SynopsisSegmented copoly(ether ester) based on poly(ethy1ene terephthalate) and poly(oxytetramethylene) suffers from having a rather low rate of crystallization. "he crystallization behavior of this elastomer can be influenced by cocondensation of selected diols and addition of nucleating agents and plasticizers. Changes of the crystallinity and morphology are studied by differential scanning calorimetry and dynamic-mechanical analysis, respectively. Mechanical properties in relation to the different crystallinites obtained are reported.

Electron transfer reactions to 2-nitropropyl p-tolyl sulfone (1) using different electron donors, are described. Using potassium 2-propylnitronate as the electron donor, the product formation is proposed to occur via a free radical chain process involving rapid elimination of p-toluenesulfinate anion from the anion radical derived from 1. When the carbon atom connecting the nitro and sulfonyl groups bears hydrogen, the corresponding a-sulfonyl nitronate is formed as the only product under comparable conditions. Treatment of I-iodo-I-nitro-I-@-tolylsulfonyl) propane with potassium 2-propylnitronate in ethanol affords the potassium salt of I-nitro-l-@-tolylsulfonyl) propane, 2.3-dimethyl-2.3-dinitrobutane and iodine. Possible mechanisms for the formation of these products are briefly discussed.

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Arylsulfonylalkanenitronic acid esters were obtained upon reaction of five -nitro sulfones with diazomethane or diazoethane. Four of these products readily add a variety of radicals to produce arylsulfonylalkyl alkoxy nitroxides which were studied by ESR spectroscopy. If the trapped radical is bulky, two nitrogen hyperfine splitting constants are observed. We infer that these nitroxides occur in two favored conformations, both with the -carbon to sulfonyl bond eclipsed with the half-filled orbital on nitrogen. The same types of nitroxides could also be generated by reaction of -nitro sulfones with alkoxycarbinyl radicals. When the -nitro sulfone contains a chiral center and the groups attached to the carbinyl radical site are different from each other, diastereomeric nitroxides are formed. The dependence of the nitrogen hyperfine splitting constant on the substitution pattern in the nitroxides is discussed. The reaction of several nitronic acid esters with lead tetraacetate led to the production of -sulfonyl iminoxy radicals. This reaction most likely proceeds via thermal decomposition into ti-oximino sulfones and subsequent oxidation.The spin trapping technique2-3 has proven to be extremely useful for the detection and identification in solution of paramagnetic species which are too short-lived to be studied directly by electron spin resonance (ESR) spectroscopy