scholarly journals An Enzymatic Flow-Based Preparative Route to Vidarabine

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1223 ◽  
Author(s):  
Lucia Tamborini ◽  
Clelia Previtali ◽  
Francesca Annunziata ◽  
Teodora Bavaro ◽  
Marco Terreni ◽  
...  
Keyword(s):  
Aeromonas Hydrophila ◽  
Enzymatic Synthesis ◽  
Purine Nucleoside Phosphorylase ◽  
Flow Reactor ◽  
Antiviral Drug ◽  
Molar Ratio ◽  
Uridine Phosphorylase ◽  
Flow Conditions ◽  
Reaction Parameters ◽  
Preparative Route

The bi-enzymatic synthesis of the antiviral drug vidarabine (arabinosyladenine, ara-A), catalyzed by uridine phosphorylase from Clostridium perfringens (CpUP) and a purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNP), was re-designed under continuous-flow conditions. Glyoxyl–agarose and EziGTM1 (Opal) were used as immobilization carriers for carrying out this preparative biotransformation. Upon setting-up reaction parameters (substrate concentration and molar ratio, temperature, pressure, residence time), 1 g of vidarabine was obtained in 55% isolated yield and >99% purity by simply running the flow reactor for 1 week and then collecting (by filtration) the nucleoside precipitated out of the exiting flow. Taking into account the substrate specificity of CpUP and AhPNP, the results obtained pave the way to the use of the CpUP/AhPNP-based bioreactor for the preparation of other purine nucleosides.

scholarly journals Identification and Optimisation of Lipase-Catalysed Synthesis of Betulinic Acid Amide in a Solvent System

2016 ◽  
Vol 2016 ◽  
pp. 1-5
Author(s):  
Nurul Atikah Binti Amin Yusof ◽  
Nursyamsyila Mat Hadzir ◽  
Siti Efliza Ashari
Keyword(s):  
Melting Point ◽  
Betulinic Acid ◽  
Enzymatic Synthesis ◽  
Acid Amide ◽  
Enzymatic Reaction ◽  
Solvent System ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
Reaction Parameters ◽  
Substrate Molar Ratio

Betulinic acid amide was synthesized from the enzymatic reaction of betulinic acid and butylamine catalysed by Novozym 435. The effects of different reaction parameters, such as effect of reaction time, reaction temperature, amount of enzyme, and substrate molar ratio (betulinic acid : butylamine), were studied and conventionally optimised. Based on this study, the enzymatic synthesis of betulinic acid amide was found to be 64.6% at the optimum conditions of 24 h, 40°C, 100 mg enzyme, and 1 : 1 substrate molar ratio in 9 : 1 mixture of chloroform and hexane as solvent. The identification of final product was carried out using TLC, melting point, and FTIR and NMR showed the presence of betulinic acid amide.

scholarly journals Achieving selectivity in porphyrin bromination through a DoE-driven optimization under continuous flow conditions

2020 ◽  
Author(s):  
Paolo Zardi ◽  
Michele Maggini ◽  
Tommaso Carofiglio
Keyword(s):  
Reaction Time ◽  
Design Of Experiment ◽  
Continuous Flow ◽  
Optimization Process ◽  
Porphyrin Ring ◽  
Flow Conditions ◽  
Reaction Parameters ◽  
Synthetic Procedure ◽  
Relevant Factors ◽  
Post Functionalization

AbstractThe post-functionalization of porphyrins through the bromination in β position of the pyrrolic rings is a relevant transformation because the resulting bromoderivatives are useful synthons to covalently link a variety of chemical architectures to a porphyrin ring. However, single bromination of porphyrins is a challenging reaction for the abundancy of reactive β-pyrrolic positions in the aromatic macrocycle. We herein report a synthetic procedure for the efficient preparation of 2-bromo-5,10,15,20-tetraphenylporphyrin (1) under continuous flow conditions. The use of flow technology allows to reach an accurate control over critical reaction parameters such as temperature and reaction time. Furthermore, by performing the optimization process through a statistical DoE (Design of Experiment) approach, these parameters could be properly adjusted with a limited number of experiments. This process led us to a better understanding of the relevant factors that govern porphyrins monobromination and to obtain compound 1 with an unprecedent 80% yield.

scholarly journals Immobilization of an Iridium(I)-NHC-Phosphine Catalyst for Hydrogenation Reactions under Batch and Flow Conditions

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 656
Author(s):  
Henrietta Kovács ◽  
Krisztina Orosz ◽  
Gábor Papp ◽  
Ferenc Joó ◽  
Henrietta Horváth
Keyword(s):  
Catalytic Activity ◽  
Ion Exchange ◽  
Heterogeneous Catalyst ◽  
Aqueous Phase ◽  
Levulinic Acid ◽  
Flow Reactor ◽  
High Catalytic Activity ◽  
Flow Conditions ◽  
Hydrogenation Reactions ◽  
Excellent Selectivity

Na2[Ir(cod)(emim)(mtppts)] (1) with high catalytic activity in various organic- and aqueous-phase hydrogenation reactions was immobilized on several types of commercially available ion-exchange supports. The resulting heterogeneous catalyst was investigated in batch reactions and in an H-Cube flow reactor in the hydrogenation of phenylacetylene, diphenylacetylene, 1-hexyne, and benzylideneacetone. Under proper conditions, the catalyst was highly selective in the hydrogenation of alkynes to alkenes, and demonstrated excellent selectivity in C=C over C=O hydrogenation; furthermore, it displayed remarkable stability. Activity of 1 in hydrogenation of levulinic acid to γ-valerolactone was also assessed.

