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Because of a tendency toward increased nitrogen concentration in the last three aqueous residues of Fraction VIII, these were kept separate. The remaining 1.74 gm. of this most water-soluble material were crystallized from chloroform and yielded 0.150 gm. of crystalline material. Fractions IV and V were likewise crystallized from chloroform and yielded respectively 0.375 and 0.508 gm. of crystals. These crystalline deposits from chloroform were combined with Fraction III, since according to solubility, melting point, specific rotation, and bioassay they were very similar, as can be seen from Table I. The assay of these fractions by the work test indicates that they are a mixture of 11-dehydro-17-hydroxycorticosterone and 17-hydroxycorticosterone, since assay values between those for these two compounds were obtained. These substances were obtained in pure form by following the specific rotation in 95 per cent alcohol. Melting point determinations are of no value as a criterion for separation, since they are practically identical and show little if any depression when the compounds are mixed. The specific rotations of pure samples of these compounds previously isolated were found to be 164° for 17-hydroxycorticosterone and 195° for ll-dehydro-17-hydroxycorticosterone. These values are in agreement with those reported in the literature . By fractional crystallization from acetone it was found that the material least soluble in this solvent could be obtained in pure form, since on repeated crystallization no difference in specific rotation could be effected. 1.2 gm. of this substance were obtained, which, as is evident from the data in Table I, is undoubtedly 17-hydroxycorticosterone. A mixed melting point with a pure sample of this compound previously obtained gave no depression. |
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hekai16
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xing2007(金币+10, 翻译EPI+1): 2010-08-02 07:35:44
| 由于组分三中的最后3个水相浸提物的含氮成分有增高的趋势，故将他们分开保存。将剩下的1.74克的水溶性较大物质用三氯甲烷结晶，得到0.15克结晶。组分四和五用同样的方法用三氯甲烷结晶，分别得到0375和0.508克晶体。这些用三氯甲烷结晶得到的晶体由于其水溶性，熔点、旋光性和生物性质与组分三很相似（见表一），将他们合并。通过对这些组分的分析，可知它们是11-dehydro-17-hydroxycorticosterone 和17-hydroxycorticosterone 的混合物。由此可知这两种化合物中这些成分的性质。跟踪这些物质在95%乙醇中的比旋律我们得到了高纯度的单体。将（这些）物质的熔点作为分离 的标准没有任何意义，因为他们几乎相同且混合时没有或者只有一点差异。 纯样品中17-hydroxycorticosterone 和 ll-dehydro-17-hydroxycorticosterone的比旋度分别为164和195，这些数值与文献中的吻合。通过用丙酮重结晶，我们发现该物质在丙酮中的溶解度很小，的到的晶体很纯。由于重复结晶对该物质的比旋度没有影响，我们得到了1.2克17-hydroxycorticosterone单体（数据见表一），将其与先前得到的标准物混合后混合物的熔点不变。 |
2楼2010-08-01 14:13:26
