navarones ghost
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know synthesis of benzyl magnesium chloride?
ciao everybody.
as always...i need some help from some bigbrain.
how do i get benzylmagnesiumchloride out of toluene?
i kind of know something about chlorination of toluene but i cant quite figure out how to make the magnesium bond.
the strucrure should look like this:
i read this from a printed text.
the mgcl will be substituted by something else in the future.
could i use another metal (instead of magnesium at the methyl group)that will have about the same propeties.
like:
LiCl
CuCl
FeCl
will it have the same bonding propeties as the MgCl?
anyway..please write what u know about it.
and for some other people out there:
stop the fucking dissing game....please.
its totally unneccessary.
[Edited on 14-2-2004 by navarones ghost]
WAAAZZZAAAPP VULTURE???
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Blind Angel
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This is known as a Grignard Reageant, the general formula is R-Mg-X where:
R is an organic radical (here it's BzCH<sub>2</sub>-)
and X is an halide (here its Cl)
(you should remember that R and X are the convention for these kind of radical BTW)
They are usually made some minut before the needed reaction and stored in anhydrous ether (Which may get tricky to have) since they react with water.
Look for Grignard Reageant for a general synthesis of these
PS: a rabbit one a keyboard may easyly erase an entire message
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guaguanco
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I won't diss you, but I will point out that even a non-chemist could find the answer in 30 seconds using Google, unless they were extremely lazy.
Good luck with your phenylacetone synthesis.
[Edited on 14-2-2004 by guaguanco]
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thunderfvck
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Yeah, this stuff can easily be found via google but since I made fun of you before I will tell you what I know.
Grignard reagents can be made by adding an alkyl halide to magnesium shavings (lithium works too) while stirring in ANHYDROUS diethyl ether or THF.
ANHYDROS. Yes, it was worth repeating unless you like to fail misearably. H2O will bring you back to toluene. How would you go about chlorinating that
methyl group? I could probably find the answer on google but since we're playing the lazy game and I've just answered your question, answer
mine, brother.
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Blind Angel
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I would like to mention that when you dont know the real name of these product it's pretty hard to find info on
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thunderfvck
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Oh yeah, without doubt. But he could have searched easily for his benzylmagnesium chloride and he probably would have gotten some nice results on
grignards. Besides which, wherever he had learned about this grignard reagent most likely spelled it out as a grignard reagant. Well maybe not, but
it's possible.
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anubis
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hard to find
if u search on google for benzylmagnesium chloride
u wont find nothing more than a few documents on its uses.
there's a lot on grignard reagent tho.
but many people doesnt know about it.
like me, i just discovered it here, never heard about it before.
guess nav didnt knew it to.
there is a page on the grignards synthesis that i just found:
they use ethoxyethylene as a catalist to convert the rx mg into rMgx.
so in navs case, he would need benzyl chloride as r.
the problem is that ethoxyethylene is dangerous and hard to find.
but im sure that there is another catalist.
which could it be?
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BromicAcid
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| Quote: |
but im sure that there is another catalist.
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There are many other catalysts, in my orgo labs we use one crystal of iodine, about 250 mg. Without it the reaction between the magnesium shavings
and the alkylhalide is bascially zero. I once sat there starrring at a grignard mixture stirring for twenty minutes before I remembered I forgot to
add the iodine, after that it only took about a minute to finish up.
[Edited on 2/15/2004 by BromicAcid]
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thunderfvck
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hah. Really. You used a 250 mg crystal? Holy Moses. My textbook failed to mention the use of a catalyst. Anyway, iodine can easily be extracted from
iodine tinctures. Rhodium has the extraction listed on his site.
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anubis
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iodine?
i doubt about the use of iodine cristals.
since x(chlorine) is the halogen in this reaction,and iodine too,
i think it will come out really messed up.
thre is a possibility that benzylmagnesiumiodide will form, especially under light(uv).
well...i'll search for another catalist since the substance is intersting me.
by the way...how do u guys extract the iodine from the tinture?
i read all that crap on rhodium, but the one for the povidone i2 extraction doesnt work.
since povidone doesnt evaporate,
will distillation extract the iodine along with the water?
