Structural analysis of diacyl peroxides by electrospray tandem mass spectrometry with ammonium acetate: bond homolysis of peroxide-ammonium and peroxide-proton adducts

Organic peroxides have significant implications in organic chemistry and bi ological processes, The weak O-O bond makes them extremely difficult to cha racterize by conventional analytical methods. Diacyl peroxides are one of t he major radical sources in polymerization and organic synthesis. It is wel l known that diacyl peroxides are thermal labile and thus are not amenable to study by gas chromatography/mass spectrometry (GC/MS). Electrospray tand em mass spectrometry (ESI-MS/MS) has been applied to the structural analysi s of diacyl peroxides by formation of ammonium adducts, Collision induced d issociation (CID) studies of the ammonium adducts of the peroxide [M + NH4] (+) give collision energy dependent fragments. For most diacyl peroxides, h omolysis of the peroxy bond predominates the fragmentation pathways of the peroxide-ammonium adducts, Deuterated substrates have been employed to prov ide evidence for typical fragmentation pathways. The CID studies were also used to locate the O-18 in some O-18 specifically labeled diacyl peroxides, For branched alkyl or alkoxy substrates, McLafferty rearrangement and deca rboxylation become a major pathway, By comparison with some anhydride analo gues, ESI-MS/MS can also be used to study this class of compounds. Copyrigh t (C) 2000 John Wiley & Sons, Ltd.