Neryl acetate synthesis from nerol esterification with acetic anhydride by heterogeneous catalysis using ion exchange resin

https://doi.org/10.1016/j.jiec.2021.09.015Get rights and content

Highlights

  • Neryl acetate was produced from nerol esterification by heterogeneous catalysis.

  • Catalyst content had greater effect on reaction than temperature and molar ratio.

  • High conversion and selectivity were obtained for the reaction with the catalyst.

  • The reaction mechanism was well represented by pseudo-homogeneous kinetic model.

  • Lewatit® GF 101 ion exchange resin presented good stability and reusability.

Abstract

This work aims to synthesize neryl acetate from the nerol esterification reaction with acetic anhydride through heterogeneous catalysis using the ion exchange resin Lewatit® GF 101. The reaction was monitored by gas chromatography and the neryl acetate chemical structure was confirmed by mass spectrometry and nuclear magnetic resonance spectroscopy. The variables effect on the neryl acetate synthesis was evaluated from an experimental design analysis. The reaction showed the highest combined values for nerol conversion (98.11%) and neryl acetate selectivity (86.10%) at 30 min within optimal experimental conditions of temperature at 40 °C, catalyst content at 7% wt, molar ratio at 1:4 (nerol: acetic anhydride), agitation speed at 250 rpm and nerol content at 3 mmol. The complete nerol conversion was achieved at 40 min with 82.34% selectivity. The reaction rate was controlled only by the nerol decay, an expected behavior due to the excess of acetic anhydride used. In addition, the value obtained for the main reaction kinetic constant found by a pseudo-homogeneous model was 6 times greater than that of the parallel reaction. The catalyst reuse was investigated and after 3 cycles a high conversion (96.68%) and selectivity (83.78%) were observed indicating a low loss of the catalytic activity.

Introduction

Esters play an important role in the fine chemical industry as they are widely used in solvents, lubricating oils, medicines and essences [1]. They can be obtained by different methods such as natural source extraction, chemical synthesis and biotransformation [2]. Chemical synthesis by solvolytic esterification includes the direct conversion of carboxylic compounds through a reaction with hydroxylic compounds, such as the direct esterification of acids, the alkylation of carboxylic salts, the alcoholysis – of acyl halides, anhydrides, nitriles, amides or ketones – and transesterification [3]. The acylation of alcohols is often performed by treatment with anhydride acids because they are more reactive than carboxylic acids and acid catalysis is one of the most common methods for this type of esterification [3].

Heterogeneous catalysts have been used in ester synthesis by the esterification process [4], especially solid acids, ion exchange resins, metal oxides, zeolites, treated clays and enzymatic catalysis [2], [5], [6], [7]. Among a wide variety of ion exchange resins commercially available [8], cationic resins are commonly used as heterogeneous catalysts for esterification reactions [4], [9], [10]. These resins have their surface functionalized with extremely strong acid groups (Brønsted), essentially with sulfonic groups [11], they are non-corrosive and easy to be separated from the reaction mixture [12], [13].

Ion exchange resins composed of sulfonic acid groups as an active site, linked to the carrier polymer, can offer better selectivity for the desired product and better reuse compared to homogeneous acid catalysts [4], [13]. Generally the reuse is made for several cycles with relatively low loss of catalytic activity and good thermal stability [12], which are important characteristics for large-scale application [14]. When acidic anhydrides are used, despite being more electrophilic than carboxylic acids, sulfonic resins are still frequently recommended to catalyze the esterification reaction [12].

Lewatit® GF 101 resin is a solid ion exchange resin, polymer-based, spherical in shape, opaque in appearance, strongly acidic and with the presence of sulfonic groups (sulfonic acid). It has a porous structure, a high degree of crosslinking, good mechanical stability and can be used in polar or nonpolar media [15]. The use of Lewatit® GF 101 resin as a catalyst for esterification reactions was reported by Zeferino et al. [16], for the geranyl acetate synthesis from the esterification of geraniol with acetic anhydride, and by Tischer et al. [17] for the eugenyl acetate synthesis from the esterification of eugenol with acetic anhydride. In both studies the resin showed good catalytic performance.

Nerol (3,7-dimethyl-2,6-octadiene-1-ol) is an acyclic, liquid and volatile monoterpene alcohol, an important component of essential oils, extracted from spices such as neroli (Citrus aurantium), rose (Rosa damascena) and lavender (Lavandula dentata, Lavandula stoechas and Lavandula multifida) [18], [19], [20], [21]. It has a pleasant sweet floral odor and is used in flavors in food products, cosmetics, fine fragrances, personal care products and cleaning products [18], [19], [21]. Nerol can be used in esterification reactions with different acyl donors for the production of neryl acetate [22], [23]. Neryl acetate (3,7-dimethylocta-2,6-dienyl ethanoate) is found in essential oils from several plants such as different species of salvia, Citrus lemon, Helichrysum italicum, grapefruit mint, among others [24], [25], [26], [27]. It presents a pleasant floral and fruity aroma emphasizing the orange and rose aromas, a characteristic that makes it widely applicable as a flavoring agent in food, cosmetics, perfumes and hygiene products [28], [29].

