A problem in optical isomerism . hoic acidA2-dihydro-oc-naphthoic acid^ was prepared by the reduct-ion of oc-naphthoic acid. Ten grams of the latter acid were dis-solved in dilute sodium hydroxide solution and treated with 200grams of 3% sodium amalgam. The temperature was kept at 10° andcarbon dioxide passed in rapidly to neutralize the excess of free (5) 24,442; (5) 28,56; Dessaignes, Bl. 5, 556; Jungfleisch,Bl. 18,201; hollemann, Kec. trav. chim. Fays-Bas. 17,66. 2Sowinski,B. 24,2555; Baeyer, ;.choder ,A. 266,176; hamm,,J. . 28,425. —_ alkali a
A problem in optical isomerism . hoic acidA2-dihydro-oc-naphthoic acid^ was prepared by the reduct-ion of oc-naphthoic acid. Ten grams of the latter acid were dis-solved in dilute sodium hydroxide solution and treated with 200grams of 3% sodium amalgam. The temperature was kept at 10° andcarbon dioxide passed in rapidly to neutralize the excess of free (5) 24,442; (5) 28,56; Dessaignes, Bl. 5, 556; Jungfleisch,Bl. 18,201; hollemann, Kec. trav. chim. Fays-Bas. 17,66. 2Sowinski,B. 24,2555; Baeyer, ;.choder ,A. 266,176; hamm,,J. . 28,425. —_ alkali as it was formed. After about thirty minutes tests withKM11O4 showed that all had been reduced. The acid was precipitatedin five fractions from its iiaOH solution. The first two fractionswere colored, the rest were white. Melting Ho. 5 4 5 85° 85° 85° A portion of A2 — dihydro- cL- naphthoic acid wnich hadstood for two years was similarly purified. Lelting points j1!-act ion No. 2 3 4 5 83° 82° 79° 80°. A -dihydro- oc- naphthoicacid 23- V. THE RESOLUTIONThe three classical methods of resolving a racemic com-pound were iirst developed by Pasteur. The first one1 and thatleast used, because 01 its inconvenience and uncertainty, is themethod of spontaneous separation of the two optically activeisomers on crystallization of the racemic compound. The crystalsare carefully separated from the motner liquor and dried. Theenantiomorphous forms may then he picked out by hand. Carefulregulation of temperature is necessary since the racemic form deposits unchanged above a certain temperature in many cases. o The biochemical method depends on the very different „ 5 rates at which the two isomers are destroyed by a microorganism*Its disadvantages are that dilute solutions must be employed to 1! reduce the toxic effect on the microorganism, much of the acid is lost in recovering it from this solution and only a small part of one isomer is isolated, all the rest of
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