1) iodine is soluble in hot water
2) iodine sublimise
3) water evaporates
4) povidone doesnt evaporate
so... distillation should extract a pure solution of i2.
will this work?
[Edited on 15-2-2004 by anubis]
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thunderfvck
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Iodine is used as the catalyst. Not only does BromicAcid's experience demonstrate this but I have read a few posts at the hive concerning the use
of iodine in grignard preparations. I'm not sure if the 250 mg is ideal for all procedures (probably not). I have read (at the hive) that a small
amount of iodine was added, it's probably all propotional to the amount of solvent you're using anyway. Chlorine is nicely stuck to whatever
R group, iodine doesn't have a chance displacing it, from what I understand.
The extraction I was referring to is here: http://www.rhodium.ws/chemistry/iodine.tincture.html
I should also add that you probably shouldn't use your nice glassware for this, as I have tried this and it stained my beautiful 500ml round
bottomed flask nicely. Stick with mason.
And if you're going to carry out a distillation the distillate (water in this case) will not carry any of the iodine you're trying to
extract. The whole idea of distilling is to obtain a pure liquid (although it often isn't so pure) from an impure solution. Ions will not be
carried out. It's just like distilling salt water, the salt doesn't go with it. Anyways I'm not sure if I understand your procedure so
I might be giving you some information you are not looking for.
[Edited on 15-2-2004 by thunderfvck]
[Edited on 15-2-2004 by thunderfvck]
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thunderfvck
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anubis says:
saw that too.
i tried it dut it got fucked up.
the solution became darker,
but after a while it got totally transparent.
i doubt that the thing i have inside my tincture is i2 maybe is i3- or i-.
i dont know.
damn the povidone.
its his fault.
it attracts and absorbs the iodine.
i read this from the hive.
however i managed to convert it into hi.
under heat... the povidone cant hold the iodine vibrating particle and it realeses it.
with a catalist like red phosphorus... the realesed i2 is converted into hi.
once u have the messy mixture(pvp,i2,rp),
u can distillate it to get pure hi acid.
once u have the acid, convert it into i2 somehow.
anyway.. hi is even better and faster for making iodides so i wont need the i2 for now.
i might need it in the future tho...
what could convert hi into i2 again?
h2o2?
h2so4?
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thunderfvck
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If you want to precipitate I2 I would seek for some iodine tincture. It can be found at pharmacies, walmart, etc. I have 2.5% but other stores carry
5%. I tried doing this just for the hell of it, and it didn't go transparent. I also used iodine tincture, I don't know if you did
but...Anyway, did you follow the procedure outlined as Rhodium or one his cohorts did it?
Anyway, as there are probably a million ways to get I2 from HI, but I know of one in which it is simply treated with concentrated H2SO4, as you have
guessed! (what does he win, Johnny?)
H2SO4 + 8HI ---> 4I2 + H2S + 4H2O
!!!!hydrogen sulfide!!!!!!
Now you never have to pass nasty gas again, not in light of this reaction. Your friends will truly be impressed.
Anyway, I think that it's pretty troublesome to convert it to HI, then bring it back to I2. But you've got povidone problems, right. Just
get little miss tincture, she'll be glad to blow you for free.
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thunderfvck
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There's also another way to get the iodine out of the tincture, according to a number of sources, you can just boil it. When the purple fumes
start evoling condense the fumes with some ice and the iodine will form crystals. Pretty crude but effective (haven't tried it, have read it
works).
It's strange how navarone is the last posted but it's really me. Anyways, I read the message he wrote this morning, then it disappeared. I
also had -1 posts in one of the threads I started. Weird. ANyway, I don't quite remember what navarone said, but I remember him mentioning
something about the chlorination of toluene.
Ironic that I had actually learned all about this today in my organic chemistry class! hah. It's really quite simple, free radical halogenation
it's called. Add your halogen to whatever you want halogenated and UV it, or you can heat it up. Very interesting because only one electron flows
from an atom as opposed to the pairs that are seen in most mechanisms. ANYWAYS...
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