Efficient Solvent‐Free Synthesis of Sucrose Esters via Sand‐Milling Pretreatment on Solid–Liquid Mixtures

Abstract

A general and efficient method, involving sand‐milling pretreatment and base‐catalyzed transesterification of sucrose and fatty acid methyl ester (FAME), was presented for the solvent‐free synthesis of sucrose esters. A metastable homogeneous paste with a solid particle size of 13 μm (D50) was obtained by milling at 1000 rpm for 1 h. This reaction mixture generated a total SE yield of 88.2% with a methyl stearate (MS) conversion of 91.4% using K2CO3 as a catalyst at 135 °C for 3 h at a stirring rate of 500 rpm, while those without milling (D50, 153 μm) yielded a total sucrose fatty acid esters (SE) of 49.3% with a MS conversion of 83.1% under the same reaction conditions. The reaction kinetics revealed that the reaction mixture with milling pretreatment displays a shorter induction time and a faster reaction rate for the formation of SE. The promotion of the solvent‐free synthesis of SE in the current study could be attributed to the reduction of solid particle sizes and the increased compatibility of solid–liquid phases. We believe that this strategy could be used as a general way for strengthening other heterogeneous reactions in the organic synthesis.

Solvent-Free Synthesis of High-Purity Sucrose Fatty Acid Monoesters and a Comparison of Their Properties with Those of Their Commercial Counterparts

“…Traditionally, the purities of SEs have been determined using HPLC-ELSD (high-performance liquid chromatography-evaporative light scattering detector) techniques. 23 While these methods can effectively quantify SE content, they are timeconsuming and require high concentrations of analytes. In recent years, UPC 2 -MS has emerged as a highly effective tool for the accurate quantitation of various components in complex mixtures 36−40 and was thus used in the study presented here.…”

“…Traditionally, the purities of SEs have been determined using HPLC-ELSD (high-performance liquid chromatography-evaporative light scattering detector) techniques . While these methods can effectively quantify SE content, they are time-consuming and require high concentrations of analytes.…”

“…As part of various attempts to realize inexpensive and environmentally friendly protocols for the industrial production of sucrose monoesters, solvent-free processes have been investigated. However, due to the immiscibility of the starting materials required for synthetic production, solvent-free methods frequently suffer from long reaction times, poor yields, and the formation of impure products . Potential solutions to these deficiencies have been reported and include employing sand-milling pretreatment, co-melting, ultrasonic irradiation, heterogeneous base catalysis, and the addition of surfactants. − Although such modifications have improved the yields of the target SEs, to the best of our knowledge, no protocol that can simultaneously generate sucrose monoesters in high purity (∼70%) and practically useful yields (∼50%) has been reported.…”

Solvent-Free Approaches in Carbohydrate Synthetic Chemistry: Role of Catalysis in Reactivity and Selectivity

“…Mechanochemistry has enjoyed tremendous advances over the last years and represents a useful tool to be employed in solvent-free reactions [35,36]; significant applications have already been reported in synthetic carbohydrate chemistry and examples will be discussed throughout this review. The first one described herein is represented by the synthesis of sucrose esters through a K 2 CO 3 -catalyzed trans-esterification with fatty acid methyl esters [37]. An especially interesting result of the investigation was the remarkable increase in the yields associated with a sand-milling pretreatment, which caused a reduction in the particle sizes and then a beneficial effect on the reaction kinetics.…”

Microwave‐assisted low‐cost synthesis of sucrose‐soya ester from vegetable oil refinery by‐product and its application in toothpaste formulation for oral hygiene

“…The conventional base catalyzed transesterification between SAFAME and sucrose for SE synthesis requires use of mutual solvents like pyridine, DMSO, DMF, and so forth to solubilize both polar and non‐polar reactants and heating under reflux conditions (Chortyk et al, 1996; Osipow et al, 1956; Therisod & Klibanov, 1986). Various techniques reported in the literature include microwave‐assisted (Kondamudi & McDougal, 2019), incubator shaker (Jadhav & Pratap, 2017), six‐station assembly (Deshpande et al, 2013), ultrasound (Huang et al, 2010), without solvent using sand mill (Chen et al, 2019; Gutiérrez et al, 2018), and so forth. The reported methods of SE synthesis based on use of supercritical CO 2 /enzyme catalyst/ionic liquid media or pyridine as catalyst are either low yielding, hazardous or necessitates prolonged reaction time (Ganske & Bornscheuer, 2005; Jadhav & Pratap, 2017; Osipow et al, 1956; Sabeder et al, 2006).…”