Insights into kinetics and reaction mechanism of acid-catalyzed transesterification synthesis of diethyl oxalate

The catalytic performance of different acidic catalysts for diethyl oxalate synthesis from the one-step transesterification of dimethyl oxalate and ethanol was evaluated.The effects of different factors(e.g.,acidity,electron accepting capacity,cations type and crystalline water)on the catalytic activity of acidic catalysts were investigated respectively.It was proposed and confirmed that the transesterification reaction catalyzed by a Lewis acid(FeCl3)and a Bronsted acid(H2SO4)follows a first-order kinetic reaction process.In addition,the Lewis acid-catalyzed transesterification processes with different ester structures were used to further explore and understand the speculated reaction mechanism.This work enriches the theoretical understanding of acid-catalyzed transesterification reactions and is of great significance for the development of highly active catalysts for diethyl oxalate synthesis,diminishing the industrial production cost of diethyl oxalate,and developing downstream bulk or high-value-added industrial products.

Synthesis of Diethyl Oxalate by a Coupling-Regeneration Reaction of Carbon Monoxide

This article describes a process for the synthesis of diethyl oxalate by a coupling reaction of carbon monoxide, catalyzed by palladium in the presence of ethyl nitrite. The kinetics and mechanism of the coupling and regeneration reaction are also discussed. This paper presents the results of a scale-up test of the catalyst and the process based on an a priori computer simulation.

Effect of Temperature on the Deactivation of a Pd-Fe/α-Al_2O_3 Catalyst for CO Coupling to Diethyl Oxalate

Destructive tests of the catalyst was carried out to study the effect oftemperature on the catalytic activity of CO coupling to diethyl oxalate (DEO) over a Pd-Fe/Al_2O_3catalyst. It was found that a temperature jump could cause the deactivation of the Pd-Fe/α-Al_2O_3catalyst. The catalyst deactivated at different temperatures has different characteristics. Afterdeactivation the crystal structure of α-Al_2O_3 did not change, but the Pd particle size wasenlarged. Most of the Pd^0 were oxidized to Pd^(2+), and Fe^(2+) was oxidized to Fe^(3+) on thesurface of the deactivated catalyst. The catalyst could be regenerated, but its original activitycould not be recovered completely.

Predication of Atmospheric VLE for the Binary System Diethyl Oxalate-Ethanol by Using Visual Basic

The atmospheric vapor-liquid equilibrium system of diethyl oxalate-ethanol was reproduced through the visual basic (VB6.0) computer language by using the Wilson, NRTL and the UNIFAC equation. The results of the three methods are all that could be desired. The calculated results of three different models are in perfect agreement with experiment data. The calculated results of UNIFAC equation is the optimum in several models. So the results can be used for chemical engineering calculation.

Highly active Pd-Fe/α-Al_(2)O_(3) catalyst with the bayberry tannin as chelating promoter for CO oxidative coupling to diethyl oxalate

A novel Pd-Fe/α-Al_(2)O_(3) catalyst was synthesized by incipient-wetness impregnation method with bayberry tannin as chelating promoter and commercial hollow column Raschig ring a-Al_(2)O_(3) as support for the synthesis of diethyl oxalate from CO and ethyl nitrite.A variety of characterization techniques including N2 physical adsorption,optical microscopy,scanning electron microscopy and energy dispersive system(SEM-EDS),inductively coupled plasma optical emission spectroscopy(ICP-OES),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),were employed to explore the relationship between the physicochemical properties and activity of catalysts.It indicated that a large number of phenolic hydroxyl groups in bayberry tannin can efficiently anchor the active component Pd,reduce the particle size and make the active Pd as a multi-ring distribution on the commercial a-Al2O3 suppo rt,which we re beneficial to improve the catalytic activity for the production of diethyl oxalate from CO and ethyl nitrite.0.3 wts Pd-Fe/α-Al_(2)O_(3) showed excelle nt catalytic activity and selectivity in a continuous flow,fixed-bed reactor with the loading amount of 10 mL catalysts,Under the mild reaction conditions,the space-time yield of diethyl oxalate was 978 g L^(-1) h^(-1) and CO conversion was 44% with the selectivity to diethyl oxalate of 95.5%.

A Mild and Efficient Procedure for the Preparation of Chromone-2-carboxylates

A mild and efficient procedure to build up various chromone-2-carboxylates was developed. Condensation of diverse 2-hydroxyacetophones with tetr-butyl oxalate in the presence of sodium ethoxide could be accomplished rapidly under mild condition. Cyclodehydration was carried out to achieve chromone-2-carboxylates in one-pot with impressive yield. Advantages over conventional methods with diethyl oxalate were observed in yield and reaction time.