Sciencemadness Discussion Board

Haloform Reaction With Ca(OCl)2 and EtOH

Kobold vor NH4 - 15-12-2019 at 02:51

Hello Everyone, I have seen that Ethanol can be used in place of Ketones (because it oxidizes to acetaldehyde) in the haloform reaction, and also i have seen that Ca(OCl)2 can be used instead of NaOCl, however i can't find (or i didn't look hard enough) whether or not they can be used together, or if it produces chloroform. I thought i should ask first, just to make sure it doesn't produce anything other than the usual haloform products.

I want to use ethanol in place of the ketone because it produces Formates, which is more useful to me than Acetates, and Calcium Hypochlorite because its more concentrated and easier to get pure than the Sodium salt, and conversion from Ca(OCl)2 to NaOCl is very time consuming.

DavidJR - 15-12-2019 at 05:48

I don't see any reason why not.

morganbw - 15-12-2019 at 06:12

This might be pretty exothermic. Take care and let us know how it goes.

Pumukli - 15-12-2019 at 07:18

There's a warning somewhere in this forum in circulation that reminds people of the possible explosion hazard of Ca(OCl)2 and brake-fluid (or whatever) mixtures...
My point is: be careful with this hypochlorite. Mix it with water first.
Don't try mixing denatured ethanol with dry Ca-hypochlorite!
It indeed may be "pretty exothermic" - as morganbw wrote :)

Kobold vor NH4 - 15-12-2019 at 19:12

So would the reaction proceed like this?
3Ca(OCl)2 + 2EtOH --> 2HCCl3 + 2HCOOH + 3Ca(OH)2

Metacelsus - 15-12-2019 at 20:05

I would expect the reaction to form a significant amount of chloral hydrate (trichloroacetaldehyde hydrate). But the ratio of chloral hydrate to chloroform will depend on pH (higher pH favoring chloroform), and probably also on temperature.

And I would definitely test it on a small scale first! There will be a considerable exotherm.

S.C. Wack - 15-12-2019 at 20:14

It is said that there is no formate:
https://books.google.com/books?id=xOM0AQAAMAAJ&pg=PA271
and, some ethyl chloride is formed. There are possible side reactions of chloroform such as base giving formate, and hypochlorite giving CCl4.

Kobold vor NH4 - 15-12-2019 at 22:21

Well, I gave it a try, and about half way through the ethanol additions, the solution got quite thick, (Ca(OH)2 I presume?)
It was cooled to around 7C-10C, it only spiked by about 5C. The scale I did it on was for a 500ml flask (the biggest one I have).
[Ca(OCl)2] [EtOH] [H2O]
(84.78g ) (18.42g) (500g )
Still waiting for it to settle, but should I filter it now or just use HCl once it has settled, to remove the Ca(OH)2?

Pumukli - 15-12-2019 at 23:21

Expect some chlorine on acidification!

Kobold vor NH4 - 16-12-2019 at 01:06

No chloroform has settled out yet...
I tested the ph, at first it was around 8-9 then a second later it was 4-5.
I'll try filtering it and see if there is any chloroform in there.

[Edited on 16-12-2019 by Kobold vor NH4]

S.C. Wack - 16-12-2019 at 16:15

Quote: Originally posted by Kobold vor NH4  
It was cooled to around 7C-10C, it only spiked by about 5C.


There could be a good explanation for why you have no chloroform here. Are you trying to not use reflux and distillation glassware? Trying to invent new directions? You may have slightly more success with bleach, but the yield is much better when the directions are followed, at least with acetone.

Kobold vor NH4 - 17-12-2019 at 01:51

Quote: Originally posted by S.C. Wack  
[/rquote]
There could be a good explanation for why you have no chloroform here. Are you trying to not use reflux and distillation glassware? Trying to invent new directions? You may have slightly more success with bleach, but the yield is much better when the directions are followed, at least with acetone.


What is your explanation?
Well I didn't get any chloroform out of it, so i just chucked in some KOH and put it in a waste container.
I was following the common HCCl3 synthesis, except with Ca(OCl)2 and EtOH instead of NaOCl and acetone.
So... yeah, I will try Ca(OCl)2/acetone, if that fails then NaOCl/EtOH.
What procedure for the formation of HCCl3 would require a reflux/distillation setup?
For purification, yes, but for formation?
Besides, I don't have any yet.
As for formate, it doesn't really matter to me if it doesn't produce any, its just that if it does, then I'll try to extract it for my collection.

