The Multiple Roles of Imidazolium Ionic Liquids in Transition‐Metal Catalysis: The Palladium‐Catalyzed Telomerization of 1,3‐Butadiene with Acetic Acid

Abstract

The telomerization of 1,3‐butadiene with acetic acid catalyzed by palladium(II) acetate associated with a series of phosphines in 3‐(2‐methoxyethyl)‐1‐methylimidazolium acetate was used to investigate the role of the ionic liquid. The ionic liquid plays multiple roles in this reaction as it acts as the solvent, stabilizer, ligand, and cocatalyst. The reaction performed in the presence of Dan2phos, a trifluoromethylated sulfonated triarylphosphine, at 100 °C for 24 h gave a turnover number of 14 600 with 89 % selectivity to telomers at 75 % 1,3‐butadiene conversion and complete acetic acid conversion.

The Telomerization of 1,3‐Dienes – A Reaction Grows Up

“…The only exception to this that we are aware of is the telomerization of 1,3‐butadiene with acetic acid, as investigated by Dupont et al in 2015 . The reaction yields 2,7‐octadienyl acetate, as is shown in Scheme .…”

Telomerization of 1,3‐Butadiene with Carbon Dioxide: A Highly Efficient Process for δ‐Lactone Generation

“…Recently, we reported that the addition of an ionic liquid that contains the 1,3‐dialkylimidazolium cation to the telomerization reaction of butadiene and acetic acid has a remarkable effect in the Pd/phosphine catalyst performance . However, it is known that the addition of this type of ionic liquids to the telomerization reaction of 1,3‐butadiene with methanol leads to the complete deactivation of the catalyst, likely by the formation of a catalytically inactive palladium‐carbene species.…”

“…[16,25] Recently,w er eportedt hat the addition of an ionic liquid that contains the 1,3-dialkylimidazolium cation to the telomerization reactiono fb utadiene and acetic acidh as ar emarkable effect in the Pd/phosphine catalyst performance. [26] However,i t is knownt hat the addition of this type of ionic liquids to the telomerization reactiono f1 ,3-butadiene with methanol leads to the complete deactivation of the catalyst, [27] likely by the formation of ac atalytically inactive palladium-carbene species. The formation of this speciesr equires ab asic mediumt od eprotonate the C2ÀHp osition of the imidazolium cation (Scheme 5), [28][29][30] such as that provided by the methoxide used as cocatalyst in the telomerization with methanol.…”

“…1,3‐Butadiene (Linde 2.5), CO 2 (Linde 4.5), p ‐hydroquinone (Panreac Sintesis), DIPEA (Fluka), acetonitrile (Scharlau), Pd(OAc) 2 (Aldrich), PPh 3 (Acros Organics), PT o Me (Avocado), PT p Me (Fluka), and PT p OMe (Aldrich) were used without further purification. Phosphines NaTPPMS, Na 2 TPPDS, PT mm CF 3 , and Dan2phos (commercially available currently from Strem), and the ionic liquids BMImBF 4 , BMImPF 6 , BMImCl, and BMMImBF 4 , and MeOImAcO were prepared according to reported procedures.…”

Tuning the Biginelli reaction mechanism by the ionic liquid effect: the combined role of supported heteropolyacid derivatives and acidic strength

“…ILs are widely used in the chemical industry, 8 catalysis, 9 biocatalysis, 10 extraction processes, 11 the obtention and purification of biological components, 12 and other applications. 13 For a long time, these ionic fluids have actually been claimed to be the solvents of the future 14–16 because they represent a plausible alternative towards environmental acceptability.…”