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

Several vinyl-, propenyl-, (bromoalkenyl)-, and (cyanoalkenyl)phosphonate derivatives have been synthesized. The (2-cyanovinyl)phosphonates have been obtained with an important improvement in the yield (40% versus 6%). The separation of the E and Z isomers of the cyano derivatives and their hydrolysis to the corresponding phosphonic acids have been studied. The bromination and dehydrobromination of some alkenylphosphonic 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 weak in all these compounds. Dipole moments and C=C/P=O conformational populations have been calculated theoretically by ab initio methods. The effect of the solvent polarity on the conformational population has been observed by IR spectroscopy disclosing two C=C/P=O conformers. Experimental and theoretical results have been compared, a high level of agreement has been found.