Reactions of Quinonemethides: Stereoselective Oligomer Syntheses by Michael Additions

Helena L. Chum, David K. Johnson, Peter D. Palasz, Carmen Z. Smith, James H.P. Utley

Research output: Contribution to journalArticlepeer-review

12 Scopus Citations


Novel lignin-model polymers have been prepared from a β-aryl ether quinonemethide by base-catalyzed condensations which were either chemically or electrochemically initiated. The principal intermonomer linkage appears to be of the Cα-04ether type. The key bonding features and functionalities are similar to those exhibited by lignins, except the latter has a much higher level of Cβ-04intermonomer linkages. The polymers can be prepared with weight-average molecular weights of 700–7000 and small polydispersities (1.2-1.5). These simple polymers could be highly suitable as standards for the calibration of molecular weight distributions of lignins in the low molecular weight range. The stereochemistry around the α- and β-side-chain carbons of the polymers was shown to be dependent on the nature of the countercation present during polymer preparation. In the presence of tetraalkylammonium cations, the thermodynamically more stable erythro isomer is preferentially formed. The threo isomer is preferentially formed in the presence of alkali metal cations. An explanation based on the application of Cram's empirical rule concerning nucleophilic addition reactions, combined with the well-established template roles of alkali metal cations, is proposed.

Original languageAmerican English
Pages (from-to)2698-2702
Number of pages5
Issue number11
StatePublished - 1 Nov 1987

NREL Publication Number

  • ACNR/JA-234-8705


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