A Parameter Study of Ultrasound Assisted Enzymatic Esterification

2021 ◽  
Author(s):  
Anamaria Vartolomei ◽  
Ioan Calinescu ◽  
Mircea Vinatoru ◽  
Adina Ionuta Gavrila
Keyword(s):  
Enzyme Activity ◽  
Flow Rate ◽  
Reaction Times ◽  
Isoamyl Acetate ◽  
Parameter Study ◽  
Enzymatic Esterification ◽  
Equilibrium Concentrations ◽  
Ultrasound Assisted ◽  
Reaction Concentration ◽  
Short Time

Abstract This work is focused on the study of esterification parameters for the ultrasound assisted synthesis of isoamyl acetate catalyzed by lipase Lipozyme 435 in a continuous loop reactor. Investigating the influence of different parameters shows that a higher concentration of ester (462 mg/gmixture) can be obtained at temperature 50 °C, flow rate 0.16 mL/min. The best ultrasonication conditions are: continuously applied sonication for a short time (20 minutes), ultrasound power 32 mW, and amplitude 20 %. The enzyme can be successfully reused tree times without loss of enzyme activity. Reaction kinetics for isoamyl acetate ultrasound assisted production showed that satisfactory reaction concentration (close to the equilibrium concentrations) could be reached in short reaction times (2 h). Ultrasound assisted enzymatic esterification is consequently a cleaner and a faster process.

scholarly journals Amide-Type Substrates in the Synthesis of N-Protected 1-Aminomethylphosphonium Salts

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 552
Author(s):  
Dominika Kozicka ◽  
Paulina Zieleźny ◽  
Karol Erfurt ◽  
Jakub Adamek
Keyword(s):  
Reaction Times ◽  
The Other ◽  
Hydroxyl Group ◽  
Other Hand ◽  
Step Procedure ◽  
Higher Temperature ◽  
Short Time ◽  
Work Up

Herein we describe the development and optimization of a two-step procedure for the synthesis of N-protected 1-aminomethylphosphonium salts from imides, amides, carbamates, or lactams. Our “step-by-step” methodology involves the transformation of amide-type substrates to the corresponding hydroxymethyl derivatives, followed by the substitution of the hydroxyl group with a phosphonium moiety. The first step of the described synthesis was conducted based on well-known protocols for hydroxymethylation with formaldehyde or paraformaldehyde. In turn, the second (substitution) stage required optimization studies. In general, reactions of amide, carbamate, and lactam derivatives occurred at a temperature of 70 °C in a relatively short time (1 h). On the other hand, N-hydroxymethylimides reacted with triarylphosphonium salts at a much higher temperature (135 °C) and over longer reaction times (as much as 30 h). However, the proposed strategy is very efficient, especially when NaBr is used as a catalyst. Moreover, a simple work-up procedure involving only crystallization afforded good to excellent yields (up to 99%).

scholarly journals Measurement of 1-aspartamido-β-N-acetylglucosamine amidohydrolase activity in human tissues

1977 ◽  
Vol 163 (1) ◽  
pp. 9-14 ◽  
Author(s):  
B Dugal
Keyword(s):  
Enzyme Activity ◽  
Incubation Time ◽  
Human Liver ◽  
Enzyme System ◽  
Total Concentration ◽  
Reaction Times ◽  
Human Tissues ◽  
Human Organs ◽  
Crude Homogenate ◽  
Enzyme Fraction

The activity of 1-aspartamido-beta-N-acetylglucosamine amidohydrolase (aspartylglucosylaminase, EC 3.5.1.26) was measured in normal and diseased human liver, brain and kidney. Organs from patients with aspartylglucosaminuria show very little activity. Crude homogenates of human organs show a reaction catalysed by a complex enzyme system. With homogenate, the formation of product was linear with time up to about 6 h. Reaction times longer than 6-7h resulted in a decrease in the total concentration of product. This phenomenon was not found with the partially purified enzyme fraction. Linearity of the enzyme activity with different protein concentrations was found, independent of the incubation time. Longer incubation of the crude homogenate resulted in the utilization of the product, N-acetylglucosamine. This phenomenon was not observed with the partially purified enzyme fraction. This amidase from human organs differs from that obtained from other sources and apparently represents a rather complex enzyme system.

scholarly journals Evaluation of Process Conditions for Ultrasonic Spray-Freeze Drying of Transglutaminase

