I got a hair up my ass this morning and decided to see how clean and dry I could get some ethanol. So I distilled 500ml, then cleaned and dried the flask in the oven and redistilled. Only this time instead of having the receiving flask attached I had a funnel full of MgSO4 with a little heap of activated carbon on top. I decided when the ethanol is done I will do the same with methanol. I thought about doing some xylene or toluene, but distilling these changes your blend of isomers thereby changing the solvent, is this right? While I'm setup I wonder if you guys have any suggestions of things I can run through this little Rube Goldberg distillation apparatus.

I'm in one of those moods where I don't wanna synth anything, I wanna do shit like this. If I do synth anything it'll be stuff to use in other synths; hydroxylamine, methylamine, pretty much anything that is just a couple functional groups stuck together. I love these compounds that are just a couple functional groups. They seem to be among the handiest things you can have just lying around. I guess I should find out more about methylamine before I make any. Because honestly, I don't know if it's just heavily watched or if it's outright illegal. If it's outright illegal that's just gonna blow my mind, I mean seriously? I guess it's no stranger than making a plant illegal, though.

Here's my feeble little drying funnel. Is it adequate?

I thought metadata was stripped automatically. Guess not. Thanks for the heads up.

cant see the pics, but mgso4 isnt good for ethanol. it dissolves in it. the same applies to methanol. however methanol does not form an azeotrope with water, so you can just distill it as is to relatively dry it. ethanol requires a drying agent to break the azeotrope. 3a mol sieves work very well. CaO is also a common alcohol drying agent since as it reacts with water it forms Ca(OH)2 which is insoluble in the common alcohols.
toluene is self drying. its azeotrope is such that allows you to distill it to almost complete dryness. if you need it extra dry use some magnesium sulfate. isopropanol I dry with MgSO4 also.

It depends on what you are using the solvent FOR as to what can be considered anhydrous.

A trace of H2O isn't going to bugger a borohydride reduction, and one can get away with more water in a LAH reduction I imagine, than one can when handing tert-butyllithium, which has to be done under a schlenk line.

The solvent has to be dry enough for a specific use..if a certain trace water content is acceptable or not depends on what your use is for the intended reaction.

Distillation from calcium carbide can be used for final stage drying for very, very, very dry alcohols, then sparge with dried He, Ar or N (lead through conc. H2SO4, suckback trap, CaO,) to drive off any dissolved acetylene.

If you need to be that thorough, thats some seriously involved, careful work, that you plan out in advance for a specific project, not just something to keep lying around, thats likely only to be needed for sensitive organometallic reactions. Grignards even are not THAT sensitive as far as I know.

any anhydrous is solvent isnt really dry. it still usually contains few ppms of water. there are a few good papers on drying agents and solvents, heres one especially good, and quite new -
Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants. D. Bradley G. Williams* and Michelle Lawton. J. Org. Chem. 2010, 75, 8351–8354.
Sorry i dont upload, but my articles identify me. Super dry solvents as Tsathoggua said, are usually only needed for organometallic reactions, not only for the dangerous ones (t-BuLi, LiAlH4) but also for the sensitive organometallic coordinated transition metal catalysts, many of the new stuff will decompose under h2o or o2.
however, for most of my needs, 3a mol sieves are the choice for me. unless the solvent is sensitive to base (like acetone), since the mol sieves are somewhat basic and can cause autopolymerization (aldol type) of acetone.
when i want to keep solvents very dry, i usually dry them with the drying agent of choice and then distill if i need ti super clean. i collect the solvents straight into bottles 1/5-1/4 full of mol sieves and close the cap. this will keep your solvents dry for a long time, and also wont become too wet by opening them, since the excess mol sieves will suck up any moisture.

3A works fine for Ethanol, I've never seen it dissolve.  We use drierite for Methanol. 

Beware drying the 3A - we have a little fisher oven in the garage and the first time he tried it the door blew open with flames so you wouldn't want to have been doing that in the kitchen.  Now I think he heats the flask with the 3A in it and distills off whatever solvent was in it before he puts it in the oven.

He uses the 3A for IPA too, but also CaO.  He refluxes the IPA in the CaO for a while, stuff is drier than Heet!

Where on earth have you been Salat? I haven't seen you post in AGES? are you and your other half doing ok? was beginning to wonder if you had been arrested/abducted by aliens/'extraordinarily rendered' by the CIA/NSA/KGB/FSB/ mistaken for an taliban spy  and spirited off to guantanamo bay.

Or have you just been a bit tied up lately?

Sigma aren't going to serve anybody here with so much as a drop of distilled water. Making H2O reference standards, having no standard to go on is going to be beyond the means of anybody working for themselves. I'd thought of karl-fisher titrations, but I don't see how it could be done without a front company or somehow going through a university.

I doubt it would be a suspicious item, after all, most meth cooks, LSD chemists,  people making MDMA, amphetamine, growing herb, they don't need that, nor do the grignard PCP cooks, but its obscure, and nobodody is going to bee selling those buggers easily.