Reactivity of Carbon Dioxide with n-Butyl(phenoxy)-, (alkoxy)-, and (oxo)stannanes:  Insight into Dimethyl Carbonate Synthesis

Abstract

The CO2 insertion into Sn−O bonds of a series of butyl(phenoxy)-, (alkoxy)-, and (oxo)stannanes has been investigated. The tributyl derivatives Bu3SnOR (2a, R = Me; 3a, R = iPr; 4a, R = tBu; 5a, R = SnBu3)1 give quantitatively Bu3Sn(OCO2R), 2b−5b; the analogous tributylphenoxystannane, 1, is less reactive. For the dibutyl series, Bu2Sn(OR)2, steric effects of tBu groups in OR (8a) suppress carbonation under atmospheric pressure. With R = Me (6a) or R = iPr (7a), only one Sn−OR bond reacts, resulting in Bu2Sn(OR)(OCO2R), 6b or 7b. Treating 6a with 2-propanol affords under CO2 the mixed compound Bu2Sn(OMe)(OCO2 iPr), selectively. Facile deinsertion of CO2 is a common property of all compounds, occurring more readily in the dibutyl series. The stoichiometric transformation of the carbonato ligand in 2b, 5b, or 6b to dimethyl carbonate (DMC) on reaction with MeI requires nucleophilic assistance by F- to proceed. In the presence of MeOH, 2b and 5b are almost inactive forDMC formation, in contrast with 6b. The best yield is obtained under supercritical CO2−methanol conditions.

Distannylations and Silastannylations of In Situ Generated Allenes

“…At the beginning it was unclear how this product could be formed, but we speculated that also the palladium-catalyzed reaction provided 2 a as an intermediate, which might undergo elimination to an allene under the reaction conditions. Therefore, we investigated the reaction by NMR, which confirmed that tributylstannylphenolate [18] was formed during the reaction, which is a clear indication for such an elimination process. [19] Because it is well known that Pd complexes can convert Bu 3 SnH into (Bu 3 Sn) 2 by elimination of H 2 , a subsequent distannylation of the in situ formed allene might explain the outcome of the reaction.…”

Carbon Dioxide Utilization: Greening Both the Energy and Chemical Industry: An Overview

“…All parameters considered, the route based on carbon dioxide is more convenient from the environmental, energetic and economic point of view. A few catalytic systems have been discovered able to drive the synthesis of carbonates from methanol and carbon dioxide (41,42). A major problem to be solved is the formation of water that may destroy the catalyst or reverse the reaction (Scheme 6, Eq.vi).…”

Tin‐Based Mesoporous Silica for the Conversion of CO2 into Dimethyl Carbonate

“…Dimethyl ether is the by-product formed in trace amounts from methanol dehydration. Soluble precursors such as dialkyl-tin(IV)-organometallics [19,20] are even more selective to DMC and the presence of by-products, if any, are below the detection limit of gas chromatography (GC) analysis. Although these catalytic systems suffer from low activity, they retain activity upon successive recycling, suggesting thermodynamic limitations as well as reversible poisoning of the active sites by water.…”