2020 ◽  
Vol 58 (1) ◽  
pp. 38-48
Author(s):  
Hilal Isleroglu ◽  
Izzet Turker
Keyword(s):  
Enzyme Activity ◽  
Flow Rate ◽  
Freeze Drying ◽  
Desirability Function ◽  
Spherical Particles ◽  
Optimum Process ◽  
Process Conditions ◽  
Plate Temperature ◽  
Ultrasonic Spray ◽  
Spray Freeze Drying

In this study, a commercial transglutaminase enzyme was dried using an ultrasonic spray freeze drying method and the effects of the process conditions were optimized to maximize the final transglutaminase activity. Accordingly, process parameters affecting enzyme activity were selected, such as nozzle frequency (48 and 120 kHz), flow rate (2, 5 and 8 mL/min) and plate temperature for secondary drying (25, 35 and 45 °C). Moreover, the effects of different pH values (pH=2.0 and 9.0) and high temperature (80 °C) on enzyme activity, physical properties and particle morphology of transglutaminase were discussed. According to the results, transglutaminase preserved its activity despite ultrasonic spray freeze drying. Sonication enhanced the enzyme activity. Using the desirability function method, the optimum process conditions were determined to be flow rate 3.10 mL/min, plate temperature 45 °C and nozzle frequency 120 kHz. The predicted activity ratio was 1.17, and experimentally obtained ratio was 1.14±0.02. Furthermore, enzyme produced by ultrasonic spray freeze drying had low moisture values (2.92-4.36 %) at 8 h of drying. When the morphological structure of the transglutaminase particles produced by ultrasonic spray freeze drying under the optimum conditions was examined, spherical particles with pores on their surfaces were observed. In addition, flow properties of the transglutaminase powders were considered as fair under most conditions according to the Carr index.

Optimization of Biodiesel Ultrasound-Assisted Synthesis from Castor Oil Using Response Surface Methodology (RSM)

2015 ◽  
Vol 10 (2) ◽  
pp. 123-133 ◽  
Author(s):  
Mohammadreza Sabzimaleki ◽  
Barat Ghobadian ◽  
Mohsen Mazloom Farsibaf ◽  
Gholamhassan Najafi ◽  
Masoud Dehghani Soufi ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Reaction Time ◽  
Response Surface ◽  
Castor Oil ◽  
Molar Ratio ◽  
Reaction Yield ◽  
Ultrasound Assisted ◽  
Short Time ◽  
The Relationship ◽  
Central Composite

Abstract Production of biodiesel from castor oil (CO) using ultrasound-assisted has been investigated in this study. The objective of the present work was therefore to determine the relationship between various important parameters of the alkaline-catalyzed transesterification process to obtain a high reaction yield in a short time. The response surface methodology (RSM) was used to statistically analyze and optimize the operating parameters of the process. A central composite design (CCD) was approved to study the effects of the reaction time, the methanol to oil molar ratio, the ultrasonic cycle and the ultrasonic amplitude on reaction yield. The optimum conditions for alkaline-catalyzed transesterification of CO was found to be a reaction time of 540 s, methanol to oil molar ratio of 8.15:1,ultrasonic cycle of 0.73% and ultrasonic amplitude 64.34%. By exerting the calculated optimum condition in the process, the reaction yield reached 87.0494%. The results from the RSM analysis indicated that the reaction time has the most significant effect on the reaction yield.

scholarly journals Tannase Production by Aspergillus niger

2007 ◽  
Vol 4 (2) ◽  
pp. 192-198 ◽  
Author(s):  
N. Lokeswari ◽  
K. Jaya Raju
Keyword(s):  
Enzyme Activity ◽  
Aspergillus Niger ◽  
Gallic Acid ◽  
Incubation Period ◽  
Pollution Control ◽  
Glucose Concentration ◽  
Culture Broth ◽  
Mole Percent ◽  
Percent Conversion ◽  
Short Time

A method for assay of microbial tannase (Tannin acyl hydrolase) based on the formation of chromogen between gallic acid and rhodanine is reported. Maximum Tannase production occurred in the culture broth containing 1-2% (w/v) tannic acid and 0.05 – 0.1% (w/v) glucose. The pH, incubation period, temperature and Glucose concentration optima of Tannase production was found at 5.5, 36 h, 35°C and 0.5% respectively. These properties make the enzyme suitable for pollution control and bioprocess industry. This assay is very simple, reproducible, and very convenient, and with it Tannase activity can be measured in relation to the growth of the organism. Aspergillus niger exhibited higher enzyme activity showing about 65 mole percent conversion respectively after a 36 h incubation period. The assay is complete in a short time, very convenient and reproducible.

