ChemHack:

I've had pretty shitty yields trying to make Acetamide at home. The amounts
used in the reaction below were experimentally derived so your milage may
very with the quality of starting materials. RatHead provided the
motivation for this experiment and I desparately seek his or anyone's
advice on how to improve it.

Materials:
Aqua Ammonium (low grade? $8/gallon)
Kodak Glacial Acetic Acid
Large pot of cool water (10 quart or larger is good)
Glass graduated cylinder
Distilling apparatus
2 glass mayonaise jars
Long stem funnel (improvised via short funnel w/tubing)


Step One: Ammonia Acetate

Measure 42ml Ammonium and pour into jar #1. Put the jar in the freezer to
chill. Measure 30ml Glacial Acetic Acid, submurge entire glass graduated
cylinder in large pot of cool water. For better stability, make sure no air
bubbles are trapped under the base of the cylinder.

Place funnel into graduated cylinder so that the end extends well below the
level of the Acetic Acid. Pour Aqua Ammonium into funnel, the first few
drops will react very vigorously and may spit Ammonium back out of the
funnel so slow at first or wear goggles. Execpt for the first little bit,
the Ammonia can be added very quickly this way. Considerable heat is
evolved but the water bath effectivly cools the cylinder. Bubbles are
formed but are mostly absorbed by the liquid as they rise, this is the
reason for the long funnel.

Once all of the Ammonium has been added (should take less than 1 minute) a
sweet candy smell may be present in addition to the lingering smell of
Ammonia. Don't put your nose over it just in case. Pour the solution into
Jar #2 and repeat the process two more times. The time from start to
clean-up is 30 minutes or less.


Step Two: Acetamide

Ammonium Acetate degrades into Acetamide at 88C. I don't really know how
long it takes to happen so I guessed one hour. This is only a guess with no
experiment to back it up. Anyway, pour the contents of Jar #2 into a
boiling flask. Boil some tap water in the large pot that you used for a
cool water bath in step #1. Heat the boiling flask containing the combined
liquid from the three iterations of step #1 in the boiling water for an
hour. Don't let the water get into the flask, also don't let all the water
boil out of the pot. If there is any excess free Ammonia it will boil out
now so be prepared for a stink. Rigging up an odor control device now will
also benifit you in the next step but it is not necessasary.


Step Three: Recovery/Purification

Set up your rig for fractional distillation with a water cooled condenser.
The temperature will rise as you heat the solution, it will begin boiling
in the neighborhood of 108C but the temperature will quickly rise under
strong heating until it gets to 118C. It will stick at 118C for a while as
Acetic Acid comes over. Soon, the temperature begins to rise again and the
smell, which until this point was getting better, will begin to get worse.
Clear watery distillate will come over all the way up to 200C. I don't know
what it is but it smells pretty nasty. Third party noses have described it
as the smell of "rotting ammonia" and "rotting food with ammonia." I think
it smells like my urine after a night in the coffee house drinking java
after java and smoking cigarettes.

Replace the collection flask when it gets to 200C and collect everything
between 200 and 225. It is still a clear liquid and there is no doubt that
there is some of that smelly stuff in there with it. Stopper the flask and
set it aside to cool down. When it cools down somewhere below 80C it will
form white crystals.

If you just heat it to 200C and keep everything that is left it will still
crystalize but it seems to melt at a lower temperature and never be quite
dry. Actually, you can usually stop heating at 150C and it will crystalize
at room temperature but it will melt in your hand. The MSDS for Acetamide
says that it melts at 81C.

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				 Org Syn Coll Vol 1, p3-4
                                 ACETAMIDE
                        CH3CO2NH4 => CH3CONH2 + H2O
               Submitted by G. H. COLEMAN and A. M. ALVARADO.
                 Checked by H. T. CLARKE and E. R. TAYLOR.
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                                1. Procedure

    In a 5-l. flask is placed 3 kg. (2860 cc., 50.0 moles) of glacial
acetic acid and to this is added a weight of ammonium carbonate
corresponding to 400g. (23.5 moles) of ammonia (Note 1). The flask is
fitted with a one-hole stopper holding an efficient fractionating column
90 cm. long with condenser and receiver. An air condenser 150-200 cm. long
may be employed. The mixture in the flask is heated to gentle boiling and
the flame so regulated that the rate of distillation does not exceed 180
cc. per hour. The distillation is continued in this way for eight to ten
hours, until the temperature at the head of the column reaches 110ø. The
distillate, which is a mixture of water and acetic acid, amounts to
1400-1500 cc. The receiver is changed, the flame under the flask is
gradually increased, and the distillation is continued at about the same
rate until the temperature at the head of the column rises to 140ø. The
distillate, which amounts to 500-700 cc., is largely acetic acid and may be
used in the next run.

    The contents of the flask are transferred to a 2-l. flask for
fractional distillation, having a column 40 50 cm. long, and distilled
under atmospheric pressure, using an air condenser. The fraction boiling
below 210ø, amounting to 250-300 cc., is collected separately. The material
remaining in the flask is nearly pure acetamide and may all be distilled,
1150-1200 g. passing over at 210-216ø. By redistilling the fraction boiling
below 210ø, the yield may be increased to 1200-1250 g. (87-90 per cent of
the theoretical amount). The acetamide thus obtained is pure enough for
most purposes, but if a purer product is desired it may be recrystallized
from a mixture of benzene and ethyl acetate; 1 1. of benzene and 300 cc. of
ethyl acetate are used for 1 kg of acetamide (Note 2). Colorless needles
melting at 81ø are thus obtained (Note 3). The solvent and the acetamide it
contains may be recovered by distillation.

