roamingnome
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pathways to trimethylene chlorohydrin ( or Bromo)
By simple chance I found Scheme 7 on page 7 of this nice chemistry paper...
http://www.rsc.org/ej/CS/2000/a901713e.pdf
the chemical players become
1,3-Propanediol
propane-1,2-diol
first i found this
http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleFo...
...prepared by passing the dry halogen hydride into
propylene glycol....
clearly ORGSYN shows
http://orgsynth.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0...
1,3-Propanediol is used
but looking to buy my bulk de-icer im afraid that
it can be more like WIKIPEDIA shows
http://en.wikipedia.org/wiki/Propylene_glycol
that is propane-1,2-diol
so I guess my question is, during the synthesis does it matter?
Yes fractional distillation becomes apparent
I would also guess it comes down to an elimination of substitution type reaction. I just dont see it
are there other ways to trimethylene chlorohydrin?
making the allyl alcohol first from general racemic isomers of
Propylene glycol?
Then the adding of the CN! if the halogen is terminal or not...
ill admit it i got a C in O-Chem
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not_important
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The route 1,2-propanediol to 1,3-propanediol or 3-chloropropanol is not easy. Your best bet is through the allyl alcohol or halide using
anti-Markovnikov type additions.
Note that a number of fermentations convert glycerol into 1,3-propanediol. These are starting to come into industrial use as the production of
biodiesel results in large amounts of glycerol on the market. You could just wait for 1,2-propanediol to be replaced by 1,3-propanediol.
I assume you are trying you're shooting for GHB. Try looking into some of the degradations of glutamic acid.
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Sauron
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Buy 1.3-trimethylene glycol.
Treat with 1 molar equivalent of the TCT/DMF adduct in DCM at RT.
Use a hood.
You will have a very high yield of the chlorohydrin in 15 minutes plus workup time.
If you try this the Org.Syn. way you will spend a lot of time seperating isomers.
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roamingnome
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Thankyou for entertaining the thought process.
Hydrolysis and cyclization of the nitrile seemed all so strait forward, but some where after looking at catalyst directed polypropylene thermolysis i
said what a crap shoot.
but to complete the pathways to said target compound
2.5 g (0,078 mol) of methanol, 1.0 g (0.01 mol) of 1,2-dichloroethane and
0.015 g (0.041 mmol) of europium trichloride hexahydrate were placed in a
10 ml Pyrex glass reaction tube.................as a result, it was
apparent that 0.02 mmol of 2,3-DCP, 0.07 mmol of 3-CP( 3-chloro-1-propanol) and 0.05 mmol of EG were produced.
http://www.patentstorm.us/patents/5345003/fulltext.html
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Sauron
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I assumed you want to do this on a prep scale. Isn't europium chloride a little dear for that?
The problem really devolves to trimethylene glycol, doesn't it? I mean you can either buy it or prepare it. If the cyclic ether were readily available
you could cleave that much like THF is cleaved with dry HCl to yield the chlorohydrin. But if you have to buy the ether, why not just buy the glycol
(trimethylene glycol) which is certainly available and then just half chlorinate it by whatever reagent you prefer.
I remember looking into this problem some time back and never found a particularly facile way to make 1,3-propane glycol. The dichloride is available,
so is the dibromide, and so is the chlorohydrin. Even the 1-chloro-3-bromopropane is available. Sometimes buying is the shortest path between two
points.
Reducing malonic acid to the glycol just seems like a lot of effort compared to the cost of the glycol.
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ScienceSquirrel
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If I was aiming to make this stuff I would be tempted to try this;
http://www.freepatentsonline.com/3922313.html
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Sauron
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Oh, for joy. Acrolein. Charming stuff. I hope there's a good hood available.
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ScienceSquirrel
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I would not be doing this outside a properly equipped laboratory so a good hood would be available.
Whichever way you go, distilling the alkyl halide is a must and doing that outside a hood is a bit muppetish and the next proposed step is reacting it
with a sodium cyanide!
