[smart (OP)]

Propylene glycol (PG) is a electrophilic solvent (Lewis base) found in most vaping liquids. Furthermore PG is a secondary alcohol (ether) containing a free hydrogen-bond, thus participating in nucleophilic attacks in presence of oxygen and a halogen (ie: fluoride), giving yield to fluorocarbons derivatives. Hence, ether-based fluoroalkylation seem likely to produce water-vapor and a enol tautomer with potentially toxic effects to human health....

Consequently, can PG be used as a Lewis solvent for producing fluorocarbons (fluoroalkynes) in presence of an halogen such as fluoride?

Thank you in advance,
smart

[paul cotter]

This sounds rather confused. Halogens can add to alkynes but propylene glycol is certainly not a halogen. Neither is propylene glycol an ether, it is a primary and secondary alcohol. And I don't know where fluorine could find it's way into vaping fluid. And enol tautomers occur with ketones which possess an alpha hydrogen.

[smart (OP)]

Thanks for the reply, Paul.

Water fluorination is common in a lot of place in North America. For instance in Quebec (Canada) the standard level is 0.7 mg /L. Anyways, i believe electrophilic halogenation is the prefered term when a secondary alcohol (ie: glycol ether) is used to substitute hydroxyl groups into fluoroalkyne derivatives.

If interested the original patent for this procedure is here:  https://patents.google.com/patent/EP0735992A1/en

[Zer0]

Welcome Back @ smart!

Chemistry Section is mostly dead.
I see Hope now.

ps - Nice signature line.

[smart (OP)]

Welcome Back @ smart!

Chemistry Section is mostly dead.
I see Hope now.

ps - Nice signature line.

Thanks @Zer0 .

Here is some more updates on this thread :

1. Halogenation by itself can induce mild anesthesia. The exact mecanism appears to be linked to the blockade of CNS neurotransmission.
2. In addition glycerol-mediated halogenation has been linked to specific liver effects and glycerol-mediated modulation of energy homeostasis in chronic e-cigarette users.(Lechasseur et al, 2023)

Thus, chronic e-cigarette vaping (aka glycerol halogenation) appears to be functionally equivalent to one-pot synthesis of DHA, as explained here:  https://www.sciencedirect.com/science/article/abs/pii/S0040403906015401

[paul cotter]

You really need to understand some basic chemistry first. I have no idea what is meant by "halogenation causes anaesthesia". Inorganic fluoride is extremely stable and non-reactive: to introduce fluorine into a molecule an activated reagent is needed such as a fluoro-sulphur compound, fluoride will not do it. Enol tautomers occur in ketones with an alpha hydrogen: acetone will exhibit keto enol tautomerism while benzophenone will not. There is no such thing as an enol tautomer of fluoride. Where did you get the idea that 1, 3 dichloropropanol would be an anaesthetic?, I very much doubt it. 

[Eternal Student]

Hi.

    I'm also not finding many references to the anaesthetic properties of the compound    1,3 dichloro propan 2-ol.

     There almost certainly are some adverse effects from e-cigarette vaping but it's not clear that  PG  is the biggest concern.   The "flavourings" that are added are sometimes considered as big a risk as anything else.    However, as you ( @smart ) have indicated, there is a small concern about the production of new compounds created during the heating and vapourisation process that were not present in the original liquid.  PG may contribute to the production of these new compounds.

    Some information is here:   https://www.ncbi.nlm.nih.gov/books/NBK507184/
Their assessment of the risks of PG inhalation were quite low.

Best Wishes.

[paul cotter]

Hi, ES, I had a brief look at that article you posted. I was horrified to find ethylene glycol was found in some samples of fluid. Glycerol and propylene glycol are relatively safe but ethylene glycol is definitely not suitable for use in a product that is consumed. When I say glycerol and propylene glycol are relatively safe what I mean is that ingestion of either is considered quite safe but vaporising either may not be: both of these substances are quite capable of producing toxins if sufficiently heated. I too picked up the noxious habit of smoking for a short while in my 20's-30's, long since dropped. I always missed my nicotine and my solution is nicotine gum.

[smart (OP)]

Hi.

    I'm also not finding many references to the anaesthetic properties of the compound    1,3 dichloro propan 2-ol.

     There almost certainly are some adverse effects from e-cigarette vaping but it's not clear that  PG  is the biggest concern.   The "flavourings" that are added are sometimes considered as big a risk as anything else.    However, as you ( @smart ) have indicated, there is a small concern about the production of new compounds created during the heating and vapourisation process that were not present in the original liquid.  PG may contribute to the production of these new compounds.

    Some information is here:   https://www.ncbi.nlm.nih.gov/books/NBK507184/
Their assessment of the risks of PG inhalation were quite low.

Best Wishes.

Dear Eternal Student...

Thank you for this update. Glycerol halogenation is likely to happen without the need of fluorine or any specific secondary alcohol/ether. Hydroxyl radicals can substitute themselves for a halogen tautomer in presence of propylene glycol acting as a eletrophilic reagent. I am deeply sorry for this unintended confusion about 1,3-DCP.

In contrast, the real problem seems to be with glycerol halogenation of propylene glycol which produces 1,3-DHA (please see link below). Lastly, please note that TEMPO was used as a reagent in the study for simulating free radical based synthesis of DHA, a glycerol derivative.

I hope this helps,
smart

Method and process is here: https://www.sciencedirect.com/science/article/abs/pii/S0040403906015401