Author Topic: Corrections to Cheapskates chloroform writeup  (Read 7756 times)

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  • Guest
Corrections to Cheapskates chloroform writeup
« on: June 23, 2002, 08:19:00 PM »
Cheapskate messed up in his calculations in

3 mol bleach is required for 1 mol acetone. The overall reaction is:

2 CH3COCH3 + 6 Ca(OCl)2 -> 2 CHCl3 + (CH3COO)2Ca + 2 Ca(OH)2 + 3 CaCl2

340g of acetone is 431mL or 5.85mol. 5.85mol of acetone requires 3x the equiv of NaOCl, or 17.56mol of NaOCl. That is 1.306kg of pure crystalline NaOCl, or 12.098kg of 10.8% NaOCl. 10% NaOCl has a density of 1.16g/mL. So that is a volume of 10.4L of NaOCl. Or 3.2 U.S. gallons (1gal = 3.78L). Cheapskate is using 2 gallons, ie he is 1.2 gallons short on bleach. Not enough bleach to oxidize all of the acetone...

Where I live, bleach is sold in 4L containers... so all this makes no sense to me anyways!  :)

So I'll redo the calculations.

The final word is:

For every 1g of acetone (0.788mL) you want to oxidize, use 35.5g (30.6mL) of 10.8% NaOCl.

Also, if you're having trouble oxidizing anything with NaOCl, use 1 mol of HCl to 1 mol of NaOCl required, and drip it in with what you're oxidizing. Ie, if you want to make sure the NaOCl oxidizes the acetone easily, add 1 mol eq's of 10% HCl relative to the NaOCl mixed together with the acetone, and drip the acetone/HCl into the mixture slowly (with the whole thing on an ice-bath and ice-water running through the condenser). Otherwise what can happen is you'll have nothing happen, then all of a sudden the reaction picks up, and with the heat, it picks up even more... until it starts to boil over... 100s of mLs of chloroform evaporating into your working area within seconds, is NOT fun.

Data I used for the calculations:
10.8% NaOCl (w/w)
31.25% HCl(aq) (w/w)
0.03646 g/mmol HCl
0.0744 g/mmol NaOCl
0.05808 g/mmol acetone
0.788 g/mL acetone
1.16 g/mL 10.8% bleach


  • Guest
Just do this in a 5 gal bucket
« Reply #1 on: June 23, 2002, 09:45:00 PM »
I don't know about adding HCL, SWIM used to do it this way.
For every 500ML of household bleach (in 5 Gal Bucket) He adds 35 ML of acetone.
Then. sealed up bags of crushed ice are thrown in to keep everything cool.
the bucket can be sealed up too to prevent chloroform from escaping into the room.
Once everything is nice and cool just remove the ice bags and if you like to can use salt to "salt out" any chloroform in dispersion.
SWIM never did he just decanted most of the top aqueous layer until he had something he could work with in a sep funnel.
You know the rest, Sep funnel, distillation, add  1Ml alcohol/100 ml distilled chloroform, blaa, blaa, blaa.


  • Guest
« Reply #2 on: June 23, 2002, 10:49:00 PM »
>For every 500ML of household bleach (in 5 Gal Bucket) He adds 35 ML of acetone.

NO! Read my post.

For every 35ml of acetone (27.5g, 0.474 mol) you need 2.1kg (1.96L, 1.42 mol) of 5% household bleach (density 1.08 g/mL). Your calculations are worse than Cheapskate's!


  • Guest
« Reply #3 on: June 24, 2002, 12:39:00 AM »
The document at my page has been updated with your corrections. Thanks, Chromic!


  • Guest
Verifying that this works
« Reply #4 on: June 24, 2002, 01:49:00 AM »
I'm in the process of verifying that this works with a 0.5 mol batch.  Using 0.2 eq of hydrochloric acid just so the reaction kicks off easily. I'm expecting 35.9mL as a theoretical yield (accounting for losses of CHCl3 to the aqueous layer), but it looks like the actual might be significantly lower. We'll see.

Rhodium, thanx, just one addendum to that comment in the document: 1 mol of HCl is, I think, not really needed. I think 0.2 mol, ie 410g 31.25% HCl per 340g acetone is a better amount to go with. The oxidation starts fast, and is easily controlled. It might not be absolutely necessary, but it does make it easier.

I should be able to let you know soon what the yields are like and give a short account of the reaction. I'm really pleased how this has worked this time around. If I can find THF OTC, we're going to have to find a short, sweet way to OTC GHB using a technique similar to this.  8)


  • Guest
« Reply #5 on: June 24, 2002, 02:38:00 AM »
Yes, that is true SWIM did'nt bother using stochiometric calculations, among others.
He did'nt really care since the reaction is so simple.


