Fluoro-substituted amphetamines and chirality

[lolwhatzdrugs]

Are the 4,3,2 fa and fmas racemic or dextro-whatever? Like how methamphetamine from psuedo-ephedrine is dextromethamphetamine, but methylamine/phenylacetone is racemic. Note, I don't care about making them, just the chirality. Thanks!

 

[Jktm]

Yes they are chiral.

Things that are racemic are an equal mix of both enantiomers, which can be referred to as dextrorotatory (+), or levorotatory (-), which refers to the direction they rotate the plane of polarized light.

Thought I might add, for a substance to be dextrorotatory or levorotatory, they must be all of one or all of the other.

 

[sekio]

They are chiral, the compounds commonly sold are racemic though, because they're not derived from ephedrine.

 

[lolwhatzdrugs]

They are chiral, the compounds commonly sold are racemic though, because they're not derived from ephedrine.

Isn't ephedrine/pseudoephedrine irrelevant?

I guess I should have been more clear. I'm just kind of buzzed off some stilll; I was merely wondering whether they were enantiomerically pure. Since they're chiral, as you say, shouldn't it follow that the dextro rotory is the truly "active" one with the levorotory producing overt vascoconstriction and mostly unwanted effects, therefore for stimulation with less negative effects you could just use a enantiomerically pure form.

I'm familiar with the basic chemistry but not the doing. What does it take in addition to basic synthesis to separate the two? Like in breaking bad, walt mentions he cooks an enantiomerically pure dextro-methamphetamine. Is seperating a chiral compound that much more difficult of a task, what would it take? Enantiomerically pure precursor or some other steps when crystallizing the compound? I'm sure it makes no sense from a business standpoint... unless you're selling desoxyn, and in that case you'd have the levorotory left to still sell as a pharmaceutical OTC drug.

Are all scheduled chiral compounds defined by which enantiomer produces effects? I'm aware of the meth, and dextrorphan, and its levorotory schedule II opioid half, Is it legal to posses dextromethadone? Were most of shulgins compounds they entiomerically pure? Do all amphetamines and and methamphetamines follow the dextro/levo difference? I know he defines which one some of the time in the trip reports, like just plain old d- and l tryptamine by itself with little effect.

Sorry, so many questions.

 

[i are spectre]

you need special enzymes (usually) to seperate enantiomers. it is a difficult, expensive, and usually pointless task. it is economically unfavored.

i HIGHLY doubt an enantiomer of any illegal compound would be legal. im sure all the possible stereoisomers would be considered the same compound.

also, any atom that has sp3 hybridization with other atoms/electrons/chains is going to be chiral. unless those atoms/chains are identical.

 

[sekio]

The reason desoxyn (and some street meth) is "enantiomerically pure" D-methamphetamine is because it is derived from the natural product ephedrine/pseudoephedrine, which onyl occurs as a single enantiomer in nature (and it just so happens reduction of the hydroxyl group turns it to D-meth). That's the easiest way to have a chiral product - start with natural chiral molecules and work from there.

"Normal" amphetamines are racemic by default, if made from either a phenylacetone and amine, or from a benzaldehyde and nitroethane. The seperation into D- and L- forms does not involve enzymes (though some processes for inducing chirality do involve e.g. selective esterases that will break bonds of the D-compound but not the L-) but rather, as I understand it, crystallization with a chiral salt like tartaric or mandelic acid.
Alternatively I am sure there are chiral auxillaries that could be used in the synthesis to 'direct' formation of predominantly D- or L- amphetamines, look into asymetric transfer hydrogenations.
Neither of those is very applicable on a "street" or "home lab" setting though. The seperation of enantiomers via crystallization is how people formulate Adderall for instance.

Since they're chiral, as you say, shouldn't it follow that the dextro rotory is the truly "active" one with the levorotory producing overt vascoconstriction and mostly unwanted effects

Maybe. Don't be fooled into thinking 'enantiomerically pure' is neccesarily better though, as compounds like MDMA pretty much have to be racemic to achieve what is thought of as 'full effects'. With dextroamphetamine versus laevo, that is certainly the case, but with the fluoroamphetamines that may not neccesarily hold true.

Usually the text of scheduling laws includes "... and optical isomers" or "... and enantiomers". In the case of DXM or L-methamphetamine, the compounds are mentioned by name as explicit exceptions. Methadone isomers would therefore be illegal.

Shulgin did test chirality of some of his compounds, namely DOx series. Most of his compounds were racemic though. And tryptamine is achiral... perhaps you meant AMT or tryptophan.