Comments on: More lab disasters 2

By: easong

easong — Fri, 13 Mar 2009 04:27:55 +0000

Ah, youth. When I started working in an organic lab ca. 1981, my boss first off taught me proper drying and distillation of ethereal solvents. He showed me how to prepare Na-K alloy from the solid metals and put it into the THF still. I was fascinated with how two solids became, after melting together, a room temperature liquid like mercury. Then I attempted to transfer the liquid alloy from the melt to the still with a large pipette, and the rubber bulb popped off, releasing about 10 mL (yep!) liquid NaK into the hood and all over the lab floor. The little beads in the hood rolled all over of course, then burst spontaneously into blue flame as they picked up moisture. The larger beads of metal rolling on the lab floor hit a puddle next to the sink and went off like a meteorite. I stomped on the fire and dispersed it into a thousand little blue flames from wall to wall. My boss ran in and covered everything in celite.

That was my first full day on the job, as I recall. Almost 30 years later I am still making a living in the lab. Amazingly.

By: Ron

Ron — Wed, 04 Feb 2009 18:46:18 +0000

Thanks, milkshake – I appreciate your comments

By: milkshake

milkshake — Wed, 04 Feb 2009 17:46:42 +0000

I worked mostly with triethyl oxonium BF4 , about 20 years ago, and it is not very stable – I made it myself using the OrgSyn procedure and stored it as a stock solution in DCM – and the solution titer decreased over few months in the fridge. I think it is better to store the solid reagent. Also if you can buy the hexafluorophosphate or hexafluoroantimonate salt, these should be slightly less hygroscopic than the tetrafluoroborate salt. I have seen people storing these things in common fridge but I suppose freezer is just as good. The main killer is moisture, so it is important to let the bottle to warm up in a dry place like desicator (to prevent condensation) before opening it. Since you are going to use it frequently I suppose you can divide a big bottle of the reagent into several smaller ones, so that they get open fewer times.

But I don’t have any experience with alkylating alcohols with it – I suppose it very much depends on what kind of alcohol you have.

By: Santosh Kumar Gurung

Santosh Kumar Gurung — Wed, 04 Feb 2009 05:25:57 +0000

Hello!!!

1)ease, i m seeking for process/procedure to generate HCl gas.

2)used BF3. Et2O/ Ac2O/ toluene/ reflux/ 2 hrs to generate 2′,4′-dihyroxy-3′,6′-dimethoxy acetophenone (acylation) from 2′,4′-dihydroxy-3′,6′-dimethoxybenzene. Unfortunately i could not get the acylated product. Please, i seek ur favor and suggestion for any other suitable methods.

By: Ron

Ron — Wed, 04 Feb 2009 01:21:40 +0000

How do you store trimethyloxonium tetrafluoroborate? I’ve read different things about its storage (dessicator at -20 C, glove box either at rt or in the freezer). Also, I’m using it to derivatize a product so I can track the reaction kinetics by GC – how fast does it alkylate an alcohol at room temperature? I remember reading that you have experience handling this salt, so I thought I’d ask. Thanks for any comments you can provide!

By: vasili

vasili — Sun, 01 Feb 2009 17:35:22 +0000

Aqueous means a solution of something in water. So, 25% aqueous MeOH means 25% MeOH in H2O.
Your first option is correct.

By: Rennip

Rennip — Sat, 31 Jan 2009 22:19:46 +0000

“25% aqueous MeOH”

Is that 25 mL MeOH and dilute to 100 mL with water, or is it 25 mL water and dilute to 100 mL with MeOH?

By: Chemjobber

Chemjobber — Sat, 17 Jan 2009 03:58:06 +0000

So Kai — continuing my question, is triolein or oleic acid the main constituent of olive oil? I would imagine (and milkshake seems to confirm) that it is the triglyceride, triolein. Online, though, the vast majority of sites seem to think that it is oleic acid.

By: Kai

Kai — Mon, 12 Jan 2009 22:15:28 +0000

just for the record, “triolein” is a name for the triclyceride of oleic acid…

By: milkshake

milkshake — Tue, 06 Jan 2009 16:34:43 +0000

sorry I don’t know what’s in you molecule and what kind of Ar substitution reaction are you running but for example
triisopropylsilyl is perfectly suitable for protecting phenols.