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Procedure for the Racemization of Optically Active Ephedrine and Pseudoephedrine
Patent DE673486

Example 1

1 gram of sodium was dissolved in 20 mL methanol and the solution was added to a solution of 60g l-Ephedrine in 500 mL decahydronaphtalene (Decalin).

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In the following, a criticism of the above is expressed:

Post 480374 (Rhodium: "Racemization of Optically Active Ephedrines", Stimulants)
Racemization of Optically Active Compounds
Patent US2214034

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This process which includes the use of alkali metal alcoholates possesses disadvantages. For example, side reactions take place resulting in the formation of unwanted materials, the reaction mixture darkens and extensive decomposition ensues. The necessity for extensive purification coupled with the resulting relatively poor yields due to the side reactions and formation in most instances of considerable amounts of unwanted pseudo ephedrine are, from a practical point of view, serious disadvantages. In addition, this previously suggested process has a tendency to continuously liberate water during the reaction, the presence of which during conversion accelerates decomposition.

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The purpose of this post is to stipulate that
avoidance of the conditions which gave rise to
the criticsm expressed in reference # 2 above can
be realized by the following protocol.

Further, the conditions of extreme basicity derived
promote the degredation of foilant materials such as are
the subject of Post 499089 (UncleFester: "deconstructionist thought", Stimulants)

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procedure:

Sodium is placed in 95-105C xylene on a heating
stirplate, _{(the xylene volume is marked on the side of the
flask)}with a condenser and an addition funnel or
other means of  adding liquids periodically.

(The experimenter used a suction flask,
with the suction port blocked by an "addition syringe",  
(a "meat syringe", $1.98 from your supermarket,
{used to inject tenderizers into
the cheap tough flank-steak you buy,":<)}
fitted with a vinyl hose that was a force-fit
into the suction port......)

Pseudo-ephedrine dissolved in about 10X the amount of
methanol (approx.) minimally required to effect it's disssolution,  is slowly introduced into the circulating
xylene/Na to control the release of gas which otherwise could
be a hazard.

Since the xylen is  above the boiling point
 of the alcohol, it refluxes
from the condenser.

Once the total amount of pseudo in methanol
has been added,
the plunger is removed from the addition syringe,
allowing
the alcohol to slowly escape. (from the small hole..)

The temperature slowly rises to 110-120C, and is then allowed to cool.

The solution is filtered and gassed to provide extremely
clean salt of what is presumed to be the racemic blend.

(A laser pointer test will be used next time on the "before"
and "after" solutions to substantiate the effect: at the very least it
makes clean pseudo..  ":<)  )
(note: handle the filter and reaction flask
safely in consideration of the potential hazard of
unreacted sodium metal..)