The microwave spectrum of 5-methylthiazole was investigated by employing both Fourier transform and Stark spectroscopy. 5-methyl thiazole undergoes alkylation with n-butyl bromide followed by anion exchange of Br- for BF4- to give mobile, room-temperature ionic liquids.A chemical building block. The microwave spectrum of 5-methylthiazole was investigated by employing both Fourier transform and Stark spectroscopy. 5-methyl thiazole undergoes alkylation with n-butyl bromide followed by anion exchange of Br- for BF4- to give mobile, room-temperature ionic liquids. A chemical building block.