XeonTheMGPony - 17-12-2019 at 03:41

When I do the Normal Chloroform reaction I take the pool shock (calcium hypochlorite at 63% Cl) Grind it with water to make a well dispersed slurry, add that to flask, then rinse every thing into flask with distilled water till I have a moderately thick suspension.

This is where I start additions of Acetone, then once additions are don reflux for a few minutes then distill.

S.C. Wack - 17-12-2019 at 04:02

Quote: Originally posted by Kobold vor NH4  
I was following the common HCCl3 synthesis, except with Ca(OCl)2 and EtOH instead of NaOCl and acetone.
So... yeah, I will try Ca(OCl)2/acetone, if that fails then NaOCl/EtOH.
What procedure for the formation of HCCl3 would require a reflux/distillation setup?
For purification, yes, but for formation?


The published routes in the old literature. I posted a few of my own experiments here trying cold bleach but that was just to see if it could be done. It and other deviant methods are fast but unsatisfactory.

S.C. Wack - 17-12-2019 at 15:59

In the year 1883 I was in charge of a chloroform plant, comprising six cylindrical stills standing on end, each still being 6 feet in diameter and 8 feet high.

This was German import F.W. Frerichs at Mallinckrodt in St. Louis, speaking as president of the American Institute of Chemical Engineers in 1911. He apparently found some formate, but mostly not.
The Manufacture of Chloroform from Bleaching Powder and Ethyl Alcohol
https://books.google.com/books?id=YtbNAAAAMAAJ&pg=PA135

Kobold vor NH4 - 18-12-2019 at 16:51

Well I tried it with Ca(OCl) and acetone and glob of HCCl3 appeared at the bottom after I had reacted the Ca(OH)2 with HCl, it appears that the calcium hydroxide had soaked it up or something. I will try some variations of the haloform reaction once I have a distillation setup, which might be sometime in January.

@S.C. Wack. Those books you mention I can't appear to access them, In the search part, I found the reagent list for the crude chloroform, but only a few paragraphs after the are available.

S.C. Wack - 18-12-2019 at 19:05

I was thinking such a problem could be solved in a minute or two spent finding and connecting to a proxy site, US proxy server, or VPN.

Attachment: chloroform from ethanol.pdf (1.2MB)
This file has been downloaded 243 times


Kobold vor NH4 - 18-12-2019 at 23:55

Quote: Originally posted by S.C. Wack  
I was thinking such a problem could be solved in a minute or two spent finding and connecting to a proxy site, US proxy server, or VPN.


Thank you for the Link!
I could access google books, there just wasn't a download link, and it was just snippets only.

etherealvapour - 20-12-2019 at 06:41

I've considered the same idea before, of using bleaching powder (Ca(OCl)2) and ethanol in the haloform reaction as an easy, cheap and accessible route to not just chloroform, but formic acid and formaldehyde.
It seemed like a natural optimization because if using the NaOCl route, you'd end up with sodium formate, which you would have to acidify, get the formic acid that way, then react with Ca(OH)2 to form the salt and dry distill/decompose the calcium formate salt to formaldehyde.
The latter version means "wasting" both some acid and some base and has more steps, thus if the mechanism allowed for using bleaching powder directly, you'd have gotten calcium formate which you could just decompose right away.
I wonder if there's no way to make the reaction work with Ca(OCl)2? perhaps with the right pH or a suitable catalyst? or put this a different way, what makes the reaction fail?
What other options would there be to use the haloform reactions to get formates?
Use acetaldehyde? But if you're making acetaldehyde from ethanol, you most likely would use a fairly similar process to make formaldehyde from methanol.
Or just use NaOCl, some appropriate acid and Ca(OH)2, even if it'd be more steps, more cumbersome and more expensive, then decompose the formate salt to formaldehyde?

S.C. Wack - 20-12-2019 at 13:39

Quote: Originally posted by etherealvapour  
what makes the reaction fail?
What other options would there be to use the haloform reactions to get formates?


Formate is acetaldehyde with O attached instead of CH3. It's oxidized to CO2.
As said earlier, alkaline hydrolysis of the chloroform.