Synthesis of Cyclic Sulfites from Epoxides and Sulfur Dioxide with Silica‐Immobilized Homogeneous Catalysts

Abstract

Quaternary ammonium- and amino-functionalized silica catalysts have been prepared for the selective synthesis of cyclic sulfites from epoxides and sulfur dioxide, demonstrating the effects of immobilizing the homogeneous catalysts on silica. The cycloaddition of sulfur dioxide to various epoxides was conducted under solvent-free conditions at 100 °C. The quaternary ammonium- and amino-functionalized silica catalysts produced cyclic sulfites in high yields (79-96 %) that are comparable to those produced by the homogeneous catalysts. The functionalized silica catalysts could be separated from the product solution by filtration, thereby avoiding the catalytic decomposition of the cyclic sulfite products upon distillation of the product solution. Heterogenization of a homogeneous catalyst by immobilization can, therefore, improve the efficiency of the purification of crude reaction products. Despite a decrease in catalytic activity after each recycling step, the heterogeneous pyridine-functionalized silica catalyst provided high yields after as many as five recycling processes.

A Copper Metal–Organic Hydrogel as a Catalyst for SO2 and CO2 Fixation under Ambient Conditions

“…Various Lewis bases, as well as alkali metals, have been used as homogeneous catalysts for the reaction of SO 2 with epoxides . There is only one report on the amine functionalized silica as a heterogeneous catalyst for the reaction of SO 2 with epoxides . However, the reactions were carried out at 100 °C, and the diastereoselectivity was found to be very poor.…”

“…Takenaka et al reported that in the reaction of propylene oxide in the initial stage poly(propylene sulfite) was formed in more amount and cyclic sulfite was formed in low amount and with time the yield of the cyclic sulfite increased . Accordingly, after 8 hours we removed the SO 2 source, and stirred the mixture of the products of the reaction of SO 2 with 1,2‐ epoxybutane in the presence of the MOG for 60 hours at room temperature, and the yield of 4‐ethyl‐dioxathiolane‐2‐oxide increased from 21 % to 51 %.…”

“…1,3,2‐Dioxathiolane‐2‐oxides are important electrophilic synthons in the field of organic chemistry due to their high reactivity towards nucleophiles and are more reactive than epoxides. The sulfites are used as an additive in the electrolyte of the lithium‐ion batteries . Although the chemistry of the 1,3,2‐dioxathiolane‐2‐oxides is known since 1932, an efficient method for the synthesis of 1,3,2‐dioxathiolane‐2‐oxides remains a challenge.…”

Green Catalytic Synthesis of Heterocyclic Structures Using Carbon Dioxide and Related Motifs

“…As a variation on this, the formation of quinazoline-2,4(1H,3H)diones using a similar methodology was reported using a different catalyst system (i.e., 1-butyl-3-methylimidazolium acetate: [Bmim]Ac; an IL) [148]. The silalactones are good substrates for the Hiyama cross-coupling [144] FIGURE 18 Cyclic sulfite formation using a heterogeneous catalyst system. Also, the catalyst could be recycled 4 times (5 cycles in total) making it thus an attractive system for the formation of quinazoline-2,4(1H,3H)-diones using CO 2 as one of the key reagents under relative green conditions.…”

“…Thus, chemical routes toward the fixation of this harmful gas can be beneficial in particular when useful products can be derived from it. A heterogeneous catalyst based on quaternary ammonium-and amino-functionalized silica was developed by Yasuda, Takenaka, and coworkers for the synthesis of cyclic sulfites ( Figure 18) [144]. Conventional technologies, however, focused on the conversion of SO 2 and 1,2-diols into cyclic sulfites in the presence of thionyl chloride as reagent and a stoichiometric amount of base [141].…”