Sciencemadness Discussion Board

Acetamide synthesis

mewrox99 - 28-6-2010 at 02:32

I'm still a really noob at o-chem. This is one of my first organic reactions with the exception of simple halogenations.

Will adding dilute acetic acid to ammonia solution produce a solution of ammonium acetate that can be heated to decompose to solid acetamide.

[Edited on 28-6-2010 by mewrox99]

kclo4 - 28-6-2010 at 03:12

This probably ought to be in the beginnings section of the forum, as it has no reference, or that you have done research.
I believe this is a synthesis that should be easy to find online.


Also, whatever it is you are proposing, doesn't make any sense at all -- Copper (II) Oxide, reacting with ammonia (anhydrous liquid? aquas solution? gas?) to produce an ammonium compound that I don't think exists? Where did the carbon come from, where did the copper go?


I think there is probably some serious confusion, so make sure you research and at least have a general idea of what you are talking about, make sure certain compounds exist, and probably a few other things before you post.

The best way to make acetamide, so it has been said on this forum already is to reflux glacial acetic acid with urea -- I have no performed it, so you will need to look into it.

Sulfuric acid is likely going to react with a few intermediates which you are using to make acetamide, keep in mind that ammonia, acetamide, and also copper oxide are all basic in nature, and will form sulfates or hydrolyse.



Picric-A - 28-6-2010 at 03:21

Acetamide is made by reacting Ammonia solution with acetic acid glaciel, producing Ammonium acetate.
This salt can be dehydrated by heat to produce acetamide.

mewrox99 - 28-6-2010 at 13:58

I was really tired when I was writing that and wasn't concentrating (who knows where CuO came from????)

Will adding dilute acetic acid to 12% NH3 solution and boiling yeild some Actamide.

DJF90 - 28-6-2010 at 14:31

No, that will just reduce the volume of the solution of ammonium acetate formed. Acetamide can be formed by distilling (?) dry ammonium acetate, or by heating in a sealed tube for a few hours at high temp (200 ish IIRC). Check Vogel for actual details, and Orgsyn may have some info also.

Magpie - 28-6-2010 at 15:03

Acetamide can also be made from ethyl acetate and con. ammonium hydroxide, per Brewster et al. I have done this and it is fairly easy. The only challenge was distillation of the acetamide as it has a bp of 221.2C. I had to insulate the pot and half the condenser. No water was used in the condenser. Yield = 85%.

Waffles SS - 7-5-2012 at 04:29

Magpie How you done it?
I read some where that acetamide decompose on boiling water

Magpie - 7-5-2012 at 10:14

Quote: Originally posted by Waffles SS  
Magpie How you done it?


I would think that a procedure could be found in the forum library such as in Gatterman, but I haven't been able to access the library now for at least 2 days. So, from Brewster et al:

1. Place 50mL ethyl acetate and 70 mL con ammonium hydroxide in an erlenmeyer flask and stopper. Let this stand for at least 48 hr. This should be a homogeneous solution after 48 hr.

2. 1st distillation: Transfer the solution to a 500 mL RBF and add a few boiling chips. Set up for simple distillation. Trap the escaping NH3 gas from the vacuum adapter by leading it to an inverted funnel placed over dilute sulfuric acid solution. Distill using a water condenser until the temperature reaches 180C.

3. 2nd distillation: Transfer the acetamide to a 100 mL RBF pot. Replace the water condenser with an air condenser. Use a small flask as receiver. No gas trap is needed here. Use a bunsen burner with a slightly luminous flame. Collect 2 fractions: 150-210C and 210-225C. The 2nd fraction is mainly acetamide. The 1st fraction can be refractionated to collect more acetamide.

NOTE: Throughout the distillation any acetamide that solidifies in the condenser should be removed by warming the tube. Otherwise the flask may burst if the tube becomes clogged.

Crystallize a small portion of the acetamide from chloroform. Its mp is 82C.

TIETSE - 7-5-2012 at 13:06

look this pdf

http://orgsyn.org/orgsyn/pdfs/CV1P0003.pdf

Waffles SS - 7-5-2012 at 21:32

I think if Acetamide didnt decompose on first distillation(as i said before it decompose in boiling water and first solution contain water)then we can ignore second distillation and use Xylene for Extraction of Acetamide from solution

I think this can be good idea.
Quote:

SOLUBILITY IN WATER:Soluble (decomposes in hot water)
http://www.chemicalland21.com/industrialchem/organic/acetami...



Interesting method(Acetamide by Urea):
Quote:

Acetamide by Urea:
CH3COOH + NH2CONH2 -> CH3CONH2 + NH2COOH ( -> CO2 + NH3)
Acetic acid + urea -> acetamide + carbamic acid(Carbon dioxide + Ammonia)

Place 25 g. of glacial acetic acid and 25 g. of urea in a
100 ml. Claisen flask. Fit an air condenser into the short neck and a
360° thermometer (with bulb in the mixture and 1 cm. from the bottom of
the flask) into the long neck ; close the side arm with a small cork. Tilt
the flask at an angle of about 30° from the vertical so that liquid does not
collect in the side arm (compare Fig. / / / , 31, 1). Heat the mixture gently
either on a wire gauze or in an air bath (Fig. II, 5, 3). When the urea
melts, shake the flask gently in order to mix the acid and urea layers.
Gradually raise the temperature so that the liquid just refluxes in the
condenser. The temperature is about 150° after 30 minutes and a white
Solid (probably ammonium carbamate) commences to form in the condenser
push the solid back into the flask by means of a stout glass rod
when complete blocking of the condenser appears likely. Continue the
heating until the temperature of the liquid is 195-200° ; this temperature
is attained after a heating period of 3-3 • 5 hours. Both carbon dioxide
and ammonia are evolved. Allow the apparatus to cool and rearrange it
for distillation. Heat the flask slowly at first; some ammonium carbamate
first sublimes into the air condenser. When the acetamide just
reaches the condenser, stop the distillation momentarily, replace the
condenser by another of similar size and continue the distillation. Collect
the acetamide at 200-216° (most of it passes over at 214-216°); if it
crystallises in the condenser, it may be melted by the cautious application
of a flame. The yield of almost pure, colourless acetamide, m.p. 80 • 5°,
is 22 g. It may be recrystallised, if desired, as detailed under 1.

Vogel, Practical Organic Chemistry (3rd ed., 1959) p 401


[Edited on 8-5-2012 by Waffles SS]