Aggregation and Solvation of n-Butyllithium

Abstract

Solution characterizations and ligand binding constants were determined for n-butyllithium in hydrocarbon and ethereal solvents using diffusion-ordered NMR. In hydrocarbon solvents, n-butyllithium exists primarily as an octamer at -40 °C and deaggregates to a hexamer when the temperature is increased. In the presence of THF or diethyl ether, n-butyllithium exists predominantly as a tetra-solvated tetramer and deaggregates to a tetra-solvated dimer in the presence of a large excess or neat THF. The ligand binding constants for the tetra-solvated tetramers were measured using H NMR/DOSY titration.

Improved Synthesis and Isolation of Bedaquiline

“…The temperature of 0 °C resulted in a quite messy reaction indicating several undesirable reactions taking place. At this point, we considered using solvents such as toluene, diethyl ether, cumene, and hexane as they have been reported as typical solvents to conduct lithiation. , However, the limitation was the insolubility of the reagents irrespective of concentration or temperature. Thus, THF remained as the only option to conduct further experiments.…”

CeCl3/n‐BuLi: Unraveling Imamoto's Organocerium Reagent

“…trace II/left). [ 45 , 46 ] The two signal sets are clearly indicative of n ‐BuLi dissociation in THF solution (Imamoto conditions). As in case of n ‐BuLi, the two distinct signals for the lutetium‐bounded n ‐Bu ligands might represent lutetium complexes of distinct aggregation “Li x Lu( n ‐Bu) 3+ x (thf) y ”( x= 0–3).…”

“…TheL u À CH 2 moieties resonate at about À0.5 ppm, and hence are significantly shifted to lower field compared to the characteristic pattern of n-BuLi at À1.0 to À1.5 ppm (cf.t race II/ left). [45][46] Thetwo signal sets are clearly indicative of n-BuLi dissociation in THF solution (Imamoto conditions). As in case of n-BuLi, the two distinct signals for the lutetiumbounded n-Bu ligands might represent lutetium complexes of distinct aggregation "Li x Lu(n-Bu) 3+x (thf) y "(x = 0-3).…”

CeCl3/n‐BuLi: Enträtselung von Imamotos Organocer‐Reagenz

“…Spur II/links). [45][46] Die beiden Signalsätze weisen ein- (Imamoto-Bedingungen). Wiebei n-BuLi kçnnten die beiden unterschiedlichen Signale Lutetium-gebundener n-Bu-Liganden auf die Existenz von Lutetium-Komplexen unterschiedlicher Aggregation "Li x Lu(n-Bu) 3+x (thf) y "( x = 0-3) hinweisen.…”

“…Die Resonanz der Lu‐CH 2 ‐Gruppen findet sich bei etwa −0.5 ppm und ist damit im Vergleich zum charakteristischen Signalsatz von n ‐BuLi bei −1.0 bis −1.5 ppm deutlich ins Tieffeld verschoben (vgl. Spur II/links) [45–46] . Die beiden Signalsätze weisen eindeutig auf die Dissoziation von n ‐BuLi in THF‐Lösungen hin (Imamoto‐Bedingungen).…”