scholarly journals A Simplified Method of Synthesis to Obtain Zwitterionic Cellulose under Mild Conditions with Active Ionic Moieties

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3065
Author(s):  
Nadia B. Haro-Mares ◽  
Juan C. Meza-Contreras ◽  
Fernando A. López-Dellamary Toral ◽  
Ricardo González-Cruz ◽  
José A. Silva-Guzmán ◽  
...  
Keyword(s):  
Potentiometric Titration Curve ◽  
Blue Dye ◽  
Signal Integration ◽  
Amino Acid Residues ◽  
Mild Conditions ◽  
Cotton Blue ◽  
Aqueous Conditions ◽  
Simplified Procedure ◽  
Aspartate Residue ◽  
Modified Cellulose

A simplified procedure to synthesize zwitterionic cellulose by means of N-protected aspartic anhydride under mild conditions was developed. The preparation of modified cellulose samples was carried out under heterogeneous, aqueous conditions by reacting NH4OH-activated cellulose with aspartic anhydrides N-protected with trifluoroacetyl (TFAc) and carbobenzyloxy (Cbz). Modified cellulose samples Cel-Asp-N-TFAc and Cel-Asp-N-Cbz were characterized by Fourier Transform Infrared (FTIR) and 13C solid state Nuclear Magnetic Resonance (NMR) spectroscopy. The functionalization degree of each cellulose sample was determined by the 13C NMR signal integration values corresponding to the cellulose C1 vs. the Cα of the aspartate residue and corroborated by elemental analysis. In agreement, both analytical methods averaged a grafting degree of 20% for Cel-Asp-N-TFAc and 16% for Cel-Asp-N-Cbz. Conveniently, Cel-Asp-N-TFAc was concomitantly partially N-deprotected (65%) as determined by the ninhydrin method. The zwitterion character of this sample was confirmed by a potentiometric titration curve and the availability of these amino acid residues on the cellulose was inspected by adsorption kinetics method with a 100 mg L−1 cotton blue dye solution. In addition, the synthesis reported in the present work involves environmentally related advantages over previous methodologies developed in our group concerning to zwitterionic cellulose preparation.

Investigation of the Electrocoagulation Treatment of Cotton Blue Dye Solution using Aluminium Electrodes

2008 ◽  
Vol 36 (10-11) ◽  
pp. 863-869 ◽  
Author(s):  
Renu Ahlawat ◽  
Vimal Chandra Srivastava ◽  
Indra Deo Mall ◽  
Shishir Sinha
Keyword(s):  
Blue Dye ◽  
Cotton Blue

scholarly journals Biofilm formation by Prototheca zopfii isolated from clinical and subclinical bovine mastitis in distinct growth conditions under different dyes

2019 ◽  
Vol 49 (2) ◽  
Author(s):  
Valessa Lunkes Ely ◽  
Letícia Trevisan Gressler ◽  
Fernando Jonas Sutili ◽  
Márcio Garcia Ribeiro ◽  
Mateus Matiuzzi da Costa ◽  
...  
Keyword(s):  
Crystal Violet ◽  
Biofilm Formation ◽  
Bovine Mastitis ◽  
Growth Conditions ◽  
Blue Dye ◽  
Prototheca Zopfii ◽  
Biofilm Production ◽  
Cotton Blue ◽  
Dynamic Growth

ABSTRACT: Prototheca spp. have been reported as an emergent environmental mastitis pathogen in several countries. Biofilm formation is a significant factor associated with different degrees of virulence developed by many microorganisms, including Prototheca spp. The present study aimed to compare two growth conditions and two staining dyes to determine which combination was more appropriate to evaluate qualitatively and quantitatively the production of biofilm by P. zopfii. Biofilm formation was evaluated in polystyrene microplates under static and dynamic growth conditions and staining with crystal violet or cotton blue dye. All P. zopfii isolates from cows with mastitis were classified as biofilm-producers in all growth conditions and staining. The cotton blue dye proved to be more appropriate method to classify the intensity of P. zopfii biofilm production.

The ruthenium(ii)-catalyzed C–H olefination of indoles with alkynes: the facile construction of tetrasubstituted alkenes under aqueous conditions

2020 ◽  
Vol 18 (16) ◽  
pp. 3158-3163 ◽  
Author(s):  
Ming Li ◽  
Tian-Yu Yao ◽  
Sheng-Zheng Sun ◽  
Ting-Xun Yan ◽  
Li-Rong Wen ◽  
...  
Keyword(s):  
Environmentally Friendly ◽  
Mild Conditions ◽  
Aqueous Conditions

An environmentally-friendly and facile protocol for the construction of tetrasubstituted alkenes has been established with Ru(ii)-catalyzed C–H bond functionalizations under mild conditions.

scholarly journals Sustainable ppm level palladium-catalyzed aminations in nanoreactors under mild, aqueous conditions

2019 ◽  
Vol 10 (45) ◽  
pp. 10556-10561 ◽  
Author(s):  
Yitao Zhang ◽  
Balaram S. Takale ◽  
Fabrice Gallou ◽  
John Reilly ◽  
Bruce H. Lipshutz
Keyword(s):  
Mild Conditions ◽  
Palladium Catalyzed ◽  
Aqueous Conditions ◽  
Ppm Level

Greening-up aminations: a well-defined palladium pre-catalyst enables ppm-level Pd-catalyzed C–N cross couplings in water under very mild conditions. Comparisons using this protocol vs. traditional amination conditions for preparing key medicinal intermediates are demonstrated.