Enzymatic Synthesis of Eugenyl Acetate from Essential Oil of Clove Using Lipases in Liquid Formulation as Biocatalyst

2021 ◽  
Author(s):  
Leandro Santolin ◽  
Karina G. Fiametti ◽  
Viviane da Silva Lobo ◽  
João H. C. Wancura ◽  
José Vladimir Oliveira
Keyword(s):  
Essential Oil ◽  
Acetic Anhydride ◽  
Enzymatic Synthesis ◽  
Molar Ratio ◽  
Syzygium Aromaticum ◽  
Liquid Formulation ◽  
Promising Alternative ◽  
Eugenyl Acetate ◽  
Extensive Evaluation ◽  
Pharmaceutical Industries

Abstract In this research, eugenyl acetate, a compound with flavoring, antioxidant and antimicrobial properties, was obtained from essential oil of clove (Syzygium aromaticum) via liquid lipase-mediated acetylation. Clove essential oil was extracted by drag water vapor from dry flower buds and its physic-chemical characteristics were analyzed. For the enzymatic synthesis, an extensive evaluation of reaction parameters was accomplished through employment of distinct reaction temperatures, acetic anhydride to eugenol molar ratios, enzyme loads and three different lipases (a lyophilized enzyme produced by solid-state fermentation of sunflower seed with Penicillium sumatrense microorganism and others two commercial lipases – Lipozyme TL 100L and CALB L). Characterization by Infrared Spectroscopy and Nuclear Magnetic Resonance (1H NMR and 13C) was used to confirm the presence of eugenyl acetate in the samples. Through optimized conditions (55 °C, acetic anhydride to eugenol molar ratio of 1:1, 10 wt% of Lipozyme TL 100L), 91.80 % of conversion after 2 h was achieved to the eugenyl acetate production. With the results obtained, it was possible to conclude that the use of lipases in liquid formulation is a promising alternative for the synthesis of essential esters largely applied on food, cosmetic and pharmaceutical industries.

Vapor-phase oxidation of propylene glycol-methanol mixture to methyl lactate on CeO2/Al2O3 catalyst

2021 ◽  
pp. 92-97
Author(s):  
M.E. Sharanda ◽  
◽  
A.M. Mylin ◽  
O.Yu. Zinchenko ◽  
V.V. Brei ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
Vapor Phase ◽  
Flow Reactor ◽  
Aldol Condensation ◽  
Ethyl Lactate ◽  
Molar Ratio ◽  
Methyl Lactate ◽  
Reactor Inlet ◽  
Phase Oxidation ◽  
Al2o3 Catalyst

The vapor-phase oxidation of mixtures of propylene glycol with methanol and ethanol to methyl and ethyl lactate, respectively, on supported CeO2/Al2O3 catalyst with 10 wt.% CeO2 content was studied. The steel flow reactor with a fixed catalyst bed (4 cm3) was used. 20 wt.% solution of propylene glycol in alcohol was fed to the reactor inlet by Waters 950 pump at LHSV= 0.5-0.8 h-1. Reaction temperature and pressure were varied in the interval of 190-250 0C and 1.3-1.8 bars respectively. Compressed air was given to the reactor inlet at the molar ratio of propylene glycol/O2 = 1. The reaction products were analyzed using gas chromatography (Agilent 7820A) and 3C NMR (Bruker Avance 400) methods. Studied oxidation of propylene glycol in the presence of methanol describes by total reaction CH3CHOHCH2OH +O2 + СН3OH = CH3CHOHCOOСН3 +2H2O At first, hydroxyacetone is formed that is further oxidized to pyruvic aldehyde, which attaches alcohol to form hemiacetal. Then, hemiacetal of methyl glyoxal rearranges into methyl lactate by Cannizzaro. At 220 0C and load on a catalyst of < 2 mmol PG/gcat/h, the selectivity towards methyl lactate reaches 70 wt.% at 100 % propylene glycol conversion. The main by-products are formed as the result of acetaldehyde transformation. Acetaldehyde could be formed at hydroxyacetone aldol decondensation. In the presence of ethanol, the formation of a significant amount of acetaldehyde and its aldol condensation products as well as the formation of diethoxyethane are observed. Therefore, ethyl lactate selectivity at 100 % propylene glycol conversion does not exceed 45 %. Supported CeO2/SiO2 contact was tested in this oxidation reaction also. However, CeO2/SiO2 provides the low, up to 25%, selectivity towards methyl lactate at full propylene glycol conversion. It was shown that at the same conditions methyl lactate is formed with higher selectivity then ethyl lactate. The high methyl lactate yield up to 70 wt.% could be obtained via vapor-phase oxidation of 20% mixture of propylene glycol with methanol by air oxygen on supported CeO2/Al2O3 catalyst at 210 - 220°С and at time contact of 3-4 seconds.

