New synthetic approach to oh‐functionalized poly(p‐xylylene)s by coupling of aromatic dialdehydes and diketones in the presence of smi₂

Abstract

1,2-dihydroxysubstituted poly(p-xyly1ene)s were synthesized in the presence of samarium(r1)-iodide. The structure and endgroups of the polymers were verified by spectroscopy and chromatography. The structure-property relationships of the poly-1,2-diol structures obtained were investigated. Polymer analogous transformations were carried out for poly- (1,4phenylene-1,2-ethanediol). The reaction parameters were investigated with respect to degrees of polymerization. Although some of the polymers were soluble, precipitation was found to be the reason for limited molecular weights.

Samarium(II) iodide: A diastereoselective reagent for the synthesis of aromatic 1,2‐diol structures — model reactions

“…Motivated by the investigations of Kagan et al, we investigated different reaction conditions for the reductive C-C coupling of aromatic aldehydes and ketones in the presence of samarium(I1) iodide. First, monofunctional model compounds were used to investigate the formation of byproducts in order to optimize Kagan's reaction for polyreactions of bifunctional compounds [2]. The resulting products were identified by standard analytical methods (e.g.…”

Synthesis of OH-functionalized poly(p-xylylene)s by reductive coupling polymerization of aromatic dialdehydes with stoichiometric amounts of divalent samarium compounds

“…In spite of the radical character of the intermediates control of the stereochemistry of this coupling reaction is possible to a certain extent as shown previously [8]. Based on the results mentioned above a new approach has been developed for the synthesis of OH-PPX by the reductive coupling of aromatic dialdehydes with SmI 2 [9,10]. The limitation of synthetic approach is precipitation of intermediate products in the initial stage of the reaction resulting presumably in the formation of polymer-alkoxy-Sm(III) compounds, which can be cleaved by hydrolysis.…”

Synthesis of OH-functionalized poly(p-xylylene)s by reductive coupling polymerization of aromatic dialdehydes with stoichiometric amounts of divalent samarium compounds

“…In spite of the radical character of the intermediates control of the stereochemistry of this coupling reaction is possible to a certain extent as shown previously [8]. Based on the results mentioned above a new approach has been developed for the synthesis of OH-PPX by the reductive coupling of aromatic dialdehydes with SmI 2 [9,10]. The limitation of synthetic approach is precipitation of intermediate products in the initial stage of the reaction resulting presumably in the formation of polymer-alkoxy-Sm(III) compounds, which can be cleaved by hydrolysis.…”

“…Sm(II) compounds have been established as exceedingly useful reagents for promoting reductive coupling reactions to generate carbon-carbon bonds in organic synthesis [5 -7]. Based on the results mentioned above a new approach has been developed for the synthesis of OH-PPX by the reductive coupling of aromatic dialdehydes with SmI 2 [9,10]. The reaction proceeds most likely by formation of a Sm(III)-alkoxy compound with an unpaired electron on the former carbonyl C-atom.…”