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Author: Subject: Trichloroacetic Acid

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[*] posted on 5-2-2008 at 03:32
Trichloroacetic Acid

Hello, long time lurker, first time poster.

I am currently doing some research into home brew chlorine donors for pyrotechnic purposes. I have found a promising chemical - Trichloroacetic Acid. It contains around 60% chlorine and seems easyish (possible) to make at home. I want to experiment and see if I can create some nice blues from the copper salt of it.

So how would I go about making it? I can find barely any information on the web pertaining to the actual synthesis. The only info I found was for Chloroacetic Acid. I know jack all about organic chemistry, so this is where I turn it over to you guys - how the hell do I add my three Chlorines to my Acetic acid?

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[*] posted on 5-2-2008 at 04:56

Making this from acetic acid is not easy at all. You should go via chloral (or chloral hydrate).

From ethanol you can make chloral (there are syntheses for this chemical on the web). Chloral in turn can be oxidized to chloroacetic acid.

I'm not sure about the stabilioty of the trichloroacetate salt of copper. Trichloroacetates can be prepared (e.g. the sodium salt), but the trichloroacetates are not nearly as stable as normal acetates. They easily decompose in alkaline environments, giving chloroform and carbonate:

Cl3C-C(=O)O(-) + OH(-) --> Cl3C-H + (-)O-C(=O)O(-)

Altogether, the route from ethanol+chlorine to trichloroacetates is not a really easy one. If you really want copper/chlorine blue for pyrotechnics, then why not try a mix of CuCl and PVC? CuCl can be prepared fairly easily (although making it pure is very difficult, but for pyro-purposes some contamination with basic copper(II) chloride is not an issue at all). I would not go for CuCl2. The latter is very hygroscopic.

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[*] posted on 5-2-2008 at 06:41

Below is a link to a patent that describes the preparation of trichloroacetic acid from acetic acid, acetic anhydride and chlorine.

Manufacture of trichloroacetic acid
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[*] posted on 5-2-2008 at 20:18

Worse yet is the ability of this compound to abscond with water from the air (as you watch) to become TCA "soup". Whilst an adequate halogen source to make your colors pretty, etc., I think you'll have trouble initiating a soupy (or merely moist) mess.



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[*] posted on 5-2-2008 at 20:32

would it make a good water scavenger for gas supplies? say, in an inline tube?

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[*] posted on 6-2-2008 at 17:14

Any good chlorine donor should be stable, unreactive at low temperatures, of minimal toxicity to workers and preferably not hygroscopic. As I mentioned in another post, try C2CL6 if your looking for a high Cl content donor. Sure it's not the least toxic of the bunch but if you read and believed the MSDS on everything you came in contact in pyrotechnics, you wouldn't get out of bed in the morning.

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[*] posted on 6-2-2008 at 20:06

I believe trichloroacetic acid can be made straight from ethanol just like chloral; instead of controlling the temperature during the chlorination, allow it to heat up. The alcohol gets oxidized to a carboxylic acid by the chlorine.

I believe some references appeared in a thread regarding the synthesis of chloral, sauron was the poster of this information.

Spend some time searching the forum, I know you will find it (I am too sleepy to look).

(I don't have the memory of an elephant so I am not completely positive about the rxn conditions)
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