The formation of macrocycles containing two imidazolium rings such as 1.2X and 2.2X is anion-directed through hydrogen bonding. The template effect exerted by the chloride anion in the ring-closure reaction of the monocationic model intermediate 9(+) to yield the [1(4)]imidazoliophane 2(2+) has been evaluated. This effect was quantified following the kinetics of the macrocyclization by using a LTV-vis technique. The rate of the ring closure of monocation 9(+) is increased up to 10 times, in the presence of Bu4NCl 0.04 M. This finding confirms that the template effect is operative in the macrocyclization. leading to dicationic [1(4)]imidazoliophanes.
Quantitative evaluation of the chloride template effect in the formation of dicationic [1(4)]imidazoliophanes / Ramos, S.; Alcalde, E.; Doddi, Giancarlo; Mencarelli, Paolo; PÉREZ GARCIA, L.. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - STAMPA. - 67:(2002), pp. 8463-8468. [10.1021/jo0262311]
Quantitative evaluation of the chloride template effect in the formation of dicationic [1(4)]imidazoliophanes
DODDI, Giancarlo;MENCARELLI, Paolo;
2002
Abstract
The formation of macrocycles containing two imidazolium rings such as 1.2X and 2.2X is anion-directed through hydrogen bonding. The template effect exerted by the chloride anion in the ring-closure reaction of the monocationic model intermediate 9(+) to yield the [1(4)]imidazoliophane 2(2+) has been evaluated. This effect was quantified following the kinetics of the macrocyclization by using a LTV-vis technique. The rate of the ring closure of monocation 9(+) is increased up to 10 times, in the presence of Bu4NCl 0.04 M. This finding confirms that the template effect is operative in the macrocyclization. leading to dicationic [1(4)]imidazoliophanes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
