0000000000088512
AUTHOR
Stéphane Chambrey
Reactivity of di-tert-butyldimethoxystannane with carbon dioxide and methanol: X-ray structure of the resulting complex
Abstract The synthesis of dimethyl carbonate from carbon dioxide and methanol was studied with ditert-butyldimethoxystannane under pressure at temperatures ⩽423 K. The formation of dimethyl carbonate is accompanied by transformation of the stannane into a trinuclear complex, the structure of which has been determined by single-crystal X-ray diffraction technique. The relevance of this specie in the catalytic cycle is demonstrated by conducting recycling runs. A preliminary kinetic study underlines the steric influence of the tert-butyl ancillary ligands in the stabilisation of intermediates, by comparison with the n-butyl homologue.
Di-n-butyltin oxide as a chemical carbon dioxide capturer
Abstract Several synthetic routes to the decakis(di-n-butyltin(IV)) oxocluster, (n-Bu2SnO)6[(n-Bu2SnOCH3)2(CO3)]2 (1), a diorganotin compound previously shown to belong to the class of organotins able to store carbon dioxide, as well as its reactivity toward dimethyl carbonate (DMC), are described. The synthetic route from n-Bu2SnO and DMC was applied for the preparation of the ethoxy analogue of 1, oxocluster 2, using diethyl carbonate. The structural relationship connecting cluster 1, with its precursor PRE-1 isolated from recycling experiments and n-Bu2SnO is discussed. For this purpose, the reactivity of PRE-1 with trifluoromethanesulfonic acid was investigated in order to trace structu…
Direct synthesis of dimethyl carbonate with supercritical carbon dioxide: characterization of a key organotin oxide intermediate
The direct synthesis of dimethyl carbonate (DMC) using carbon dioxide as solvent and reagent for its fixation to methanol was explored with din-butyldimethoxystannane in order to get insight into the reaction mechanism for activity improvement. Catalytic runs including recycling experiments allowed isolation and characterization by NMR, IR, and single-crystal X-ray diffraction of a new tin complex containing 10 tin atoms. This compound could be prepared independently and is considered as a resting species. The yield of DMC is highest under 20 MPa pressure that fits with a monophasic supercritical medium in agreement with fluid phase equilibria calculations. In line, preliminary kinetics and…
From CO2 to dimethyl carbonate with dialkyldimethoxystannanes: the key role of monomeric species.
International audience; The formation of dimethyl carbonate (DMC) from CO(2) and methanol with the dimer [n-Bu(2)Sn(OCH(3))(2)](2) was investigated by experimental kinetics in support of DFT calculations. Under the reaction conditions (357-423 K, 10-20 MPa), identical initial rates are observed with three different reacting mixtures, CO(2)/toluene, supercritical CO(2), and CO(2)/methanol, and are consistent with the formation of monomeric di-n-butyltin(iv) species. An intramolecular mechanism is, therefore, proposed with an Arrhenius activation energy amounting to 104 ± 10 kJ mol(-1) for DMC synthesis. DFT calculations on the [(CH(3))(2)Sn(OCH(3))(2)](2)/CO(2) system show that the exothermi…
Can Green Dimethyl Carbonate Synthesis be More Effective? A Catalyst Recycling Study Benefiting from Experimental Kinetics and DFT Modeling
Dibutyldimethoxystannanes are known to catalyze the reaction between carbon dioxide and methanol leading to dimethyl carbonate. Despite similarities between din-butyl- and ditert-butyldimethoxystannane, the recycled complexes have different structural features. In the din-butyl series, a decatin(IV) complex has been characterized and is less active than the stannane precursor. Kinetic experiments likely indicate that all the tin centers are not active, which is confirmed in comparing with the related dinuclear 1,3-dimethoxytetran-butyldistannoxane complex. In the ditert-butyl series, the tritin(IV) complex isolated upon recycling features the steric effect of bulky tBu ancillary ligands. In…