The Vespiary

The Hive => Novel Discourse => Topic started by: Lem2 on May 16, 2002, 11:02:00 PM

Title: Grignard rxn in xylene
Post by: Lem2 on May 16, 2002, 11:02:00 PM
I was browsing through Rhodium EXCELLENT site, when I stumbled upon this:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/grignard.notes.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/grignard.notes.html)



The part I was most intrigued with was this:
"Hydrocarbons. ...Tschelinzeff attempted the preparation of of Grignard reagents from a series of iodides (not specified) in benzene, both thiophene-free and thiophene contaminated, but noted no preceptible reaction after forty-eight hours at the boiling point. In xylene, he was able to prepare reagents from, ethyl, n-propyl, n-butyl, and n-amyl iodides without the use of a "catalyst".

My question is, would the methyl iodide work in a similar fasion? It has no mention in the document, positive or negative. I sure could use some MeMgI w/o all the nasty ether fumes/explosions!
He who makes a beast of himself gets rid of the pain of being a man.
Title: References
Post by: lugh on May 17, 2002, 01:46:00 AM
You might want to check out the original references, some are in the text of the document on Rhodium's page you cited. Some that have a bearing on your question that aren't are JCS 89 2262-73 (1906) and 119 1249-56 (1966), in the former a mixture of 250 ml thiophene free benzene, 1.5 methyl iodide and .3 grams of magnesium powder were boiled for several hours without any detectable reaction. They then added 3 grams of tribenzylphosphine oxide, and the clear liquid became cloudy and the magnesium started to dissolve and the expected reaction occured. The latter is a comparirive study featuring methyl iodide grignards in benzene, with a variety of ethers and sulfur analogs as catalysts. Chem Guy did well to bring this knowledge to the Hive, but to expect him to type in the whole article is asking a lot   :)
 
 
 
Title: Grignard
Post by: hest on May 17, 2002, 11:30:00 AM
Iff you use 1-3mole of ether (THF) to one mole Mg and then dry toluene as solvent, these reactions rum much easyer. The poin is more to raise the reactionstem than sustitute the ether.
Title: Catalysis
Post by: PrimoPyro on May 17, 2002, 11:34:00 AM
For many Grignard Reagents (but not all) anhydrous triethylamine will catalyze formation of the organomagnesium halide entity. It need only be present in very small percentages.

For some halides, though, quaternization occurs with addition of triethylamine, greatly hindering the reaction.

                                                  PrimoPyro
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Title: asdf
Post by: Lem2 on May 17, 2002, 08:42:00 PM
it is true that is in the article, but what I was interested in was the formation of grignards WITHOUT a catalyst in dry xylene. the point of clandestine chemistry is to do things with as little stuff as possible, less stuff = less to catch. if one could make MeMgI/EtMgI w/o ether, and w/o trialkylamines, that would be a great step forward.
He who makes a beast of himself gets rid of the pain of being a man.
Title: ether
Post by: hest on May 17, 2002, 09:54:00 PM
ether(usual dimethylether) is the main part of disel start. you can get it at all tankstations. Spry some into your toluen and the reaction will bee much easyer to do.
Title: Hey
Post by: hsark on May 30, 2002, 08:33:00 PM
Shouldnt that be Diethyl ether or ethyl ether.
I think i like it!
Title: Dimethylether is a common propellant for all ...
Post by: Osmium on May 31, 2002, 12:15:00 AM
Dimethylether is a common propellant for all kinds of sprays.
I'm not fat just horizontally disproportionate.
Title: you sure?
Post by: foxy2 on May 31, 2002, 09:25:00 PM
I have never seen dimethylether list on anything
Those who give up essential liberties for temporary safety deserve neither liberty nor safety
Title: DME, or Dimethyl Ether (chemical formula: ...
Post by: Osmium on June 01, 2002, 12:13:00 AM
DME, or Dimethyl Ether (chemical formula: CH3-O-CH3) is a clear colorless, nontoxic environmentally benign compound that is currently used commercially as a propellant for various aerosol products including perfumes, hair spray and other health products.  DME is used in over 10 billion aerosol cans, primarily in Western Europe and North America. 
In the atmosphere, Dimethyl Ether has a half life of one day and quickly decomposes to CO2 and water.  Dimethyl Ether is neither a carcinogen, a teratogen, nor a mutagen.  When it decomposes, it does not lead to formaldehyde formation.

http://www.dmeforpower.net/pg_background.html (http://www.dmeforpower.net/pg_background.html)


I'm not fat just horizontally disproportionate.