GC–MS study of thermochemical conversion of guaifenesin in the presence of 1-butyl-3-methylimidazolium-based ionic liquids

Thermochemical conversion of guaifenesin was performed in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] ionic liquid at 80 °C within 2 h. After evaluating the effect of different parameters, such as protic and nonprotic solvents, temperature, reaction time, 1-butyl-3-methylimidazolium-based ionic liquids as process media, and the amount of ionic liquid, the results demonstrate that [BMIM][BF4] facilitates the conversion of guaifenesin to 3-(2-methoxyphenoxy)propanal and other novel products, while [BMIM]Cl favors C–O bond cleavage to 2-methoxyphenol (guaiacol). The ionic liquid [BMIM][BF4] was used three times without any loss of catalytic activity. Gas chromatography–mass spectrometry (GC–MS) experiments were performed in this study to reveal the guaifenesin degradation and product formation characteristics. According to the distribution of the guaifenesin conversion products, the most plausible mechanisms were proposed by using GC–MS data.