There are few studies on neryl acetate synthesis reported in the literature by esterification reaction using heterogeneous catalysis. Lozano et al. [23] used enzymatic catalysis for the esterification of nerol with acetic acid and Jiang and Cheng [22] used enzymatic catalysis for the transesterification of nerol with ethyl acetate. However, there are no studies reported using ion exchange resin as a catalyst despite the technological importance of this ester and the advantages of using ion exchange resins to catalyze this class of reaction, especially the Lewatit® GF 101 resin that provided high conversions and yields with good reusability in the catalysis of similar reactions [16], [17], making it competitive when compared to enzymatic catalysis.

As there are few studies reporting the neryl acetate synthesis from nerol esterification, it is necessary to carry out further research with other catalysts, so it will be possible to compare the results with those obtained by enzymatic catalysis and enable new production routes, especially those that can provide better results for the reaction or similar results at a lower cost. Therefore, the need and opportunity for studies on the topic are imminent, especially for potential industrial applications. In this context, the present work has investigated the synthesis of neryl acetate from nerol and acetic anhydride by heterogeneous catalysis with commercial ion exchange resin Lewatit® GF 101.

Section snippets

Materials

Nerol (≥97%) from Sigma-Aldrich (Brazil) and acetic anhydride (≥97%) from Vetec (Brazil) were used as reagents. Lewatit® GF 101 resin (total capacity dry min. 4.7 eq/kg, uniformity coefficient max. 1.6, bead size 0.4–1.25 mm, effective size 0.5–0.62 mm, bulk density 760 g/L, density 1.15 g/mL, water retention 60% wt, stability −20 to 130 °C) provided by LanXess Energizing Chemistry (Germany) was used as a catalyst for the esterification reaction. N-hexane (≥95%) from Dinâmica (Brazil) and

Synthesis of neryl acetate

The esterification reaction for the catalytic neryl acetate synthesis from nerol and acetic anhydride is shown in Fig. 1.

For identical experimental conditions the conversion of the esterification reaction between nerol and acetic anhydride using the proposed catalyst (Lewatit® GF 101 resin) was approximately 83% greater than without a catalyst (Table 1). The esterification reaction without catalyst was 100% selective for neryl acetate and using the proposed catalyst demonstrated a reduction of

Conclusion

In this work, neryl acetate was synthesized by heterogeneous catalysis in an organic solvent-free system from an esterification reaction between nerol and acetic anhydride using the ion exchange resin Lewatit® GF 101 as a catalyst. The influence of temperature, catalyst content and molar ratio between nerol and acetic anhydride in the reaction was studied. The catalyst content showed a more significant effect in the nerol conversion and neryl acetate yield than the other variables. The neryl

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the Government of Santa Catarina State, the Community University of Chapecó Region (Unochapecó) and Federal University of Santa Catarina (UFSC).

The authors acknowledge the Coordination for the Improvement of Higher Education Personnel (CAPES), the Community University of Chapecó Region (Unochapecó), the Federal University of Santa Catarina (UFSC) and the Caxias do Sul University (UCS) for technical and scientific support. The authors are deeply grateful to Professor

References (51)

  • D.M. Reinoso et al.

    J. Environ. Chem. Eng.

    (2018)
  • S.-H. Pyo et al.

    Org. Process Res. Dev.

    (2019)
  • T.L.B. Pasa et al.

    Renewable Energy.

    (2020)
  • R.C.F. Zeferino et al.

    Chem. Eng. Res. Des.

    (2021)
  • Y. Wang et al.

    Food Control.

    (2015)
  • Y. Chen et al.

    Chin. J. Catal.

    (2016)
  • M.D. Murcia et al.

    Chem. Eng. Res. Des.

    (2018)
  • M.C. Bourkaib et al.

    Process Biochem.

    (2018)
  • K.C. Badgujar et al.

    Process Biochem.

    (2014)
  • A. Chakrabarti et al.

    React. Polym.

    (1993)
  • S. Miao et al.

    J. Catal.

    (2011)
  • R. Rönnback et al.

    Chem. Eng. Sci.

    (1997)
  • R. Koster et al.

    J. Catal.

    (2001)
  • C. Fan et al.

    Catal. Commun.

    (2020)
  • K.V. Bhavsar et al.

    Flavour Fragrance J.

    (2019)
  • J. Otera, J. Nishikido, Esterification: methods, reactions, and applications, second ed., Wiley ‐VCH, New York, 2009....
  • V.S. Chandane et al.

    Korean J. Chem. Eng.

    (2016)
  • G.D. Yadav et al.

    Org. Process Res. Dev.

    (2002)
  • G.D. Yadav et al.

    Clean Technol. Environ. Policy

    (2003)
  • K. Biswas et al.

    Curr. Green Chem.

    (2020)
  • C. Tempelman et al.

    Appl. Catal., A.

    (2019)
  • G. Gelbard

    Ind. Eng. Chem. Res.

    (2005)
  • H. Zhang et al.

    J. Deng. Chem. Eng. J.

    (2020)
  • N. Akkarawatkhoosith et al.

    Bioenergy Res.

    (2019)
  • LanXess, Energizing Chemistry, Product Information Lewatit® GF 101, LanXess Deutschland GmbH, Leverkusen,...
  • View full text