Investigation of Safrole and Isosafrole

[Rhodium]

_{Beitrag zur Kenntnis der Aromatischen Allyl- und Propenyl-Verbindungen.}
I. Untersuchung von Safrol und Isosafrol.
H. I. Waterman & R. Priester

Rec. Trav. Chim. Pays-Bas 47, 849-860 (1928)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/safrole.analysis-1.pdf)

Purification of safrole through fractional distillation, through its addition compound with Hg(OAc)₂, and through repeated freeze-filter-thaw cycles. The end mp of the pure safrole was always 11°C. The density, index of refraction and melting point is compared between purified safrole and isosafrole, and for two commercial brands of each.
It has been shown that safrole and isosafrole won't add iodine in the dark, so treatment with iodine soluton has been shown to be a test for impurities. As isosafrole and safrole adds different amounts of iodine, titrating with iodine and thiosulfate can be used to determine the ratios of safrole to isosafrole in a mixture of the two.
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_{Beitrag zur Kenntnis der Aromatischen Allyl- und Propenyl-Verbindungen.}
II. Ueber die geometrische Isomerie von Isosafrol.
H. I. Waterman & R. Priester

Rec. Trav. Chim. Pays-Bas 47, 1027-1036 (1928)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/safrole.analysis-2.pdf)
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Aromatic Allyl- And Propenyl-Compounds. III. isoSafrole Dibromide
H. I. Waterman & R. Priester

Rec. Trav. Chim. Pays-Bas 48, 941-943 (1929)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/safrole.analysis-3.pdf)

Bromination of trans-isosafrole gives isosafrole dibromide, which upon seeding can be crystallized, mp 52-53°C, d. 1.7682. It can only be distilled at a temperature below 60°C under vacuum (bath temp), or it may decompose explosively to hydrogen bromide and 2-bromoisosafrole.

2-bromoisosafrole has a 2-bromopropene side-chain, as opposed to the 2-bromopropane side chain of what commonly is referred to as "bromosafrole".

Could somebody more fluent in german than I am summarize the findings in Part II?

Largely, it concerns the isomerization of safrole to isosafrole and the difficulties encountered trying to separate isosafrole and safrole, and a possible azeotrope. They determine that cis-isosafrole and trans-isosafrole are impossible to separate by distillation, as the only obtainable cis-isosafrole fraction free of trans-isosafrole will invariably be contaminated by safrole instead.