nelsonB
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grignard reaction
Hi
i was looking for the grignard reaction with co2
that give a Carboxylic acid
i wonder if the following reaction is possible
Isopropyl chloride + magnesium >> isopropylmagnesium chloride + co2 = Isobutyric acid
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vulture
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EDIT: Ignore, I made a dumb comment below.
Depends on which isomer of isopropyl chloride you use...
[Edited on 17-11-2013 by vulture]
[Edited on 18-11-2013 by vulture]
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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PHILOU Zrealone
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Isopropyl chloride is simply another name for 2-chloropropane.
So it should work to make isobutyric acid (or 2-methyl-propanoïc acid).
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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nelsonB
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do we should need to acidify the final product ?
cause the acid could react with magnesium to make magnesium isobutyrate
edit:i was thinking adding dry ice as a co2 source and lightly pressurize the set up
[Edited on 17-11-2013 by nelsonB]
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Asepsis
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I'd recommend just pouring the prepared Grignard onto the dry ice with vigorous agitation; no additional pressurization needed. Let it sit until all
the dry ice has sublimed. Also, to maximize the isobutyrate, be sure to keep the dry ice 'dry' by not letting it be exposed to atmospheric water until
use. This reaction will form the magnesium salt. Adding aqueous mineral acid will render it isobutyric acid (which I imagine to be very stinky). You
can extract that into the organic phase easily for purification.
Cheers.
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UnintentionalChaos
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Quote: Originally posted by nelsonB  | do we should need to acidify the final product ?
cause the acid could react with magnesium to make magnesium isobutyrate
edit:i was thinking adding dry ice as a co2 source and lightly pressurize the set up
[Edited on 17-11-2013 by nelsonB] |
I don't mean to be condescending, but I dont think you're going to have much luck running a grignard reaction if you cant answer these questions for
yourself. It is famously difficult to start and sensitive to trace moisture. The ether can be rather dangerous if mishandled as well. I would start
with something easier and more reliable, and teach yourself mechanisms and technique along the way. I'd suggest fisher esterification or an alkyl
bromide prep (less hazardous and cheaper than iodides, easier to work with than highly volatile chlorides).
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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vulture
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Whoopsie, I was thinking about chloropropane. Indeed, with isopropyl chloride it's theoretically possible.
However, the boiling point of isopropyl chloride is 36C, which is going to complicate things when your grignard reaction starts heating up.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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DJF90
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Should be fine if you conduct it in diethyl ether, Vulture. It'll just start refluxing with the solvent, so have an efficient condenser in place.
It'll probably be better behaved than most other Grignard formations.
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vulture
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I'm not sure, I expect this reaction to show oscillating behavior.
iPrMgCl is made in large amounts on an industrial scale and is commercially available, so a patent search should provide some clues.
Anyway, I'm not sure this is an economical method of producing isobutyric acid. Biochemical synthesis or synthesis from other OTC precursors might be
more viable.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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nelsonB
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yeah i imagine using dry ice as a source of carbon dioxide also double as a method to cool down the Isopropyl chloride
that have a low boiling point
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deltaH
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? 2iPrOH(l) + 3Mg(s) + 4CO2(s) => Mg(iBuO2)2(s) + 2MgCO3(s) + H2(g) ?
Any chance in hell?
[Edited on 17-11-2013 by deltaH]
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UnintentionalChaos
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| Quote: Originally posted by vulture | I'm not sure, I expect this reaction to show oscillating behavior.
...
Anyway, I'm not sure this is an economical method of producing isobutyric acid. Biochemical synthesis or synthesis from other OTC precursors might be
more viable. |
1) wat?
2) It really isn't very economical. Isobutyraldehyde is made on a massive industrial scale by hydroformylation of propylene. Most of this is probably
hydrogenated to isobutanol (which is available online if you look hard enough). Oxidation with acidic dichromate would produce the desired acid. PMMA
(poly(methylmethacrylate)) can be thermally cracked to methyl acrylate and hydrogenated to methyl isobutyrate though this is probably not a great
approach either.
| Quote: Originally posted by nelsonB | yeah i imagine using dry ice as a source of carbon dioxide also double as a method to cool down the Isopropyl chloride
that have a low boiling point |
The isopropyl magnesium chloride would have to be formed in ether with exclusion of air, reactive gases (CO2, SO2, etc.) or proton sources (alcohols,
water, etc.) prior to addition of CO2 in any form. By the time you add dry ice, there is no iPrCl left.
| Quote: Originally posted by deltaH | ? 2iPrOH(l) + 3Mg(s) + 4CO2(s) => Mg(iBuO2)2(s) + 2MgCO3(s) + H2(g) ?
