Novel 3-Methyl-2-alkylthio Benzothiazolyl-Based Ionic Liquids: Synthesis, Characterization, and Antibiotic Activity

Abstract

Three series of novel 3-methyl-2-alkylthio benzothiazolyl ionic liquids (ILs) were synthesized for the first time. After structural identification, their melting point, solubility, and thermostability together with antibiotic activity were determined successively. As a result, 3-methyl-2-alkylthio benzothiazolyl p-toluene sulfonate was found to have the highest antibacterial activity among the three series of ILs. Meanwhile, it has a good solubility in water as well. On the basis of comprehensive comparison with similar compounds, the effect of cations and anions of these benzothiazolium ILs on typical physical properties together with antibiotic performance was explored and discussed, which is very beneficial to take the greatest advantage of their structural designability for various purposes. Furthermore, the experiment data preliminarily discovered the relationships of the structure-properties/activities of the above three kinds ILs to a certain extent, which can provide useful references for future research and for the potential application of these new ILs as surfactant antiseptics or agricultural chemicals.

Three-Component Synthesis of 2-Alkylthiobenzoazoles in Aqueous Media

“…There are a couple of ways to synthesize 2-alkyl-substituted thiobenzoazoles, such as the reaction of 2-aminoiodobenzenes with carbon disulfide and alkyl thiols, 5b the reaction of benzoheterocyclic thiols with alkyl halides, [7][8][9][10][11] and the reaction of benzoheterocycles with alkyl thiols or dialkyl disulfides (Scheme 1). 12 However, these protocols have some drawbacks such as high temperature, use of toxic reagents or large amount of organic solvents, and the requirement of stoichiometric metal catalysts.…”

“…Following the typical procedure, the crude material was purified by column chromatography on silica gel (PE/EtOAc 10:1) to give 3d as a yellow oil; yield: 135 mg (61%). 7,152.2,134.6,134.1,124.9,123.0,120.4,119.8,115.8,32.2,31.6. HRMS (ESI): m/z [M + H] + calcd for C 11 H 12 NS 2 : 220.0406; found: 220.0409.…”