Can you boil rubbing alcohol? (3 Potential Dangers)

In this brief guide, we will answer the question, can you boil rubbing alcohol? We will discuss the reasons to avoid boiling rubbing alcohol including the potential disasters and futility of doing so.

Can you boil rubbing alcohol?

You can boil rubbing alcohol but you should avoid doing so. You need to be very careful when you boil rubbing alcohol as it is a flammable liquid. 

If you decide to boil rubbing alcohol you will need to follow the utmost precautions as it can end up horribly.

 In a laboratory with specialized equipment, it is possible to boil rubbing alcohol. Be sure not to use an open flame. Use an electric hot plate or sand bath which is safer than an open flame if you must boil rubbing alcohol.

According to a market research from Nielsen, the sale of hand sanitisers skyrocketed by 300% and 470% in the last week of February and first week of March 2020, respectively, in comparison to the same time in the previous year. Similarly, in Italy – one of the most affected countries by CoViD-19 – sales of hand sanitisers in supermarkets increased by 561% during the first three weeks of the pandemic (24th February-15th March 2020) compared to the previous year (1).

What is rubbing alcohol?

According to the WHO, an alcohol based hand rub is “an alcohol-containing preparation (liquid, gel or foam) designed for application to the hands to inactivate microorganisms and/or temporarily suppress their growth. Such preparations may contain one or more types of alcohol, other active ingredients with excipients, and humectants” (1).

Alcohol is a colorless and flammable liquid. Rubbing alcohol is isopropyl alcohol, it has a strong odor and is used as a disinfectant and antiseptic. 

Rubbing alcohol is Isopropyl alcohol that is 70 percent alcohol and 30 percent water. Rubbing alcohol can be prepared with ethanol as well, and the concentrations may also vary. According to the US FDA, isopropanol should be used as an antiseptic alcohol at concentrations between 70 and 91.3% (v/v) (1).

Isopropyl alcohol belongs to the class of secondary alcohol. Rubbing alcohol is miscible in water and can dissolve many substances. Rubbing alcohol makes a good cleaner as it can dissolve gums, oils, alkaloids, and natural resins. rubbing alcohol dissolves all non-polar compounds. 

When mixed with water as in rubbing alcohol, the isopropyl alcohol has a boiling temperature of 176 (82°C) Fahrenheit (2). 

Rubbing alcohol has low toxicity and is widely used in the pharmaceutical industry. It is also used in personal care products and for household purposes. However, toxic oral ingestion of isopropyl alcohol, the primary ingredient of most rubbing alcohol, is a well-documented Emergency Department presentation. Toxicity through transdermal absorption of isopropyl alcohol is far less common, but it is also possible (3).

Rubbing alcohol has a high flammability range of 2 and 12.7 percent in air. Safety when handling rubbing alcohol is important, such as wearing gloves and eye protection. 

What happens if you boil Rubbing alcohol?

When you boil isopropyl alcohol, the alcohol will evaporate and the water will stay behind. Alcohol has a lower boiling than water and it would cause the alcohol to evaporate before water does. 

As  the  flask  is  heated,  the  lower  boiling  liquid  vaporizes  faster  than  the  higher  boiling  liquid, that is, the isopropyl alcohol evaporates before the water of the mixture (3).

If you boil it for a few seconds, the concentration of alcohol would reduce and you will end up with a greater volume of water. If you keep boiling it for longer, the alcohol will gradually deplete from the rubbing alcohol solution. Further boiling would cause the water to start boiling until that finishes as well.

As soon as the temperature of rubbing alcohol becomes 82 Celsius at sea level, the ethanol in the rubbing alcohol solution will start to escape. 

As alcohol is a colorless liquid, it will start to escape as fumes for the evaporating pan. 

The most efficient and safe way to evaporate or separate the alcohol would be using the fractional distillation apparatus. 

Be very careful and do not leave it unsupervised. Also, do not use a high flame to boil the rubbing alcohol. The rubbing alcohol can catch fire and things can get out of hand very quickly. 

Is there a better alternative to boiling rubbing alcohol?

Rubbing alcohol is not safe for consumption and the reason people would want to boil it is to clean their greasy equipment. For cleaning, however, there are better ways to try and rubbing alcohol leaves stain on the surface it is used. 

Moreover, using boiled rubbing alcohol is not as efficient as it may seem. You have a better chance at using boiling water to disinfect or clean your equipment. Soap and detergent or antiseptic detergents can remove all types of pathogens (1).

Rubbing alcohol on its own makes a good cleaning agent. At room temperature, pour some rubbing alcohol on some cloth or towel and get rubbing which is more efficient and safer than boiling. 

You can also use gasoline to clean your equipment. Let your stuff soak in gasoline at room temperature to get rid of the greasy gunk. 

What could be the disastrous consequences of boiling rubbing alcohol and what causes it?

Boiling rubbing alcohol can cause an explosion or spontaneous combustion and set your house on fire. 

The flashpoint of alcohol is 77 Fahrenheit. What could happen at this temperature is that the vapors that escape from the solution will catch fire (5). If it happens in a confined space without enough ventilation such as your kitchen, the vapors will make their way to the open flame and catch fire. 

The vapors of isopropanol are very heavy. As the vapors of ethanol escape from the pot of the boiling solution, they settle on the open flame. The vapors are twice as heavy as air and the weight would give in, making the vapors settle on the open flame (2).  

Conclusion

In this brief guide, we answered the question, can you boil rubbing alcohol? We discussed the reasons to avoid boiling rubbing alcohol including the potential disasters and futility of doing so.

Citations

  1. Berardi, Alberto, et al. Hand sanitisers amid CoViD-19: A critical review of alcohol-based products on the market and formulation approaches to respond to increasing demand. Int j pharmaceut, 2020, 584, 119431. 
  2. Said, Shahidatul Nadiah Mhd. Salt-added method for breaking azeotrope of binary Ipa-water system: using aspen plus. Diss. UMP, 2008.
  3. Wolfshohl, Jon A., Daniel A. Jenkins, and Todd M. Phillips. Toxic transdermal absorption of isopropyl alcohol with falsely elevated creatinine. Am J Emerg Med, 2021, 48, 377-e5.
  4. Teacher packs in Experimental Science. Distillation of rubbing alcohol (2-propanol) and water mixture. University of Cape Coast and The Open University, UK.
  5. Boyce, John M. Alcohols as surface disinfectants in healthcare settings. infect control hosp epidemiol, 2018, 39, 323-328.