The interaction of ferrocene with furfural has been investigated. It has been found that condensation can be achieved in the melt phase, with LEWIS acids as catalysts. The resulting polymers are predominantly linear, with chains composed of alternating ferrocenylene and methine units and 2‐furyl substituents attached to the latter. The number‐average moleculare weights range from approximately 800 to 4500. Structural evidence for these products has been derived from chemical, infrared and nuclear magnetic resonance spectroscopic analyses on non‐fractionated and subfractionated samples. Subfractions of enhanced monodispersity have been utilized for determination of degree of homoannular bonding along the polymer backbone. Several competing side‐reactions involving the 2‐furyl group have been observed.
synopsis s an extension of earlier work on the condensation of ferrocene with aldehydes, the ycondensation of ferrocene with p and o-carboxybenzaldehyde is described. While, he former case, regular polycondensation occurs giving rise to a polymer composed of ocenylene and Pcarboxybenzal units, a deviation from this route is observed in the arboxybenzaldehyde case, where a polymer containing both carbaxybenzal qnd 3,3halide bridging units between the ferrocenylene groups is formed instead. This unected behavior can be accounted for by a hydride abstraction mechanism. In supt of the polymer structure proposed, 3-ferrocenylphthalide and 3,3-diferrocenylhalide are isolated as intermediates or by-products. In both polymer series, numberrage molecular weights up to 3000 (unsubfractionated) are measured. The polymers soluble in a number of organic solvents and can be cured with epoxides.
Based on previous investigations involving the self-condensation of the ferrocenyl Mannich base, N, N-dimethylaminomethylferrocene (I), the present paper describes the co-condensation of this Mannich base with ferrocene. The reactions are conducted in the melt phase in the presence of a ZnCl2/HCI catalyst system. The resulting polymeric products are soluble and partially fusible and have number-average molecular weights in the 500-4000 range (unfractionated). The polymers, exhibiting the idealized structure III, are closely related to the products of self-condensation (II), with recurring units composed of ferrocenylene and methylene groups and homoannular substitution predominating along the chain. Due to the presence of ferrocene, however, an additional termination stepis introduced into the overall reaction, leading to a reduced degree of polymerization. The considerable excess over the stoichiometric amount of ferrocene required to achieve this competitive termination and concomitant decrease in Mn suggests that pronounced inductive and hyperconjugative effects are operative in the ferrocenylene-methylene system, resulting in activation of the methylene-substituted ring. The isolation of the lowest homolog possible, diferrocenylmethane, lends further support to the proposed structure of the recurring unit. Spectroscopic evidence obtained on subfractionated material suggests the substitution pattern along the chain to be essentially the same as in the earlier described homocondensation polymers, which is consistent with the assumption of essentially like propagation mechanisms in both cases. A small degree of branching is also inferred from spectroscopic data.In a previous publication,1) the ZnC12/HC1-catalyzed formation of ferrocene-containing polymers from the ferrocenyl Mannich base, N, Ndimethylaminomethylferrocene (I), was described. The products of condensation were shown essentially to be composed of ferrocenylene-methylene recurring units, and the overall polymer structure was depicted, somewhat idealized, by the novolactype formula II. Each polymer molecule was believed to contain a double-bridged segment resulting from termination steps through selfsubstitution on the penultimate ferrocenylene group of the growing chain, much as proposed2) for the identical polycondensation product of hydroxymethylferrocene.In continuation of these earlier efforts, the present paper describes work on the polycondensation of the Mannich base in the presence of ferrocene, in which case essentially the same propagation sequence, but a different termination step, may be expected, leading to polymer III rather than II. Results and DiscussionAs in the case of homocondensation of I, the co-condensation of this Mannich base with ferrocene, summarized in Eq. 1, will proceed in several steps, the first of these1) being the formation of adduct IV. By stepwise ionization, with V occurring as successor species,3) complex IV will generate the metallocarbonium ion VIa (or VIb from polyhomologs of IV and V in an advanced stage of t...
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