The Chemistry of Vitamin E. XX.¹ The Preparation of o-Xylohydroquinone

Abstract

o-Xylenol is not available in quantity and is difficult to prepare. The preparation of oxyloquinone and hydroquinone from it by the generally useful method previously described3 is, therefore, impracticable. The present paper reports improvements in the previously de-scribed4'5•6 synthesis of this quinone from oxylene via the o-nitro compound and the amine. The yields obtained in the three steps are, respectively, 85, 75 and 33%, or an over-all yield of 21% of quinone from hydrocarbon. The corresponding over-all yield previously reported by this method is 12%.4-5,6 Procedure 3-Nitro-o-xylene.-o-Xylene (50 g.) is nitrated at -10 to 0 0 by stirring it vigorously and dropping into it slowly a mixture of sulfuric acid (100 g.) and nitric acid (50 g., d.1.4). During the addition, the tip of the dropping funnel is shielded from spray by keeping it well up in the neck of the flask, out of the path of the droplets thrown by the stirrer. This prevents any contact of xylene with an excess

Photodecomposition of Sustar in water

“…After standing overnight, the solution was acidified to pH 5 and the precipitated phenol removed by filtration. Oxidation to the quinone was accomplished by addition of the crude 6-acetamino-mcresol to sodium dichromate (55 g) in 300 mL of glacial acetic acid at 0 °C (Emerson and Smith, 1940). The solution was stirred for 2 h, diluted with 200 mL of water, extracted with six 150-mL portions of chloroform, and the organic layer reextracted with 200 mL of 0.1 N NaOH and evaporated to dryness.…”

The Chemistry of Vitamin E.

“…The synthesis of chromans such as IV is often, but by no means always, rather simple and easy. The starting materials are hydroquinones (or phenols) having vacant one position in the ring ortho to the hydroxyl group (42,81,116). These are condensed with allylic halides or alcohols, or with conjugated dienes (7,8,79,80,119,126).…”

“…The yields in this synthesis were fair, but the synthesis cannot compare in efficiency with the direct synthesis of tocopherols from present to see how any other synthesis can possibly compare favorably with the direct synthesis, for the intermediates necessary, if phytol is not used, are themselves extremely complicated and difficult to prepare (117,120,124). The synthesis of relatively large amounts of alkylated quiñones and hydroquinones was at first a formidable task, but these preparations have been studied in two laboratories (42,81,116) with the result that this phase of the tocopherol syntheses may now be regarded as solved. Good yields of alkylated quiñones and hydroquinones can be obtained from readily accessible methylated phenols by means of efficient processes which do not involve very many steps.…”

“…It was presented in part at the Eighth National Organic Chemistry Symposium, which was held at St. Louis, Missouri, December, 1939. Paper XXIV appeared in the Journal of the American Chemical Society(38).…”

The Identification of Sulfonic Acids

“…This seemed worth while also in consideration of the fact that published data indicate a lack of agreement in the melting points of a number of these derivatives. The desirability of so doing is further indicated by recent evidence of interest in the use of the thiuronium chloride reagent (38,39,40).…”