If you suspect that isomerisation was a failure, and the quickest way to do this is by taking an atm bp-, if it boils @ safroles bp, then chill and add a seed crystal (of safrole).  If it isnt below -15 or whatever the melting point of iso, you may bee able to actually freeze out a good portion of unreacted safrole.  I just offered this suggestion as another alternative for verifying what was left after an isomerisation.  Swim managed to separate un-isomerised safrole from a botched oxone run this way, he had vac distilled, but got one solid fraction going from safroles bp up to ketones bp for his too strong of a pump (this was before he learned to slow it down, and use a vigreux)

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Im not the bearded man upstairs, Im a bald guy with a healthy penis. So open yer pie-hole!

SWIM thanks you.

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It tastes like burning!  

Inspection of swims supposed CaO was indeed Ca(OH)2. Upon reaction with water no heat was given off. Ca(OH)2 needs to be heated with a blow torch to turn into CaO.

Unfortunatley swims homemade alcohol burner doesnt cut it.

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Sink or SWIM

Swim did an atomospheric bp of sassafras oil and suspected isosafrole. Both came over at ~230C    

What the *&^! is up with my isomerization process? I did the KOH/CaO (which failed because it was Ca(OH)2. I also did at atomospheric isomerization using 5% NaOH. Arragh!!

Time to go the chem store and buy REAL CaO....

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Sink or SWIM

this is the easiest method i've seen...

Post 278285

(RoundBottom: "Re: vacuum refluxing", Chemistry Discourse), it's not rocket science, people.

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Now with 12% more Bottom!
Nymphomania is not a disease, its a goal! (Methadist)

Does anyone have thoughts for SWIDR's last post?  Has anyone never been able to get iso to distill at >250 C?!  Also, The Isomerization of Safrole: A Review on Rhodium's page citing boiling iso at 120-130 @25mm Hg (Isomerization with KOH/CaO) is wrong indeed.  At 25mm Hg the B.P. of trans-iso should be 137.5 C.  (The cis-iso might boil in the upper end of that range though.)

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TRISMUS!!!

Has anyone never been able to get iso to distill at >250°C?!

Oh yes, certainly! If you let the reaction go on for a while, any formed iso will convert to the trans form.

Here's all the physical data published on Isosafrole in Beilstein:

5-cis-propenyl-benzo[1,3]dioxole (cis-isosafrole)
mp -21.5°C¹
bp 77-79°C/3.5mmHg¹

5-trans-propenyl-benzo[1,3]dioxole (trans-isosafrole)
mp 6.6°C²
mp 8.2°C¹
bp 86-86°C/3.4mmHg¹

1: Bull.Soc.Chim.Fr. 1053-1056 (1957)
2: Z. Phys.Chem. 167; 407-419 (1934)

Isosafrole, cis/trans unspecified

252.4-252.7°C/768mmHg - Chem.Ber.; 42; 1909; 3080.
252°C/760mmHg - Ann. Soc. scient. Bruxelles; 48; 1928; 122.
253.5°C/735.4, 179.5°C/100, 135.6°C/20 and 120.2°C/10mmHg - Rechenberg,C.; Einfache und fraktionierte Destillation, 2. Aufl. , S. 300.   
120°C/15mmHg - Acta Pol.Pharm.; 17; 1960; 241,242; Chem.Abstr.; 55; 14351; 1961.
125-127°C/16mmHg - J.Amer.Chem.Soc.; 47; 1925; 1149.
127-128°C/15mmHg - J.Prakt.Chem.; <2> 115; 1927; 332.
131°C/17mmHg -

Bull.Soc.Chim.Fr.; 1964; 1892.

(https://www.thevespiary.org/rhodium/Rhodium/pdf/benzodioxole.deriviatives.pdf)
112-116°C/12mmHg - Ann.Chim.(Rome); 52; 1962; 1261,1263.
123°C/11.5mmHg - Chem.Ber.; 42; 1909; 3080.
116-117°C/9mmHg
111-112°C/6mmHg - Rocz.Chem.; 39; 1965; 1251,1255; Chem.Abstr.; 64; 12656.

Isosafrole, selected syntheses

Synth.Commun. 23(10), 1379-1384 (1993) - Safrole isomerization, KOH/Aliquat 336 (5%), 5min @ 80°C
J.Chem.Soc.Perkin Trans.1 2307-2326 (1985) - Erythro Horner-Wittig, NaH/DMF, 30min @ 50°C, 85% trans-iso, 4% cis-isosafrole
Tetrahedron Lett. 24(36), 3931-3934 (1983) - Erythro Horner-Wittig, NaH/DMF, 60min @ 50°C, 84% cis-isosafrole
J.Chem.Soc.Perkin Trans.1, 19, 2393-2397 (2001) -

Post 385717

(Rhodium: "Isosafrole via Wittig Olefination of Piperonal", Novel Discourse)
J.Pharm.Sci. 81(12), 1219-1222 (1992) -

Post 431447

(FriendlyFinger: "Safrole Isomerising methods", Methods Discourse) Safrole Isomerization (KOH/n-BuOH, 3h @ RT, 98% trans-isosafrole)
Tet. Lett. 27(22), 2529-2532 (1986) - Allylbromide/5-Bromobenzodioxole/PdCl2(dppf)/Et2O, 65% trans-isosafrole
Synthesis 701-703 (1983) - beta-MeS-3,4-MD-styrene/MeMgI, PPh3/NiCl2, Benzene/Ether, 68%
J Braz Chem Soc 11(4), 371-374 (2000) -

Post 431447

(FriendlyFinger: "Safrole Isomerising methods", Methods Discourse) Safrole Isomerization (KOH/n-BuOH, 3h @ reflux, 95% yield)

Thanks for the info!

A good way to check for sucessful isomerization if you are unsure about the boiling points of safrole/isosafrole is to add 20mL of sassafras oil to the isomerized oil and distill together. This way you will see the boiling point of safrole first, then after ~20mL later it will shoot 10-15C higher and then collect your isosafrole as you will know the correct temperature. This worked for SWIM

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Sink or SWIM

Thanks for the references Rhod!!!
hidden CLOUD said "it will shoot 10-15C higher", referring to iso- boiling point compared to safole.  This would mean 244-249 C, since safrole's B.P. is 234 C.  Well, SWIDR's safrole boils at 230-234 C, and iso- boils at exactly 16 C higher (246-250 C).  This has been repeated multiple times with the exact same results.  SWIDR has never been able to get iso- to boil >250 C, nor has SWIDR seen the broad temp range that Rhod's Isomerization Review referred to ("the trans isomer boils at approx 10°C higher than the cis, so the isosafrole isomers are usually collected as a mixture over a temperature range").  SWIDR would expect that isomerizations have been successful, however is still stumped by what not-ketone really is (slightly lighter in color, less viscous, boils 5-10 C higher than ketone, and does not aminate).  Parameters were as per buffered performic (scaled up to 3 mol) and oxone (scaled up to 1 mol) oxidations from Rhod's web page.

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TRISMUS!!!