, CDCl 3 ) δ 3.85 (s, 3H), 2.49 (s, 3H); 13 C NMR (101 MHz, CDCl 3 ) δ 190.1, 161.8, 52.2, 28.2.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Ionic Liquid-Supported Sulfonyl Azide and Its Application in Diazotransfer Reaction

2012

View full text Add to dashboard Cite

The paper describes synthesis of a novel ionic liquid-supported sulfonyl azide and its applications as diazotransfer reagent of active methylene compounds as well as deformylative diazo transfer reagent. The diazo compounds were isolated in excellent yields (82-94%) and high purity. The method offers better separation of product and reagent. This method is experimentally simple and mild, and requires very short reaction time.

show abstract

“…Literaturbekannt ist z. B. die kupferkatalysierte Umwandlung von a-Diazoacetessigsaure-methylester in or-Methoxyacetessigsaure-methylester 11) oder auch die Bortrifluorid-katalysierte Herstellung von a-Methoxyacetylaceton aus a-Diazoacetylaceton '2 Eigene orientierende Versuche mit 1 zeigten aber sehr schnell, daf3 diesem Syntheseweg fur die Herstellung von 4 bzw. 13 doch sehr enge Grenzen gesetzt sind, da sich die mit der Insertion konkurrierende Wolff-Umlagerung von 1 nur schwer unterdriicken laf3t 13).…”

Section: Verkochung Von (Diazo)dibenzoylmethan (1)unclassified

Stabile Enole von α‐[Aryl(Alkyl)oxy]dibenzoylmethanen

Regitz¹,

Schäfer²

1981

Liebigs Ann. Chem.

View full text Add to dashboard Cite

Die Enole 13a-m von a-(Ary1oxy)-und a-(A1kyloxy)dibenzoylmethanen 4 a -m werden durch Zerlegung der Kupferchelate 11 a -m mit Schwefelsaure erhalten. Zu den Kupferverbindungen gelangt man entweder durch Esterkondensation der Acetophenone 6 h -m mit Benzoesaure-phenylester (7) oder durch nukleophile Substitution von a-Bromdibenzoylmethan (9) mit den Phenolen i 0 a --g. Die in Gegenwart von Natriunihydrid bzw. Triethylamin zunachst gebildeten Enolate 8 lassen sich direkt mit Kupfer(I1)-acetat in die Chelate 11 umwandeln. Die Enole 13 sind durch lsomerisierurig zu den diketo ton en 4 wwie durch die Bromierung zu 12 charakterisiert. Stahle Enols of a-[Aryl(Alkyl)oxyldibenzoyltnethanesThe enols 13a-m of a-(ary1oxy)-and a-(alky1oxy)dibenzoylmethanes 4a -m are obtained by decomposition of the copper chelates l l a -m with sulfuric acid. The copper compounds are synthesized either by ester condensation of the acetophenones 6h -m with phenyl benzoate (7) or by nucleophilic substitution of a-bromodibenzoylmethane (9) with the phenols 1Oa-g. The enolates 8, primarily formed in the presence of sodium hydride or triethylamine, respectively, are directly converted into the chelates 11 with copper(I1) acetate. The enols 13 are characterized by isomerization to the B-diketones 4 as well as by bromination to 12.Die quantitative Bestimmung der Keto/Enol-Gleichgewichte von fi-Dicarbonylverbindungen nach Meyer') beruht darauf, da8 man deren Enolgehalt durch bromometrische Titration ermittelt. Hierbei muia man die aiul3eren Bedingungen so wahlen, da13 die Nachenolisierung ,,vernachl%ssigbar" ist und die Brornierung selbst ,,momentan" erfolgt, was in Methanol als Solvens und bei -20°C i. a. gegeben ist. Zahlreiche Anwendung dieser Technik *) oder auch der hieraus entwickelten automatisierten coulometrischen B r~m t i t r a t i o n~,~' stehen naturgemaia nur wenige Arbeiten uber die Kinetik des Bromierungsablaufes selbst gegenuber s , 6 , 7 ) . Hierbei wurde gefunden, da8 die Enole halogenierter B-Dicarbonylverbindungen bei 25 "C in Methanol etwa lOOmal langsamer bromiert werden als die Grundverbindung selbst ' ). Diese Tendenz setzt sich -wie wir fariden8] -in beeindruckender Weise bei den Enolen von a-(Ary1oxy)-bzw. a-(Alkyl0xy)dibenzoylmethan (13) fort. Um nun den sterischen und elektronischen Substituenteneinflun auf die Bromierungskinetik zu untersuchen, haben wir uns zunachst rnit der Synthese eines reprasentativen Spektrums derartiger Enole b e f d t , uber die im folgenden berichtet wird.Liebigs Ann. Chem. 1981

show abstract

The Relative Acidifying Influence of Oxygen and Sulfur Atoms on α-Hydrogen Atoms¹

Cited by 31 publications

References 0 publications

Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers

Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers

Synthesis of Ionic Liquid-Supported Sulfonyl Azide and Its Application in Diazotransfer Reaction

Stabile Enole von α‐[Aryl(Alkyl)oxy]dibenzoylmethanen

Contact Info

Product

Resources

About

The Relative Acidifying Influence of Oxygen and Sulfur Atoms on α-Hydrogen Atoms1

Cited by 31 publications

References 0 publications

Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers

Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers

Synthesis of Ionic Liquid-Supported Sulfonyl Azide and Its Application in Diazotransfer Reaction

Stabile Enole von α‐[Aryl(Alkyl)oxy]dibenzoylmethanen

Contact Info

Product

Resources

About

The Relative Acidifying Influence of Oxygen and Sulfur Atoms on α-Hydrogen Atoms¹