Kinetics of alcohol–isocyanate reactions with metal catalysts

Rand, Leon; Thir, B.; Reegen, S. L.; Frisch, K. C.

doi:10.1002/app.1965.070090514

Cited by 53 publications

(39 citation statements)

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“…Examples of similar behavior can be found for other reactions [Rand et al, 1965]. The results for sebacoyl chloride offer direct evidence of the concept of functional group reactivity being independent of molecular size, since the rate constant is independent of n as well as x.…”

Section: -1b Experimental Evidencesupporting

confidence: 70%

Step Polymerization

2004

Principles of Polymerization

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Section: -1b Experimental Evidencesupporting

confidence: 70%

Step Polymerization

2004

Principles of Polymerization

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“…37 The technology for highly efficient recovery of catalysts is one of the key issues in this context.…”

Section: Resultsmentioning

confidence: 99%

“…An alternative approach involves the polymerization of a suitable tin-containing monomer, 24 and was recently employed by Angiolini and coworkers, 37 with the preparation of grafted organotin carboxylates by copolymerization of triorganotin derivatives of p-vinylbenzoic acid ( p-VBA) with styrene and 1,4divinylbenzene. [30,31] t/2 (n = 4, 6 or 11).…”

Section: Grafted Organotin Catalystsmentioning

confidence: 99%

Tin in Catalysis

et al. 2008

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In numerous natural products and synthetic compounds, ester moieties constitute major organic functional groups. Consequently, (trans)esterification reactions are widely applied in industry, 1 e.g. in the synthesis of fatty acid esters, 2,3 of polyesters 4−9 and of macrolides. 10 More specifically, polylactones and polylactides are multipurpose, bio-compatible and -degradable polyesters, which are suitable for biomedical and pharmaceutical applications. 11−14 Tin-based Lewis acids like mono-and dialkyltin compounds 4,15−19 and tetraalkyldistannoxane derivatives 8,20−22 are very efficient catalysts for transesterification reactions under mild conditions. A considerable drawback in the use of these organotin compounds in organic synthesis is the difficulty of their quantitative removal from the reaction mixture, because some organotin compounds are toxic. These limitations to the exploitation of such reagents and/or catalysts in biomedical and pharmaceutical synthesis applications 23,24 have been recently overcome by exploring alternative and less toxic catalysts, and by the improvement of workup procedures of several types of homogeneous organotin catalysts. Otera et al. have described the synthesis and catalytic activity of perfluoroalkyl distannoxanes, which combine the advantages of efficient catalysis based on organotins with fluorous biphasic technology. 21,25 These types of organotin catalysts, being highly soluble in fluorocarbon solvents, provide solutions which become perfectly miscible with the organic reaction phase upon heating. After cooling the reaction mixture, phase separation is observed and the catalyst returns into the fluorous phase, making it easily and repeatedly recyclable. Another strategy to alleviate the aforementioned toxicity issue, involves grafting the organotin reagent onto an insoluble solid support. 26−28 In this way, other types of environmentally friendly organotin catalysts, which can easily be removed from the desired reaction products by simple filtration of the insoluble support to which they are grafted, are being designed. The forecasted deliverables of such systems include improved catalyst recycling ability and a better control

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“…19,20 Accordingly, the half-life of the reaction depends on initial reactant concentrations. All the reactions in the present study were carried out with initial concentrations of isocyanates and catalyst being kept at 0.1 mol dm À3 and 0.001 mol dm À3 respectively.…”

Section: Resultsmentioning

confidence: 99%

Efficient organotin catalysts for urethanes: kinetic and mechanistic investigations

Majumdar

Kundu

Das

et al. 2000

Appl. Organometal. Chem.

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Dibenzyltin bis(2‐ethylhexanoate) 1 (4‐YC6H4CH2)2Sn(OC(O)R1)2 [Y = H, 1a; MeO, 1b; Cl, 1c; Me, 1d; and R1 = MeCH2CH2CH2CH(Et)] were synthesized either from the reaction of corresponding dibenzyltin dichlorides with silver 2‐ethylhexanoate or from the reaction of dibenzyltin oxides with 2‐ethylhexanoic acid. Compound 1a was further utilized as a catalyst for the reaction of mono‐ and di‐isocyanates [PhNCO, CH3C6H3‐2,4‐(NCO)2 and OCN(CH2)6NCO] with alcohols (primary, secondary, tertiary, cyclohexcyl, alkyl, allyl, benzyl and aryl) leading to the formation of the corresponding urethanes. The catalytic efficiencies of 1 vis‐à‐vis industrially known organotin catalysts have been determined through kinetic studies for the reaction of PhNCO and n‐BuOH at various temperatures. Compounds 1a, 1c and 1d show higher efficiency than dibutyltin bis(2‐ethylhexanoate). FTIR studies further provide mechanistic insights into the catalytic cycle, which comprises pre‐coordination of isocyanate to tin(IV), formation of stannyl carbamate and generation of dibenzyl(alkoxy)carboxylate as the active catalyst. Copyright © 2000 John Wiley & Sons, Ltd.

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Kinetics of alcohol–isocyanate reactions with metal catalysts

Cited by 53 publications

References 0 publications

Step Polymerization

Step Polymerization

Tin in Catalysis

Efficient organotin catalysts for urethanes: kinetic and mechanistic investigations

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