The Reaction between Quinones and Metallic Enolates. XVII. Dibromo-p-xyloquinone and Sodiomalonic Ester¹

Abstract

DlBROMO-p-XYLOQUINONE AND SODIOMALONIC ESTER 1739 xanthone, m. p. 249-250 °. Ullmann and Wagner10 report 243°.o-Phenoxy-p-hydroxybenzoic Acid.-Demethylation of o-phenoxy-p-methoxybenzoic acid with aluminum chloride in benzene gave 54% of the hydroxy acid which melted at 163-164°after vacuum sublimation and crystallization from water.Anal. Caled, for C13Hio04 : 0,67.84; H, 4.27. Found: C, 67.64; H, 4.54. p-Phenoxy-o-hydroxybenzoic Acid.-The acid mixture resulting from the oxidation of the 3-methoxy aldehydes was demethylated with aluminum chloride in benzene.The product melted at 162-167°, yield 76%. Vacuum sublimation at 150-170°of 0.126 g. of this product gave 0.122 g. melting at 167-168°. Crystallization from benzene-petroleum ether raised the melting point to 180.8-181.4°. Mixed with an authentic specimen of p-phenoxyo-hydroxybenzoic acid (182.4-183°) the melting point was 180.4-181.2°.Synthesis of p-Phenoxy-o-hydroxybenzoic Acid: 2-Amino-4-chlorotoluene.-2-Nitro-4-chlorotoluene (100 g.) in 100 cc. of methanol was reduced in the presence of 3 g. of Raney nickel at 60°( 2000 lb.). The pure amine boiled at 120-125°(40 mm.), yield 83%.4-Chloro-2-hydroxytoluene.-Diazotization and hydrolysis of the above amine according to the procedure described for 3-bromo-4-hydroxytoluene (above) gave 85% of the chlorocresol melting at 67-68°. Methylation with dimethyl sulfate7 gave 80% of 4-chloro-2-methoxytoluene boiling at 104-106°( 25 mm.).p-Methoxy-o-methoxytoluene.-A mixture of potassium phenoxide (4.3 g.), 5.0 g. of 4-chloro-2-methoxytoluene and 0.1 g. of copper powder was heated for two and one-half hours at 250-270°. The products were taken up in ether and vacuum distilled. The desired diphenyl ether boiled at 275-276°, yield 10%. It was oxidized to the methoxy acid without further purification.p-Phenoxy-o-hydroxybenzoic Acid.-The above compound was oxidized with permanganate in aqueous pyridine. The crude acid melted at 74-75°, yield 31%; it was used without further purification for the preparation of the hydroxy acid, which was obtained by demethylation with hydriodic acid in acetic acid. The pure acid, crystallized from benzene-petroleum ether, melted at 182.4-183.0°.

Vitamin E Chemistry. Nitration of Non-α-tocopherols: Products and Mechanistic Considerations

“…The residue was triturated with light petroleum ether (30 mL). After cooling, a white precipitate of 2,5-dimethyl-1,4-hydroquinone (0.42 g, 83%) was obtained: , mp = 122−124 °C; TLC R f = 0.50 ( n -hexane/diethyl ether, v/v = 5:5); 1 H NMR (CD 3 OD) δ 2.10 (s, 6H, CH 3 ), 6.50 (s, 2H, Ar CH); 13 C NMR (MeOD) δ 15.90 (CH 3 ), 118.12 ( Ar CH), 123.33 ( Ar C), 148.94 ( Ar C−OH). Anal.…”

“…The residue was triturated with light petroleum ether (30 mL). After cooling, a white precipitate of 2,5-dimethyl-1,4-hydroquinone (0.42 g, 83%) was obtained: 28,29 6-Hydroxy-2,2,5,8-tetramethylchroman (6). Into a solution of 2,5-dimethyl-1,4-hydroquinone (see above, 1.50 g, 10.85 mmol) in formic acid (14.03 mL, 98-100%) and THF (3.74 mL) was added dropwise 2-methyl-3-buten-2-ol (10.81 mmol, 1.13 mL) in THF (0.93 mL) under stirring at 100 °C.…”

The Chemistry of Coumarins.

“…CHs CH CCOOC2H6 This reaction between completely methylated quiñones and sodium enolates appears to be a promising method for the synthesis of 6-hydroxy-5,7,8-trimethylcoumarins substituted in the 3-position by such groups as carbethoxyl, acyl, cyano, etc. Smith and coworkers (216,217,218,220) have exhaustively investigated this reaction with various brominated methylquinones and found that they may react with a metallic enolate to produce either a coumarin by reaction with a methyl group or a quinone malonic ester by direct replacement of a bromine atom.…”

THE REACTION BETWEEN QUINONES AND METALLIC ENOLATES. XXIII. AMINOTRIMETHYLQUINONE AND SODIOMALONIC ESTER (1)1

“…p-Xyloquinone was prepared from p-xylenol (4,5) and reduced to the hydroquinone XI by the method of Smith and Johnson (6). The hydroquinone melted at 210-213.5°.…”