Anyway if we assume that this chemistry is theoretical, then the addition of hydrogen chloride to acrolein and reduction is a neat approach.
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Sauron
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You are well advised not to work with acrolein outside of a proper lab with hood.
And I do not believe the interest of the thread author is by any means theoretical.
That patent is clearly about an industrial process. In the context of a home lab acrolein is a non-starter. There's a world of difference between
working with acrolein and working with an alkyl halide.
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ScienceSquirrel
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| Quote: | Originally posted by Sauron
You are well advised not to work with acrolein outside of a proper lab with hood.
And I do not believe the interest of the thread author is by any means theoretical.
That patent is clearly about an industrial process. In the context of a home lab acrolein is a non-starter. There's a world of difference between
working with acrolein and working with an alkyl halide. |
Um, the next step involves sodium cyanide in a home lab and the experimenter is planning to hydrolyse the product and drink the solution.
And you think acrolein is way too risky!
[Edited on 24-7-2008 by ScienceSquirrel]
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roamingnome
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acrolein... it actually is almost the perfect idea
for two reasons
Hydrocyanation of alkenes & or Cyanohydrin reaction
decomp glycerin and bubble the acrolein into a cyanide solution!
but there are many glitches upon further inspection.
The alcohol group of the cyanohydrin may become a functional group off the lactone ring, you may get double nitriles then you have to consider
protecting groups or selective reaction conditions.
of course if the initial halohydrin is circumvented this thread has wandered off its basic course.....
I have a theoretical hood for my theoretical methodologys
[Edited on 24-7-2008 by roamingnome]
[Edited on 24-7-2008 by roamingnome]
[Edited on 24-7-2008 by roamingnome]
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ScienceSquirrel
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| Quote: | Originally posted by roamingnome
acrolein... it actually is almost the perfect idea
for two reasons
Hydrocyanation of alkenes & or Cyanohydrin reaction
decomp glycerin and bubble the acrolein into a cyanide solution!
but there are many glitches upon further inspection.
The alcohol group of the cyanohydrin may become a functional group off the lactone ring, you may get double nitriles then you have to consider
protecting groups or selective reaction conditions.
of course if the initial halohydrin is circumvented this thread has wandered off its basic course.....
I have a theoretical hood for my theoretical methodologys
[Edited on 24-7-2008 by roamingnome]
[Edited on 24-7-2008 by roamingnome]
[Edited on 24-7-2008 by roamingnome] |
Acrolein is reacted with hydrogen chloride to form 3-chloropropionaldehyde.
This is reacted with sodium borohydride to form 3-chloropropanol.
[Edited on 24-7-2008 by ScienceSquirrel]
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Sauron
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I have been criticized for proposing procedures that involve aggressive and noxious compounds such as thiophosgene, trichloromethyl sulfenyl chloride,
trichloromethyl chloroformate, etc. that, while not CWC scheduled, are compounds that have been investigated in WWI for use as "war gases" (see
Sartori's book.)
Acrolein is another such material.
The patent cited by SecretSquirrel is a perfectly proper industrial process.
Org.Syn. contains a number of reactions involving acrolein. The authors do mention its hazards, and the steps necessary to prepare and handle it
safely. In a proper lab this can be done.
However, I would seriously investigate less obnoxious starting materials than acrolein in this case. There are preparations in which acrolein is the
only suitable starting material but this simple chlorohydrin just isn't one of them.
Trimethylene glycol is not an expensive material. Chlorinating only one of the hydroxyls does the job. There are reagents that will do this in high
yield. I have mentioned one such upthread. There are others.
Acrolein is quite volatile. Even in a hood, a worker will need eye protection and preferably a SCBA. A glove box for containment would be a suitable
alternative. Lacking those, look for a more user-friendly starting point than acrolein. Or take the consequences. Not many home labs are equipped to
work with this stuff. It's in same class as ketene and phosgene.
True, maybe this is all theoretical. But not all readers may take it that way.
