Why You Shouldn't Mix Bleach With Alcohol or Acetone

Mixing chemicals can be a bad idea, particularly if one of the chemicals is bleach. You may be aware household bleach gives off dangerous fumes when mixed with bases, such as ammonia, and acids, such as vinegar, but did you know it's also risky to mix it with alcohol or acetone? Bleach reacts with alcohol or acetone to form chloroform, a chemical that could knock you out and cause organ damage.

Chloroform is an example of a haloform (CHX₃, where X is a halogen). Any of the halogens can participate in the reaction, except fluorine because its intermediate is too unstable. A methyl ketone (molecule with R-CO-CH₃ group) is halogenated in the presence of a base. Acetone and alcohol are two examples of compounds that can participate in the reaction.

The reaction is used industrially to produce chloroform, iodoform, and bromoform (although there are other reactions better for chloroform). Historically, it's one of the oldest known organic reactions. Georges-Simon Serullas made iodoform in 1822 from reacting potassium metal in a solution of ethanol (grain alcohol) and water.

Many online sources mention the production of highly toxic phosgene (COCl₂) from mixing bleach with alcohol or acetone. This is a chemical with practical applications, but may be best known as a deadly chemical weapon known to have an odor of musty hay. Mixing bleach with the other chemicals doesn't produce phosgene, however, chloroform breaks down into phosgene over time. Commercially available chloroform contains a stabilizing agent to prevent this degradation, plus it is stored in dark amber bottles to reduce exposure to light, which can hasten the reaction.

While you wouldn't put bleach in a mixed drink, you might use it to clean up a spill or use it in a cleaning project with alcohol-containing glass cleaner. Acetone is found in pure form and in some nail polish removers. The bottom line: Avoid mixing bleach with anything except water.

Chloroform can also result from disinfection of water using bleach. If the water contains high enough levels of reactive impurities, haloform and other carcinogenic chemicals may be produced.

Chloroform has a sweet smell, very unlike that of bleach. If you mix bleach with another chemical and suspect a nasty fume was produced, you should:

1. Open a window or otherwise air out the area. Avoid breathing in the gas.
2. Leave at once until the vapor has had time to dissipate. If you feel faint or sick, be sure another person is aware of the situation.
3. Make certain children, pets, and other household members avoid the area until you're sure it's okay.

Usually, the concentration of chemicals is low enough that the amount of toxic chemical is low. However, if you're using reagent grade chemicals, like for a lab experiment to intentionally make chloroform, exposure warrants emergency medical attention. Chloroform is a central nervous system depressant. Exposure can knock you out, while high doses can lead to coma and death. Remove yourself from the area to avoid additional exposure!

Also, please keep in mind that chloroform is known to induce tumors in rats and mice. Even low exposure isn't healthy.

In books and movies, criminals use chloroform-soaked rags to knock out their victims. While chloroform has been used in some real-life crimes, it's actually almost impossible to knock someone out with it. About five minutes of constant inhalation is needed to cause unconsciousness.