I'm a budding o-chemist heading off for college next year. I've been reading about methamphetamine syntheses out of curiosity and found a few that used choromethane and amphetamine (and pyridine, but that's not essential). All the syntheses states that the amphetamine and CH3Cl should be vapourized. I don't understand why that would be any different from an aqueous solution. Can someone explain this to me?

Disclaimer: as I stated above, I'm a student. I have no intention of actually carrying out this reaction.

Edit: I realize that chloromethane is a gas with a very low boiling point. Does this necessarily make an aqueous solution impractical? If so, what about bubbling chloromethane through an aqueous solution of amphetamine?

Bump.

what do you mean by "vaporised" - maybe you could give us the reference you're referring to?

well here ya go
The difference between amphetamine and methamphetamine is the addition of a single methyl group (CH3) to the amino group sticking off the middle carbon atom in the chain. Fortunately, substituting amines is really simple. Vaporize your amine (your amphetamine) with a bunch of vaporized chloromethane (CH3Cl, a solvent) and some gaseous pyridine... voila, the amino group takes the methyl from the chloromethane and lets a hydrogen go. The hydrogen joins the liberated chlorine, and the resulting HCl is soaked up by the pyridine. The pyridine is optional. Adding it drives the reaction a bit by pulling the excess HCl out of the equation, but it's not neessary.

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No.

Usually, however, being predominantly hydrocarbon will make an aqueous solution impractical. However, CH3Cl apparently makes it up to about 6g/l. I wouldn't try that with chlorodecane, however.

Instead, I suggest you examine the comparative reactivity of primary, secondary, and tertiary amines with halomethane. It's become somewhat infamous in the tryptamines.

I also suggest you might want to look into how imine formation usually transpires.

"Instead, I suggest you examine the comparative reactivity of primary, secondary, and tertiary amines with halomethane. It's become somewhat infamous in the tryptamines."
whats chloromethane then?

A monohalomethane. Hence the problem...

So would a polyhalomethane like chloroform work better? Also, I don't quite see why imine synthesis is relevent...

Worse, actually.

The problem with methyl (chloride/iodide/etc) is that it is much more likely to react with dimethylamines than methylamines, and methylamines than just an amine group - it not only reacts TOO well, but it reacts BETTER as it accelerates past the point one seeks. Notoriously uncontrollable.

This is apparently much less drastic of a problem with larger haloalkanes.

The problem with trichloromethane, on the other hand, is the formation of a cyanogenic side-chain or somesuch. In fact, I don't know how HCN would work with another bond on the nitrogen... but that's what it would tend to at least try to form. 'n even if it did form a single bond, it'd quickly start trimerizing.

http://en.wikipedia.org/wiki/Formaldehyde

It might be a bit late, but this might help:
http://www.erowid.org/archive/rhodiu...thylation.html

This of course being the lesser alternative to that:
http://www.erowid.org/archive/rhodiu...thylation.html