  • Guest
« Reply #6 on: June 24, 2002, 05:27:00 AM »
29g acetone & 35g 31.25% HCl was slowly dripped into 890mL 10.8% bleach (using glassware... pressure equalized addition funnel, 3L flask in a cold-water bath, claisen adapter, reflux condenser running ice-cold water). 59.9g is the theoretical yield, and I'd expect to lose 1ml of chloroform per 200ml of aqueous. So that gives an expected yield of 53.3g.

I got 17.9g chloroform. 30% of the total theoretical. What the fuck? The reaction worked, never got out of control, the bleach lost its typical yellow color... the water stinks of chloroform, the density of the chloroform gathered is 1.30g/mL (definitely shy of 1.484g/mL)

I'm so absolutely confused.


  • Guest
« Reply #7 on: June 24, 2002, 05:32:00 AM »
Is the 'household bleach' solely NaOCl/H2O or are there other ingredients?


  • Guest
Now what?
« Reply #8 on: June 24, 2002, 05:34:00 AM »
Should I try acidifying the aqueous layer, or adding more bleach?

... perhaps there's a mistake in my calculations or in the formula listed above? Can any one spot a problem?

PP, the bleach I'm using is, I believe, stabilized with bit of sodium carbonate (I'll check the label at my lab and post the info tomorrow).


  • Guest
« Reply #9 on: June 24, 2002, 05:52:00 AM »
If you try and acidify the aqueous layer, especially after adding more bleach, be prepared for the possibility of Cl2 gas being released. Sodium carbonate or bicarbonate wouldn't affect the reaction AFAIK.


  • Guest
Add calcium hydroxide
« Reply #10 on: June 24, 2002, 09:11:00 AM »
there are actually two reactions taking place in making chloroform.

The first is chlorination of acetone to 1,1,1-trichloroacetone.

This compound reacts with a base such as calcium hydroxide to form chloroform and calcium acetate.

Assuming everything was chlorinated completely you would need to add calcium hydroxide to the mix.

On the other hand, if everything was not chlorinated completely, you would need to add more bleach.

In this case due to the addition of HCl, I would suspect that the trichloroacetone didn't convert to chloroform and acetate.

If there is acetone remaining you should add more bleach.  I would use an excess of bleach to start with and then add HCl and neutralize with calcium hydroxide.  That is if I wanted some nice relaxing chloroform  ;)


  • Guest
UK Bleach
« Reply #11 on: June 24, 2002, 12:33:00 PM »
Most thin bleaches in the UK, state they contain sodium hypochlorite and sodium hydroxide.

Some sterilizing fluids say they contain sodium hypochlorite and sodium chloride.

The best stuff I have ever used for making chloroform is calcium hypochlorite (pool shock), the reaction is really exothermic and you need to keep dipping the flask in cold water to stop the reflux over-running.

John Lennon - Working Class Hero


  • Guest
Ok, this sucks.
« Reply #12 on: June 25, 2002, 04:58:00 AM »
I tried basifying with 0.5mol of NaOH, well, no additional chloroform crashed out. What the heck? Oh well.

I'm ditching this procedure and going after distilling THF from PVC glue anyways...  :)


  • Guest
Thanks for the correction
« Reply #13 on: June 27, 2002, 02:00:00 AM »
I was never too good at the formulae so your help is really appreciated.  I never worried about the yield or getting too exact about the amounts since I can get the bleach for US4.00 for two gallons and the acetone for US9.00 a gallon.  The ice is really cheap and the buckets are reusable.  Too much research in this area just didn't seem cost effective.

Like I said once I do this in multiple buckets and make about a gallon of chloroform at a time when I need it.  Lasts a long time for me.


  • Guest
« Reply #14 on: June 28, 2002, 09:17:00 PM »
FUCK FUCK FUCK! I was using the wrong formula! No wonder my yields sucked so badly and the density of the chloroform was too low! The correct formula is up top, but no one noticed my mistake.

2 CH3COCH3 + 6 Ca(OCl)2 -> 2 CHCl3 + (CH3COO)2Ca + 2 Ca(OH)2 + 3 CaCl2

Should have been turned into:

CH3COCH3 + 6 NaOCl -> CHCl3 + NaCH3COO + 2 NaOH + 3 NaCl

ie 6 mol of NaOCl is required for EACH molecule of acetone... not 3 as I posted earlier. The FINAL word is:

Cheapskate should be using 6.4 gallons of bleach instead of 2 gallons!