scholarly journals Computer-Aided Rapid Establishment of Fingerprint of Xiaojin Capsule by HPLC

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hui Jiang ◽  
Yuansheng Xiao ◽  
Xingya Xue ◽  
Hongli Jin ◽  
Yang Xiang ◽  
...  
Keyword(s):  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Flow Rate ◽  
Column Temperature ◽  
Hplc Fingerprint ◽  
Computer Aided ◽  
Quality Markers ◽  
Short Time ◽  
Unsupervised Cluster Analysis

Traditional Chinese medicine (TCM) formulas have a significant clinical efficacy, and the fingerprint technology has been widely accepted to fully reveal the quality of TCM. Whereas, it is a great challenge to establish the fingerprint chromatogram which can fully reflect every single herb material in a short time. In this study, we used Xiaojin capsule (XJC) as a case and developed a rapid fingerprint method based on increasing the column temperature and flow rate simultaneously combined with computer-aided. First, the elution gradient was optimized based on the retention parameters and peak shape parameters of the four linear gradients, and then, the column temperature and flow rate were increased simultaneously to shorten the analysis time. Next, the standard fingerprint chromatogram of XJC, which can reflect every herb material, was generated. Finally, quality markers were screened through unsupervised cluster analysis and supervised orthogonal partial least squares discrimination analysis. Combining computer-aided with increasing column temperature and flow rate simultaneously can develop the rapid method for establishing HPLC fingerprint of XJC, which can fully reflect every single herb material and provide comprehensive quality control. The strategy for establishing HPLC fingerprint of TCM formula could be applied to other traditional Chinese medicine formulas and herbal medicine.

scholarly journals Improving Transport Properties of GaN-Based HEMT on Si (111) by Controlling SiH4 Flow Rate of the SiNx Nano-Mask

Coatings ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 16
Author(s):  
Jin-Ji Dai ◽  
Cheng-Wei Liu ◽  
Ssu-Kuan Wu ◽  
Sa-Hoang Huynh ◽  
Jhen-Gang Jiang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Electron Mobility ◽  
Chemical Vapor ◽  
High Electron Mobility Transistor ◽  
Threading Dislocation ◽  
High Electron ◽  
Threading Dislocation Density ◽  
Dimensional Electron Gas ◽  
Short Time ◽  
The Impact

The AlGaN/AlN/GaN high electron mobility transistor structures were grown on a Si (111) substrate by metalorganic chemical vapor deposition in combination with the insertion of a SiNx nano-mask into the low-temperature GaN buffer layer. Herein, the impact of SiH4 flow rate on two-dimensional electron gas (2DEG) properties was comprehensively investigated, where an increase in SiH4 flow rate resulted in a decrease in edge-type threading dislocation density during coalescence process and an improvement of 2DEG electronic properties. The study also reveals that controlling the SiH4 flow rate of the SiNx nano-mask grown at low temperatures in a short time is an effective strategy to overcome the surface desorption issue that causes surface roughness degradation. The highest electron mobility of 1970 cm2/V·s and sheet carrier concentration of 6.42 × 1012 cm−2 can be achieved via an optimized SiH4 flow rate of 50 sccm.

scholarly journals Ultrasound-Assisted Green Synthesis of Dialkyl Peroxides under Phase-Transfer Catalysis Conditions

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 118 ◽  
Author(s):  
Daniel Kopeć ◽  
Stefan Baj ◽  
Agnieszka Siewniak
Keyword(s):  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Reaction Times ◽  
Liquid System ◽  
Significant Loss ◽  
Multiple Use ◽  
Alkyl Hydroperoxides ◽  
Ultrasound Assisted ◽  
Dialkyl Peroxides ◽  
High Yields

The dialkyl peroxides, which contain a thermally unstable oxygen–oxygen bond, are an important source of radical initiators and cross-linking agents. New efficient and green methods for their synthesis are still being sought. Herein, ultrasound-assisted synthesis of dialkyl peroxides from alkyl hydroperoxides and alkyl bromides in the presence of an aqueous solution of an inorganic base was systematically studied under phase-transfer catalysis (PTC) conditions. The process run in a tri-liquid system in which polyethylene glycol as a phase-transfer catalyst formed a third liquid phase between the organic and inorganic phases. The use of ultrasound provided high yields of organic peroxides (70–99%) in significantly shorter reaction times (1.5 h) in comparison to reaction with magnetic stirring (5.0 h). In turn, conducting the reaction in the tri-liquid PTC system allowed easy separation of the catalyst and its multiple use without significant loss of activity.

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