Quaternization of N‐Heterocycles with Propylene Oxide and Epichlorohydrin

Several novel important heterocyclic N‐2‐hydroxypropyl and N‐2‐hydroxy‐3‐chloropropyl quaternary salts were prepared by reaction of propylene oxide and epichlorohydrin with the appropriate heterocyclic bases in the presence of perchloric or hydrobromic acid, giving pure compounds without colored by‐products. The reaction products have an activated methyl group in 2‐ or 4‐position and are typical precursors, suitable for the synthesis of different types of cyanine dyes. All products were characterized by 1H‐NMR spectra and elemental analysis.