For every 1g of acetone (0.788mL, 17.2mmol) you want to oxidize, use 71.1g (61.3mL, 103.2mmol, 6 equivilants) of 10.8% NaOCl.

Also using 24.1g of 31.25% HCl (aq) (206mmol, 2 equivilants) with what you want to oxidize seems to work nicely at starting the rxn and keeping it at a fast rate.

Cheapskate: it's all too easy to make a mistake with math! these calculations nearly require  a spreadsheet!

Antoncho: if you're reading this, even though I might admit to my mistakes, I sure don't like to.  :-[

Rhodium: please fix our mistakes.  :(


  • Guest
Calculations for THF =)
« Reply #15 on: June 28, 2002, 09:40:00 PM »
Ok.. I'm going to try and take a stab at the calculations for THF:

1.00g THF (1.12mL, 13.8mmol, 1 eq) requires 19.0g 10.8% NaOCl (16.4mL, 27.6mmol, 2 eq) or 41.1g 5% NaOCl (38.0ml, 27.6mmol, 2 eq)

As per the formula:

C4H8O + 2 NaOCl -> C4H6O2 + 2 NaCl + H2O

That gives a theoretical yield of 1.19g GBL (1.05mL, 13.8mmol, 1 eq).

Data for the calculations:
10.8% NaOCl (w/w)
31.25% HCl(aq) (w/w)
0.03646g/mmol HCl
0.0744g/mmol NaOCl
0.05808g/mmol acetone
0.07211g/mmol THF
0.788g/mL acetone
0.8892g/mL THF
1.08g/mL 5% bleach
1.16g/mL 10.8% bleach
0.1198g/mmol CHCl3
0.08609g/mmol GBL
1.484g/mL CHCl3
1.1286g/mL GBL

As can be clearly seen, ridiculously large amounts of NaOCl are required for the oxidation of acetone, but the volume of NaOCl for THF -> GBL is very small. Unfortunately this reaction might not even work as stated.


  • Guest
no one noticed my mistake we aren't all so eager ...
« Reply #16 on: June 29, 2002, 04:03:00 AM »
no one noticed my mistake we aren't all so eager to find fault with anothers work


  • Guest
Ahah!!! Finally!!! =)
« Reply #17 on: June 29, 2002, 10:17:00 PM »
20.9g acetone (26.5mL, 0.359mol, 1 eq) was loaded into a pressure equalized addition funnel. It was placed ontop of a 3L flask containing 1280mL 10.8% bleach (1485g, 2.155mol, 6 eq). A reflux condenser was added to the top of the addition funnel. Stirring was started, the stop cock was opened, and the acetone dumped in. The stop cock was then closed. After 10 mins, the rxn started to heat up. Some vapours refluxed back into the closed addition funnel. After it started to slow down, the stop cock was opened. After the flask started to cool down, the flask was cooled overnight in the fridge. Most of the aqueous was poured off, and the rest loaded into a 500ml sep funnel. 19.7ml (28.5g) (density = 1.45) of chloroform was recovered corresponding to an 85% of the expected yield. 43.0g was expected (29.0mL, 0.359mol) with 6.4mL of chloroform lost to the aqueous layer (soluble at 1/200) giving an expected yield of 33.5g.

This is great news! The density is very close to what we'd expect, and the yield seems right! Yay! The chloroform caper is closed.

note: there was no external cooling of the flask and no acid & the aqueous layer lost its scent of chlorine. and this means 52ml can be made from a 4L jug of bleach, that costs about $4.. ie you're paying $80/L to make it this way. (OUCH!)

I'd say the only reason to use this synthesis is if you need chloroform as a reagent and can't purchase it, otherwise using methylene chloride is definitely the way to go.

The only synthesis I know of that uses chloroform as a reagent, that is of interest to us, is making chlorbutol... and guess what? That drug sucks. You may as well huff the chloroform.


  • Guest
Way to go Chromic! Please keep in mind, that ...
« Reply #18 on: June 30, 2002, 01:13:00 AM »
Way to go Chromic! Please keep in mind, that chloroform is needed as a reagent in the Reimer-Tiemann formylation :) .


  • Guest
Very true...
« Reply #19 on: June 30, 2002, 02:58:00 AM »
You're right... and that's something that bees at the Hive absolutely need to look into. I'd love to formylate, methylate, condense, reduce & brominate some hydroquinone. I'd be very willing to spend some time looking into it, if only we could find an OTC way to reduce the 2,5-dimethoxynitrostyrene...