Oxazolidone isocyanate-epoxide reaction

Poly-2-oxazolidone by the Reaction of Isocyanates with Epoxides. 136... 

POLY-2-OXAZOLIDONE BY THE REACTION OF ISOCYANATES WITH EPOXIDES... 

An alternative route involves the reaction of 1,2-epoxides with isocyanates to yield poly-2-oxazolidones (Figure 27.12). 

Farrissey and Nashu105 reported that the reaction of an epoxide with phenyl isocyanate, which previously had been claimed to yield a tetrahydro-l,3-oxazin-2-one,1,106 produced, in fact, a 2-oxazolidone derivative. 

The reaction of -NCO isocyanate groups with epoxidic rings, in the presence of special catalysts, leads to the formation of cyclic urethanes (oxazolidones) [1, 3, 12, 13, 23-25] ... 

Experi- ment No. Epoxide (moles) Isocyanates (moles) Catalyst (gm) Solvent Reaction conditions 2-Oxazolidone m.p. (°C) Yield (%) Characteristic infrared spectral bands and comments Ot)... 

An alternative mechanistic explanation for the formation of oxazolidone, derived from the reaction of isocyanate and epoxide, has been given by Gulbins et al. (Reaction 4), Here the oxide anion derived from the epoxy ring attacks the carbonyl (C 0), rather than the imino (C N) double bond as shown in Reaction 2, Ring closure then produces an N-substituted imino-1,3-dioxolane, which isomerises to the 2-oxazolidone. Support for this mechanism was gained from the isomerism of an N-phenyl-2-imino-l,3-dioxolane to the corresponding 2-oxazolidone, using the same reaction conditions. 

The reaction of the isocyanate and the epoxide group, to produce an oxazolidone ring, was studied through the model reaction between the monofunctional epoxide, PGE and the bifunctional isocyanate MDI. Their reaction was followed by DSC. Two catalysts for the reaction were evaluated tetraethyl ammonium bromide (R NBr) and ethylmethylimidazole (EMI). 

Figure 3.10 The use of epoxide-functionalized olefins and subsequent reaction with di-isocyanate to give segmented copolymers connected with oxazolidone linkages [94].

Oxazolidones result from the reaction of epoxides with isocyanates. Oxazolidones have a high thermal stability. A one-component foam system was developed, based on the formation of urethane and oxazolidone from an isocyanate. Mixing an excess of cmde 4,4 -MDl with an aliphatic polyester polyol and an... 

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