Iodine-mediated sulfenylation of 4-hydroxycoumarins with sulfonyl hydrazides under aqueous conditions

2018 ◽  
Vol 42 (18) ◽  
pp. 14738-14741 ◽  
Author(s):  
Zan Yang ◽  
Yueqiao Yan ◽  
An Li ◽  
Jiashu Liao ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Metal Free ◽  
Mild Conditions ◽  
Aqueous Conditions

An efficient, metal-free approach to the synthesis of sulfenylated coumarins based on the iodine catalyzed regioselective sulfenylation of 4-hydroxycoumarins with arylsulfonyl hydrazides was developed under mild conditions in water.

Biocatalyst-Initiated Ortho-Quinone Methide Formation and Derivatization

2019 ◽  
Author(s):  
Tyler Doyon ◽  
Jonathan Perkins ◽  
Summer A. Baker Dockrey ◽  
Kevin Skinner ◽  
Paul M. Zimmerman ◽  
...  
Keyword(s):  
Reactive Intermediates ◽  
Heme Iron ◽  
Quinone Methide ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Non Heme Iron ◽  
Common Strategy ◽  
Aqueous Conditions ◽  
Ortho Cresol

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

scholarly journals Fast room temperature lability of aluminosilicate zeolites

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Christopher J. Heard ◽  
Lukas Grajciar ◽  
Cameron M. Rice ◽  
Suzi M. Pugh ◽  
Petr Nachtigall ◽  
...  
Keyword(s):  
Liquid Water ◽  
Solid State Nmr ◽  
Room Temperature ◽  
Isotopic Substitution ◽  
Zeolite Framework ◽  
Covalent Bonds ◽  
Mild Conditions ◽  
The Stability ◽  
Aqueous Conditions ◽  
Zeolitic Framework

Abstract Aluminosilicate zeolites are traditionally used in high-temperature applications at low water vapour pressures where the zeolite framework is generally considered to be stable and static. Increasingly, zeolites are being considered for applications under milder aqueous conditions. However, it has not yet been established how neutral liquid water at mild conditions affects the stability of the zeolite framework. Here, we show that covalent bonds in the zeolite chabazite (CHA) are labile when in contact with neutral liquid water, which leads to partial but fully reversible hydrolysis without framework degradation. We present ab initio calculations that predict novel, energetically viable reaction mechanisms by which Al-O and Si-O bonds rapidly and reversibly break at 300 K. By means of solid-state NMR, we confirm this prediction, demonstrating that isotopic substitution of 17O in the zeolitic framework occurs at room temperature in less than one hour of contact with enriched water.

scholarly journals HYDROPHOBIC COATINGS ON CELLULOSE MATERIALS

2018 ◽  
Vol 13 (6) ◽  
pp. 28-34
Author(s):  
O. V. Baranov ◽  
L. G. Komarova ◽  
A. V. Rushevskaya ◽  
V. I. Gomzayk
Keyword(s):  
Moisture Absorption ◽  
Ethanol Solution ◽  
Hydroxyl Groups ◽  
Optimal Conditions ◽  
Hydrophobic Coatings ◽  
Small Thickness ◽  
Mild Conditions ◽  
Modified Layer ◽  
Cellulose Materials ◽  
Modified Cellulose

A new hydrophobizator - tetra(ethoxy)di(octyl)disiloxane (TEDODS) - was synthesized in an ethanol solution at boiling point for 6 hours and characterized by NMR and IR spectroscopy. New hydrophobic coatings based on this compound were obtained under mild conditions by direct chemical modification of the surfaces of the cellulose materials (textile of different composition). The formation of a modified layer on the materials surface occurs due to the interaction of the ethoxy groups of the modifier and the hydroxyl groups of cellulose followed by heat treatment to fix it on the materials surface. The optimal conditions for obtaining the coatings were determined: 8% TEDODS weight gain with maximum hydrophobicity, with a wetting angle of 135°. The properties of the modified cellulose materials were studied (hydrophobicity, moisture absorption, etc.). The efficiency of using tetraethoxydioctyldisiloxane as a hydrophobizator when the content from 1% and a relatively small thickness of the coating of 2 microns was shown. It was found that hydrophobic coatings on the surface of cellulosic materials have little effect on moisture absorption and breathability of the original tissue.

scholarly journals Chemoenzymatic ortho-quinone methide formation

2019 ◽  
Author(s):  
Tyler Doyon ◽  
Jonathan Perkins ◽  
Summer A. Baker Dockrey ◽  
Evan O. Romero ◽  
Kevin Skinner ◽  
...  
Keyword(s):  
Reactive Intermediates ◽  
Heme Iron ◽  
Quinone Methide ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Non Heme Iron ◽  
Common Strategy ◽  
Aqueous Conditions ◽  
Ortho Cresol

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

Biocatalyst-Initiated Ortho-Quinone Methide Formation and Derivatization

2019 ◽  
Author(s):  
Tyler Doyon ◽  
Jonathan Perkins ◽  
Summer A. Baker Dockrey ◽  
Kevin Skinner ◽  
Paul M. Zimmerman ◽  
...  
Keyword(s):  
Reactive Intermediates ◽  
Heme Iron ◽  
Quinone Methide ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Non Heme Iron ◽  
Common Strategy ◽  
Aqueous Conditions ◽  
Ortho Cresol

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

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