## Isomerization Procedure for Converting Safrole to Isosafrole v1.5

### by Eleusis

This procedure is so simple it's not even funny. The reference to the procedure, courtesy of Jacob W. Smith, is from Chemical Abstracts, volume 47, article number 9360. However, this procedure does *not* like to be scaled up or down at all. The reactant ratios apparently were empirically derived, not in molar ratio, as considerably poorer yields result when screwed with. 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.

- eleusis@netcom.com - Safrole Isomerization Doc - 02/27/96 -