Hydroquinones monoalkylation

Contrary to monoalkyl derivatives, the presence of two alkyl groups in positions 2 and 5 (Type Ic) and 2 and 6 (Type lib) lowered the efficiency of 4-alkoxyphenols. Similar influences of substitution can be shown when comparing the activities of 4-acetoxy-2-terf-octylphenol and 4-acetoxy-2,5-di-ferf-octylphenol (Table IV). The change in the nature of alkyl groups influences the activity of Type lib antioxidants in a manner similar to that of 2,4,6-trialkylphenols the antioxidative efficiency decreased in the latter group, introducing a bulkier alkyl group into position 4, when the substituents in the positions 2 and 6 remained the same (the values of relative activities are referred to hydroquinone). 

The major by-product of these syntheses is the hydroquinone of the starting quinone, which can be recovered and oxidized. Quinones with several unsubstituted positions are alkylated nonspecifically, but only products of monoalkylation are observed. 

Hydroquinone can be monoalkylated cleanly with supercritical methanol at 350 C/120 bars for 1 h (8.18). Ani-... 

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