                                  2. Notes

    1. Ammonium carbonate of commerce is often extremely impure, and care
must be taken to obtain a representative sample for the determination of
the ammonia content by titration with standard acid. The ammonium carbonate
used in this preparation contained 27.2 per cent of ammonia, and 1470 g.
was used in each run.

    2. Crystallization of acetamide, by solution in hot methyl alcohol (0.8
cc. per g.) and dilution with ether (8-10 cc. per g.), has been recommended
as the best method of purification(1).

    3. As acetamide is somewhat hygroscopic, it cannot be exposed to the
air unless precautions are taken to have the air dry.


                         3. Methods of Preparation

    Acetamide can be prepared by the rapid distillation of ammonium acetate
(2) by heating ammonium acetate in a sealed tube and distilling the product
(3) by treating acetic anhydride with ammonia (4) by heating a mixture of
ammonium chloride and sodium acetate to 240ø (5) by the action of cold
aqueous ammonia on ethyl acetate (6) by boiling a mixture of glacial acetic
acid and ammonium thiocyanate for four days (7) by saturating glacial
acetic acid with dry ammonia and then refluxing (3) by distillation of
ammonium acetate through a reflux condenser filled first with glacial
acetic acid and then with aniline until the temperature of the mixture
reaches 220ø (9) by passing a stream of ammonia through heated acetic acid
(10) and from formamide and hydrogen at 200-500ø (11).

    The procedure described is based on the method of Noyes and Goebel (12)
in which equimolecular proportions of ammonium acetate and acetic acid are
heated together, the acetic acid having been shown to accelerate both the
dehydration of ammonium acetate and the hydrolysis of acetamide.

    1  Wagner, J. Chem. Education 7, 1135 (1930).
    2  Kundig, Ann. 105, 277 (1858).
    3  Hofmann, Ber. 15, 977 (1882).
    4  Gerhardt, Ann. chim. phys. (3) 37, 327 (1853).
    5  Dunlop, J. Am. Chem. Soc. 24, 762 (1902).
    6  Phelps and Phelps, Am. J. Sei. (4) 24, 429 (1907)
    7  Sehulze, J. prakt. Chem. (2) 27, 514 (1883).
    8  Grant and James, J. Am. Chem. Soc. 39, 933 (1917).
    9  Franeois, J. pharm. ehim. (6) 23, 230 (1906) [Chem. Zentr. I, 1089
       (1906)].
    10 Mitchell and Reid, J. Am. Chem. Soc. 53, 1879 (1931).
    11 Soc. franchise de catalyse g‚n‚ralis‚e, Fr. pat. 708,084 [C. A. 26,
       995 (1932)].
    12 Noyes and Goebel J. Am. Chem. Soc. 44, 2286 (1922); Rosanoff,
       Guliek, and Larkin, ibid. 33, 97i (1911): Hitch and Gilbert. ibid.
       35. 1780 (1913).
    
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Posted to the Hive 12-07-98 by Drone #342

Acetamide is a useful compound. When reacted with bleach, it makes
methylamine gas. So you may say to yourself: "Damb! How do I get me some of
that?". Aside from purchasing it, its incredibly easy to make! Here's how:

44.055 g (0.5 moles) of ethyl acetate is combined at room temperature with
59 grams of concentrated aqueous ammonia (1 mole; conc.=approx 29%) in an
Erlenmeyer flask. A stirbar is added, and the flask is stoppered. The flask
is stirred at room temperature for three days. At this point the contents
of the flask is distilled. At standard pressure, aceamide will distill over
between 200-220°C. If a vacuum is used (highly recomended), pure acetamide
distills at 158°C (100 torr), 136°C (40 torr), 120°C (20 torr), 105°C 
(10 torr), or 92°C (5 torr).

Acetamide is a white, crystalline substance substance that readily disolves
in water. It has a melting point of 81°C.

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Practical Organic Chemistry, Sudborough and James, 1931, p179-180, Exp. #131

20g dry acetamide is mixed with 54g Bromine in a 500ml flask. A solution of 20g 
KOH in 200ml H2O is added dropwise with the flask resting in an ice bath. (Look 
for a red-brown->yellow color change) Disolve 60g KOH in 100ml water, cool, and 
add to a 1l RBF. Add the acetbromide dropwise to the flask w. a thermometer 
checking that the temp doesn't exceed 75C. Once addition is complete, and when 
the rxn mix begins cooling, maintain a temperature of 65C on a water bath for 30 
minutes. Set the flask up for distillation, in the receiving flask place 100ml 
of dilute HCL (probably; calc. 2x mol's needed to form salt of a 60/40 MeAm/NH3 
mix). Distill the MeAm+NH4 out of the flask and stop when the distillate coming 
over is no longer alkaline (how to test that?). Evaporate the H2O out of the 
HCl+distillate on a water bath (75C). Dissolve the colorless residue in hot 100% 
EtOH (It MUST be 200proof) NH4Cl will be insoluble. Filter off what should only 
be a few grams of NH4Cl. Pour the EtOH into a beaker and cool. Later filter out 
the Methylamine and dry it in a dessicator.

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