Phenols 6-Methoxy-2-naphthol

three-necked flask equipped with a condenser and containing 27 g. (1.1 mole) of magnesium is flame-dried and the atmosphere replaced with nitrogen. A 200-ml. portion of tetra-hydrofuran (Note 1) is added along with several lumps, totaling about 95 g., of 6-bromo-2-methoxynaphthalene (Note 2) and a small crystal of iodine. The mixture is heated to reflux until the boiling becomes spontaneous. An additional 600 ml. of tetra-hydrofuran is added with more of the bromide to maintain a vigorous reflux, until 237.4 g. (1 mole) of 6-bromo-2-methoxy- 

The mixture is allowed to warm up over 20 minutes and is poured into a 2-1. separatory funnel. The purplish solution is washed with a saturated ammonium sulfate solution (about 1.51.) containing ferrous ammonium sulfate until the rust-brown ferric color is no longer produced. The organic layer is dried over magnesium sulfate and concentrated, leaving a dark solid. Purification of the solid by high-vacuum short path distillation gives 127-142 g. (73-81%) of a pinkish or tan-colored product, b.p. 148-150° (0.15 mm.), m.p. 145-147°. It may be further purified by sublimation, or reciystallization from benzene-hexane, m.p. 148-149°. 

Reagent grade tetrahydrofuran (MallLnckrodt) has been used directly. The formation of the Grignard reagent starts readily and no precipitates are formed. Tetrahydrofuran obtained from the Quaker Oats Company in 1-gal. cans has also been used the reaction, however, is slower to start, a cloudy jirecipitate is formed, and the yield is slightly lower. 

This starting material is obtained conveniently from the bromination and methylation of 2-naphthol. The procedure is modified by not removing the tin salts. 

After bromination of 144 g. (1 mole) of 2-naphthol, the hot solution is poured into water and filtered. The dry precipitate is mixed with a solution of 200 ml. of concentrated sulfuric acid in 500 ml. of technical methanol and heated to vigorous reflux for 4 hours. An oily layer separates during the heating period. The hot mixture is poured into 3 1. of ice and water, and the solids are removed by filtration. The moist solid is triturated with 11. of hot 5% sodium hydroxide. After chilling the mixture to solidify the oil, it is filtered and the product is washed and dried. The 6-methoxy-2-bromonaphthalene is purified by distillation, b.p. 114-118° (0.2 mm.). After distillation the product is most conveniently handled by remelting and pouring it into a mold to solidify. The overall yield is 173-208 g. (73-88%), m.p. 

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In geteilter Zelle und 2 n Schwefelsaure laBt sich Phenol an Platin-Kathoden zu Cyclo-hexanol hydrieren (niedrige Stromdichte 56% d.Th.)6,7. Analog reagieren Methyl-phe-nole, -aniline und -benzoesauren sowie Methoxy-toluole usw.7. 1-Naphthol wird zu 7-Hydroxy-dekalin und 2-Naphthol zu 6-Hydroxy-tetralin in mittleren Ausbeuten reduziert7. 

When hypofluorous acid reacts with aromatic substrates 7 the isomeric distribution of phenols formed suggests the nature of the transformation is electrophilic, rather than radical 4-methoxy(2-2H)phenol (8) isolated from (4-2H)anisole shows a marked NIH effect (77% incorporation of deuterium).11 A similar reaction with naphthalene gives a mixture of up to three products in low yield (1-naphthol 2.9%, 2-naphthol 0.75% and 1.4-naphthoquinone 7.4%).9... 

Other phenols and phenol ethers were examined to assess the breadth of activity of this catalyst. Anisole was selected as an electron rich aromatic system though less so than phenol. A cleaner reaction at lower conversion was expected. Under similar conditions employed for phenol hydroxylation, a 20% conversion of anisole was measured with selectivity to 4-methoxy phenol of 15% and to guiacol of 42%. 1-naphthol was also assessed. No conversion was seen, presumably due to the bulky nature of the molecule. These findings are consistent with a mechanism involving an electrophilic oxidant species. 

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