SYNTHESIS, MOLECULAR-STRUCTURE, AND SPECTROSCOPICAL PROPERTIES OF ALKENYLPHOSPHONIC DERIVATIVES .1. VINYL, PROPENYL, (BROMOALKENYL), AND (CYANOALKENYL)PHOSPHONIC COMPOUNDS

Several vinyl-, propenyl-, (bromoalkenyl)-, and (cyanoalkenyl)phosphon ate derivatives have been synthesized. The (2-cyanovinyl)phosphonates have been obtained with an important improvement in the yield (40% ver sus 6%). The separation of the E and Z isomers of the cyano derivative s and their hydrolysis to the corresponding phosphonic acids have been studied. The bromination and dehydrobromination of some alkenylphosph onic derivatives have also been studied. Spectroscopical studies from UV, IR, Raman, and H-1, C-13, and P-31 NMR have been performed in most of these derivatives. The C=C/P-O pi conjugation exists but it is wea k in all these compounds. Dipole moments and C=C/P=O conformational po pulations have been calculated theoretically by ab initio methods. The effect of the solvent polarity on the conformational population has b een observed by IR spectroscopy disclosing two C=C/P=O conformers. Exp erimental and theoretical results have been compared, a high level of agreement has been found.