Kinetic study of organotin-catalyzed alcohol–isocyanate reactions

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

“…Indeed, Stassin et al 26 observed that the polymerization of ε-caprolactone initiated by a tin alkoxide (i.e., tin dibutyldimethoxide) was much faster in a conventional organic medium (e.g., in toluene) than in scCO 2 , Okawara et al 14,15 postulating that a coordination of CO 2 onto the metal of the initiator may happen and slow the reaction. A similar observation has been reported by Bergeot et al 27 for anionic ring opening polymerization of ε-caprolactone in scCO 2 using different metal alkoxides (i.e., Y(OiPr) 3 , La(OiPr) 3 , and Al(OiPr) 3 ). They noticed that carbonates formed from the reaction between ionic alkoxides and CO 2 lead to a strong decrease of the polymerization rate compared with that carried out in regular solvents.…”

“…Conflicting theories on the way they catalyze alcohol-isocyanate reactions have been put forth, and the debate is still very active. [3][4][5][6][7][8][9][10][11][12] To better understand their unique catalytic efficiency, some investigations have been reported about the molecular structure and conformation of such compounds. [13][14][15][16] While the first description of dialkyltin diacetates was given by Cahours in 1860, 13 the FTIR spectra of DBTDA were reported later in 1967 by Okawara et al 14,15 These authors pointed out the nonsymmetrically chelated octahedral configuration of the catalyst in diluted benzene solutions ( Figure 1a) and the partial bridging of the acetoxy group at higher concentrations ( Figure 1b).…”

On the Versatility of Urethane/Urea Bonds: Reversibility, Blocked Isocyanate, and Non-isocyanate Polyurethane

“…The n−π* transition of CO absorbs at 282−283 nm. Tondeur et al 28,52,53 studied cyclopentanol−phenylisocyanate kinetics of reaction by calculating the conversion ratio according to eq 10: (10) where A 282 stands for absorbance at 282 nm and ε NCO and ε ure stand for the extinction coefficients of phenylisocyanate and urethane, respectively. When heat is applied to blocked isocyanate adducts, the urethane linkage scission leads to an endothermic transition in the DSC curve, possibly preceded by a sharp transition that corresponds to the adduct melting.…”

Catalytic Kinetics and Mechanism Transformation of Fe(acac)3 on the Urethane Reaction of 1,2‐Propanediol with Phenyl Isocyanate

“…In addition to their application, the reaction kinetics of hydroxyl compounds with isocyanates has been widely investigated [3,4]. Many factors affect the reaction, such as reactant [5][6][7][8], catalyst [9][10][11][12][13], and solvent [14,15].…”