Elementary (Hive Addict)
06-18-02 09:09
No 322732
      Drying Ether  Bookmark   

In most grignard procedures the ether to be used is normally refluxed with sodium to ensure that it is completely anhydrous.

My question is, can lithium metal be used to dry the ether instead of sodium ?

John Lennon - Working Class Hero
 
 
 
 
    Osmium
(Stoni's sexual toy)
06-18-02 09:27
No 322738
      Yes, that should work too.  Bookmark   

Yes, that should work too.

But the whole point becomes moot if you don't know how to properly handle the ether afterwards. If you simply put it into a bottle and have no idea about properly handling stuff under anhydrous conditions then such drying is pretty much useless.

I'm not fat just horizontally disproportionate.
 
 
 
 
    starlight
(Stranger)
06-18-02 12:38
No 322781
      and if that is difficult  Bookmark   

and if you are not able to maintain anydrous conditions, then maybe you could use ultrasound to initiate Grignard reactions....

../rhodium/chemistry /grignard.wet.html

not that i have ever tried it. smile

./
 
 
 
 
    El_Zorro
(Hive Bee)
06-18-02 15:19
No 322829
      Well, Os, you gonna keep those anhydrous ...  Bookmark   

Well, Os, you gonna keep those anhydrous condition tips to yourself, or are you gonna share 'em with the group?wink

Do not go gentle into that good night.  Rage, Rage, against the dying of the light.  --Dylan Thomas
 
 
 
 
    Osmium
(Stoni's sexual toy)
06-18-02 15:31
No 322838
      Well, obviously you shouldn't pour that ether ...  Bookmark   

Well, obviously you shouldn't pour that ether from a flask into a bottle through a funnel! Store it in the flask under inert gas, transfer it with oven-dried pipettes, syringes or flexible, needle-tipped teflon hoses, always use dry N2 or Ar, dry all your glassware and everything else before use and purge them with the gas, find out what Schlenk glassware looks like etc.

http://www.ilpi.com/inorganic/glassware/vacline.html
http://www.ilpi.com/inorganic/glassware/schlenkflask.html

I'm not fat just horizontally disproportionate.
 
 
 
 
    lugh
(Moderator)
06-18-02 16:55
No 322862
      Dehumidifier  Bookmark   

Those are all good tips, but bees should know that in addition to what was previously posted, SWIL likes to keep the humidity down with a dehumidifier; since SWIL doesn't live in the desert laugh
 
 
 
 
    El_Zorro
(Hive Bee)
06-18-02 19:57
No 322912
      I wanna know why nobody uses CO 2 as an inert ...  Bookmark   

I wanna know why nobody uses CO2 as an inert gas.  It's gotta be the cheapest and easist gas to buy, and it is completely unwatched.  Not to say the other gases are watched, just that CO2 is less watched.  Is CO2 not inert enough?  Is it not dry enough?  Why does no one use CO2?

Do not go gentle into that good night.  Rage, Rage, against the dying of the light.  --Dylan Thomas
 
 
 
 
    Bwiti
(PVC-Analog Taste-Tester)
06-18-02 21:17
No 322938
      Won't most Grignards react with C02?  Bookmark   

  Won't most Grignards react with C02?

Love my country, fear my government.
 
 
 
 
    former_chemist
(Newbee)
06-19-02 00:08
No 322992
      CO2  Bookmark   

CO2 is sold for use as an inert gas for welding.  Argon is prefered though. Nitrogen is also used but that depends on the metal, some form nitrides which is either good or bad depending on the application.

Oh you mean for a chemical reaction!  CO2 is fine as long as your reaction isn't harmed by acid. CO2 reacts with basic compounds and complexes (like sodium and magnesium) to form carbonates.
 
 
 
 
    lugh
(Moderator)
06-19-02 03:18
No 323023
      Carboxylic Acids  Bookmark   

Carbonation of the Grignard reagent is a standard method for preparing carboxylic acids, unless that's the product desired, one shouldn't introduce carbon dioxide smile
 
 
 
 
    terbium
(Old P2P Cook)
06-19-02 20:46
No 323250
      Dryness is relative.  Bookmark   

Is it possible to dry ether with epsoms? 
Dry enough for use as the solvent in a Grignard reaction? Probably not, magnesium sulfate is not a very powerfull drying agent.
 
 
 
 
    El_Zorro
(Hive Bee)
06-19-02 21:31
No 323260
      I meant in relation to shit like keeping ether ...  Bookmark   

I meant in relation to shit like keeping ether anhydrous while you're getting it into a flask for storage, storing the ether under CO2 for storage, etc.  I would go ahead and use Ar anyway for a reaction.

Do not go gentle into that good night.  Rage, Rage, against the dying of the light.  --Dylan Thomas