Optimizing Acid−Base Bifunctional Mesoporous Catalysts for the Henry Reaction: Effects of the Surface Density and Site Isolation of Functional Groups

Langmuir ◽  
2008 ◽  
Vol 24 (24) ◽  
pp. 14306-14320 ◽  
Author(s):  
Krishna K. Sharma ◽  
Robert P. Buckley ◽  
Tewodros Asefa
Keyword(s):  
Functional Groups ◽  
Surface Density ◽  
Henry Reaction ◽  
Acid Base ◽  
Site Isolation ◽  
Mesoporous Catalysts

scholarly journals Optimizing Spacer Length for Positioning Functional Groups in Bio-Waste

Environments ◽  
2018 ◽  
Vol 5 (9) ◽  
pp. 100 ◽  
Author(s):  
Revathi Iyengar ◽  
Maria Faure-Betancourt ◽  
Saleh Talukdar ◽  
Jinting Ye ◽  
Abel Navarro
Keyword(s):  
Functional Groups ◽  
Amine Group ◽  
Ambient Conditions ◽  
Tea Leaves ◽  
Acid Base ◽  
Spacer Length ◽  
Dipole Interactions ◽  
Green Tea Leaves ◽  
Better Than ◽  
Spent Tea Leaves

The goal of this study was to determine the optimal chain length needed for tethering functional groups on bio-wastes. The purpose of modifying the surface of bio-waste is to improve their affinity for phenols. To this end, four different aminated green tea leaves, with the amine group located at the end of 6, 8, 10, and 12 carbons were synthesized. Green approaches to functionalization lead to fewer reactive sites. Optimizing spacer length is one way to ameliorate this. The aminated tea leaves were prepared by a tosylation reaction followed by displacement with a diamine used in excess. The tea leaves with the amine at the end of six carbons proved to have the best ability to remove 2-chlorophenol (2-CP) from its aqueous solution. It was at least 3–4 times better than native spent tea leaves. The mechanism by which the phenol was removed proved to be primarily an acid–base reaction followed by H-bonding and dipole–dipole interactions. Because of the acid–base interactions, the relatively low-boiling 2-CP did not volatilize off the aminated tea leaves enabling recycling. On the other hand, with activated charcoal, the adsorbed 2-CP volatilized almost completely under ambient conditions.

scholarly journals New possibility for characterization of dissociation behaviour of supramolecular electrolytes: results obtained for the International Humic Substances Society standard and reference samples by coulometry

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Martina Klučáková
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Humic Substances ◽  
Functional Groups ◽  
Dissociation Constants ◽  
Fulvic Acids ◽  
Molecular Organization ◽  
Humic And Fulvic Acids ◽  
Acid Base ◽  
Reference Samples

Abstract Background Humic substances can be considered as polyelectrolytes with supramolecular character and complicated behaviour in water environment. The fractions of humic substances dissolved in water are the most active ones and determinative for their functioning in nature, where the proton-binding and dissociation ability play a crucial role. The dissociation behaviour of humic and fulvic acids can be affected by different circumstances including their concentration which is directly connected with the molecular organization of humic particles in solution and the accessibility of their ionizable functional groups. This study is focused just on these active fractions and their dissociation behaviour in the dependence on their content in studied system. Results Standards and reference samples of International Humic Substances Society were used. Flow-through coulometry was used to determine the total content of acidic functional groups in fulvic solutions and humic leachates. The amount of dissociated acidic groups was determined on the basis of potentiometry. Several differences between the behaviour of humic and fulvic acids were found. While whole samples of fulvic acids including the weakest functional groups were analysed, only the active dissolved humic fractions containing stronger acidic functional groups were characterized. The fractions containing higher amounts of the weakest functional groups remained insoluble. The dissociation degree of fulvic acids decreased with their increasing content, but a maximum on its concentration dependence obtained for humic acids was observed. Conclusions Two different values of dissociation constants were determined for each sample. The first was determined on the basis of the extrapolation of infinite dilution, second was determined as their average value in the region of high concentrations in which it was constant. Obtained values characterize the functioning of dissolved humic substances from point of view of their dissociation ability. The results obtained by this approach can help to predict the acid–base behaviour of dissolved organic carbon in soil and generally in nature. The acid–base behaviour of dissolved organic carbon depends on its ratio to water. It behaves differently in soil which is dry and in soil which is wet or saturated by water.

scholarly journals Development of an Intermittent-Flow Enantioselective Aza-Henry Reaction Using an Arylnitromethane and Homogeneous Brønsted Acid–Base Catalyst with Recycle

2016 ◽  
Vol 20 (2) ◽  
pp. 215-226 ◽  
Author(s):  
Sergey V. Tsukanov ◽  
Martin D. Johnson ◽  
Scott A. May ◽  
Morgan Rosemeyer ◽  
Michael A. Watkins ◽  
...  
Keyword(s):  
Intermittent Flow ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Base Catalyst ◽  
Henry Reaction ◽  
Acid Base ◽  
Brönsted Acid

scholarly journals Acid-base properties of fibrous polyampholytes with aminodiacetic functional groups

2020 ◽  
Vol 64 (3) ◽  
pp. 300-307
Author(s):  
E. G. Kosandrovich ◽  
P. V. Nesteronok ◽  
L. N. Shachenkova ◽  
V. S. Soldatov
Keyword(s):  
Cation Exchange ◽  
Anion Exchange ◽  
Potentiometric Titration ◽  
Functional Groups ◽  
Supporting Electrolyte ◽  
Experimental Results ◽  
Monochloroacetic Acid ◽  
Polyacrylonitrile Fiber ◽  
Acid Base ◽  
Amination Reaction

Polyampholytes, containing aminodiacetic functional groups, on the base of polyacrylonitrile fiber Nitron C were obtained by the amination reaction of nitrile groups with polyamines (number of repeating units from 1 to 5) and subsequent alkylation with monochloroacetic acid. The experimental results of potentiometric titration and sorption of supporting electrolyte (kCl) ions by synthesized ion exchangers were obtained, which made it possible to determine the acidity parameters of functional groups: the presence of four types of cation exchange and two types of anion exchange groups was detected in polyampholytes, the sequence of their neutralization in the titration process was established.

scholarly journals Cover Feature: Tunable Acid‐Base Bifunction of Hierarchical Aluminum‐Rich Zeolites for the One‐Pot Tandem Deacetalization‐Henry Reaction (ChemPlusChem 10/2019)

ChemPlusChem ◽  
2019 ◽  
Vol 84 (10) ◽  
pp. 1450-1450
Author(s):  
Duangkamon Suttipat ◽  
Thittaya Yutthalekha ◽  
Wannaruedee Wannapakdee ◽  
Pannida Dugkhuntod ◽  
Piraya Wetchasat ◽  
...  
Keyword(s):  
Henry Reaction ◽  
Acid Base ◽  
One Pot ◽  
The One

Tunable Acid‐Base Bifunction of Hierarchical Aluminum‐Rich Zeolites for the One‐Pot Tandem Deacetalization‐Henry Reaction

ChemPlusChem ◽  
2019 ◽  
Vol 84 (10) ◽  
pp. 1503-1507 ◽  
Author(s):  
Duangkamon Suttipat ◽  
Thittaya Yutthalekha ◽  
Wannaruedee Wannapakdee ◽  
Pannida Dugkhuntod ◽  
Piraya Wetchasat ◽  
...  
Keyword(s):  
Henry Reaction ◽  
Acid Base ◽  
One Pot ◽  
The One
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