Fancy uploading it somewhere and posting it? might just become one of some other wasp's favourite reads if you do. Would bee appreciated. (If you are willing, please do so publicly in the request thread here, so others can read it, and find it, however I haven't yet actually read, and do not currently follow, although I guess I should, those threads, and Toady, he has a medical memory problem, so alerting him if you are willing to share it, and have actually done so, via PM, would bee much appreciated) Toad face administered multiple IV doses of methoxetamine last night, and insufflated a considerable quantity over the previous few days to this post being written, so the ability of his hippocampus to organize the encoding of memories and consolidate them from short and working to long term memory, via glutamatergic AMPA receptor-dependent hippocampal long term potentiation is impaired. So he may not remember he asked. A PM would bee most appreciated if you can upload that book on oxidations.
Drawback to the Swern oxidation if I remember rightly, is the use of DMSO. Low volatility/high boiling under atmospheric pressure, reduction in this particular reaction to dimethyl sulfide, at least to a degree, which is most certainly volatile, and most certainly foul smelling (and probably not particularly a pleasant substance to come into significant contact with either, certainly though, I don't recall reading it having the same extremely potently lethal, and highly carcinogenic properties of dimethyl sulfATE) and there is to consider, the danger inherent with DMSO in any reaction, of it coming into contact with the skin. It absorbs very quickly transdermally, and is capable of carrying substances with it. It has indeed, been used with multiple compounds (never by myself however) to deliver drugs transdermally.
Not a toxic solvent, particularly, compared to most, and has medical applications, BUT, I do recall reading a journal paper not too long ago, although I can't remember what, or which issue to cite it, search should reveal it, where DMSO used alone was shown to exert a neurotoxic or neurodegenerative effect upon the brains of lab animals. I cannot remember if this neurotoxic and/or neurodegenerative effect was targeted at a specific location/structure within the brain, or was generalised and diffuse in character. (uggh...disgusting, cruel bastard fucks, poisoning animals and torturing them...I HATE it, to see animals treated that way, even though I have to eat them [no, not rats
])
My guess is that it (DMSO) would also penetrate the blood brain barrier extremely efficiently and quickly once it is either applied to or spilled on the skin, carrying whatever might be dissolved, if anything with it. Weather a transition metal ion that lacks a specific affinity for being deposited in fat would go through the lipid portion of the BBB very well once it gains access to the bloodstream (such as for example the insidious, lethal and altogether cunting scary dimethylmercury, which does so as though it were born for causing that specific effect and goes STRAIGHT to the brain, and once there, stays there tenaciously, killing cells left right and center) is anyone's guess, I do not know.
But I sure as hell wouldn't want to spill DMSO with a load of CrO3 or dichromate in there on me....that would NOT be a good thing to come into contact with and medical consequences if exposed to anything more than a minute quantity, would be unsurprising, and indeed quite probable, and near certain in the case of a large quantity. Hexavalent Cr being particularly nasty, appearing to me to act locally as a carcinogen upon sites of contact (skin contact sans DMSO, being washed off in timely fashion, I consider relatively unlikely to cause harm. Occupational inhalation of chromium hex is known to cause lung cancer, and also kidney cancer, and increases risk likewise of cancer of the lower GI tract. Purely oral exposure I assume will not selectively target lungs but instead concentrate the manifestation of the toxic effects in the GI tract, and kidneys. Presumably also the bladder if it gets absorbed well into the bloodstream and circulates, after being accidentally orally intaken although I am unsure weather this happens to a significant extent after exposure.
Toad features had to replace some furniture after getting chromium hex distributed all over the show once, years back, glass shattered during distillation of a quantity of chromyl chloride, perhaps 150, maybe 200ml or so. It was being synthesized by addition of 98% H2SO4 to an intimate mixture of table salt and he forgets now, but either potassium or sodium dichromate. An excellent way to produce chromyl chloride by the way, analagous iodides, or bromides do not exist, by way of an interesting tidbit of info, nor, he believes, do fluorides.
Stuff went everybloodywhere in the wooden wardrobe his only workspace, as a kid, at the time, had to be in. Oh boy did he ever vacate the room, luckily it stayed localised, what was released being absorbed mostly by the wooden surface, or unfortunately, volatilizing to a degree. HCl fuming everywhere, leaving a slowly spreading pool of conc. H2SO4, dichromate sludge, and chromyl chloride slithering across the work surface. Toady stopping in only to grab his gas mask, put absorbent material down to soak up the escaping tide of shite, close the door, to avoid contaminating the house, and opening all windows possible within the area of effect. The salt being in there, acting like sand would, to a degree, although itself causing release of minor quantities of further halide. Left for a long, long, long walk, and when he had to come home, sleeping in his mask. He had to cut a piece of wood to size, after cleaning up the aftermath, once the shit had stopped hitting the fan and dripping down therefrom, to cover the green stains (looked approximately the color of somewhere between the tetraminecopper complex formed by CuSO4 and aq. ammonia mixed with the green hue of nickel chloride), and then permanently glue it securely over that part of the wardrobe.
That episode, looking back on it was fuck ugly in toady's opinion. Could have got nasty, very nasty in fact.
In the case of exposure via DMSO he imagines it [ Cr(VI) ] would have the tendency to cause cancer in ALL areas of the peripheral body, perhaps not penetrating the BBB if absorbed onto the skin in solution, but given the lipophilic nature and rapid absorption, presumably correspondigly rapid distribution in vivo also, that is likely, in his opinion not to be the case.
So Swern oxidations, whilst sounding and seeming like an excellently useful reaction for preparing aldehydes from the appropriate precursor or intermediate experimental/synthetic substrates in Tsathoggua's opinion have some very significant safety issues associated with them, and in the case of a private lab, should, responsibly, be very well protected from environmental release, and the possibility of Me2S release dealt with.
DMS being of course, the thioether counterpart to dimethyl ether, which is extremely flammable, this one is stinky too, and its the sort of chemical which will get everywhere if not watched.
Quick question for the sake of learning.....do small molecule thioethers tend to peroxidise like their oxygenated counterparts?
Not relevant, I would thought, from my reading on the safe handling of THF, and by extension, other simple ethers, as peroxidation seems, according to my reading, to occur exclusively in the liquid phase, and not in THF vapor. In the liquid underneath it, yes, but not the vapor itself if no liquid THF is present.
Topic: Short Questions Thread (Read 10827 times)
