Three polyether sulfones were prepared by polycondensation of 4,4'-difluorodiphenyl-sulfone and 1,6-dianhydrosorbitol (isosorbide), 1,6-dianhydromannitol (isomannide) or 1,6-dianhydroiditol (isoidide) in dimethyl sulfoxide (DMSO). Depending on the optimization of the reaction conditions, moderate to high molecular weights were obtained. Cyclic polyethers were the predominant reaction products in the MALDI-TOF mass spectra indicating that the chain growth was mainly limited by cyclization under optimized reaction conditions. The differential scanning calorimetry (DSC) measurements revealed an amorphous character with glass transition temperatures in the range of 213—253°C.
The 400.13MHz ' H and 100.6MHz uC NMR spectra of 12 corticosteroids and related compounds were investigated and the signals assigned by two-dimensional techniques. The effects of snbstituents, carbonyl groups and epoxide formation on the chemical shifts of both nuclei are discussed in terms of intramolecular interaction and stereochemical dependence.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.