Mechanism of Amine-Catalyzed Reaction of Isocyanates with Hydroxyl Compounds

Farkas, A.; Strohm, P. F.

doi:10.1021/i160013a005

Cited by 49 publications

(22 citation statements)

References 7 publications

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“…For the higher polyol functionalities, the rate constant had reached grater values. It is found out that in the particular case of polypropylene glycol and castor oil , k 1 is equal to 2.54 × 10 −4 and 4.02 × 10 −4 L mol −1 s −1 , respectively. In this study, the type and same concentration of catalysts (Table ) were selected to keep similar process requirements such as cream times, gel times, and even cure of the outer surface skin between formulations A and B.…”

Section: Resultsmentioning

confidence: 96%

Determination of Polyurethane Foam Growth Kinetics by a Simple Column Height Test

Saavedra¹,

Gracia-Fadrique²

2015

Int. J. Chem. Kinet.

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In the present work, the height of foam column has been used to monitor the reaction of the isocyanate group. Kinetic modeling describes the conversion versus time curves. The global reaction can be divided into two different paths: the blowing reaction and the polymerization. The kinetics of the reaction of toluene diisocyanate with a polypropylene glycol has been studied with auxiliary blowing agents; the concentration of NCO and OH groups could be considered equivalent during all the experiments as a model for similar polyurethane systems. Despite the complexity of the system in which different kinetic orders are possible, as well a physically controlled diffusion process, data were fitted to a simple kinetic model of an apparent order. The results obtained have enabled us to propose a reaction path and catalyzed second‐order kinetic model.

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Section: Resultsmentioning

confidence: 96%

Determination of Polyurethane Foam Growth Kinetics by a Simple Column Height Test

Saavedra¹,

Gracia-Fadrique²

2015

Int. J. Chem. Kinet.

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“…The first route consists of the formation of a complex between the amine and the isocyanate, followed by attack by the alcohol [33]. The second mechanistic pathway is based on the formation of a complex between the amine and the hydroxyl group of the alcohol, followed by reaction with the isocyanate [34]. Whatever the mechanism might be, steric hindrance in the neighborhood of the nitrogen atom as well as the solvent basicity are the limiting factors [35].…”

Section: Synthesismentioning

confidence: 99%

Cellulosic and Polyurethane Aerogels

Rigacci

Achard

2011

Aerogels Handbook

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International audienceThis chapter focuses on isocyanurate and cellulose-based aerogels. First, it presents the global sol-gel synthetic path by polycondensation. Then, it summarizes all the main results on these two families of organic aerogels. Finally, some of the recent advancements concerning their use for hybridization of silica aerogels are shortly presented. Through a brief description of the basics, together with a short overview of the main properties, this article highlights the huge potential of those two classes of urethane-based aerogels

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“…On peut donc s'attendre a ce que, dans certains cas, les amines aliphatiques secondaires, engagees comrne reactifs, catalysent la reaction de I'agent de blocage avec I'isocyanate et donc aussi la dissociation de I'isocyanate bloque. En designant par a le coefficient catalytique de I'amine, la relation (9) devient, dans ces cas :…”

Section: Introductionunclassified

“…Les constantes catalytiques des amines sur la reaction des isocyanates avec le phenol (k-lu) deduites de k p et KD (relation 3) (Tableau V) sont en accord avec les valeurs determinees a plus basse temperature [9]. L'energie d'activation de cette etape est faible.…”

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Isocyanates Bloques: Etude Cinetique Et Thermodynamique

Deaguirre

Collot

1989

Bulletin des Soc Chimique

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A kinetic and thermodynamic study of the deblocking of urethanes is presented; the blocking agents are phenols, aliphatic alcohols and a polyether. The deblocking occurs via the elimination-addition mechanism. n the transamination reaction, the rate determining step is the amine catalyzed dissociation of the blocked isocyanate. The equilibrium constants of these reactions give the relative stability of blocked isoc anates. The dissociation equilibrium of several urethanes were also determined; temperature higher than T70"C are required to obtain a significant dissociation in the case of usual urethanes.

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Mechanism of Amine-Catalyzed Reaction of Isocyanates with Hydroxyl Compounds

Cited by 49 publications

References 7 publications

Determination of Polyurethane Foam Growth Kinetics by a Simple Column Height Test

Determination of Polyurethane Foam Growth Kinetics by a Simple Column Height Test

Cellulosic and Polyurethane Aerogels

Isocyanates Bloques: Etude Cinetique Et Thermodynamique

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