scholarly journals ENZYMATIC PRODUCTION OF ETHYL OLEATE ESTER USING A LIPASE FROM CANDIDA ANTARCTICA B

2012 ◽  
Vol 2 ◽  
pp. 21
Author(s):  
N. Sampaio Neta ◽  
J. A. C. Cunha ◽  
S. O. Sancho ◽  
R. F. A. Abreu ◽  
D. F. Pontes ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Sodium Sulfate ◽  
Ethyl Oleate ◽  
Reaction Times ◽  
Candida Antarctica ◽  
Enzymatic Esterification ◽  
Type B ◽  
Enzymatic Production ◽  
Wide Range ◽  
Candida Antarctica B

Lipases are biocatalysts of great importance in different areas, being able to catalyze reactions in aqueous or organic media. Furthermore, these enzymes are capable of using several substrates being stable in a wide range of pH and temperatures. Lipases promote the esterification between fatty acids and ethanol producing oleate esters. The aim of this work is to produce ethyl oleate ester by enzymatic esterification of oleic acid with ethanol. A lipase from Candida antarctica type B was used at a temperature of 55 °C. The reaction was conducted using oleic acid, sodium sulfate anhydrous, lipase and ethanol, with a ratio of oleic acid (0.03 mol or 10 ml), lipase (0.1 mol or 0.01 g), sodium sulfate anhydrous (5 g) and ethanol 99 % (100 ml). Several reaction times were studied, namely 48, 72, 96 and 120 hours. Nuclear Magnetic Resonance (1H and 13C) and Infrared spectra confirmed the production of ethyl oleate ester for the studied conditions. The highest ethyl oleate production yield was obtained for 96 hours reaction time. Ethyl oleate esters have been reported to possess interesting applications in several industrial fields, such as food, aromatics, cosmetics, detergents, flavors and pharmaceuticals.

Enzymatic Esterification of Oleic Acid with Aliphatic Alcohols for the Biodiesel Production by Candida antarctica Lipase

2013 ◽  
Vol 143 (9) ◽  
pp. 863-872 ◽  
Author(s):  
Isac G. Rosset ◽  
Maria Cecília H. T. Cavalheiro ◽  
Elisabete M. Assaf ◽  
André L. M. Porto
Keyword(s):  
Oleic Acid ◽  
Candida Antarctica ◽  
Aliphatic Alcohols ◽  
Biodiesel Production ◽  
Enzymatic Esterification ◽  
Candida Antarctica Lipase

scholarly journals Immobilization of Candida antarctica B (CALB) in Silica Aerogel: Morphological Characteristics and Stability

2020 ◽  
Vol 10 (6) ◽  
pp. 6744-6756 ◽  
Keyword(s):  
Sol Gel ◽  
Morphological Characteristics ◽  
Amorphous Structure ◽  
Industrial Applications ◽  
Candida Antarctica ◽  
Type Iv ◽  
Wide Range ◽  
The Stability ◽  
Immobilized Calb ◽  
Candida Antarctica B

Enzymes have been extensively used due to their catalytic properties, and immobilization is a promising technique to enhance their catalytic activity and stability. Lipases are enzymes naturally efficient, can be employed for the production of many different molecules, and have a wide range of industrial applications thanks to their broad selectivity. The objective of the present study was to characterize the Candida antarctica B CALB immobilized obtained using the aerogel technique regarding the morphological characteristics of the aerogel silica and its stability. For this purpose, analyzes of XRD, adsorption-desorption isotherms, TGA, SEM, and stability (storage, operational, and thermal) were performed. The supports obtained have an amorphous structure and isotherm type IV. Regarding TGA, two distinct regions were obtained and studied. Aerogels showed an increase in thermal, storage, and operational stability in relation to the free enzyme and demonstrated between 8 and 12 cycles of reuse. The contribution of this work was to present the stability advantages of the immobilized CALB enzyme through the sol-gel technique.

