Find in Library

Fragmentation mechanisms of some prazoles and their related substances were newly investigated in this paper via positive mode ESI-TOF HRMS¹ and HRMS². Some novel fragmentation rules or ions were found or detected in the research. The pyridine and the benzoimidazole ring remained in most cases during the ionization, and heterolytic fragmentations often occurred near the -S(O)_nCH₂- linker to give the [1,3]-H migration ion or [1,7]-H migration ion rearranging across the benzoimdazole ring. Smiles rearrangement ionizations also frequently occurred, initiated by the attack of the lone pair electrons from the pyridine ring, and the sulfones gave special <i>N</i>-(2-benzoimdazolyl) pyridine ions (<b>11b</b> and <b>12c</b>) by a direct extraction from SO₂, and the thioethers gave similar framework ions (<b>8c</b>, <b>9c</b> and <b>10c</b>) via the rearrangement and a further homolytic cleavage of SH radicals. However, the sulfoxides were seldom detected in the corresponding Smiles rearrangement ions during our measurement, and the <i>N</i>′-oxides of the pyridines did not undergo the Smiles rearrangement ionization due to the absence of the lone pair electrons. The 5/6-membered chelating ions with Na⁺ or K⁺ were frequently detected as the molecular and further fragment ions. Some novel and interesting fragment ions containing bivalent (<b>8b</b> and <b>9b</b>), tetravalent (<b>4b</b>, <b>5c</b> and <b>6c</b>) or hexavalent (<b>15b</b> and <b>16b</b>) sulfurs were first reported here.