Actually I have quite a major concern about the ones based on glycerine as well as PG.
The PG, I am not bothered about. What worries me so much is the glycerine. Because glycerine can be dehydrated, either by means chemical, or thermally. Glycerine's structure is simple enough; 1,2,3-propanetriol
This can undergo dehydration and rearrangement to a real little charmer and no mistake, prop-2-ene-1-al or to give a trivial name, acrylic, or allylic aldehyde. Its produced as I said by dehydration
to give acrolein, in bulk form enough to handle, more than whatever is being vaporised, I mean, having deliberately synthed some many years ago, using anhydrous sodium bisulfate, I simply mixed the two chemicals together, hooked up the appropriate glassware to do so, stuck both in the rxn vessel chosen (don't ask me what kind of flask, condenser, still heads I used, this was years ago, and not something that ever led to any truly interesting projects, that was just a diversion for me really when I wanted something to occupy my mind, and , oppoywant of money, but for want either of a supplier which HAS those things, or if they do, but only companies with shitty bad attitudes like sigma-aldrich, who with the most disgusting condecension, won't deign to sell an individual so much as a single grain of table salt; and I am not affiliated with officialdom in any sense, nor am I through a university or similar, so theres plenty places that are of no use to the citizen chemist, or to the more clandestine variety either.)
Anyhow, make some prop-2-enal I did. Wished I hadn't, too. Its really noxious stuff, volatile, it stinks to high heaven, not really an easily definable smell. And its masked by the fact that its a powerful, aggressive lachrymatory agent (tear gas, choking agent type stuff), and the slightest whiff in the air makes sharing that space intolerable, it'll leave you gasping for breath, with your nose and eyes pouring forth a huge torrent of tears and nasal secretions. Makes one feel like they are about to vomit, probably makes it happen too, to anyone willing to remain near some acrolein.
Smelll itself, though relatively faint compared to some, is like rotting animal fat, thats been set on fire, with heavy overtones of burnt grease, and acrid, irritant beyond belief. Its toxic as all hell, mutagenic and carcinogenic.
Ive been meaning to switch to pure propylyne glycol, even if it means making the liquid from flavour concentrates and nicotine sulfate myself, I am sure that the E-cigs aren't anything like as
terrible for health as smoking tobacco, so an improvement at least. Compared to the thousands of nasty things in tobacco, such as nitrosamines, hydrogen cyanide gas, HCHO, CO, hell, tobacco plants apparently bioaccumulate polonium from the soil, presumable 210Po given its the commonest isotope in human general use.
In the end, I had to get rid of some acrolein another time too, after I'd finished using it, the leftovers had to go since it can polymerize violently if it gets old. So, down the sink it went, flushed with water. Ufortunately for me I turned the hot tap on instead of cold, which promptly vaporized whilst down the plug hole, sending a gout of acrolein vapor in my direction.
Lachrymatory? the word really doesnt at all do justice to this substance. To compare it with capsaicin or blazing hot peppers, the latter can't hold a candle to it, mono- or dichloroacetone doesn't do it justice, nor CS 'gas', I've never made CN, CR, adamsite or phosgene oxime, so I can't compare those. A lot worse too, than the likes of acyl halides (like acetyl chloride, propionyl chloride, allyl bromide,elemental bromine fumes or chlorine gas. Chromyl chloride comes close if allowed to escape. Which is why it shouldn't be, nasty, toxic, corrosive, and hydrolyses into hexavalent Cr species and HCl fumes. Its an orangy-dark red liquid, looks like bromine, powerful oxidizer (made by distilling a mixture of either a dichromate salt, or chromic anhydride, aka trioxide with salt and concentrated sulfuric acid, collecting the distillate in a suitable vessel until one wishes to make use of it.)
Acrolein is typically exposed to people, thankfully only in small quantities, when fat burns (lipids are often based on glyceryl esters)(anyone working in F can work it out themselves, because I confess, its such a useless, 'proprietary' almost, scale, C, based on the BP of H2O actually makes sense, and is at least,I never use it, and really never bothered to learn it either since its little more than a nuisance used by americans and really old farts he or in cigarette smoke.re in england haha. ) but at 280'C glycerine dehydrates, losing two molecules of H2O.
I advise using the lowest satisfactory voltage level if the efags one uses be the variable yield type.
Anyone wants to find out just what a vicious little utter bastard of a chemical acrolein is, take a few ml of glycerine, and some sodium bisulfate (look around online, its available without
difficulty or restriction in some cleaning products, iirc 'sani-flush' is one such, although I've always just bought bisulfate from my suppliers, but take a ml or two of glycerine and some bisulfate, after evaporating off the water from the cleaning product (this is a DEhydration, after all
) and heat the two together strongly, a tin can will do really, if you haven't a test-tube or other long container that resists heat. Once your done, and believe you me, you will KNOW about it, take one or two drops of the resulting liquid, onto a tissue or something, and use one's hands to waft the vapor to one's nose from a foot or so off, that tiny kind of exposure isn't going to do anyone real harm, I myself surely copped a lot more when I accidentally
vaporised the lot, after tipping it down the sink and flushing, stupidly, with HOT water, ugh yuck!.
Hehe, something tells me that not very many people will be tempted to do it twice
Propylene glycol isn't anything to worry about, its often used like glycerine, as a humectant in things that are intended for human consumption, and a medicine excipient. Not toxic stuff, ethylene glycol (antifreeze) is toxic, but thats because it gets metabolized to the toxic oxalic acid mainly, that doesn't follow through either to POLYethylene glycols, or to propylene glycol (glycol is a synonym for 'diol', btw). PG is harmless stuff.
