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MEXCHEM2006
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Synthesis of Allylbenzene
Im looking for a suitable synthesis for allylbenzene , I found several synthesis but all have several drawbacks (expensive , rare reagents etc) , and
I dont like friedel crafts alkylations
Cinnamyl alcohol reduction with HI doesn't work
http://content.arkat-usa.org/ARKIVOC/JOURNAL_CONTENT/manuscr...
Reduction with zinc dust uses too much solvent
http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/c...
I have access to Cinnamaldehyde and Cinnamyl alcohol and all the common reagents.
Any suggestions are welcome
El respeto al derecho ajeno es la paz
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chemrox
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| Quote: | | I dont like friedel crafts alkylations |
Friedel Krafts?
It's like saying you want to make alcohol but don't like fermentation.
I appreciate the paper and the old thread. What I don't understand is why you think the old thread didn't have enough possible approaches for you..
ithe thread seemed loaded with ideas to me and it's not a very interesting problem as things around here go.
Finally, it looks a lot like an amphetamine precursor ... boring!
[Edited on 17-10-2007 by chemrox]
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Sergei_Eisenstein
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It is possible to prepare allylbenzene via a Grignard reaction: bromobenzene, Mg and allylbromide. Suitable?
[Edited on 18-10-2007 by Sergei_Eisenstein]
damnant quod non intelligunt
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solo
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Reference Information
CATALYTIC SYNTHESIS OF ALLYLAROMATIC HYDROCARBONS
N. I. Shuikin and N. A. Pozdnyak
Russian Chemical BulletinVolume 14, Number 2,329-331, 1965
Summary
1. A simple method was developed for obtaining allylaromatic hydrocarbons by the alkenylation of benzene, toluene and tetralin with ally1 alcohol in
the presence of zinc chloride. The yields were respectively 50.0, 72.9, and 60.0% of theory, when based on ally1 alcohol
2. Allyltetralin and allyltoluene are easily copolymerized with butadiene, forming elastomers.
[Edited on 18-10-2007 by solo]
[Edited on 18-10-2007 by solo]
Attachment: CATALYTIC__SYNTHESIS__OF__ALLYLAROMATIC__HYDROCARBONS__.pdf (193kB)
This file has been downloaded 3565 times
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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maniacscientist
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I´ve been reading of a Grignard-like reaction with FeAcAc as a metallo organic catalyst that would yield allyl and even phenylacetone with this
reaction. Never tried it though it´s on my list for the next 3-4 years.
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Nicodem
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I guess you are talking about the newest C-C coupling reaction involving Grignard reagents (Angewandte Chemie International Edition, 46,
4364–4366; attached bellow). It is an interesting reaction since before it was not possible to couple aryl grignards with alkyl halides with Pd and
Ni catalysts generally used in the usual Kumada coupling (that is aryl halide + alkyl grignard) due to the dreaded alpha-hydride elimination.
Apparently the Fe(acac)<sub>3</sub> causes no such side reaction while still being able to catalyze the Kumada coupling. That alone is
reason enough for it being published in Angewandte.
Anyway, again you did not read the thread or else you would have noticed that Sergei already explained that phenyl grignard can be coupled with allyl
halides. This is due to allyl (and also benzyl) halides not having eliminable hydrogens while being much more electrophilic than alkyl halides at the
same time. Therefore they need no catalyst whatsoever to couple with Grignard reagents.
Attachment: Iron-Catalyzed Alkylations of Aromatic Grignard Reagents.pdf (115kB)
This file has been downloaded 2492 times
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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maniacscientist
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I did read it and I know about the coupling of grignard with allylbromide/iodide, I just wanted to add to therudiemental works like Friedel Crafts and
alkyl or allyl grignard, as these are the known methods.
Why´re you attacking me, I thought this forum were more gentle on beginners, yet you´re not very gentle and criticism might curb an intersting
discussion, when there seems to be more interest behind as "just cooking" a drug precursor", which, I must admit, might not be the case here for most
of the members around but to some it is; also, with shutinng-up an intersted in chemstry you might force him to not look at other promising parts of
chemstry, because he feels to be left alone and just commences "cooking".
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Nicodem
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I would not consider my behavior as attacking you. It is more like attacking a certain kind of behavior and mentality. I consider this as some kind of
accelerated learning and adaptation. You might have not noticed it, but in a couple of hours you managed to completely alter the way you post. Now you
actually take care in writing comprehensible posts, spell check and verify before pressing the post button. And I'm sure you will also soon take care
to read the threads before posting and avoid further off topic posts. The quality of your posts has improved immensely which is all I wanted.
Now I can finally welcome you here: Welcome! 
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maniacscientist
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Thanks a lot... I realized this and now give me a rest *lol*
[Edited on 18-10-2007 by maniacscientist]
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MEXCHEM2006
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I dont find suitable a Grignard reaction because magnesium metal is forbidden in my country , you need a special permission from the Army to buy it .
El respeto al derecho ajeno es la paz
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chemrox
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Don't we all love governments? (Without them there'd be no wars.)
Anyway, can't you grind up automobile wheels?
Question: are Mg alloys used in automotive applications high enough in Mg to use for the Grignard? I think I've read about using such but might have
been from not so reliable sources ... Rhodium par exemple ...
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MEXCHEM2006
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I already tried using Mg alloys from wheels in a synthesis of alarm pheromone 4-methyl-3-heptanol (with bad results).
