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Topic: Scariest Experimental Set ups and The Worst Reagents to Work With  (Read 5087 times)

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Offline Guitarmaniac86

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Since I have been doing my Masters, I have been doing reactions under some pretty scary set ups. Sure I have used a reflux condeners and distillation apparatus, but I think the scariest set up I have used is the schlenk line. I am constantly paranoid that:

- My reaction vessel will implode because it cant take the vaccum when Im drying under product
- That liquid oxygen will condense in the line and go bang because I have been careless at some stage

The worst reagent I have personally worked with is MOM-Cl because of all the precautions and paperwork before I can use it, not that I really want to use it (sometimes I have no choice).

Don't believe atoms, they make up everything!

Offline discodermolide

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #1 on: May 31, 2012, 01:23:05 PM »
Since I have been doing my Masters, I have been doing reactions under some pretty scary set ups. Sure I have used a reflux condeners and distillation apparatus, but I think the scariest set up I have used is the schlenk line. I am constantly paranoid that:

- My reaction vessel will implode because it cant take the vaccum when Im drying under product
- That liquid oxygen will condense in the line and go bang because I have been careless at some stage

The worst reagent I have personally worked with is MOM-Cl because of all the precautions and paperwork before I can use it, not that I really want to use it (sometimes I have no choice).



You want to try making a benzyl azide on a 10 KMol scale and repeating it 50 times! The scary part is the HN3 and the aqueous waste treatment with sodium nitride, which generates vast amounts of laughing gas and nitrogen so if you see lots of liquid/foam rising in the condenser of the reactor you RUN AWAY fast.
The worst reagents on scale are trimethylaluminium, phosphines and boron compounds, especially DIPCl. Talk about pyrophoric!
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Offline Guitarmaniac86

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #2 on: May 31, 2012, 01:46:49 PM »


You want to try making a benzyl azide on a 10 KMol scale and repeating it 50 times! The scary part is the HN3 and the aqueous waste treatment with sodium nitride, which generates vast amounts of laughing gas and nitrogen so if you see lots of liquid/foam rising in the condenser of the reactor you RUN AWAY fast.
The worst reagents on scale are trimethylaluminium, phosphines and boron compounds, especially DIPCl. Talk about pyrophoric!

I think I'll stay at ╬╝mols  :P Have you ever had to run away from a scenario before, and have you had pyrophoric compounds combust?

Process chemists must have it tough
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Offline Babcock_Hall

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #3 on: May 31, 2012, 02:47:02 PM »
The most depressing reagent I worked with was iodotrimethylsilane (TMSI).  IIRC even when I distilled it onto copper shot, I could watch the distillate gradually pick up a pink color within minutes.  IT gave very variable yields in the reaction I was doing.

Offline discodermolide

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #4 on: May 31, 2012, 03:11:09 PM »


You want to try making a benzyl azide on a 10 KMol scale and repeating it 50 times! The scary part is the HN3 and the aqueous waste treatment with sodium nitride, which generates vast amounts of laughing gas and nitrogen so if you see lots of liquid/foam rising in the condenser of the reactor you RUN AWAY fast.
The worst reagents on scale are trimethylaluminium, phosphines and boron compounds, especially DIPCl. Talk about pyrophoric!

I think I'll stay at ╬╝mols  :P Have you ever had to run away from a scenario before, and have you had pyrophoric compounds combust?

Process chemists must have it tough

No, fortunately I never experienced a runaway. In the lab we had a 5L cylinder of lithium aluminum hydride as a 1 molar solution in THF. After some months I noticed the bottom of the container was convex indicating a pressure build- up. I informed the works fire brigade who appeared and removed the cylinder for disposal. They took it to one of their training areas and one of them in full protective gear opened the valve. A jet of gass/liquid immediately spurted up in the air and caught fire. The container eventually exploded. This was all due to the polymerization of THF caused by LiAlH4
I dread to think what that would have been like in the lab.
Also I dread electrostatic charges, which account for many of the "explosions" we hear about.

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Offline g-bones

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #5 on: May 31, 2012, 05:27:24 PM »
Distillation of TiCl4 is like having a hood of fuming and flaming death.

Offline Dan

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #6 on: June 01, 2012, 05:49:26 AM »
The worst reagent I have personally worked with is MOM-Cl because of all the precautions and paperwork before I can use it, not that I really want to use it (sometimes I have no choice).

I'd suggest chloromethyl ethyl ether instead (EOM-Cl; CAS:3188-13-4).

Similar R/S phrases (so you need to be careful), but much less paperwork. Similar to the paperwork difference between NaCN and NaN3 despite having comparable associated risks.
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Offline Nosterius

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #7 on: June 01, 2012, 07:29:54 AM »
I'd suggest reading Derek Lowe's blog. He has a category conveniently named "things I won't work with. It is very entertaining...

http://pipeline.corante.com/archives/things_i_wont_work_with/

On this page, you will also find a link to Max Gergel's memoirs. It is a long (~200 pages) document, but it is interesting to see how a chemical company could be built during the 40'+. Let's say that health and safety was not a concern in these days... neither was the environement!

Have fun reading these!

Offline azmanam

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #8 on: June 01, 2012, 08:17:18 AM »
I fused ZnCl2 several times in grad school.  This requires direct heating with a flame under hi-vac until it starts boiling.

One time, the flame started softening the glass bottom of the rbf and the rbf started curling up inside itself.

Fortunately no implosion or anything... but I let that rbf cool and started fresh with a new rxn setup.
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Offline Alberto_Kravina

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #9 on: June 01, 2012, 12:02:04 PM »
Nice topic.

the most nasty stuff I worked with was during a gram-scale Grieco elimination. Tons of Selenium stuff....nasty.

Offline Guitarmaniac86

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Re: Scariest Experimental Set ups and The Worst Reagents to Work With
« Reply #10 on: June 01, 2012, 03:34:05 PM »


I'd suggest chloromethyl ethyl ether instead (EOM-Cl; CAS:3188-13-4).

Similar R/S phrases (so you need to be careful), but much less paperwork. Similar to the paperwork difference between NaCN and NaN3 despite having comparable associated risks.

Thanks Dan, I shall try EOM-Cl when Im next doing a protection.

I'd suggest reading Derek Lowe's blog. He has a category conveniently named "things I won't work with. It is very entertaining...

http://pipeline.corante.com/archives/things_i_wont_work_with/

On this page, you will also find a link to Max Gergel's memoirs. It is a long (~200 pages) document, but it is interesting to see how a chemical company could be built during the 40'+. Let's say that health and safety was not a concern in these days... neither was the environement!

Have fun reading these!

That will keep me busy. Its very interesting so far! Thanks for posting the link
Don't believe atoms, they make up everything!

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