Synthesis of methyl ester sulfonate surfactant from methyl ester

Abstract

Methyl ester sulfonate (MES) is a potential anionic surfactant derived from palm oil methyl ester. MES shows several advantages, such as excellent cleaning properties, good biodegradability, and tolerance to hard water. Although alpha methyl ester sulfonate (α -MES) is commercially available, it still has some drawbacks, such as disalt formation and low water solubility. Since ozone possesses high oxidizing power, it can react with organic compounds rapidly under mild conditions. In this work, the investigation on the sulfoxidation reaction of methyl ester to methyl ester sulfonate was divided into three parts; (1) characterization of starting methyl ester and α -MES, (2) the effect of different reactants and initiators, and (3) the effect of reaction time. The reaction was performed at 40 ℃ under atmospheric pressure in a photochemical reactor with 16 UV lamps (253.7 nm). The outlet product was transferred to separation and purification processes by using liquid extraction techniques. For the first part, the starting methyl ester was comprised of 36.0 % Cl6 and 64.0 % Cl8. Methyl ester and α -MES were characterized and used as a standard. For the second part, there were four different systems aiming to study the influence of reactants (O2 and SO2) and initiators (UV and O3). The presence of sulfonate groups and molecular weight of MES solution was confirmed by using FT-IR (Fourier Transform Infrared Spectrometer) and ESI- MS (Electrospray Ionization Mass Spectrometry). Conversion increased as follows: UV/O3/O2 > UV/O2 > O3/O2 > UV/O3. For the third part, since MES could be synthesized and yield the highest conversion on the UV/O3/O2 system, this system was chosen to study the effect of reaction time. It was found that when the reaction time inclined, conversion increased, but selectivity slightly decreased.