A SIMPLE METHOD OF MAKING QUINONE HERBERT N. McCOY Los Angeles, California
THE approved method of making benzoquinone in first nearly black crystalline quinhydrone as an interthe laboratory' seems to be that of oxidizing hydro- mediate product. Without further heating, the temquinone with bichromate and sulfuric acid, followed by perature rises spontaneously to about 75'. After ten filtration, extraction with benzene, and distillation to fifteen minutes the oxidation is complete, the dark with steam. The process involves three or four opera- color changing to the clear bright yellow of quinone. tions, which require several hours and the yield leaves The mixture is then heated to 80' to dissolve the quisomething to be desired. none completely, cooled to zero, filtered and washed The procedure here described which can be carried free of potassium bromide with a little ice water, and out in 30 minutes, gives a practically quantitative dried. No by-products are formed. The quinone is yield of quinone of exceptional purity. The reaction crystalline and exceptionally pure. is the following: 3GH4(OH)a+KBrO~3CeH102+KBr The proportion of sulfuric acid seems to be critical. +3HeO. With no added acid the reaction is slow and incomA little sulfuric acid, an active catalyst for the re- plete; with 12 ml. of normal acid added to the solution action, is required. a t 60°, the temperature rises rapidly to 80' or 85" and A mixture of 10 g. of hydroquinone, 5.5 g. of potas- the oxidation is complete in one or two minutes. A sinm bromate, 100 ml. of water, and 5 ml. of normal little bromine is set free, and the final color is orange sulfuric acid is warmed to 60' in a 200-ml. flask. The instead of clear yellow. With the proportion of acid solids dissolve and the reaction starts promptly, giving specified the reaction takes place smoothly, no bromine beina formed. For appreciably laraer quantities of 1 -organic collective Volume John wiley & Sons, hydroquinone the initiii heating nee; not be so high;: a temperature of 50" will suffice. Inc., New York City, 1932, p. 469.