El respeto al derecho ajeno es la paz
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chemrox
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try a simple one like Ph-Mg-Br-etherate. It's the easiest Grignard to make I know of. I had a job once making the shit by the carload for a
ChemE/inventor. (He paid me to distill his ether too but that's another story)
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Fleaker
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Magnesium from alloy wheels is nowhere near good enough for a Gringard. I have pure magnesium turnings, and ingot, but given what it's going to...
BTW, there is an efficient pyrolytic way to allybenzene.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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JohnWW
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Mg from old Mg alloy car wheels ('mags") are, in fact, Mg-Al-Si alloys, possibly with traces of other elements. The Al in particular is likely to
interfere with many reactions of Mg metal.
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chemrox
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Any chance of turning (couldn't resist) up a Cu-Mg alloy? These can enhance the yield. I agree that Al would be a poison and I didn't know, but
should have expected, that to be a good percentage of wheel alloy. Please disregard the suggestion. Where would a Mg-Cu alloy be used in industry?
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vulture
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You don't want copper in your grignard reagents because you'll be making copper organometalics.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Antwain
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copper oraganometalics have their uses, basically a less potent form of grignard, to put it simply. But if you want a grignad reaction then you dont
want copper.
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vulture
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Copper organometalics are only useful if you want 1,4-conjugate addition instead of 1,2-addition. Which is not the case here. Their reactivity and
basicity is also lower.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Nicodem
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The chemistry of alloys has little to do with the chemistry of the metals from which it is composed. It is absurd to think that any magnesium alloy
can be used to prepare Grignard reagents. Not to even consider that any alloy containing magnesium made for common use will be such as not to be prone
to corrosion, oxidation, dissolution, etc. – thus also inert to alkyl and aryl halides.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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MEXCHEM2006
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Reduction of cinnamaldehyde to cinnamyl alcohol with LiAlH4
http://www.ch.ic.ac.uk/local/organic/0405Expt5.pdf
Synthesis of allylbenzenes by cross-coupling of allyl bromide with arylboronic acids using a palladium chloride and tetraphenylphosphonium bromide
intercalated clay catalyst
http://www.rsc.org/ej/GC/1999/a905846j.pdf
[Edited on 26-10-2007 by MEXCHEM2006]
El respeto al derecho ajeno es la paz
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trilobite
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| Quote: | Originally posted by vulture
Copper organometalics are only useful if you want 1,4-conjugate addition instead of 1,2-addition. Which is not the case here. Their reactivity and
basicity is also lower. |
Actually allylic couplings is one of the traditional uses for copper organometallics. In these cases copper salts such as CuI, CuCl*2LiCl, CuCN*2LiCl
etc. are typically used in catalytic amounts. For example the Rhodium archive contains a preparation of safrole from catechol by Psychochemist (who
obviously knew his shit) that employs CuI as a catalyst in this sort of reaction.
However it is my understanding that one of the problems is decomposition of the organometallic with liberation of copper metal which is able to
catalyze the same decomposition. Optimal temperature depends on the reactants and employed copper species. Lithium salts are added to make copper more
soluble in ethers. It appears that soluble salts of stoichiometry CuCN*2LiCl would give reasonably stable organometallics. This is the main reason I
would feel uncomfortable with a magnesium alloy containing copper.
I'm also pretty certain that this question has been researched. Trying out different metal salts in Grignard reactions originates from the fact that
in the beginning of 20th century magnesium metal had various impurities depending on the location, so the Europeans got different results compared to
the Americans. The subject is discussed in Grignard Reactions of Nonmetallic Substances by M. S. Kharash and O. Reinmuth, published by Prentice Hall
in New York year 1954. That is the book where I would look for answers on different alloys, but not on the modern organocopper chemistry.
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-TheMadMen-
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Hey man you'd be pretty dumb not to make allylbenzene by friedel-crafts, infact there is no excuse, what could be more simple, economical, cheap,
infamous, and ( socially speaking ) dangerous than such a simple little benzene-Allyl alchohol conversion procedure? Heh. Allylbenzene synthesis is
easy.
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pip
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phenol derivitives
Which alkylation would be best to apply to resorcinol instead of regular benzene? Shorter chain olivetol's are what i'm curious about. I have found a
lot of literature about alkylating benzene derivitives however 5-alkylating resorcinol isn't mentioned in anything I have found only 4 alkylation
unless it is about olivetol itself or the analogs for thc synthesis which have longer side chains than i'm interested in. Also i'm hoping that the
olivetol synthesis I have found are more complex than nessesary because of the longer side chain or to increase yeild either of which isn't important
to me.
Or am I just barking up the wrong tree trying to directly 5-alkylate resorcinol or Phloroglucinol (1,3,5 trihydroxybenzene)
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Arrhenius
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pip: Resorcinol (3-hydroxyphenol) is not going to get you to olivetol. If you try to alkylate that ring , you're going to end up
with a mess, and none of the 5-alkyl product you want. Do also keep in mind that chain homologation of THC analogues has already been done...
Friedel-Crafts won't work well on phenols, as O-alkylation is a competing reaction.
-TheMadMen-: Friedel-Crafts reaction is really not that glorious. The 'atom economy' of the reaction is pretty awful considering it takes a mole equivalent of Lewis acid. Palladium chemistry is probably a better
option.
I presume the desire to make allyl benzene is to access a renowned illicit substance. In that regard 1-phenyl-2-propene is a more easily had product.
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