Question Sodium hypochlorite

[ASheSChem]

Hello;

I am currently preparing my notes for future synthesis and I have a question about the choroform synthesis

I have this product:

it says 13% so I'm doing my calculations... (if i was good)

right?

but then I see in the datasheet these details:

and so I'm confused... should I base it on 13%? 10%? 12.5%? according to these details...

so as not to have an excess of acetone

 

[G.Patton]

Can you write reaction equation, please? I try to understand how you want to obtain chloroform from acetone

 

[ASheSChem]

from bleach ; if it's not correct please correct me

here is my note (from mixed source) :

- The principle is to mix a little acetone with bleach.

- The dosage of acetone will be calculated precisely according to the concentration of the bleach. It is ideally necessary to put the exact quantity otherwise it will be difficult to get rid of it later. (See calculations at the end of the synthesis description)

- Cool the bleach as much as possible before the synthesis, and this can take place in a tank with ice, if the temperature rises too high there will be a drop in yield.

- Leave to act for several hours, even overnight depending on the temperatures applied and whether you have a view of the result or not in order to see if chloroform has formed in the bottom of the container.

- bring together all the chloroform in the bottoms of the containers.

- Wash your product with water to remove certain impurities, decant and drain the lower layer.

- Add a liquid solution of sodium chloride, mix, decant, drain the lower layer.

- Add calcium chloride to your soon to be pure product to remove as much water as possible.

- To have a truly pure chloroform, it must now be distilled. The cloudy distillate is collected around 60° and below and discarded, and the pure, translucent chloroform is collected between 60 and 62° (officially 61.2°).

- 1% of the mass of chloroform harvested is calculated and this weight is added in methanol or absolute ethanol in order to stabilize the chloroform and so that it does not create toxic phosgene gas.

- Store in an amber bottle or covered with aluminum foil. Protected from light.

 

[G.Patton]

You have to count this as smallest possible amount 10%. Excess of Cl2 doesn't spoil your reaction.

 

[MadHatter]

The MDS will never give you an exact concentration, especially not with sodium hypochlorite solutions that tend to decompose with time.
You need to determine the concentration of hypochlorite through measuring the amount of chlorine gas produced by a known amount of the solution.
You do this by adding dilute hydrogen peroxide dropwise to a small, exactly measured amount of the hypochlorite solution in a 2-or 3-neck RBF. Say 5 or 10 ml. This produces oxygen gas. The gas is led by a tube into an upside down measuring cylinder filled with water. Hydrogen peroxide is dripped till no more bubbling occurs, and the volume of the gas can be measured by how much water it has pushed out. Since every mole of sodium hypochlorite reacts with H2O2 to produce an equal amount moles of oxygen gas, the concentration can be calculated from these data:

Sodium Hypochlorite + H2O2 --> H2O + NaCl + O2

1 mole of oxygen = 22.39 L

Concentration would therefore be:

(O2 ml/ 22390) * (1000 ml / volume of solution)

And TLDR, here's NileRed doing it:

 

[ASheSChem]

thanks guys

 

[MadHatter]

This volumetric calculation of bleach concentration is the worst part of the chloroform manufacture process, and hated by many hobby chemist. It's not very complicated though, just a pain in the ass. And it's always disappointing to see how low the concentration of hypoclorite actually is in the commercial bleach. Like 5-10% usually.
It makes you want to make A LOT of chloroform in one go to not have to repeat the process unnecessarily often. But chloroform also tends to degrade over time and is difficult to store.
It's just one of those bitch-ass tiresome chemist things, like cleanup routines. Makes you want an assistant. Or access to exact, clean reagents in abundance.