高分子酸化防止剤の研究(第2報) : 線状及び環状メチレン結合フェノールオリゴマーについて

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Linear type, novolak type and cyclic type phenol-aldehyde oligomers were prepared and their antioxidant effects on autoxidation of lard were evaluated by oven tests at 60°C. Their antioxidant effects were affected both by their molecular weights and structures. The most effective molecular weight and ratio of ortho methylene linkage for acyclic oligomers was from about 6001000 and 91 % respectively. The introduction to a methyl group to the methylene linkage weakened the antioxidant effects. In this case, intramolecular hydrogen bonding between hydroxyl groups is essential to the expression of antioxidant effects, and the introduction of the methyl group to the methylene linkage apparently prevents the hydrogen bonding. Cyclic oligomers did not exert antioxidant effects on the autoxidation of lard. Such effects by oligomeric phenolic compounds arise possibly from cooperative intramolecular hydrogen bonding with adjacent aromatic hydroxyl groups and stabilized phenoxy radicals in oligomeric chains (Cage effect).
社団法人日本油化学会の論文