Chapter Four — Secrets

Preparation of N-Methyl formamide

N-Methyl formamide is best made by the reaction of methylamine with formic acid. The reaction proceeds like this:

The methylamine (a base) reacts with folic acid to find the methylamine salt of formic acid. The
heat that this reaction builds up then causes this intermediate salt to lose a molecule of water and form N-Methylfonnamide. Since water is a product of this reaction, the underground chemist wants to keep water
out of his starting materials as far as possible. That is because having less water in them will shift the
equilibrium of the reaction in favour of producing more N-methyl formamide.
Both of the starting materials have water in them. The usual grade of formic acid is 88% pure and 1 2%
water. It cannot be made any purer by distilling. The chemist can put up with the 1 2% water, but if a
higher purity phonic acid is available, it is worth the extra cost. The usual grade of methylamine is 40%
by weight in water. The majority of this water can be removed by using the apparatus shown in Figure
1 8. Methylamine may also be obtained as a gas in a cylinder. In that case, the methylamine can be piped
directly into the formic acid.

Ice
water
out
Glass
tubing
Figure 18
Formic
acid

Secrets of Methamphetamine Manufacture
Eighth Edition

The glassware is set up as shown in Figure 1 8. The 40% methylamine is in a 1 000 ml round bottom
flask attached to a long condenser. The top of this condenser is a one-hole stopper. A bent piece of
glass tubing is pushed all the way through this stopper so that the end of the piece of tubing extends
about one or two millimetres below the bottom of the stopper. This bent piece of tubing then extends
down through the centre of the other condenser into the flask containing the formic acid. It should extend
below the surface of the formic acid and end about one centimetre above the bottom of the flask
containing the formic acid. The idea here is simple. The 40% methylamine is heated causing
methylamine gas to be boiled out along with some water vapor. These gases then travel up the condenser
where the water is condensed out, allowing nearly pure methylamine gas to be forced by pressure through
the glass tubing into the formic acid.
The bent tubing has to be bent by the chemist himself from a 3-foot-long piece of glass tubing. Its
outer diameter should be about V. inch. The glassware is set up as shown in Figure 1 8 and he decides
about where the tubing should be bent. If necessary, he will consult the chapter on bending glass in an
Organic Chemistry lab manual. With a little practice, it is easy. A good source of flame to swell up the
glass is a propane torch with a flame spreader attachment. After it is bent, he will blow through the
tubing to make sure he did not melt it shut.
He is now ready to proceed. All pieces of glassware are clean and dry. Into the round bottom 1 000 ml
Ilask sitting on the heat source is placed 500 grams (about 500 ml) of 40% methylamine in water, along
with 3 or 4 boiling chips. Into the other 1 000 ml round bottom flask is placed 250 ml of 88% formic acid.
Water flow is begun through the longer condenser. It is advantageous to use ice-cold water in this
condenser because it will then do a better job of removing water vapour from the methylamine. A good
way to get ice-cold water for the condenser is to get a couple of 5-gallon pails. One of them is filled with
ice cubes no bigger than a fist and topped off with water.
Then the section of plastic tubing that runs to the lower water inlet of the condenser is placed in the
pail. Its end is weighted to keep it on the bottom of the pail. This pail is placed on the table along with
the glassware. The other pail is placed on the floor and the plastic tubing from the upper water exit of the
condenser is run to this pail. By sucking on the end of the water exit tubing, the ice-cold water can be
siphoned from the pail on the table, through the condenser, to the pail on the floor. The rate of water flow
can be regulated to about one gallon per minute by putting a clamp on the tubing to slow its flow. When
the pail on the table is about empty, the water that has flowed to the pail on the floor is returned to the
table.
The heat on the methylamine is turned on to about V. maximum. Soon the methylamine begins boiling
out and moving through the tubing into the formic acid. The underground chemist checks for gas leaks in
the system by sniffing for the smell of escaping methylamine. If such a leak is detected, the joint it is
escaping from is tightened up.
The methylamine bubbling into the formic acid produces a cloud of white gas inside the flask
containing the formic acid. It makes its way up to the condenser and then returns to the flask as a liquid.
For this condenser, tap water flow is fine. The rate of methylamine boiling is adjusted so that the white
gas does not escape out the top of the condenser. As more methylamine is boiled out, a higher heat
setting is required to maintain the same rate of methylamine flow.
In this process, the formic acid gets very hot. [t must get hot to produce good yields of N
methyl formamide. It sometimes gets hot enough to boil a little bit ( 1 05° C), but this is no problem. As the
chemist continues bubbling methylamine into the formic acid, its volume increases until it is double its
starting volume, about 500 ml. At about this time, the cloud of white gas thins and then disappears. This
white gas is formed by the fumes of formic acid reacting with methylamine above the surface of the
liquid formic acid. It disappears because there is no longer much folic acid left. The chemist now
begins checking to see if the reaction is complete. He pulls out one of the stoppers from the 3-necked

