Bloody hot today, 25+ 'C, and going to get hotter tomorrow. Got the bay windows at the back of the lounge wide open but its still sweltering. At least the bottle of toluene that I had been as I usually do unless its actually either in use, or I am about to use it, is warming up quickly. I think I'm going to leave it in a sunny spot on the kitchen counter ledge so it can hurry up and get warm, because things are less soluble when cold in solvents, other than gases which behave the opposite way, becoming more soluble the colder the solvent gets.
I keep my solvents in the fridge, because I often use ice-cold solvent portions to wash things, etc., and its much faster to say, heat up a pan of water on the stove, or from the kettle, let it cool a little, and of course without the flame being on, then immerse the outside of a bottle in the warm or hot water. Takes a lot less time to warm it back up from being cold, than it does to get it really cold, at least without using chemical freezing mixtures to shock-cool it, after putting them in the freezer for a while (my chemical fridge hasn't got a freezer, unfortunately, so I use the food fridge, but only for solvents, and not for any that would either have a truly foul stench (for example, say, pyridine being one that falls under that category), and while it doesn't smell nasty, benzene is one I wouldn't put in there either (I mean actual C6H6, the planar molecule which if it forms part of a larger structure is known as a phenyl ring).
Toluene is related, its monomethyl benzene, but the reason benzene itself is so dangerous, is that it has a propensity to cause leukaemias. This is because the molecule is a cyclic structure, held rigid and planar in structure, like a flat disk, and because of the shape, it can slip between the two chains of a DNA helix and intercalate with DNA, which in the way it does it, has as a result, of causing cancers of the blood and bone marrow. I don't want either, and I wouldn't wish them on my old man either, so benzene is one that doesn't go in the freezer, only the chemical fridge and using ice-salt-antifreeze baths, or chemical mixtures for shock-freezing below zero within moments are used, usually both, precooling in the fridge and then immersing them in the freezing mixture and adding the second or last needed ingredient of the mixture once the already chilled bottle is in there, when I want it for using it to wash things with icy-cold solvent.
Toluene I have no problem putting in the freezer, over the frozen peas or something, because the methyl group on the benzene molecule distorts the planar structure of benzene, and in toluene it is rendered no longer planar, and cannot intercalate with DNA due to that -CH3 group. Obviously any containers are tightly closed, but I am still selective about what I would put in there. Things like ether, alcohols, toluene, alkane hydrocarbons like naphtha blends, heptane, pentane and the like, acetone, dioxane, THF, acetonitrile (methyl cyanide), DMSO, DMF, sure. But benzene, HMPA, pyridine, carbon disulfide, carbon tetrachloride, no.
(methyl cyanide, commonly known as acetonitrile is quite commonly used as a handy polar aprotic solvent with a relatively low boiling point (below 100 'C) compared to other commonly used polar aprotics, which in the case of DMSO, DMF, HMPA, they all have boiling points considerably greater, DMF boiling a little over 150 'C, whilst HMPA boils at 232.5 'C and DMSO is high boiling too, at 189 'C, so all of these need a good vacuum pump to strip the solvent from a reaction using any of them once you are finished, but a boiling water bath is enough to strip acetonitrile/methyl cyanide off, so its pretty useful for any reactions which tolerate the nitrile functional group. Ionic cyanides like potassium, sodium cyanide etc. and hydrogen cyanide gas are all extremely toxic, as they bind to iron with great avidity, including the iron atom which is essential for the redox chemistry of the electron transport chain at cytochrome oxidase III within the active catalytic site of the enzyme. (this iron affinity for cyanide ion is the reason also why ferricyanide and ferrocyanide, unless made to release cyanide gas etc. are vastly, vastly less toxic, ferrocyanide even being used in table salt in some brands as an anticaking agent, although I wish they wouldn't so I don't have to go around making sure I buy the correct brand of table salt, to make sure I can't accidentally cause a release of deadly cyanide gas.) In ferri- and ferrocyanides, there are multiple cyanide moieties already bound to a central iron atom, and they have, in a manner of speaking, already sated their hunger for iron, and they don't liberate free cyanide anions if absorbed into the body.
Organic cyanides, although there are some exceptions, are not non-toxic, but they are hugely less so than are ionic inorganic cyanides, and although methyl cyanide can liberate free cyanide when metabolized if absorbed, it isn't what you could call particularly a dangerous solvent. One would need to be exposed to quite a lot, for it to come up behind you later to make a sneaky stealth kill. So working with it really doesn't bother me much.
Ah, good. Looks like my tolly is warming up and getting closer to room temperature. I think I'll go ahead and start draining the first portion, so that when I come for the second to be added the first lot will be ready and tapped off, making it ripe time for adding the next solvent pull to my extraction.