Heterogeneous Microwave Irradiation Biodiesel Processing of Jatropha Oil

2014 ◽  
Vol 554 ◽  
pp. 500-504 ◽  
Author(s):  
Farid Nasir Ani ◽  
Ahmed Bakheit Elhameed
Keyword(s):  
Reaction Time ◽  
Methyl Ester ◽  
Microwave Irradiation ◽  
Calcium Oxide ◽  
Production Cost ◽  
Catalyst Concentration ◽  
Molar Ratio ◽  
Biodiesel Fuel ◽  
Jatropha Oil ◽  
Reaction Parameters

This paper investigated the three critical reaction parameters including catalyst concentration, microwave exit power and reaction time for the transesterification process of jatropha curcas oil using microwave irradiation. The work is an attempt to reduce the production cost of biodiesel. Similar quantities of methanol to oil molar ratio 6:1 and calcium oxide as a heterogeneous catalyst were used. The results showed that the best yield percentage 96% was obtained using 300W microwave exit power, 8 %wt CaO and 7 min. The methyl ester FAME obtained was within the standard of biodiesel fuel.

scholarly journals A facile and effective method for preparation of 2.5-furandicarboxylic acid via hydrogen peroxide direct oxidation of 5-hydroxymethylfurfural

2017 ◽  
Vol 19 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Shuang Zhang ◽  
Long Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Time ◽  
Oxidation Mechanism ◽  
Molar Ratio ◽  
Alkaline Condition ◽  
Optimal Parameters ◽  
Direct Oxidation ◽  
Reaction Parameters ◽  
Alkaline Conditions ◽  
Furandicarboxylic Acid

Abstract In this paper, 2,5-furandicarboxylic acid (FDCA) was efficiently prepared by the direct oxidation of 5-hydroxymethylfurfural (5-HMF) using hydrogen peroxide (H2O2) in alkaline conditions without any catalysts. The effects of reaction parameters on the process were systematically investigated and the optimal parameters were obtained as follows: molar ratio of 5-HMF:KOH:H2O2 was 1:4:8, reaction temperature and reaction time were determined as 70°C and 15 minutes, respectively. Under these conditions, the yield of FDCA was 55.6% and the purity of FDCA could reach 99%. Moreover, we have speculated the detailed oxidation mechanism of 5-HMF assisted by hydrogen peroxide in alkaline condition to synthesize FDCA.

scholarly journals A STATISTICAL APPROACH FOR OPTIMIZING THE HIGH YIELD GREEN PRODUCTION OF THE FLAVOR ESTER BUTYL BUTYRATE

2017 ◽  
Vol 79 (7) ◽  
Author(s):  
Ida Nurhazwani Abd Rahman ◽  
Fatin Myra Abd Manan ◽  
Nur Haziqah Che Marzuki ◽  
Naji A. Mahat ◽  
Nursyafreena Attan ◽  
...  
Keyword(s):  
Molar Ratio ◽  
High Yield ◽  
Esterification Reaction ◽  
Reaction Parameters ◽  
Chemical Route ◽  
Butyl Butyrate ◽  
Novozyme 435 ◽  
Yield Production ◽  
Green Production ◽  
Percentage Conversion

Being the prevailing approach for producing esters such as butyl butyrate, the use of chemical route has been linked to numerous disadvantages. Hence, a green alternative method for higher yield production of butyl butyrate by esterification reaction utilizing Novozyme 435 as biocatalysts in a solvent-less system may prove useful. Such approach can be further improved by optimizing the relevant reaction parameters using the Response Surface Methodology by the Box-Benkhen Design attempted in this present study. The reaction parameters evaluated were: substrate molar ratio, time and temperature, and the response of each parameter was measured as percentage conversion yield. Using the Design Expert 7.1.6 optimization functions, the two sets of optimum conditions selected viz. [i] molar ratio butyric acid:butanol 1:3.93, 9.93 h at 56.09°C and [ii] molar ratio butyric acid:butanol 1:3.35, 9.79 h at 53.90°C had afforded the highest yield of butyl butyrate i.e. 99.62% and 99.55%, respectively. The ester product obtained from the reaction were confirmed as butyl butyrate by FTIR and GC. Therefore, the results substantiated the applicability of the RSM prediction technique as well as efficacy of Novozyme 435 as biocatalysts in the high yield solvent-less synthesis of butyl butyrate, adhering to the philosophy of Green Chemistry.

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