Advances in Triazole Synthesis from Copper-catalyzed Azide-alkyne Cycloadditions (CuAAC) Based on Eco-friendly Procedures

2019 ◽  
Vol 16 (2) ◽  
pp. 244-257 ◽  
Author(s):  
Marcus Vinicius Nora de Souza ◽  
Cristiane França da Costa ◽  
Victor Facchinetti ◽  
Claudia Regina Brandão Gomes ◽  
Paula Mázala Pacheco
Keyword(s):  
Biological Activities ◽  
Reaction Times ◽  
Water Extract ◽  
Fish Bone ◽  
New Drugs ◽  
Bone Powder ◽  
Wide Range ◽  
Recoverable Catalysts ◽  
Egg Shell ◽  
Work Up

Background: 1,2,3-triazoles are an important class of organic compounds and because of their aromatic stability, they are not easily reduced, oxidized or hydrolyzed in acidic and basic environments. Moreover, 1,2,3-triazole derivatives are known by their important biological activities and have drawn considerable attention due to their variety of properties. The synthesis of this nucleus, based on the click chemistry concept, through the 1,3-dipolar addition reaction between azides and alkynes is a well-known procedure. This reaction has a wide range of applications, especially on the development of new drugs. Methods: The most prominent eco-friendly methods for the synthesis of triazoles under microwave irradiation published in articles from 2012-2018 were reviewed. Results: In this review, we cover some of the recent eco-friendly CuAAC procedures for the click synthesis of 1,2,3-triazoles with remarks to new and easily recoverable catalysts, such as rhizobial cyclic β-1,2 glucan; WEB (water extract of banana); biosourced cyclosophoraose (CyS); egg shell powder (ESP); cyclodextrin (β- CD); fish bone powder; nanoparticle-based catalyst, among others. Conclusion: These eco-friendly procedures are a useful tool for the synthesis of 1,2,3-triazoles, providing many advantages on the synthesis of this class, such as shorter reaction times, easier work-up and higher yields when compared to classical procedures. Moreover, these methodologies can be applied to the industrial synthesis of drugs and to other areas.

scholarly journals ChCl: Gly (DESs) Promote Environmentally Benign Synthesis of Xanthene Derivatives and Their Antitubercular Activity

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3667
Author(s):  
Mashooq A. Bhat ◽  
Ahmed M. Naglah ◽  
Siddique Akber Ansari ◽  
Hanaa M. Al-Tuwajiria ◽  
Abdullah Al-Dhfyan
Keyword(s):  
Reaction Times ◽  
Antitubercular Activity ◽  
Antimycobacterial Activity ◽  
Environmentally Benign ◽  
Reaction Yield ◽  
Benign Synthesis ◽  
Xanthene Derivatives ◽  
Wide Range ◽  
Major Application

A ChCl: Gly (DESs) promoted environmentally benign method was developed for the first time using the reaction of aryl aldehydes and dimedone to give excellent yields of xanthene analogues. The major application of this present protocol is the use of green solvent, a wide range of substrate, short reaction times, ease of recovery, the recyclability of the catalyst, high reaction yield, and ChCl: Gly as an alternative catalyst and solvent. In addition to this, all the synthesized compounds were evaluated for their in vitro antimycobacterial activity against M. tuberculosis H37Ra (MTB) and M. bovis BCG strains. The compounds 3d, 3e, 3f, and 3j showed significant antitubercular activity against MTB and M. bovis strains with minimum inhibitory concentration (MIC) values of 2.5−15.10 µg/mL and 0.26–14.92 µg/mL, respectively. The compounds 3e, 3f, and 3j were found to be nontoxic against MCF-7, A549, HCT 116, and THP-1 cell lines. All the prepared compounds were confirmed by 1H NMR and 13C NMR analysis.

