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The search for charge‐remote reactions of even‐electron anions derived from 1,3‐disubstituted adamantanes in the gas phase. Retro Diels‐Alder and Norrish II processes
Author(s) -
Dua Suresh,
Bowie John H.
Publication year - 2001
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.369
Subject(s) - chemistry , substituent , photochemistry , medicinal chemistry , fragmentation (computing) , carboxylate , isopropyl , adamantane , alkoxy group , ion , ketone , partial charge , stereochemistry , organic chemistry , molecule , alkyl , computer science , operating system
The collision induced decompositions of 3‐substituted adamantane carboxylate anions have been studied with a view to uncovering charge‐remote fragmentations of the 3‐substituent. The 3‐substituent is chosen so that it cannot approach the anion site, and so any fragmentations of that substituent should proceed independently of the charged centre, viz. charge‐remote reactions. The following systems have been studied (i) the 3‐cyclohexenyl system shows no charge‐remote retro Diels‐Alder fragmentation (ΔH = +157 kJ mol −1 ), instead, charge‐remote loss of the cyclohexenyl radical is noted, (ii) the 3‐isobutyl ketone system shows no Norrish II cleavage (loss of C 3 H 6 , ΔH = +18 kJ mol −1 ), instead, the competitive losses of CO 2 from the charged carboxyl centre, together with charge‐remote radical loss of the 3‐substituent are observed, and (iii) the corresponding 3‐isopropyl ester does show the ‘Norrish II’ loss of C 3 H 6 , together with competitive losses of CO 2 and the 3‐substituent. It is concluded for cases (ii) and (iii), that an adamantane carboxylate anion system with a carbonyl group directly attached at the 3‐position is not a suitable model system for studying charge‐remote reactions. Copyright © 2001 John Wiley & Sons, Ltd.