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ScienceSquirrel
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All of this chemistry is faintly ridiculous as GBL is legally available in quite a few places and there are people around who will post to anywhere.
The oxidation of THF is an easy one step method of preparation. THF may be hard to obtain in some places but it is almost OTC in most of Western
Europe. Specialist cleaning firms use it to remove chewing gum etc and it is a common solvent in lots of things.
Here we have a multistep synthesis. Even if the yields were high for all stages, the overall yield would be poor and there would be side products.
One step has to involve cyanide, which has accounted for a few 'homebrew' PCP chemists in the past.
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Sauron
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Pardon me but who is talking about GBL?
If GBL then you are right, make it from THF.
If roaminggnome is putzing around to get to GBL then he is jerking us all off, and this thread is a waste of time.
A few years ago I wanted to replicate Al Meyer's beautiful work with protected preps of aldehydes using thioacetals and lithiation and I needed to
make 1-bromo-3-chloropropane for that purpose. The stuff is commercial but expensive, the same for the dichloro compound and the chlorohydrin. The
glycol was cheap.
But I guess you are right as it is the only conclusion to draw from that little segue he made with the cyanohydrin.
I guess I will have to look twice at the gnome's threads before participating in the future.
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ScienceSquirrel
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| Quote: | Originally posted by roamingnome
Then the adding of the CN! if the halogen is terminal or not...
ill admit it i got a C in O-Chem |
Who mentioned GBL?
The Ggggggnome in his first post!
3-Chloropropan-1-ol + CN -> 3-Cyanopropan-1-ol -> GBL (after acid hydrolysis)
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Sauron
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Thanks for elucidating the patently obvious.
The question then becomes why did he not start with tetramethylene glycol aka 1,4-BDO, or the chlorohydrin of same (from THF and lots of chlorinating
agents inclusing HCl? Laboriousness for its own sake is just...work. Adding a carbon to a 3-charbon chain via a nitrile group is simple but
unnecessary when the 4-carbon chain is commonplace.
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ScienceSquirrel
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More to the point.
Why is a red blooded Yankee gnome trying to make a drug overwhelming associated with the London Limey gay scene?
Methinks Broke Back Mountain is getting to those fine upstanding American boys 
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Sauron
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This is neither a cinema critique nor a guide to the lavender side of London night life. Let's stick to chemistry, if there is any to be had. As far
as this thread is concerned, that sound you are hearing is me washing my hands of it.
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roamingnome
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you both are really something...
its about mental exercise, not a gay bar
its about A priori , not a cleaning solvent from eastern Europe
and its certainly not about a freaking fume hood!
tell me then if Acrolein is bubbled into the cyanide will
delta H be positive or negative?
netflicks
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ScienceSquirrel
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Acrolein would undergo hydrocyanation and if it were not for a better way of making GBL it might be made this way industrially.
As it is, acetylene and formaldehyde react to form butyne-1,4-diol, reduction and cyclisation form THF which is then oxidised to GBL.
If you do some research on hydrocyanation you will find that a nickel phosphite complex is commonly used as a catalyst, often under pressure.
Reaction to form the cyanohydrin is an equilibrium process so the hydrocyanation product would form under thermodynamic control.
http://www.patentstorm.us/patents/6284865/description.html.
Because hydrocyanation requires some special precautions to handle the hydrogen cyanide it is unlikely that this would be a feasible laboratory
process.
Whether delta H is positive or negative is not always a good indication of if a reaction is feasible or not. Reaction kinetics, the lack of a good
pathway etc may make a reaction a complete non starter.
Nitrous oxide looks like a good oxidising agent on paper, structural similarity to ozone etc, and delta H for a lot of possible reactions is large and
negative but the stuff is kinetically inert at room temperature.
That said, it is reactive in the presence of a catalyst and there are a few industrial processes that utilise it.
http://resources.schoolscience.co.uk/GreenerIndustry/pages/p...
[Edited on 28-7-2008 by ScienceSquirrel]
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