March 13, 2005
Carbon Tetrachloride form Acetone and Hypochlorite
Today was my attempt at CCl4 from acetone and hypochlorite in two steps.
Reaction of 3 mols hypochlorite to one mole acetone with the overall effect being the production of chloroform, in this case 5 ml being present from the reaction between 260 ml 10% NaOCl and 5.5 ml acetone. The reaction was complete in about an hour. Being that the solution still had chloroform dissolved (nearly 2 ml) I preformed the conversion to carbon tet in the solution with the intention of converting the solvated chloroform to the less soluble carbon tet.
The solution was treated with 10 drops over the counter iodine solution (potassium iodide, iodine, and ethanol) which had no impact on the clear colorless solution*. Thirty-Seven grams of solid calcium hypochlorite were added and them mixture shaken. Ambient temperature was ~ -3 C. A colloidal solution formed and 5 ml 28% HCl was added, immediately chlorine was formed and the solution capped and shaken. The chlorine was quickly taken up by the solution and a vacuum formed on the inside making the cap hard to remove to add more HCl. Overall 50 ml hydrochloric acid was added and the mixture allowed to stand for three hours.
The mixture was allowed to react for an additional three hours and upon shaking chlorine gas was evolved, presumably form the addition of chlorine to the chloroform present resulting in a molecule of HCl being liberated decomposing more hypochlorite, which was the plan. In the end I had the solution shown in the pictures above shown before and after shaking. I attempted to filter it but the organic at the bottom failed to go through the glass wool, I'm assuming it was too hydrophobic. As such the wad of glass wool and the green viscous liquid pooled on top of it was put into 200 ml warm water in a 500 ml reagent bottle and shaken. The organic lost its color and a clear organic liquid sank to the bottom. It's identity to be ascertained at a later date.
It is my opinion that this transformation would be better affected by adding the HCl with the aid of a sepretory funnel very slowly under constant agitation though magnetic stirring. This should result in better uptake of the chlorine from the system and thus conversion to carbon tetrachloride. If the reaction worked it looks to have a very small yield. There appears to be less product here then there was chloroform in the in-between step, however during one of the shakings massive gas evolution caused the top to pop and a small amount of liquid was lost, this may account for some of the lack of product.
* = CHCl3 + 2ICl ----> CCl4 + HCl + I2 My intention was the iodine would act catalytically and that the HCl produced would decompose more hypochlorite.
Disposal of Bromine water
After my recent attempts to prepare bromine I am often left with large amounts (>400 ml) of water saturated with bromine, acidic, and containing unreacted bromate. Not really the most environmentally friendly of things. Today I treated this in three ways.
Treatment with NaOH solution: This only works well if the NaOH is pre-solvated in water. Else wise the reaction is incomplete and slow. E.g., if there is still solid NaOH in solution and you are relying on it reacting you'd be surprised by how slow the reaction takes place. Dissolve NaOH and saturate the solution first then add your bromine water. If you use carbonate I learned before to expect lots of frothing which causes excessive bromine vapors in your work area (overall reaction is still contaminated with bromate, and hypobromite).
Removing the bomine through organic reaction: 25 ml Tetrachloroethylene (Cl2C=CCl2) was added to 250 ml of bromine water and shaken. After some time the bromine color started to fade and the solution started to become orange. And even more time later (~1.5 hours) the solution cleared up and was light orange and at the bottom there was a material that looked like wax and flowed a little. If shaken it stuck all over different parts of the inside of the flask. It worked but I was left with a highly halogenated organic to take care of. Plus the BrCl2CCCl2Br that I obtained stuck to everything and was hard to clean up (reaction mixture still contaminated with bromate).
Reaction with Aluminum turnings: To 400 ml bromine water in a 1000 ml Erlenmeyer was added a handful of aluminum turnings. The mixture heated up as expected and bromine started to waft from the top. Aluminum turnings were gently added to fill the neck of the flask so escaping vapors would react away. The mixture heated up to roughly 80 C and turned from red to gray. After one hour it was still bubbling and fizzing but there was no bromine odor. The mixture was dumped and the aluminum was sizzling still. This disposal method is somewhat better then the other two in that bromate left over should be reduced under these conditions.
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