Chapter Four
Preparation of N-Methylformamide

a flask that contains the N-methyl formamide and sniffs the escaping fumes for the odour of methylamine.
He does this periodically until he smells methylamine. Once he smells it, he turns off the heat on the
methylamine. When the methylamine stops bubbling into the N-methyl formamide, he immediately
lowers the level of the 3-necked flask so that the bent glass tubing is above the surface of the N-methyl formamide. This is done because, as the methylamine cools, it will contract and create a vacuum
which would suck the N-dimethylformamide over into the other flask in a flash, ruining his work.
Both flasks are allowed to cool down. The methylamine is almost gone, so it can be poured down the
drain. The next step is to fractionally distil the N-methyl formamide. The glass-packed c1aisen adapter is
used as the fractionating column. The glassware is set up as shown in Figure 13, back in Chapter Three.
The distilling flask is a 1 000 ml round bottom flask with 5 boiling chips i n it. The collecting flask is a
250 011 round bottom flask. Unlike the distillation of phenylacetone, in this case, the distillation is done
under a vacuum from the beginning. The ice water siphoning system is used for the condenser, because
N-methyl formamide has a very high latent heat of vaporization, and, without this precaution, it may
collect very hot in the collecting flask.
The underground chemist is now ready to distil the N-dimethylformamide. All of the crude product is
put in the 1 000 ml round bottom flask filling it about half full The vacuum is applied at full strength, and
the heat source is turned on to 113 to Y, maximum. The water in the mixture begins distilling. The
temperature shown on the thermometer will show a steady climb during the process.
In a while, the temperature rises high enough that the chemist can begin collecting the distilled liquid
as suspected N -methyl formamide. If he is using an aspirator, he begins collecting in a clean, dry 250 ml
round bottom flask when the temperature reaches 95–1 00° C. If he is using a good vacuum pump, he
begins saving the distilled material at about 85° C. As the N-methyl formamidedistils, the temperature
rises a little bit above the temperature at which he first began collecting the N-methyl formamide, then
holds steady. This temperature is noted. Distilling is continued until he has collected 1 00 ml. Then the
heat is turned off. When the boiling stops, the vacuum hose is disconnected from the glassware.
During the distillation process, a fair amount of methylamine was lost, leaving the N-methyl formamide
with too much formic acid. The next step is to correct this problem.
The 1 00 ml of N-methyl formamide that has been distilled is poured back into the distilling flask with the
undistilled material!’ The distilled material is clear, while the undistilled material has turned yellow from
the heat of distilling. The glassware is set up again as shown in Figure 1 8. This time, the round bottom
flask holding the methylamine is a 500 ml flask. It has 1 00 ml of fresh 40% methylamine in water in it.
The bent glass tubing leads into the flask containing the N-methyl formamide. This flask does not need to
have a condenser on it.
The heat is turned on the methylamine and the Ilow of ice water through its condenser is begun. Soon
the methylamine gas is bubbling into the N-methyl formamide, reacting with the excess formic acid in it.
Within about 1 0 seconds, the odour of methylamine can be detected above the N-methyl formamide. The
heat is turned off and when the bubbling stops, the level of the N-methyl formamide is lowered so that It is not sucked into the other flask. Once the methylamine has cooled off, it can be poured back in with the
good methylamine, because it is not exhausted. Once a bottle of methylamine has been opened, it should
be reclosed tightly and the cap sealed with vinyl electrical tape in order to hold in the methylamine gas.
Now the N-methyl formamide is to be distilled again. The glassware is set up again for fractional
distillation as shown in Figure 13. The distilling flask is a 500 ml round bottom flask, while the
collecting flask is 250 ml All pieces are clean and dry.
The N-methyl formamide is placed inside the distilling Ilask with 5 boiling chips. (Fresh chips are used
every time.) The vacuum is reapplied and the heat is turned on again to 1 /3 to y, maximum. A little bit of
water is again distilled. The temperature shown on the thermometer climbs as before. When it reaches a
temperature r C below the temperature at which it leveled off the first time around, the chemist begins

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Eighth Edition
24
collecting in a clean dry 250 ml flask. The distilling continues until it has almost all distilled over. About
1 0 or 15 ml is left in the distilling flask. If he is using an aspirator, the chemist makes sure that no water is
backing into the product from the vacuum line. The yield is about 250 ml N-methyl formamide. If he gets
a little more, it won’t all fit in the 250 ml collecting flask. If that happens, he pours what has collected
into a clean dry Erlenmeyer flask and continues distilling. N-methyl formamide is a clear liquid with no
odour.
The N-methyl formamide underground chemist has just made is perfect for the Leuckardt-Wallach
reaction. Because he began collecting it 7 degrees below the levelling-off temperature, it contains a
mixture of N-methyl formamide, formic acid and methylamine. To get good results, he uses it within a
few hours after distilling it.
There are other variations of this procedure. A lot of methylamine was lost during the distillation of the
mixture. Much of this could be prevented if the reaction mixture between the formic acid and the
methylamine was forced to completion. If one has a large stainless-steel pipe, the initial reaction mixture.
could be heated under pressure at about 1 40 C for an hour or so to make the reaction to N-Methyl formamide further before distilling the mixture.

References
Journal of the American Chemical Society, Volume 53, page 1879 ( 1931 ).