A Combined Spectroscopic and Theoretical Study of Dibutyltin Diacetate and Dilaurate in Supercritical CO₂

Abstract

Two organotin catalysts, namely, dibutyltin dilaurate (DBTDL) and dibutyltin diacetate (DBTDA), commonly used in the synthesis of polyurethanes, have been investigated combining vibrational spectroscopic measurements with molecular modeling. The structure and vibrational spectra of the DBTDA molecule have been simulated using density functional theory. Thus, because of the Sn...O interactions, the lowest energy conformer reveals an asymmetrically chelated structure of the acetate groups with a C2v symmetry. The experimental IR spectra of DBTDA and DBTDL diluted in carbon tetrachloride and in supercritical CO2 show unambiguously that these molecules adopt the asymmetrically chelated conformation in the solvent. A new attribution of the main peaks constituting the respective IR spectra of the catalysts could be carried out. Finally, from the IR spectra of the two catalysts diluted in supercritical CO2 reported as a function of time, it was found that both molecules react slightly with CO2. However, their spectrum remains unchanged at the earliest stage of the polymerization, indicating that these molecules preserve a catalytic activity similar to that noted in conventional organic solvent.

From CO2 to dimethyl carbonate with dialkyldimethoxystannanes: the key role of monomeric species

“…Interestingly, the geometry of 12 is very similar to that of di-n-butyltin diacetate with comparable Sn-O distances determined by DFT calculations. 15 The dicarbonated species 12 is more stable than the monocarbonated ones, 9 and 10, by 53 and 33 kJ mol À1 , respectively. Moreover, the energy barriers of the two successive CO 2 insertion steps amount to 30 and 12.5 kJ mol À1 , respectively.…”

“…The evaluation of Sn-O bond association with dimethyldimethoxystannane and related distannoxane as well as the role of monomeric di-n-butyltin diacetate in polyurethane synthesis have been reported recently. 14,15 Whilst our work was in progress, Miyake et al 16 published a DFT study on the activation of CO 2 by dimethyldimethoxystannane for the synthesis of DMC. The strong association of the Sn-O bond is the driving force for the facile reaction.…”

Substituent effect on the interaction of aromatic primary amines and diamines with supercritical CO2 from infrared spectroscopy and quantum calculations

“…tolylene-2,4-diisocyanate) in the presence of dibutyltin dilaurate (DBTDL) as a catalyst in both cyclohexane and supercritical carbon dioxide used as dispersant media. [6][7][8][9] It is worth noting that scCO 2 was found to be quite attractive, not only as a neat substitute of organic media for dispersion polymerizations, but also as a unique way to synthesize high molecular weight polyurethane (PUR) materials using only low molecular weight monomers. 10 In this case, scCO 2 was used as the solvent but one of the most interesting challenges is to use CO 2 as a reactant in the synthesis of polyurethanes.…”

Atmospheric atomic layer deposition of SnO2 thin films with tin(ii) acetylacetonate and water

“…At higher deposition temperature, the precursor decomposition cannot be neglected, as stated by Marichy et al 57 Heteroleptic complexes that contain two different ligands, for instance, butyl and acetate as in the case of dibutyltin diacetate (P3), could provide a good compromise between volatility, reactivity, and thermal stability. Several conformers of P3 have been optimized by DFT calculations as demonstrated by Renault et al 58 Among them, three conformers having two terminal oxygen atoms pointing toward the metal atom are the lowest energy ones. In this work, we also performed DFT optimization and obtained similar results, i.e.…”