No abstract

The conformation and configuration analysis of the dimer bis(N,N-dimethyl-2,4-dimethylglutarylamide) was carried out by means of both conventional 1H and 13C NMR spectroscopy and advanced (INEPTLR and 2D HETCOR) methods. The γ-gauche effect method appears to reproduce the observed chemical shift difference between m- and r-isomers. Stereochemical structure of poly(N,N-dimethylacrylamide) (PDMAA) was studied using proton spectrum (at the triad level) and DEPT spectra (at the triad and pentad level). For PDMAA prepared by radical polymerization, the Bernoullian statistics are required to fit the observed intensities at the pentad level.

The stereochemical structure of polytcyclohexyl acrylate) (PCHA) prepared under different polymerization conditions was studied by the combination of one-and two-dimensional 13C NMR methods. The assignments of the triad, tetrad, and pentad signals were carried out according to conformational and configurational approaches. In general, the sensitivity of the observed 13C NMR signals assigned to sequences of triad and tetrad is well reproduced by the 13C chemical shifts estimated via the y-gauche effect method. For PCHA prepared by radical and anionic polymerization (using different solvents and catalysts), a first-order Markov model is required to fit the observed intensities at the tetrad and pentad level, rather than the classical Bemoullian statistics.

A high molecular weight, linear aromatic poly(ether ketone ether ketone ketone) (PEKEKK) has been synthesized by electrophilic Friedel-Crafts acylation condensation of 1,4-diphenoxybenzophenone with terephthaloyl chloride. The syntheses were performed as precipitation polycondensations, and the polyketones were obtained in particle form. The viscosity (molecular weight), shape and size of these particles were found to be strongly dependent on the reaction conditions. For low monomer concentration, highly ordered needle-like particles were also obtained. The chemical structure of the polymers obtained was confirmed by 'H and 13C NMR spectroscopy, and para-substitution in aryl fragments of the main chain was identified. Analysis of the expanded 'H NMR spectra for the ring proton resonances reveals defect mefa-and ortho-structures. The amount and isomer ratio of these defect structures depend on the monomer concentration used. a) part 1: cf. ref.'). b, Structure-based name: Poly(oxy-1,4-phenylenecarbonyl-1,4-phenyleneoxy-1 ,4-phenylenecarbonyl-1,4-phenylenecarbonyl-1,4-phenylene).

Treatment of tetracyanoethylated ketones (I) with hydrochloric or hydrobromic acid results in the formation of the dicyanopyridines (III).