Sciencemadness Discussion Board

Isopropanol + O2 -> TATP (just wait 12+ years)

Metacelsus - 3-6-2022 at 03:38

On November 21, 2019, at approximately 2:00 AM, in Halifax, Nova Scotia, Halifax Regional Police carried out a controlled detonation of a bottle outside an apartment building. (1) The bottle originally contained 500 mL of Life brand 99% isopropyl alcohol (rubbing alcohol, 2-propanol), with an expiry date of February 2007, and was stored in the dark underneath a bathroom sink. In August of 2017, and again in May 2019, application of the rubbing alcohol to sterilize an area of skin (on two different people) resulted in scab formation, thought originally to be a sensitivity to rubbing alcohol. Some time after May 2019, the bottle had tipped over, cracking the plastic top and partially spilling the contents, which were slower to volatilize than expected for pure rubbing alcohol, and whose odor was a little off. In mid-November, 2019, the owner partially discarded some of the remaining liquid, and at this time noticed gas evolution at the sink drain and the presence of approximately 25 g of a white solid mass remaining in the bottle. The owner initially thought that it might have been a result of product tampering, so a small sample of the solid was analyzed by X-ray crystallography (2) and found to be a polymorph (3) of triacetone triperoxide (TATP), an organic peroxide and high explosive. Once the solid compound was identified as such, emergency services were called to handle the disposal at the apartment building.

The ability of 2-propanol to form peroxides has been mentioned before. (4) The exact nature of the solid peroxide formed has not been known until now. Stoichiometrically, 2-propanol and oxygen gas is equivalent to acetone and hydrogen peroxide, the ingredients required for classic TATP synthesis, (5) which may be relevant to its formation under these conditions. Similar compounds are known to form upon photosensitization with benzophenone. (6) Given the use of 2-propanol in clandestine drug laboratories and of TATP in recent terrorism incidents, the implications for police work are clear.

RustyShackleford - 3-6-2022 at 04:40

>the implications for police work are clear

Tsjerk - 3-6-2022 at 13:10

Nice, I also usually send my unknowns for x-ray crystallography.

XeonTheMGPony - 3-6-2022 at 16:52

so that's why it is all most impossible to find 99% iso on the shelf's now, good thing I can get 4L jugs through the agro store

Mush - 4-6-2022 at 06:23

Peroxide formation has been known for a while in 2-propanol.

4. Chemical safety: peroxide formation in 2-propanol

Two years ago we experienced an explosion in our lab at the end of 2-propanol distillation. Luckily, it was a small-scale distillation. To elucidate what happened, we prepared several samples of 2-propanol and kept them on a shelf away from direct sunlight at room temperature.

We filled transparent glass bottles, tinted glass bottles, and polyethylene bottles 75% full with high-purity commercial 2-propanol. We prepared additional transparent glass bottles with the following:

a) 97% 2-propanol and 3% deionized water.

b) 2-propanol refluxed for 1.5 hours with magnesium chips and a small amount of iodine, followed by distillation; the first 10% of distillate was discarded.

c) 2-propanol from sample (b) after additional distillation; fresh 0.3-nm molecular sieves were added to the final sample to 20% by volume.

We replaced the air above the 2-propanol every two months by flashing the interior of the bottles with an airstream. After 24 months, we tested the content of all containers for peroxides using the standard iodide method (ASTM International 2008, DOI: 10.1520/e0298-08).

We found peroxides only in sample (b), which had a peroxide concentration of approximately 0.004 mol/L. We suggest that diisopropyl ether, a well-known peroxidizable substance, formed during refluxing of 2-propanol with magnesium. Diisopropyl ether boils at 69 °C, which is 14 °C lower than the boiling point of 2-propanol, and should be removed by distillation. Our results indicate that the first distillation performed without a Vigreux column was not sufficient [sample (b)], while an additional second distillation led to complete removal of all of the formed peroxidizable substance [sample (c)].

Prior to this incident, we were not aware that primary and secondary alcohols are peroxidizable. We hope this report is a reminder to the chemistry community that they are and that distillation procedures should take the hazard into account.

For more information, see the 7th edition of “Bretherick’s Handbook of Reactive Chemical Hazards”; Chem. Health Saf. 2001, DOI: 10.1016/s1074-9098(01)00247-7; and J. Chem. Educ. 1988, DOI: 10.1021/ed065pa226.

Metacelsus - 4-6-2022 at 14:01

Yeah most chemists know they need to keep a close eye on ether and THF, but fewer are aware that iPrOH is also a peroxidation hazard.

Tsjerk - 5-6-2022 at 02:00

Quote: Originally posted by Mush  

We found peroxides only in sample (b), which had a peroxide concentration of approximately 0.004 mol/L. We suggest that diisopropyl ether, a well-known peroxidizable substance, formed during refluxing of 2-propanol with magnesium.

So the conclusion is that pure isopropyl alcohol doesn't form peroxides?

Metacelsus - 5-6-2022 at 04:14

No, it totally does, see here:

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ManyInterests - 6-6-2022 at 05:01

Damn, I have a bottle of that in my medicine cabinet. I think I should be getting rid of it now...

Fantasma4500 - 13-6-2022 at 14:20

yes its known to have somewhat similar issue as ether which also forms this kind of danger upon standing
theoretically- couldnt any oxidizer along with some acid form it? H2CrO4 maybe? KHSO5? acidified and then airbubbled? ozone?
what im thinking about in this situation is that... it <should> probably be the dimer, which with acetone forms at +5*C- would it then not be logical to assume its not the trimer? maybe the trimer is more likely outcome with slow oxidation using air
it is interesting on its own that ... 25 grammes of the material cropped up in the bottle, supposedly with an airtight lid? is it that willing to form that it invites air in?