Premium
Spectroscopic and Theoretical Investigations of Electrophilic Bromination Reactions of Alkynes: The First Evidence for π Complexes as Reaction Intermediates
Author(s) -
Bianchini Roberto,
Chiappe Cinzia,
Lo Moro Giacomo,
Lenoir Dieter,
Lemmen Peter,
Goldberg Norman
Publication year - 1999
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/(sici)1521-3765(19990503)5:5<1570::aid-chem1570>3.0.co;2-a
Subject(s) - halogenation , alkene , electrophile , chemistry , adduct , alkyne , reactive intermediate , molecule , electrophilic addition , stereochemistry , photochemistry , computational chemistry , organic chemistry , catalysis
The first direct detection of a 1:1 Br 2 –alkyne complex as an intermediate during the addition of Br 2 to alkynes is reported. The measured negative apparent activation energies for bromination of arylalkylacetylenes are only compatible with the formation of a reactive complex that precedes the rate‐determining step. Quantum‐chemical calculations suggest that the Br 2 in the 1:1 complex functions as a donor for a second Br 2 molecule as depicted here, giving a trimolecular complex structurally very similar to a stable Br 2 –Br 2 –alkene adduct reported some time ago.