In situ immobilization of Candida antarctica B lipase in polyurethane foam support

2016 ◽  
Vol 124 ◽  
pp. 52-61 ◽  
Author(s):  
Nadia Ligianara D. Nyari ◽  
Ilizandra A. Fernandes ◽  
Cindy E. Bustamante-Vargas ◽  
Clarisse Steffens ◽  
Débora de Oliveira ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Candida Antarctica ◽  
In Situ Immobilization ◽  
Candida Antarctica B ◽  
Candida Antarctica B Lipase

scholarly journals Ureido Functionalization through Amine-Urea Transamidation under Mild Reaction Conditions

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1583
Author(s):  
Natalia Guerrero-Alburquerque ◽  
Shanyu Zhao ◽  
Daniel Rentsch ◽  
Matthias M. Koebel ◽  
Marco Lattuada ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Reaction Times ◽  
Reaction Rates ◽  
Secondary Amines ◽  
Isocyanic Acid ◽  
Advantages And Disadvantages ◽  
Major Disadvantage ◽  
Wide Range ◽  
Potential Alternative ◽  
Full Conversion

Ureido-functionalized compounds play an indispensable role in important biochemical processes, as well as chemical synthesis and production. Isocyanates, and KOCN in particular, are the preferred reagents for the ureido functionalization of amine-bearing compounds. In this study, we evaluate the potential of urea as a reagent to graft ureido groups onto amines at relatively low temperatures (<100 °C) in aqueous media. Urea is an inexpensive, non-toxic and biocompatible potential alternative to KOCN for ureido functionalization. From as early as 1864, urea was the go-to reagent for polyurea polycondensation, before falling into disuse after the advent of isocyanate chemistry. We systematically re-investigate the advantages and disadvantages of urea for amine transamidation. High ureido-functionalization conversion was obtained for a wide range of substrates, including primary and secondary amines and amino acids. Reaction times are nearly independent of substrate and pH, but excess urea is required for practically feasible reaction rates. Near full conversion of amines into ureido can be achieved within 10 h at 90 °C and within 24 h at 80 °C, and much slower reaction rates were determined at lower temperatures. The importance of the urea/amine ratio and the temperature dependence of the reaction rates indicate that urea decomposition into an isocyanic acid or a carbamate intermediate is the rate-limiting step. The presence of water leads to a modest increase in reaction rates, but the full conversion of amino groups into ureido groups is also possible in the absence of water in neat alcohol, consistent with a reaction mechanism mediated by an isocyanic acid intermediate (where the water assists in the proton transfer). Hence, the reaction with urea avoids the use of toxic isocyanate reagents by in situ generation of the reactive isocyanate intermediate, but the requirement to separate the excess urea from the reaction product remains a major disadvantage.

scholarly journals Severe violations of independence in response inhibition tasks

2021 ◽  
Vol 7 (12) ◽  
pp. eabf4355
Author(s):  
Patrick G. Bissett ◽  
Henry M. Jones ◽  
Russell A. Poldrack ◽  
Gordon D. Logan
Keyword(s):  
Response Inhibition ◽  
Theoretical Foundation ◽  
Reaction Times ◽  
Stop Signal ◽  
Experimental Paradigm ◽  
Signal Delay ◽  
Independence Assumption ◽  
Analysis Techniques ◽  
Wide Range ◽  
Saccadic Responses

The stop-signal paradigm, a primary experimental paradigm for understanding cognitive control and response inhibition, rests upon the theoretical foundation of race models, which assume that a go process races independently against a stop process that occurs after a stop-signal delay (SSD). We show that severe violations of this independence assumption at short SSDs occur systematically across a wide range of conditions, including fast and slow reaction times, auditory and visual stop signals, manual and saccadic responses, and especially in selective stopping. We also reanalyze existing data and show that conclusions can change when short SSDs are excluded. Last, we suggest experimental and analysis techniques to address this violation, and propose adjustments to extant models to accommodate this finding.

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