Sciencemadness Discussion Board

Is this true about chloroform and amonia?

solarflare99 - 29-6-2004 at 12:29

I heard a rumor that mixing chloroform and amonia will result in hydrogen cyanide, and the reason why I make this post is to confirm or deny the validity of that assumption. I do not intend to try this myself at the moment, as it's probably extremely dangerous if true.

Is it true that if you accidently or intentionally and simply mix the liquids of chloroform and ammonia at room temperature, deadly hydrogen-cyanide fumes will be emitted?

Or, will the mixture itself combine to form liquid hydrogen cyanide?

Or, is it safe to mix the two chemicals and the two ingredients will simply "sit together", but not mix?

[Edited on 29-6-2004 by solarflare99]

unionised - 29-6-2004 at 14:47

No, It isn't true.
There are plenty of old procedures for extracting alkaloids that rely on making the mixture basic with ammonia and extracting into chloroform.
You might be able to get HCN if you flash heated the vapours together at about 1000C or , then again, you might not; who cares?

Organikum - 30-6-2004 at 02:22

Polverone wrote here:
http://www.sciencemadness.org/talk/viewthread.php?fid=2&...
Quote:

The "easiest thing ever" that I have found, from my good friend the Hive, is that when certain chlorine-containing solvents are gently heated and stirred for a long time with a mixture of aqueous ammonia and sodium (or potassium) hydroxide, they will form NaCl or KCl and NaCN or KCN (look it up for balanced equations and specific directions.) Sadly, this leaves you with a mixture of salts, and I am obsessed with purity. If I were to prepare large quantities perhaps I could separate the salts by recrystallization, but that sounds hazardous (because of larger quantities.)


So in the presence of an alkali-metal hydroxyde and with lots of time there will be cyanide formed.

Nick F - 1-7-2004 at 04:23

Or, as unionised said, you can pass a mixture of the gases through a hot tube. I think it was around 500*C. A quick search should find the patent...
Hexamine vapours also make HCN when heated enough, along with methane I assume.

Organikum - 1-7-2004 at 06:43

Do you have some details on the hexamine to HCN Nick? Temperature etc.?

regards
ORG

Nick F - 1-7-2004 at 08:18

Originally posted by rikkitikkitavi at E&W:

"hexamine (hexamethylentetramin, (CH2)6N4) ) decomposes above 200 C to ammonia and a resninous oil. Inreasing the temperature to 330 C
HCN, CH4, N2, H2 are the basically products.

At 800 C major decomposition product is HCN!

This is utilized in a patent(country germany ?) by Plischke and Zettl for producing HCN in 90 % yield from hexamine.

First vapourizing hexamine at 260 C then heating the vapours in a ceramic oven to 800-1200 C yielding HCN.

Unfortunately this is all I could dig out from my 40 cm pile of papers regarding chemicals... ,I can produce a reference to the patent but I be gone for R&R for a week from now."

Organikum - 1-7-2004 at 09:57

Thanks Nick!

I found it:
DE1076104


A short translation of the procedure:

Hexamine in a closed retort is heated to about 260°C (160-270°C) at which it sublimes. The vapours are vented into a tube furnace (1) which is insides coated with ceramics and heated to 1150°C (800-1200°C) wher they are pyrolysed. The vapours have to be vented directly into the hot zone of the furnace and cooled rapidly after leaving it. Ammonia and HCN are separated by the ususal ways (2), the rest gasses are recirculated. The whole reaction system is kept below atmospheric pressure (just a little bit).

(1) A tube of 3cm diameter and 60cm length is named lateron.
(2) The "usual ways" of separating ammonia and HCN are lateron named. It is scrubbing with H2SO4 and lye (NaOH).

Other quite similar methods are described, it comes out that the RAPID heating from 260°C to 800°C+ and the RAPID cooling after the pyrolysis are essential.

If it would not be for the damned high temperatures it would be a good way, but hot tubes capable for temps over 800°C are not so easy to build after my experience because corrosion of the heating wires becomes a serious problem then. But for it would probably need only a very small tube to do this it still catches my interest. 3/60cm is industrial, 0,5/15 should suffice with ease and the ceramic tube could be conveniantly made by drilling a hole into a firebrick. A wider tube filled with porcelain shards for a few cm serving as the "hot zone" would be another possibility.

ideas, ideas....
ORG

DDTea - 1-7-2004 at 10:25

Chloroform and Ammonia DOES, in fact, form Hydrogen Cyanide and was mentioned in War Gases:
Quote:
Hydrogen Cyanide may be prepared in various ways...or by heating Chloroform with Ammonia,

HCCl3 + H3N --> 3 HCl + HCN



Naturally, this gives you a mixture of gases--most of which are Hydrogen Chloride. Also, it requires heating, so I imagine the reaction occurs in the vapor phase--not as a liquid. As such, it is unlikely that mixing liquid ammonia and chloroform would pose a great risk for Cyanide gassing. :)

DDTea - 1-7-2004 at 11:09

On the note of Ammonia, Ammonium Cyanide may be something to consider if we're interested in Cyanide salts. It can be prepared by passing Ammonia gas over hot coals. Naturally, other Cyanide salts--or Hydrogen Cyanide, if need be--can be made from Ammonium Cyanide.

unionised - 1-7-2004 at 12:01

Nitriles hydrolyse under alkaline conditions to give ammonia and the corresponding acid (as the salt).
HCN is the nitrile of formic acid and that's what you will get if you leave ammonia, CHCl3 and a base in solution for long enough. You might get some cyanide on the way but I don't think the yield will be up to much.

I'm not convinced that the reaction of ammonia with chloroform in solution in water will produce HCN in anything like a hazardous or useful quantity.

If anyone remembers the original question it was about accidentally producing enough cyanide to kill someone by just mixing the liquids. From that point of view, the answer is "no".

DDTea - 4-7-2004 at 15:54

Taking this discussion somewhere else... If Ammonia reacts with Chloroform at high temperatures to produce Hydrogen Cyanide and Hydrogen Choride, could Cyanogen be formed by reacting Hexachloroethane with Ammonia? Or perhaps the aggressive lachrymator Chloroacetonitrile by Ammonia with 1,1,1,2-Tetrachloroethane?

stygian - 19-9-2004 at 20:02

I may have read it on this very forum, it's called the Hoffman isonitrile synthesis, I think it needs a little PTC to go at an appreciable rate