the red impurity in my phenylisopropylamine...

joe_aldehyde · huxleys associate

...where does it come from? i've gotten it every time, after Al/Hg - NaBH4/Zn/Formic - NaBH4/Pd/Formic. it distills along with the amine and colours the salt slightly pink. does not go into the aq. layer on A/B.

loki · guinea pig

perhaps its polymerised ketone?

joe_aldehyde · huxleys associate

you are some crazy intelligent fucker, loki...hell yeah, that could be. but how come it distills along with the base? btw. what bp. does the freebase have? used a rotavap with aspirator to get rid of water/toluene and the amine was also in the receiver, sick, huh?

loki · guinea pig

freebase bp is pretty low, boils somewhere around 80 for the methylated phenylisopropylamine at least, shouldn't be too far different i would think.

but yeah, if its distilling its something else cos it's low temp... maybe you should isolate it and do a bp/mp determination on it and maybe u figure it from that. it comes out before the end tho right?

joe_aldehyde · huxleys associate

yes it does come out before the end of distillation. maybe some pretty stable ketone/amine schiff base? wonder where the colour change upon a/b comes from, though...

did you mean the freebase bp. of met-thamph at atmospheric pressure? can't believe it's that low...

amp-hetamine freebase boils at approximately 200°C @ 760mm/Hg

longimanus · Mon Aug 29, 2005 2:22 pm

Estimated values of boiling points of amphetamine and N-substituted amphetamines (in degC):

Standard Error: 20.400K... or something like that.

And now a little about the impurities. Possibly the first place to start is Here. And more precisely:

Impurities Found in Illicit Amphetamine and methedrine

methedrine Impurity Profiling

References regarding impurities from the synthesis of methedrine

Impurities in clandestinely produced amphetamine; A review

And, at the end, the estimated BP of the impurities mentioned in the sources above:

These values (especially the higher ones) are not very accurate and the error may vary from +/-10 deg for the lower temperatures to possibly -120 deg for the higher ones. Frankly, I was tooo lasy to check my databases and the calculation of the BPs was easier. Probably later... Now it would be interesting to find wich one of these is redish.

bio · Working Bee

........used a rotavap with aspirator to get rid of water/toluene and the amine was also in the receiver, sick, huh?..................

This can be largely eliminated by using a short column at atmospheric. However some carry over still occurs due to the amine mixing with the 84deg water/PhMe azeotrope.

So remove the water before and forget the vacuum or use only 75-100mm if you must and go very slowly through a column.