Model structures for vinyl polymers. I. Polyacrylonitrile

Abstract

A model dimer of acrylonitrile (2,4 dimethylglutaronitrile) was synthesized and separated into an isotactic (meso) isomer, m.p. = 8.8"C., and a syndiotactic (racemic) isomeg m.p. = 50°C. Infrared and NMR spectra of the dimers were measured. The methylene protons of the isotactic dimer resonate at a lower magnetic field strength and show a more complex spiu-spin splitting than the syndiotactic methylene protons. ZUSAMMENFASSUNG:Ein Modell eines dimeren Acrylnitrils (2,4.-Dimethylglutaronitril) wurde synthetisiert und in eine isotaktische (meso) Form, Schmp. = 8,8"C, und eine syndiotaktische (racem.) Form, Schmp. = 50 "C, aufgetrennt. Ultrarot-und Kernresonanzspektren der Dimeren wurden gemessen. Die Methylenprotonen des isotaktischen Dimeren zeigten Resonauz bei geringerer magnetischer Feldstiirke sowie eine kompliziertere Spin-Spin-Aufspaltung als die Methylenprotonen der syndiotaktischen Form.

Isotopic exchange reactions of the tertiary hydrogen in polyacrylonitrile accompanied by acid and base hydrolyses

“…The observations that identical spectra were obtained for isotactic PMA before and after treating with NaOD and that no deuterium was detected in the polymer also offer direct evidence that the tacticity of P A A w a s unchanged when treated with NaOH under similar conditions used by Matsuzaki et al It is then concluded that the extensive exchange reaction of the a hydrogen during the transformation of PAN to PMA takes place during the hydrolysis of PAN. This conclusion is consistent with the results on racemization of the low molecular weight compounds (4,5) a s well a s the model compound of PAN (9). fails to detect any difference in tacticity in PAN, it is applicable to the determination of the tacticity of polyacrylates, poly(acry1ic acid), and the like.…”

Nitric Oxide-Releasing Fabrics and Other Acrylonitrile-Based Diazeniumdiolates

“…We have explored the mechanism of this reaction using 2,4,6-tricyanoheptane ( 3 ) as a model compound. Reaction of 3 with NO in the presence of sodium trimethylsilanoate produced a material that, consistent with previous observations of base-treated PAN, proved to be extremely insoluble in any solvent except water, in which it was converted to 2,4-bisdiazeniumdiolated-2,4,6-tricyanoheptane ( 5 ).…”

NMR spectra of model compounds of poly(vinyl chloride)

“…This assignment is supported by the three-unit model compounds. The chemical shifts of the Hy methine protons of the three stereoisomers, which represent the configurations of the above three CH groups in the polymer, are 5.56 7 for synd-TCH, 5.76 7 for hetero-TCH, and 5.87 7 for iso-TCH, and this order is the same as that in the polymer. This also confirms the assignment of the ineso CH2 resonance appearing at lower field than the racemic CH2 one.…”