We have vials (with septa) of benzophenone in isopropanol with a drop of glacial acetic acid sitting on the windowsill in our organic lab from the spring semester. There are crystals of the product in the liquid (normal) and crystals on the side of the vial above the liquid (not normal).

I would have not given this any thought but the 6/12/20 safety headlines (below) have a statement "Similar compounds [to TATP] are known to form upon photosensitization with benzophenone.(6)". The reference is Schenck, G. O.; Becker, H.-D. (1958), "Photosensibilisierte Autoxydation des Isopropanols; Darstellung einfacher Alkylidenhydroperoxyde" [Photosensitized auto-oxidation of isopropanol; Representation of simple alkylidene hydroperoxides]. Angew. Chem. 1958, 70 (16), 504.

I do not have access to this article and I cannot read technical German. My question for you is there any concern about peroxide formation in the vials? If so, what can I do about it?

Paul Weller

Paul Weller

Senior Science Laboratory Manager-Chemistry
Elon University

2625 Campus Box

Elon, NC 27244

Phone 336.278.6225

Location MCMI 302

wellerp**At_Symbol_Here**elon.edu

CHEMICAL SAFETY: TATP FORMATION IN 2-PROPANOL

https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpubs.acs.org%2Fdoi%2F10.1021%2Facs.chas.0c00061&data=02%7C01%7Cwellerp%40elon.edu%7C98bce7ccce1e4c193c3b08d80ec99158%7Cba18326d711f4ae286816115493a7a53%7C1%7C0%7C637275606192705614&sdata=2Ll1SMBdvwMnRrNGeuT0NiH%2B0jtltEahyQ6aS7hkE9s%3D&reserved=0

Tags: Canada, public, discovery, environmental, explosives

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 approximate!

ly 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.

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