Mass spectral fragmentation of bis(1-arylimino-1-alkyl/arylthiomethyl) disulfides under positive electrospray ionization conditions

GRAPHICAL ABSTRACT

ABSTRACT

The mass spectral fragmentation of bis(1-arylimino-1-alkyl/arylthiomethyl) disulfides under positive electrospray ionization conditions has been investigated. The protonated molecular ions predominantly produce trisulfide thiocarbonimidate ions by elimination of a molecule of arylisonitriles. The trisulfide thiocarbonimidate ions further lose a sulfur atom to yield disulfide thiocarbonimidate ions and then eliminate a molecule of thiols or disulfanes to give rise to the corresponding dithioisonitriliums or thioisonitriliums, respectively. Both alkyl dithio and thioisonitriliums can undergo a McLafferty-type rearrangement to yield the corresponding protonated arylisothiocyanoates. The major characteristic of bis(1-arylimino-1-alkyl/arylthiomethyl) disulfides is loss of diverse neutral molecules, such as isonitriles, thiols, thioaldehydes, and disulfanes under positive electrospray ionization conditions.

KEYWORDS:

• Arylisonitrile
• dithiocarbonimidate
• disulfide
• ESI-MS
• fragmentation

Acknowledgment

We thank Dr. Mingwu Yu at the Beijing University of Chemical Technology for the determination of HRMS data.

Funding

This work was supported in part by the National Basic Research Program of China (No. 2013CB328905) and the National Natural Science Foundation of China (Nos. 21372025 and 21172017).