Sciencemadness Discussion Board

Stuff to Pick Up at Chem Supplier

JJay - 21-12-2015 at 03:35

I live in a remote area with limited access to chemicals. I am going to be in the city that is home to my second favorite chemical supplier in the next few days, and I'm trying to figure out what I should pick up while I'm there, particularly, items that are useful, not available OTC, and with especially outrageous HAZMAT handling requirements.

So far all I can think of is aluminum chloride, zinc chloride, and potassium permanganate (which doesn't seem to be available OTC around here), reagent grade 37% hydrochloric acid (which actually is available here for just under $100/500 mL), lithium aluminum hydride, and sodium metal.

What else should I get?

User123 - 21-12-2015 at 04:23

I am a bit confused as to why you need to ask. If you are competent enough to be using lithium aluminium hydride (I have never used it in my entire professional career; NaBH4 can be substituted in all non-exceptional cases), then surely you are competent enough to know what experiements you want to do, and what reagents you will need to perform them?

I imagine that you are doing the equivalent of graduate-level organic chemistry?

If you really want some sugesstions, then make sure that you have the means to make acyl chlorides from carboxylic acids, alkyl halides from alcohols -- personally I use PPh3, NXS for these transformations. You can also use NXS for a-halogenations of ketones, and conversion of amino-acids, amines and amides to nitriles, so you may as well get both.

Fuctional group reductions (ketones, aldehydes, imines, nitriles, carboxylic acids): I use NaBH4 and additives.

Oxidizing agents: I made some PCC using CrO3, HCl, pyridine. Get some pyridine, it's a good solvent too. Also triethylamime as a useful generic base.

If you're interested in organometallic reactions, PdCl2 and RuCl3 are good entry points into a range of coupling catalysts, and of course you can make Pd/C hydrogenation catalyst (used in DCM at rt, under an atmosphere of H2, removes any benzyl groups).

Stains for TLC: I2, ninhydrin, bromocresol green, cerium sulfate.

Camphor for molecular weight determinations.

Aside from that just make sure you're stocked up on organic solvents, I suppose: MeCN, DMF, DMSO, alcohols.

You can make ether from ethanol and sulfuric acid, and use it to make Grignards and so on. You may not use most of those solvents (I don't), but it's always good to have them to hand.

That's all that I can think of 'in general'. Anything else would be too target-specific.

[Edited on 21-12-2015 by User123]

Praxichys - 21-12-2015 at 07:59

I just did this. I got:

CrO3 (Although it can be made from sulfuric acid and dichromate, but rather tedious/wasteful)
Pyridine (Although it can be made from niacin in good yield, somewhat tedious)
N,N'-DMF (It can be made a number of ways but not worth the effort for the quantity required.)
Cyanuric trichloride (IIRC not practical to make. Just about as useful as SOCl2 for preparing acyl chlorides)
P2O5 (Hard to get in the USA)
Ethylenediamine (Very difficult to make on a lab scale, but not that useful either)
Glyoxal 40% (Again, annoying/difficult to make in quantity. Can preserve as bisulfite adduct.)
Dimethyl carbonate (Impractical to make. Can be photochlorinated to bis(trichloromethyl)carbonate for use in phosgenations. Be careful with this)

Most the other stuff you can get for cheap on ebay. (Alcohols, indicators and stains, even DMSO)

User123, if the NXS you're referring to is n-(halo)succinamide, it's pretty easy to prepare. Use ammonia to make a solution of succinic acid slightly basic (acid available on eBay) and distill to end up with succinamide. Basify and add your favorite halogen.

I wish I had picked up some PPh3 now. Pd/C 5% would also be useful but I'll get it when I need it.

User123 - 21-12-2015 at 08:42

Do you use P2O5 as a reagent, or just as a dessicant? As far as I know, using separate beakers of NaOH and H2SO4 in a dessicator provides just as agressive a system, and has the benefit of moping up any volatile solvents too. It's much cheaper, I imagine. If as a reagent, perhaps you could give a brief overview -- I only know of amine to nitrile conversions.

I've never made succinimide, but I might give it a go if it's easy. Strike NCS and NBS from the list!
I just read about cyanuric chloride and "Gold's reagent", made by adding it to DMF, and providing a Mannich reagent equivalent.* Very interesting. I'll probably get some of that.
Another versatile reagent is DCC. Aside from its use for making amides and esters and so on, one can use it to alkylate amines and alcohols by reacting it first with an alcohol, to give an isourea, then using this to alkylate either alcohols to give ethers, or amines to give N-alkylamines, depending upon reaction conditions. In fact, one can selectively alkylate an alcohol in the presence of an amine on the same molecule, and vice-versa, with no need for protecting groups. A practical use that I have put this to is in the O-methylation of bufotenine. The tertiary amine was unaffected by the methylating agent.
In effect, it turns an alcohol into an alkylating agent. It can all be done at rt in DCM or methanol.

*Edit: actually it's not. But interesting all the same.

[Edited on 21-12-2015 by User123]

Praxichys - 21-12-2015 at 10:13

Quote: Originally posted by User123  
Do you use P2O5 as a reagent, or just as a dessicant? As far as I know, using separate beakers of NaOH and H2SO4 in a dessicator provides just as agressive a system, and has the benefit of moping up any volatile solvents too. It's much cheaper, I imagine.

Hmm, I've never thought to use both NaOH and H2SO4 in combination. I will have to try that. Yes, that would be much cheaper than P2O5. I haven't used P2O5 in the desiccator yet. I mostly use sulfuric acid, CaCl2, and NaOH, application dependent.

The P2O5 is useful as a reagent. It is, as you mentioned, one of about two ways available to the amateur chemist to prepare nitriles, the other involving poisonous and difficult to obtain NaCN/KCN and hard-to-handle, often volatile or lachrymatory organohalides. Nitriles are some of the most versatile building blocks around, and otherwise tedious preparations are made simple with P2O5. That, and POCl3 is easily made from it, which has quite a wide range of similar, milder uses.

A convenient, low(er)-temperature preparation of SO3 simply involves distilling a solution of P2O5 in sulfuric acid. Regular borosilicate can be used rather than the quartz glass required for the high temperature, low-yielding pyrosulfate or persulfate methods. This is indispensable for difficult sulfonations and the preparation (rather than purchase) of oleum. Arylsulfonic acids lead to rich volumes of dye chemistry.

N2O5 in chloroform is prepared rather easily as well, and this is great for high-yielding nitramine synthesis. This can be achieved with the direct action of P2O5 on a chloroform/100% HNO3 mixture or by POCl3 on Ag(NO3)2.

JJay - 21-12-2015 at 10:18

I have phosphorus oxychloride. I haven't used DCC but have read good things about it.

I don't have P2O5 but can get it... it is a little hard to find... I haven't ever actually used it but have seen a couple of procedures that called for it.... It is almost always possible to substitute other reagents.

It would be nice to have some DMF...

I have a couple of specific uses in mind for LiAlH4. I could probably use sodium borohydride instead but I still want some LiAlH4.

Pyridine... I definitely want some of that.