A study of factors influencing the yield of products resulting from the addition of nitric acid to ethylene oxide (oxirane) compounds has been made. For reactions in aqueous solutions, it was demonstrated that the ratio of nitrated products to side products was directly proportional to the ratio of nitrate ion (in moles per liter) to water (in moles per liter) at a given temperature. An increase in temperature increased the yield of nitrated product. Several new nitrato alcohols have been prepared in good yield by two nitration procedures. In addition, information relating to positional isomerism, heats of reaction, and major side reactions is included.
Number-average moleculsr weights bf poly(ethylene oxide) (PEO) are generally determined from changes in solvent colligative properties, viscoeity relationships, or by terminal hydroxyl analysis. It has now been established that good estimate of their molecular weights can be obtained from simple measurements of refractive index at any reasonable temperature above the softening range.A aeries of PEO polymers having number-average molecular weights, M,, from -300 to -20,000 were obtained and their refractive indices measured at 75 f 0.02"C. with a Valentine Improved Precision Model 450A refwtometer. Values of M, were determined from end-group hydroxyl by acetylation.It is The results are given in Table I.
synopsisFurther studies on the thermal degradation of POPG-TDI polymer have been carried out. It has been shown that at temperatures of -2OO0C., the predominant degradation process involves random scission of the urethane linkages to give substantial amounts of isocyanate and hydroxyl. Kinetic data suggests that the weakest links in POPG-TDI polymer are spaced a t intervals of -10,000 in molecular weight and that they may be eliminated by pretreatment of the POPG with ethylene oxide to form a block COpolyether which is used to prepare the polyurethane. At temperatures exceeding 250°C. and a greater conversion to volatile fragments (>lo%) the kinetics of degradation of POPG-TDI are similar to results for POPG and indicate scission of the polyether bonds by a combination of intramolecular proton abstraction and free radical unzipping reactions, in agreement with previous studies of POPG of much higher molecular weight.
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