A problem in optical isomerism . for some time with a dilute solution of 50 grams of KaOE. The so-lution was diluted with water, filtered, and the diphenyleneglycollicacid precipitated by the addition of dilute HG1. The acid wasfiltered off and washed. It was oxidised to fluorenone by boilingwith chromic acid mixture (250 water, yO concentratedsulphuric acid and 100 grams of potassium dichromate). On filtra-tion washing and drying on a plate 25 grams of greenish fluorenonewere obtained. This product was not purified, but was used di-rectly to make o-diphenyl carboxylic acid. This is
A problem in optical isomerism . for some time with a dilute solution of 50 grams of KaOE. The so-lution was diluted with water, filtered, and the diphenyleneglycollicacid precipitated by the addition of dilute HG1. The acid wasfiltered off and washed. It was oxidised to fluorenone by boilingwith chromic acid mixture (250 water, yO concentratedsulphuric acid and 100 grams of potassium dichromate). On filtra-tion washing and drying on a plate 25 grams of greenish fluorenonewere obtained. This product was not purified, but was used di-rectly to make o-diphenyl carboxylic acid. This is the series ofsteps in the preparation of o-diphenyl carboxylic acid: 1 Graebe and 279,25V. n2Laeyer, B. 10,125; ^riedlander B. 10,534; Auschutz and Japp,E. 11, acid by Graebe and Eatenaus method. Seventy-five grams of XOHwere placed in a metal crucible in an oil bath, 5 of wateradded and the bath heated to 180°. Ihe fluorenone (25 grams)v/as added in small portions which were stirred up quickly. Theheating v/as continued for 1 hour without allowing the temperatureto exceed 200°. The melt was dissolved in hot water, most of theKOH neutralized with HG1, and the unchanged fluorenone filteredoff. The acid was precipitated from the filtrate with HC1, andafter standing l/2 hour v/as iiltered off. Yield - 20 grams. Theacid was impure, of a brown color and melted at 105°. Graebe andEatenau state that the acid which they obtained was practicallypure. Five successive recrystallizations from alcohol did notpurify the product in the least and served to cause the loss ofmuch material. Finally, fractional precipitation was resorted acid was dissolved in 5% KaOH and reprecipitated by the add-ition of very dilute HQ! from a pipette with vigor
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