Organic microanalysis -- II. Drying and analysis of hygroscopic substances

“…Melting points. Unless stated otherwise, the microanalyses were performed by Dr. E. W. D. Huffman, Wheatridge, Colorado, on samples which were dried to constant weight in uucuo over phosphorus pentoxide a t 80-90" according t o Milner and Sherman(29). 's were determined with the Fisher-Johns melting point apparatus.…”

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confidence: 99%

INVESTIGATIONS ON STEROIDS. XXII. STUDIES ON OUABAGENIN. I^*

Florey¹,

Ehrenstein²

1954

J. Org. Chem.

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Of the therapeutically important cardiac glycosides, ouabain is the only one for which the exact structure of the aglycone (ouabagenin) still has to be established. Ouabain was discovered and so named by Arnaud (1) who in 1888 isolated from the bark and roots of the ouabaio tree (Acokanthera ouabaio) a toxic glycoside which was used by the Somalis of East Africa as an arrow poison. Later ( 2 ) he found the same glycoside in another arrow poison, the in6e or onaye of the Pahouins which was prepared from the seeds of Strophanthus gratus (S. glaber). The name g-strophanthin, introduced by Thoms (3, pp. 114, 119) to distinguish it from the strophanthins of other species, is frequently used in the German literature for ouabain. Of all cardiac active principles, ouabain is the most easily obtainable since it can be isolated and crystallized from the seeds of Strophanthus gratus in 5 % yield (4).As early as 1898 Arnaud (5) identified rhamnose as the sugar moiety of ouabain.Efforts to prepare the true aglycone (ouabagenin) remained fruitless for a long period of time. Various modifications of acid and enzymatic hydrolysis had yielded only resins which were the result of dehydration and possibly simultaneous polymerization. It was a major accomplishment when in 1942 Mannich and Siewert (4) succeeded in preparing the true crystalline aglycone by hydrolysis of its acetonide which in turn had been obtained by treatment of the glycoside with small amounts of concentrated hydrochloric acid in acetone. The early investigators, therefore, studied the crystalline glycoside rather than the altered aglycone. Jacobs (6) established for ouabain the formula CaH44012.

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“…On the basis of the analytical results, the interpretation was advanced with reservations that these products represented the 3,5-diacetate (V) and the 3-monoacetate (III) respectively, a conclusion now shown to be erroneous. It is now known that both III and V are hygroscopic when dry and require special precautions on analysis (9). Inasmuch as the amorphous product from the reaction of I with boiling acetic anhydride served as an intermediate in the preparation of 19-norprogesterone and 19-nor-11 -desoxycorticosterone, and especially because all subsequent intermediates in these preparations were also amorphous, a reinvestigation of the acetylation of I has been made.…”

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confidence: 99%

“…As a precautionary measure special drying(9) was performed though it proved unnecessary 6. Special drying(9) was essential.…”

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confidence: 99%

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Investigations on Steroids. XVI. Acetylation Studies on 3β, 5-Dihydroxy-14-ISO-17-ISO-21-Norpregnane-19,20-Dioic Acid and its Ethyl Esters

Barber¹,

Ehrenstein²

1951

J. Org. Chem.

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The conversion of strophanthidin into 19-norprogesterone and 19-nor-lldesoxycorticosterone was reported from this laboratory in 1944 (l).2 Both products were amorphous. It was assumed that they were mixtures of stereoisomers, the isomerism involving in particular carbon atom 10. In analogy to conclusions drawn by Swiss investigators on structurally related compounds, carbon atoms 14 and 17 were tentatively assigned the iso-configurations (3). The 19-norprogesterone was found to possess high progestational activity (4).

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Organic microanalysis -- II. Drying and analysis of hygroscopic substances

Cited by 16 publications

References 5 publications

INVESTIGATIONS ON STEROIDS. XVIII. CHLORIDES AND CYCLIC SULFITES IN THE SERIES OF 3β, 5, 19-TRIHYDROXYETIOCHOLANIC ACID. A CASE OF ASYMMETRIC SULFUR^*1

INVESTIGATIONS ON STEROIDS. XVIII. CHLORIDES AND CYCLIC SULFITES IN THE SERIES OF 3β, 5, 19-TRIHYDROXYETIOCHOLANIC ACID. A CASE OF ASYMMETRIC SULFUR^*1

INVESTIGATIONS ON STEROIDS. XXII. STUDIES ON OUABAGENIN. I^*

Investigations on Steroids. XVI. Acetylation Studies on 3β, 5-Dihydroxy-14-ISO-17-ISO-21-Norpregnane-19,20-Dioic Acid and its Ethyl Esters

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Organic microanalysis -- II. Drying and analysis of hygroscopic substances

Cited by 16 publications

References 5 publications

INVESTIGATIONS ON STEROIDS. XVIII. CHLORIDES AND CYCLIC SULFITES IN THE SERIES OF 3β, 5, 19-TRIHYDROXYETIOCHOLANIC ACID. A CASE OF ASYMMETRIC SULFUR*1

INVESTIGATIONS ON STEROIDS. XVIII. CHLORIDES AND CYCLIC SULFITES IN THE SERIES OF 3β, 5, 19-TRIHYDROXYETIOCHOLANIC ACID. A CASE OF ASYMMETRIC SULFUR*1

INVESTIGATIONS ON STEROIDS. XXII. STUDIES ON OUABAGENIN. I*

Investigations on Steroids. XVI. Acetylation Studies on 3β, 5-Dihydroxy-14-ISO-17-ISO-21-Norpregnane-19,20-Dioic Acid and its Ethyl Esters

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INVESTIGATIONS ON STEROIDS. XVIII. CHLORIDES AND CYCLIC SULFITES IN THE SERIES OF 3β, 5, 19-TRIHYDROXYETIOCHOLANIC ACID. A CASE OF ASYMMETRIC SULFUR^*1

INVESTIGATIONS ON STEROIDS. XVIII. CHLORIDES AND CYCLIC SULFITES IN THE SERIES OF 3β, 5, 19-TRIHYDROXYETIOCHOLANIC ACID. A CASE OF ASYMMETRIC SULFUR^*1

INVESTIGATIONS ON STEROIDS. XXII. STUDIES ON OUABAGENIN. I^*