Oxidation of Iodine to Dihaloiodate(I) Salts of Amines With Hydrogen Peroxides and Their Crystal Structures

Herein we report a general preparation of dihaloiodate salts of heterocyclic amines (tertiary and quaternary) with sterically accessible and hindered nitrogen atom. A number of such compounds were prepared from preformed HICl2 or HIBr2 formed in situ by the reaction of corresponding hydrogen halide, iodine and H2O2. The salts of 1,4-diazabicyclo[2.2.2]octane (DABCO) and its methylated derivatives, 1,3,5,7-tetraazaadamantane (HMTA), diazabicycloundecene (DBU) and 2,4,6-tri-tert-butylpyridine (TBP) were obtained in excellent yields and their structure was determined by NMR and Raman spectroscopy and single crystal X-ray diffraction. Non-hindered bases such as DABCO, HMTA and DBU formed IX2- salts, which further decomposed to complexes with interhalogen compounds due to formation of N horizontal ellipsis X halogen bonds. The dihaloiodiate(I) salts of sterically hindered 2,4,6-tri-tert-butylpyridine were stable. Its dichlorobromate(I) salt was also prepared via a different synthetic method using N-chlorosuccinimide as oxidant.

Automated summary

In this paper, a general method for preparing dihaloiodate salts of heterocyclic amines with sterically accessible and hindered nitrogen atom was reported. These compounds were prepared from preformed HICl2 or HIBr2 formed in situ by the reaction of corresponding hydrogen halide, iodine, and H2O2. Salts of various heterocyclic amines, including DABCO, HMTA, DBU, and TBP, were obtained in high yields and their structures were determined by spectroscopy and crystallography. Non-hindered bases formed IX2- salts, while the salts of hindered bases were stable.