Monitoring technical lignin partition in aqueous/alcohol biphasic systems according to pH: influences of the molecular structure and solvent characteristics

2020 ◽  
Vol 22 (20) ◽  
pp. 7031-7046
Author(s):  
Quentin Schmetz ◽  
Claire Muzyka ◽  
Thomas Berchem ◽  
Aurore Richel
Keyword(s):  
Molecular Structure ◽  
Aqueous Phase ◽  
Aqueous Alcohol ◽  
Technical Lignin ◽  
Biphasic Systems

This study deals with the comprehension of lignin partition in biphasic systems constituted of an alkaline aqueous phase containing dissolved lignin and a non-miscible alcohol phase.

scholarly journals Theoretical investigation of the molecular structure and molecular docking of naratriptan

2020 ◽  
Vol 85 (10) ◽  
pp. 1291-1301
Author(s):  
Wendolyne López-Orozco ◽  
Reyes Rios ◽  
Huizar Mendoza
Keyword(s):  
Molecular Structure ◽  
Molecular Docking ◽  
Aqueous Phase ◽  
Chemical Study ◽  
Docking Studies ◽  
Reactivity Descriptors ◽  
Chemical Behaviour ◽  
Global And Local ◽  
5Ht1b Receptor ◽  
Local Reactivity Descriptors

In this work, a computational chemical study of the naratriptan was carried out at the X/DGDZVP (where X = B3LYP, M06, M06L and ?B97XD) level of theory, the results suggest the existence of two possible conformers in the aqueous phase. The evaluation of the global and local reactivity descriptors indicates that both conformers show the same chemical behaviour. The docking studies reveal that both conformers bind to TYR359 residue of the 5HT1B receptor. Also, the first conformer binds to the receptor through THR209 and THR213 while the second one through THR209 and SER 212.

Biphasic Reaction Engineering

2001 ◽  
Author(s):  
L. K. Doraiswamy
Keyword(s):  
Organic Solvent ◽  
Aqueous Phase ◽  
Homogeneous Catalysis ◽  
Enzymatic Catalysis ◽  
Immobilized Enzymes ◽  
Organic Reactions ◽  
Biphasic Reaction ◽  
Catalyzed Reactions ◽  
Biphasic Systems ◽  
Enzyme Catalyzed Reactions

The chemical equilibria of many industrially important organic reactions in aqueous solutions are often displaced in the direction of the reactants, leading to very low conversions. Therefore, there is a need for an environmentally friendly strategy that will shift the equilibria toward the products, resulting in enhanced conversions. A particularly effective technique is to add a second phase, appropriately termed biphasing. In general, biphasing is the intentional addition of an immiscible phase to a reaction mixture to increase the yield of the desired product or to facilitate separation of product from (say) catalyst. Much of the effort till recently has been on adding a water-immiscible organic solvent in enzyme-catalyzed organic reactions in the aqueous phase. Although strictly the term biphasing should apply only to soluble catalysts, thus preserving the purity of its definition, in practice it also includes insoluble catalysts such as immobilized enzymes (which would constitute a third phase). Biphasing received an exciting stimulus around 1984 when it was used to overcome the inherent and perhaps the most telling deficiency of homogeneous catalysis. By biphasing with an aqueous phase (unlike in enzymatic catalysis where the biphasing liquid is an organic solvent), the catalyst was fully retained in that phase, whereas the product (and unused reactant) remained in the organic phase. The consequent easy separation of catalyst from product added a new dimension to homogeneous catalysis that gives it a decided edge over its heterogeneous counterpart for many reactions. Yet another dimension to biphasing was added in the last decade when it was found that both phases could be aqueous. This variant of traditional biphasing has many obvious advantages. Although still in its infancy, its enormous potential is not difficult to visualize. The chief advantages and disadvantages of biphasing are listed in Table 18.1. We begin our treatment of biphasing by developing the theoretical foundation for predicting an apparent or effective equilibrium constant for a biphasic reaction. This will be done specifically for enzyme-catalyzed reactions, but it can be extended to straight organic synthesis. Several important aspects of these biphasic systems, such as solvent selection and the role of mass transfer, will be discussed.

Extraction of Zn(II), Cd(II), and Hg(II) by dodecyloligo(oxyethylene) carboxylic acids

1988 ◽  
Vol 66 (7) ◽  
pp. 1695-1700 ◽  
Author(s):  
Jerzy Strzelbicki ◽  
Witold Charewicz ◽  
Jorg Beger ◽  
Lutz Hinz
Keyword(s):  
Molecular Structure ◽  
Carboxylic Acids ◽  
Aqueous Phase ◽  
Metal Cation ◽  
High Selectivity ◽  
Extraction Process ◽  
Experimental Conditions ◽  
Chemical Equilibria ◽  
Complex Chemical ◽  
Solution Parameters

The synthesis of a series of n-dodecyloligo(oxyethylene) carboxylic acids of general formula C12H25(OCH2CH2)nOCH2COOH (n = 0 to 5) and application of these compounds for the separation of Zn(II), Cd(II), and Hg(II) in extraction are reported. Negligible extractability of the metal ions investigated was found using dodecyloxyacetic acid (n = 0) which indicated that complexation resulted from metal–cation interaction with oxygen atoms of the polyoxyethylene chain incorporated into the molecule of complexon. In extractions from aqueous solutions containing ZnCl2, CdCl2, HgCl2, and NaOH (pH regulator), loading of the organic phases increased for extractants with more oxyethylene units. In particular, Hg(II) extractability and molecular structure of the extractant are related. The selectivity of extraction increased drastically if NaCl was added to the initial aqueous phase, as the extractabilities of Cd(II) and, particularly, Hg(II) declined while the extractability of Zn(II) remained high. Selectivity of extraction is produced by the complex chemical equilibria resulted from complexation of the metal cation by an alkyloligoether carboxylic acid in the organic phase and by Cl− and OH− anions in the aqueous phase. Thus, aqueous solution parameters greatly influence the efficiency and the selectivity of the extraction process and suitable experimental conditions are very important.

scholarly journals Catalyst-Free and Highly Selective N,N-Diallylation of Anilines in Aqueous Phase

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Zhengyin Du ◽  
Xiaohong Wei ◽  
Wenwen Zhang ◽  
Yuanmin Zhang ◽  
Qunji Xue
Keyword(s):  
Aqueous Phase ◽  
Potassium Carbonate ◽  
Allyl Bromide ◽  
Alcohol Solution ◽  
Aqueous Alcohol ◽  
Tertiary Amines ◽  
Complete Conversion ◽  
Catalyst Free ◽  
Aqueous Alcohol Solution ◽  
Wide Range

A highly selective diallylation reaction of anilines with allyl bromide was achieved in aqueous alcohol solution in the presence of potassium carbonate and without the use of any catalyst. The reaction tolerates a wide range of functionalities, and various tertiary amines were obtained in the yield of up to 99% with complete conversion of anilines.

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