CnH2nCl+ ion formation in electron impact MS conditions: a theoretical study

• Published in: Structural chemistry Vol. 25; no. 2; pp. 659 - 665
• Main Authors: Benkő, Zoltán, Göröcs, Noémi, Könczöl, László, Nyulászi, László, Szieberth, Dénes, Balla, József
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-04-2014
• Subjects: Chemistry; Chemistry and Materials Science; Computer Applications in Chemistry; Original Research; Physical Chemistry; Theoretical and Computational Chemistry; 1-Chloroalkanes; Mass spectral fragmentation; DFT calculations; Hydrogen bond
• ISSN: 1040-0400; 1572-9001
• DOI: 10.1007/s11224-013-0371-5

The mass spectral fragmentation of different 1-chloroalkanes (of the 1-chlorohexane-1-chlorooctadecane series) has been investigated, quantifying the relative abundance of the fragment ions. The base peak is dominantly at
m
/
z
91, 93 in each investigated case, although with the increasing chain length, its contribution to the total ion current exhibits some reduction. Among the possible fragmentation products, the five-membered chloronium containing ring is the most stable as measured by an isodesmic reaction, although the six-and seven-membered rings exhibit only slightly reduced stability. The most stable structure of the 1-chlorohexane radical cation has a hydrogen bonded structure with the involvement of chlorine and the H
C(δ)
, pre-forming the five-membered cationic ring. Accordingly, among the reactions leading to alkyl (or H) radical and a chloronium containing ring, this transition structure has the lowest energy, providing explanation for the experimental observations.