Historically chloroform was widely used as an anesthetic but nowadays it's
mostly used just as a solvent.
Interestingly it can be easily made from common household products.
In this experiment the major chemicals I used were 3.6 liters of
concentrated bleach and a hundred milliliters of acetone.
The first thing that must be done is to determine the concentration of sodium
hypochlorite in the bleach.
This is done by reacting about five milliliters of bleach with three percent
hydrogen peroxide.
As shown in the equation above the hydrogen peroxide reacts with the sodium
hypochlorite to form water, sodium chloride and oxygen gas.
Hydrogen peroxide is added until no more bubbling occurs and the reaction is complete.
The level of the water in the graduated cylinder is measured before and after
the addition of the gas. By calculating the amount of gas that has evolved and
on the assumption that one mole of gas occupies a volume of 24 liters we can
calculate the concentration of the bleach. The equation that I used as shown
above and the result I obtained was that sodium hypochlorite concentration was
about 1.28 molar.
This isn't necessary but I used the hydrometer to measure the density of the
bleach and I determine that the concentration was about 8.6
percent.
The bleach was chilled to about -2 degrees Celsius and a hundred and
fifty milliliters was poured out. A hundred and fifty milliliters is removed
to make sure that it has enough space to add the acetone as well as to shake it.
The reaction of bleach with acetone is extremely exothermic and it's absolutely
necessary to cool it to at least zero degrees Celsius before the addition.
I added about a hundred milliliters of acetone to the bleach which represents
an excess of bleach at around eleven percent. I think an access between three
to five percent is better and eleven percent as much too high. Use an excess of
bleach because we want to make sure that all of the acetone is consumed.
Any leftover acetone could form a difficult to separate azeotrope with the
chloroform.
After adding the acetone the bottle is capped and shaken. The cap is then
removed in place lightly on top to allow any gases to escape.
I left the bottle overnight to allow for a complete separation of the chloroform
from the aqueous layer. Chloroform is denser than water and immiscible
so it should form a layer on the bottom. After five minutes the temperature is
already at around 30 degrees Celsius. The temperature peaked at around 45 degrees
Celsius.
The purpose of the video I will visually demonstrate the reaction between the
acetone and the bleach. When the acetone is added it reacts with three
equivalents of sodium hypochlorite to form chloroform, sodium hydroxide and
sodium acetate.
After allowing the solution to sit undisturbed for a short period of time
it's possible to see chloroform in a separate layer on the bottom.
The solution is still yellow due to the presence of unreacted sodium
hypochlorite.
Carefully decant the upper aqueous layer. To the large amount of water you're
going to need to do this several times.
You should empty the aqueous layer into a waste container labeled bleach and
chloroform waste.
Eventually the remaining liquid of the bleach bottle is poured into the beaker
and the chloroform layers allowed to settle on the bottom. You might notice
that the solution is much less yellow in the previous example that I showed. this
This is because it was allowed to react overnight and the concentration of
sodium hypochlorite in the solution is much less. Leave it for several minutes
until the chloroform layer fully separates. Decant off as much of the
aqueous layer as possible and then add the rest to a separatory funnel.
Allow the two phases to separate and then drain the lower chloroform layer.
Add the upper aqueous layer to your waste container. The chloroform was washed once
with saturated sodium chloride and then it was added to a distillation flask
containing calcium chloride. The simple distillation of the chloroform was
carried out using a hot water bath.
The distillate that came over below 60 degrees Celsius was cloudy and it was
discarded.
The temperature then remain constant at around 60 degrees and the distilled was
collected as a clear liquid.
The total volume of chloroform obtained was about 58 milliliters.
The chloroform is transferred to a bottle that was wrapped in tin foil to protect
it from light.
About 1 milliliter of absolute ethanol was added to stabilize the chloroform
and prevent the formation of phosgene. Again the final yield was about fifty
eight milliliters which represents a final yield of about 53 percent.