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All 4 posts   Subject: microwave calamus oil to asaronaldehyde in minutes   Please login to post   Down

(Hive Bee)
11-11-04 12:46
No 541016
      microwave calamus oil to asaronaldehyde in minutes
(Rated as: excellent)

Preparation of asaronaldehyde from crude calamus oil: The rhizomes of `Acorus calamus Linn was collected in March-April 1999 from Palampur (H.P.) and was confirmed by comparison with the specimen (IHBT no. 1066) kept in the herbarium of our Institute. The hydrodistillation of rhizomes of Acorus calamus gave pungent smelling oil in 1.7% yield (w/w) with a presence of .beta.-asarone (85%) and (.alpha.-asarone (3-4%) (by GC) and used directly for oxidation step. A mixture of pale yellow crude calamus oil (9.00 g), catalytic amount of OsO.sub.4 ((0.08 to 0.002 g), NaIO.sub.4 (50 to 55 g) and dioxane-H.sub.2 O(50-60 mL or more, 4:1) were taken in a 500 ml beaker fitted with a loose watch glass at the top. The beaker was placed inside a microwave oven operating at medium power level and irradiated for 3-16 minutes in parts. After completion of the reaction (monitored by TLC), the contents of the beaker were filtered and washed with ethyl acetate. The ethylacetate layers were washed with water, aqueous sodium bisulphite (to destroy the excess periodate) and brine, dried over (anhydrous sodium sulphate) and filtered. The solvent was removed under reduced pressure and crude solid was recrystallised with hexane and chloroform to obtain 5.66 g (76%, based on % of .alpha. and .beta.-asarone in crude calamus oil) of pure asaronaldehyde as a white solid; mp C. The physical and spectral data was found similar as above (Example I).

yes, I know, osmium tetroxide oxidising double bonds to glycols is nothing new, nor is periodic acid cleaving glycols to aldehydes.

notice, no modified oven is required, a watch glass is simply placed over a beaker..  and before the whining begins about OsO4, please notice that the main advantage of this procedure is that it allows for a catalytic amount of OsO4 to be used, thus it is not all that expensive if you consider OsO4 goes for about $51/500mg.  This is enough to produce over 200g of 2,4,5-triMeO-BA using this process..  sodium periodate is cheap and I doubt that kind of excess is really required.  i.e. for anethole they use only a 3:1 molar excess of periodate and get a 71% yield in about 5 minutes.

of course, it's up to you to decide whether microwaving extremely toxic chemicals is something you'd like to try.. other than that thou, it doesn't get any easier than this..see the patent for the examples with other propenylbenzenes.

Patent US6544390

- phenethylman -
(Hive Bee)
11-11-04 16:24
No 541040
      nuke it..!     

This method is great for isosafrole! would produce piperonal in no time!wink
(Hive Bee)
11-12-04 05:19
No 541162
      It really is quite humorous ..     

It really is quite humorous that there exists a microwave procedure for almost every step in the production of MDP2NP from safrole.  microwave-isomerization, MW-oxidative cleavage, MW-condensation w/EtNO2, etc.

microwaves.. they ain't just for popcorn anymore..

- phenethylman -
(Hive Bee)
11-12-04 17:35
No 541259
User Picture 

Yeah - better get yourself a nice 30$ microwave oven before DEA starts monitoring their sales...wink

Post 533836 (indole_amine: "Reactions promoted by Microwaves and Clays", Novel Discourse)


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