Изомеризация без вакуума.
Это - "старый добрый", но не самый лучший метод. См. ниже для усовершенствований.
Charge a round bottom flask with 100g of safrole (note - tested with Oil of Ocotea Cymbarum), setup for reflux (water cooled condenser inserted vertically into the flask neck) and heat on an electric mantle until boiling.
As soon as boiling commences, add 1g of 85% Potassium Hydroxide (pellets, 15% water) and 15g of Calcium Oxide (technical grade ok). Replace the condenser and continue heating on the electric mantle (or for the truly brave and well-ventilated, a DOT 5 silicone brake fluid oil bath) for 15 more minutes.
When done heating, keep stirring off of the heat for an additional 10 minutes to prevent the solids from totally crudding up your flask then pour off all the mixture into a glass beaker and let settle for an hour.
Filter the beaker contents on the vacuum Buchner funnel and wash the filter cake with a little ether or methylene chloride (rinse the flask out with the solvent as well, and pour the rinse through the funnel).
Note - the filtration is very tedious and will take at least 1 hour. Gravity filtration (ie - coffee filters stuffed into plastic funnel) is *NOT* possible.
Pour the filtered solution into a round bottom flask and strip off the solvent by simple distillation. Continue distilling at atmospheric pressure to collect the isosafrole (the only fraction besides the solvents) at 245-255╟C. The yield, if filtered and washed with ether, is around 85%.
The yield, if the post-isomerization solution is merely decanted and then distilled, is closer to 60%, but will take significantly less time. The distilling flask will also be difficult to clean.
Finally, clean your glassware by swirling with mineral spirits then with concentrated hydrochloric acid. This will remove the particulate matter and any burnt-on crud most effectively.
При атмосферном давлении:без рефлюкса:
No reflux is needed, just heating to 120 to 160 C for at least 6 to 12 hours with 2 to 10 % KOH added to your distilled safrole. And then you don't get that ugly tar, you still get a blackish solution ofcourse, but no tar left after distilling your isosafrole out.
Это точно работает - опробовано многими пчёлами - но более распространённое описание метода мне искать в ломы - сорри.
А вот ещё, из ПиХКАЛь №58:
Apiole, as the crystalline essential oil 1-allyl-2,5-dimethoxy-3,4-methylenedioxybenzene, is isolated directly from commercial Oil of Parsley, by careful fractional distillation. It is the fraction that boils at 165-167 deg C at 27 mm/Hg. A solution of 19.8 g apiole in a mixture of 43 g KOH and 60 mL hot EtOH was heated in the steam bath for 24 h. With vigorous stirring, it was diluted with H2O, at a rate which the crystals that formed spontaneously could accumulate from the turbidity that was generated. When no more H2O could be added (there was persistent oiling out of material) the reaction mixture was filtered to give 12.1 g of an amber solid material. This was recrystallized from 20 mL boiling hexane, which was filtered while hot to remove insolubles. From the cooled filtrate, there was obtained 9.3 g of 2,5-dimethoxy-3,4-methylenedioxy-1-propenylbenzene, isoapiole, as pale cream-colored solids.