Nitration of lignin and of model compounds containing an arylcarbinol grouping

Abstract

1. A study was made of the reactions of l-(4-hydroxy-3-methoxyphenyl)-l-propanol (VI), l-(3,4-dimethoxyphenyl)-l-propanol (I), and l-(6-nitro-3,4-dimethoxyphenyl)-l-propanol (II) with nitric acid in ether and in carbon tetrachloride. 2. When l-(4-hydroxy-3-methoxyphenyl)-l-propanol (model VI, containing a free phenolic hydroxyl) reacted with ethereal nitric acid, the main direction of the reaction with low concentrations of nitric acid (0.2–0.3 N) was condensation with formation of diisoeugenol; under the action of 4 N ethereal nitric acid the main reaction was the replacement of the side chain by an NO2 group. 3. In the nitration of l-(3,4-dimethoxyphenyl)-l-propanol (model I) with 4 N ethereal HNO3, one nitro group entered the aromatic nucleus, mainly in the 6-position or in the place of the side chain. 4. The nitration of l-(6-nitro-3,4-dimethoxyphenyl)-l-propanol with concentrated nitric acid in a CC14 medium led to the esterification of the arylcarbinol grouping with formation of a nitric ester, which was formed also in the nitration of (I) under the same conditions, together with other nitro compounds. 5. The presence of nitrate nitrogen in the nitrolignin obtained by nitration with concentrated nitric acid (in a CC14 medium) can be explained by the esterification of arylcarbinol groupings present in lignin.