Tetrabutylphosphonium-Based Ionic Liquid Catalyzed CO₂ Transformation at Ambient Conditions: A Case of Synthesis of α-Alkylidene Cyclic Carbonates

Abstract

A series of tetrabutylphosphonium ([Bu4P]+)-based ionic liquids (ILs) with multiple-site for CO2 capture and activation in their anions, which could efficiently catalyze the cyclization reaction of propargylic alcohols with CO2 at ambient conditions, are reported. Especially, the IL, [Bu4P]3[2,4-OPym-5-Ac], which has three interaction sites for attracting CO2 together with a pK a1 value of 9.13, exhibited the best performance, affording a series of α-alkylidene cyclic carbonates in moderate to good yields. The mechanism exploration demonstrated that IL served as a bifunctional catalyst with anion simultaneously activating CO2 via multiple-site cooperative interactions and the CC triple bond in propargylic alcohol via inductive effect, thus resulting in the production of α-alkylidene cyclic carbonates.

A Noble‐Metal‐Free Metal–Organic Framework (MOF) Catalyst for the Highly Efficient Conversion of CO2 with Propargylic Alcohols

“…16.8 g2methyl-3-butyn-2-ol as the substrate was reacted with CO 2 , which is described in supporting information. Markedly,even after reacting six weeks,the product is also obtained in 72 % yield under mild conditions.T he corresponding TONc an reach to 14 400, which is even higher than that AgOAc/(n-C 7 H 15 ) 4 NBr catalyst (TON 6024, Table S6). [20] Next step,s everal control experiments were systematically performed to investigate the roles of Cu I and In III in this reaction (Table 2).…”

“…[1] As ar esult, much effort has been devoted to developing effective methods to chemical fixation of CO 2 ,m ainly including the cycloaddition of epoxides or aziridines with CO 2 , [2] and carboxylation of terminal alkyne molecules with CO 2 . [3] Recently,the cyclization of propargylic alcohols with CO 2 has also aroused intense interest, [4] because the resultant products a-alkylidene cyclic carbonates are ac lass of important heterocyclic compounds in nature products synthesis,p harmaceutical chemistry,a nd polymers, such as b-ketocarboxylic acids, [5] nitropyrrolins A-E, [6] 2cyclopentenones, [7] poly(urethane)s and poly(carbonate)s. [8] However,o wing to the thermodynamic stability of C = O bond (bond enthalpy + 805 kJ mol À1 )a nd stable electronic structure of p 4 3 in CO 2 ,highly active catalysts are often needed in promoting this cyclization reaction, like Ag nanoparticles, [9] Ag salts, [10] and Ag-MOF or nanoparticle Ag@MOFs, [11] and it should be noted that most of these catalysts are associated with noble metal Ag. Therefore,t or educe the cost, the explorations on efficient catalysts with free noble metals are still highly desirable but ag reat challenge.…”

Polymers Based on Cyclic Carbonates as Trait d'Union Between Polymer Chemistry and Sustainable CO2 Utilization

“…a-Alkylidenec yclic carbonates (ACCs) such as 3c display an exocyclico lefin moiety.R ecently published efficient catalysts for the cycloaddition of CO 2 to propargylic alcohols include tetrabutylammonium acetate, [90] ionic liquids [91] and several silverbased [92] systems. a-Alkylideneb is-5CC speciesw ere recently employed for the synthesis of polyurethanes and polycarbonates by Detrembleura nd co-workers (see Section2.2).…”

Ionic Liquids Catalysis for Carbon Dioxide Conversion With Nucleophiles

“…Although various kinds of substrates are suitable for this system, a high temperature (353 K) is needed to get α-alkylidene cyclic carbonate in that work. To lower down the energy demanding, they then use a new IL, [Bu 4 P] 3 [2,4-OPym-5-Ac], as catalyst in the cyclization reaction of propargylic alcohols with CO 2 at ambient conditions (Wu et al, 2017 ; Figure S15 ). In addition, cations in ILs also exhibit a significant effect on this transformation, only the quaternary ammonium with C 4 chain can it have good activity.…”