Any chance in hell?
[Edited on 17-11-2013 by deltaH] |
No. Just because you can balance an equation doesn't mean it happens. If you knew anything about the mechanism of a grignard reaction, you would know
that this is impossible.
Furthermore, isobutyrate would be iPrCO2-1 not iBuO2-1.
[Edited on 11-18-13 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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nelsonB
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yeah Asepsis
that stuff must stink but as ester usualy are fruity
as ethyl butyrate has a odor that is close to pineapple
i wonder what would be the smell of ethyl 2-methyl-propanoate
here some description
| Quote: |
ethyl 2-methylpropanoate Organoleptic Properties Odor Type : fruity Odor Strength : high , recommend smelling in a 10.00 % solution or less Odor
Description: at 10.00 % in dipropylene glycol. sweet ethereal fruity alcoholic fusel rummy Odor Description: Sweet, etherial and fruity with
pungent, alcoholic, fusel and rummy nuances Mosciano, Gerard P&F 22, No. 2, 69, (1997) Taste Description: at 12.50 ppm. Pungent, etherial and
fruity with a rum-and egg nog-like nuance Mosciano, Gerard P&F 22, No. 2, 69, (1997) Substantivity : 4 Hour(s) |
[Edited on 18-11-2013 by nelsonB]
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deltaH
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| Quote: | | If you knew anything about the mechanism of a grignard reaction, you would know that this is impossible. |
What exactly in the Grignard mechanism prevents this from happening with iPrOH please, I had a look at it and cannot decide why this is a problem? I'm
not saying that this is possible, I am simply trying to understand, if not, why not.
As for the iPrCO2, good point!
[Edited on 18-11-2013 by deltaH]
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nelsonB
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if the isopropylmagnesium chloride react with water
would not it make propane ?
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Crowfjord
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@deltaH: magnesium reacts with alcohols to give the alcoxide, i.e., it reduces the hydroxyl hydrogen rather than the ipso-carbon.
@nelsonB: reacting Grignard reagents with water gives the alcohol.
BTW, Wikipedia has a good article on the Grignard reaction, check it out
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nelsonB
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| Quote: |
Reactions of Grignard reagents Grignard reagents and water Grignard reagents react with water to produce alkanes. This is the reason that
everything has to be very dry during t he preparation above. For example: |
| Quote: |
The inorganic product, Mg(OH)Br, is referred to as a "basic bromide". You can think of it as a sort of half-way stage between magnesium bromide and
magnesium hydroxide. |
http://www.chemguide.co.uk/organicprops/haloalkanes/grignard...
[Edited on 18-11-2013 by nelsonB]
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Crowfjord
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Whoops, my mistake! I was thinking of reaction with oxygen for some reason...
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nelsonB
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when reading on grignard its support lot of chemical reaction i wonder why i din't study more on this
Victor Grignard have done an amazing job
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vulture
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Thread Split
18-11-2013 at 12:27 |
zenosx
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I found these video's helpful when first studying grignard reagents. I will also say again from above that they are Incredibly difficult to get
started sometimes and Incredibly sensitive to moisture. The I2 crystal trick is handy however...
Introduction to Grignards.
A question that sometimes drives me hazy: am I or are the others crazy?
Albert Einstein
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Pickardjr
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the mag chlorides aren't prepaid like the mag bromides. I read that chlorobenzene is added directly to magnesium and heated in a sealed tube without
solvent. don't know about chloropropane but I bet its a bastard to get going under ordinary conditions like other grignards.
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zed
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Umm. Are you trying to produce a specific molecule? If so, the production of (CH3)2- CH-COOH, MIGHT be more easily achieved by the hydrogenation
of Methyl Methacrylate, followed by hydrolysis. Methyl Methacrylate itself, can be produced by the pyrolysis of Lucite.
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