If you can get methamphetamine by mixing
methylamine and phenylacetone, would you
get regular amphetamine by substituting
ammonia for the amine? (I would think so,
since it says you can substitute different
amines for the methamine, and it seems to
me that NH3 would do fine).

Also, it says to "reduce the condensation
product". I don't exactly get what that means,
someone explain?

Well you get an imine from knovenvagel condensation of the phenylacetone with methylamine. A suitable reduction makes the amphetamine and yields are best when you are reducing the imine as it forms. You will not get amphetamine by a simple reaction from ammonia. You need to do a leukart reduction with formamide and formic acid to get the amphetamine. Or reduce with Na cyanoborohydride and ammonium acetate.

So if methylamine makes meth, why doesn't
ammonia make amphetamine?

bump, can anyone answer?

It does. An amine will condense with a ketone to form what is called a schiff base imine, and water. The schiff base is lacking a hydrogen at the amine and is very unstable. To correct this, the product is protonated, or reduced, by using hydrogen or a hydrogen producing substance and a catalyst to reduce the imine to the amine.

Lets look at this for a minute. The imine can be formed by simply mixing the amine and the ketone in an alcohol. However, most reactions are done by mixing the amine in with the ketone while doing the reduction at the same time. That way the imine is formed invitro, which gets to be reduced before it can become ketone and amine again (which is what happens when the schiff base breaks down, remember I said it was unstable). This raises yeilds and shortens reaction times.

Whatever reduction someone chooses to do all depends on what type of equipment and chemicals they can get their hands on. If you had a bunch of palladium and a hydrogen tank laying around, of course it would be more practical to do a Pd/C reduction. These types of reductions are called external reductions, because the hydrogen comes from an outside source. Otherwise it may be more practical for you to do what are called internal reductions, which are those that produce the needed hydrogen chemically on the spot.

For instance, phenylacetone can be dissolved into ethanol. The solution is placed into an ice bath, and freebase methylamine is bubbled through until the solution is saturated, and remains saturated (freebase ammonia can also be used to produce amphetamine, of course in gaseous form, not aqueous). This is then placed in a hydrogenation flask and Pd/C is added. The flask is sealed and presurized with hydrogen (after blowing out all the atmosphere inside). As long as the reaction continues, pressure will drop. Add more pressure. Keep doing this until uptake of hydrogen ceases. This indicates that the reaction is finished. Reaction is worked up in the usual manor.

In internal types, dissolving metal reductions are the most popular, like the use of amalgums, or like Tryptamine mentions above, using the Luekart.
In the amalgum, a small amount of a mercury salt is mixed with aluminum in an alcohol. This strips the aluminum oxide coat from the aluminum, allowing the highly reactive elemental aluminum to begin to swap electrons with the mercury. When each molecule does this, it breaks down into salts and bases that are no longer reactive in that way, so the reaction can only proceed so long. There are many variations of this reaction, but most often the ketone and amine are mixed with a little alcohol, and dripped into the amalgum over a certain period of time. Methylamine is used for methamphetamine (in the case of phenylacetone), ammonia can be used for amphetamine, but because of ammonia's low bp, heat from the reaction will drive it off quicker, so yeilds are low. Hexamine can also be used for amphetamine, however I am unsure of the yeilds. Also, with reactions like these, methylamine can be also produced on the spot. Some amalgums are ran with nitromethane and phenylacetone. The amalgum is made big enough to reduce the nitro group on the nitromethane to an amine group. So in this case, nitromethane (wich is bought mixed with methanol at any hobby shop by the gallon for those piston rc cars) is reduced by the amalgum first into methylamine, then it reacts to form the imine, which is also reduced by the amalgum to the desired amine. Because of the poisoness nature of the chemicals involved in this reaction, work-up's need to be a bit more extensive, but are still easy enough.

In the Luekart, the desired amine is reacted with formic acid and ketone, my guess would be that the amine and ketone condense to form the imine, and formic acid adds to it, reducing it to the amine, but leaving the formyl group attatched to the nitrogen as a result. In this case, P2P and methylamine condense, form the imine, and formic acid reduces it and forms N-formyl-methamphetamine. The formyl group is removed by adding a little muriatic and refluxing for so long. The result is diluted with water, filtered through charcoal, and worked up. The HCl hydrolizes the formyl group, forming methamphetamine.

There are other types. There is use of Platinum Dioxide as a catalyst for reducing the imine, which works in incredibly high yeilds. There are also other types of ways of generating that much needed hydrogen, like electrolytic methods, which use electricity to do the job. Just do your research.

I don't suppose HCl could reduce the imine,
could it?

No.

using ammonia in water is actually ammonium hydroxide, I don't think you can get it to condense with a phenylacetone using an aluminum amalgam reduction. I've never heard of anyone doing this succesfully. And because it is so obvious and no writeups exist for this I don't think it is possible. This is because there is little free ammonia available it is all in the form of ammonium hydroxide.

Who said anything about water? I seriously hope your not doing your amalgums in water.

Also, ammonia and water have a very low affinity for each other, and just about anything will tear it apart back to plain NH3 and H2O (ever wonder why pure NH4OH is never obtainable?). The reason why ketones won't condense with any amine in water is because when an imine is formed, water is formed as a by product. Imines also have low affinity for each of it parts. The condensation of the ketone and amine is a reaction in itself, and too much water will shift the equalibrium, which is why water hinders condensation greatly. Don't get me wrong, some still will condense no matter what, but yeilds will be horrible.