Microwave-assisted heterogeneous esterification of dibutyl maleate: Optimization using response surface methodology

doi:10.1016/j.cdc.2021.100740

Chemical Data Collections

Volume 34, August 2021, 100740

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Highlights

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Microwave assisted synthesis of dibutyl maleate using Amberlyst-15 was studied
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Optimization of operating parameters by Response Surface Methodology
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Process intensification was studied in comparison to conventional synthesis route
•
Kinetic parameters were investigated

Abstract

Microwave-assisted synthesis of dibutyl maleate was carried out with heterogeneous catalyst, Amberlyst-15. Effect of process parameters such as mole ratio, reaction temperature, catalyst loading, and molecular sieves on the conversion was reported using Response Surface Methodology (RSM). Reaction conversion of 62.6% was achieved at optimum parameters of 1:3 acid to alcohol mole ratio, 5.5% (w/w) catalyst loading, 70°C temperature, and 6% (w/w) molecular sieves for reaction time of 60 min. The optimum parameters based on RSM were 1:3.14 acid to alcohol mole ratio, catalyst loading 5.35% (w/w), 77.19°C, and 64.77% predicted conversion. Pseudo- Homogeneous (PH), Eley Rideal (ER), and Langmuir Hinshelwood Hougen Watson (LHHW) models were used to fit experimental kinetic data. Studies revealed that the Eley-Rideal model suited the experimental data. The activation energy of the esterification reaction was calculated as 10.17 kJ/mol. Gibbs free activation energy (ΔG‡), enthalpy of activation (ΔH‡), and entropy of activation (ΔS‡) were evaluated.

Graphical Abstract

Maleic acid and n-butanol are introduced in a Multiwave PRO microwave reactor for esterification reaction of dibutyl maleate in presence of heterogeneous catalyst; Amberlyst-15.

Section snippets

Rationale

Esterification is a prime reaction having wide applications in the production of flavors and fragrances, solvents, plasticizers, pesticides, and herbicides [1], [2], [3], [4]. Dibutyl maleate (DBM), an unsaturated ester produced with the reaction of maleic acid and n-butanol, is used for creating sulfosuccinate surfactants in detergents and paints. It is widely used as a comonomer in emulsion polymerization for paints and adhesives and also used as plasticizer for aqueous dispersion of

Materials

Maleic acid and Molecular Sieves (4A^o type), and n-butanol were procured from S.D. Fine Chemicals Pvt. Ltd., Mumbai. Amberlyst-15 was purchased from Rohm and Haas Co., USA (supplied by S.D. Fine Chemicals Pvt. Ltd., Mumbai). All chemicals were used without any further purification.

Method

MW assisted esterification reaction was performed in a Multiwave PRO microwave reactor (Anton Paar GmbH, Graz, Austria). The reactor consisted of 16 reaction vessels having a capacity of 100 mL each. Reaction vials

Effect of mole ratio

Theoretically, 2 moles of n-butanol and 1 mole of maleic acid are required as per stoichiometry of the reaction. Esterification reactions are reversible reactions. Therefore, excess alcohol was added to accelerate the reaction equilibrium towards a forward direction. Heterogeneous synthesis of maleic acid and n-butanol was studied using excess alcohol at varied mole ratios of 1:02, 1:03, and 1:04. The catalyst was loaded at 5.5 % (w/w) with 6% (w/w) of molecular sieves, and the reaction

Comparison of conventional and microwave irradiated synthesis of dibutyl maleate

The experimental results obtained by MW synthesis of DBM were compared with the conventional method reported earlier [6]. As inferred from Table 5, it reveals that traditional reaction was carried out for 240 min while MW-assisted reaction took place for 60 min. The MW reaction temperature lowered to 70°C as compared to 80°C in the case of the conventional synthesis route [6]. Further, the mole ratio (acid: alcohol) showed a decline in comparison to the conventional route. The versatile MW

Conclusion

MW-assisted synthesis of DBM was investigated using Amberlyst-15 as a heterogeneous catalyst. RSM was successfully employed to gain knowledge on the interaction of various parameters. ANOVA predicted the relative performance of the parameters obtained through a model fitting resulting in R² as 0.98. Parameters such as mole ratio, catalyst loading, and reaction temperature imply a significant effect on conversion. Kinetic model was developed for PH, ER and LHHW, where ER model was found to be

Funding

No funding was provided

Declaration of Competing Interest

We declare no conflicts of interest

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Data ArticleMicrowave-assisted heterogeneous esterification of dibutyl maleate: Optimization using response surface methodology

Highlights

Abstract

Graphical Abstract

Section snippets

Rationale

Materials

Method

Effect of mole ratio

Comparison of conventional and microwave irradiated synthesis of dibutyl maleate

Conclusion

Funding

Declaration of Competing Interest

React. Polym.

React. Funct. Polym.

Resour. Technol.

React. Funct. Polym.

Ultrason. Sonochem.

Tetrahedron Lett.

Chem. Eng. Process. Process Intensif.

J. Mol. Catal. B Enzym.

Bioresour. Technol.

J. Mol. Catal. A Chem.

Energy Convers. Manag.

Renew. Sustain. Energy Rev.

Chem. Eng. Process. - Process Intensif.

Ultrason. Sonochem.

Renew. Energy.

Appl. Catal. A Gen.

Chem. Eng. Res. Des.

Chem. Eng. Process. - Process Intensif.

Chem. Sci.

Data Article
Microwave-assisted heterogeneous esterification of dibutyl maleate: Optimization using response surface methodology