Synthesis of Bifunctional Phosphonium Salts Bearing Perfluorinated Side Chains and Their Application in the Synthesis of Cyclic Carbonates from Epoxides and CO₂

Abstract

The synthesis of three bifunctional phosphonium salts bearing perfluorinated side chains is reported. These compounds were employed as catalysts for the synthesis of cyclic carbonates from epoxides and CO 2 . The most efficient catalyst comprised a phenolic substructure and allowed the synthesis of various carbonates at room temperature and a CO 2 pressure as low as 0.1 MPa. The reaction could be performed in perfluorodecalin which in some cases led to improved yields and facilitated the separation of the catalyst. Furthermore, the isolation from the reaction mixture and recyclability of two catalysts was evaluated. However, the activity of the recycled catalysts gradually decreases due to partial decomposition. In total 16 cyclic carbonates were prepared in yields up to 97%.

Tuneable reduction of CO2 – organocatalyzed selective formylation and methylation of amines

“…42 These reports and our interest in using phosphonium salts as organocatalysts for the utilization of CO 2 motivated us to explore a phosphorus-based organocatalyst in combination with PMHS as a reductant for the methylation of amines. [43][44][45][46] We focused on methylcarbonate salts which were first reported as a CO 2 surrogate in the preparation of propylene oxide in 2006, 47 and subsequently have been employed in the transesterification 48 and Henry reactions, 49 and as vinylation reagents in the Wittig reaction. 50…”

Guanidinium iodide salts as single component catalysts for CO2 to epoxide fixation

“…However, the multistep preparation, meticulous purification, and the elevated price associated with the synthesis of most metal-based catalysts could be the bottlenecks of their largescale production, which make it desirable to develop metal-free catalysts or organocatalysts to perform the cyclic carbonate production. In fact, numerous compounds of this type based on N-heterocyclic carbenes, 46,47 phosphonium, [48][49][50][51] or ammonium salts 49,[52][53][54][55] have reported exceptional results for this process.…”

Phosphonium-Salt-Catalyzed N-Methylation and N-Formylation of Amines with CO2

“…Organic salts such as tetrabutylammonium fluoride (TBAF), acetylcholine-carboxylate, and phosphonium methylcarbonate have also been used as catalysts. ,, Moreover, a selectivity switch has been achieved utilizing zwitterionic salts such as glycine betaine and lecithin as catalysts. ,, Organocatalysts are desirable to circumvent the problematic availability, costs, and/or toxicity of metals . Based on our work on the synthesis of bifunctional phosphonium salts for the coupling of CO 2 with epoxide to prepare cyclic carbonates, − we herein report the preparation of air-stable internal phosphonium salts and their use in selective reductive coupling of amines with CO 2 yielding N -methylated or N -formylated products.…”