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RESEARCH PRODUCT

Alkylumlagerungen und acidolyse der ethylidenbrücken bei der synthese von ethylidendiphenolen

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For the synthesis of symmetrical and unsymmetrical ethylidenediphenols the corresponding hydroxyphenylethanols (1a–c) were prepared by hydrogenation of hydroxyphenyl methyl ketones with hydrogen/Raney nickle or with lithium aluminium hydride. Condensations of the hydroxyphenylethanols with different phenols under the usual acidic conditions gave products formally resulting form transalkylations. Only the reaction of 1-(3-bromo-2-hydroxy-5-methylphenyl)ethanol (1c) with p-cresol gave the expected product 2d with 82% yield. Experiments with ethylidenediphenols showed that with acids in presence or absence of phenols cleavage and recondensations take place leading to products of formal transalkylation. Based on these results a method of synthesis was developed (the so-called “gaseous HCl-method”) leading to the desired ethylidenediphenols, as shown in the case of 4,4′,6-trimethyl-2,2′-ethylidenediphenol (2b).