John paul III
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1,4-butanodiol from butadiene
Would the hydration of alkenes to alcohols also work for dienes, yielding diols?
For example: butadiene - > 1,4 butanediol
Is there a way to predict on which carbons will the hydroxy group attach or will it be a mixture of isomers?
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fusso
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Markovnikov's rule.
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CuReUS
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yes
| Quote: | | Is there a way to predict on which carbons will the hydroxy group attach or will it be a mixture of isomers? |
https://chemistry.stackexchange.com/questions/59964/addition...
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draculic acid69
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Hbr acid would add to the double bonds giving the do bromo compound which will be reacted with NaOH to form the alcohol.i can't remember where but it
has been asked before. If I remember correctly heat and light may affect where the bromines end up.not sure how where or why just what I read.or you
could wrestle with separating 1,4/1,3/2,3 dibromo butane isomers.just looked up b.p.'s for the alcohols and 2,3 and 1,3 butanediols boil at 177'c
&197'c so that's 30'c lower than 1,4 BDO.
[Edited on 21-5-2019 by draculic acid69]
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draculic acid69
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Two ppl posted in the time it takes me to write a paragraph. Any way that link shows that addition of one hbr to one butadiene equals either 1bromo
2,3butene or 3bromo1,2butene both useless for getting to 1,4butylene glycoll.but would 2eq of hbr to one of butadiene equal the 1,4 glycol when using
high temp like the paper in the above link? Would u.v. inclusion or exclusion be relevant in this case?
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draculic acid69
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How and why does the double bond move with the formation of 1bromo2butene from the butadiene?I've only heard of using KOH to isomerize a propenyl
benzene to an allylbenzene which if two eq of KOH was used on 1bromo2butene maybe you would substitute the bromo for OH and isomerize the 2butene back
to a 3,4 butene in one rxn which after purification would need to be reacted with hbr all over again.either way it seems like the butadiene would be a
good source of 1br2butene and 3br1butene which when made into the alcohols and having the double bonds saturated is a great way to make n & sec
butanol which I believe can be used directly in a petrol engine as is.
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Pumukli
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"why does the double bond move with the formation of 1bromo2butene from the butadiene?"
1,4-addition of HBr.
Br goes to the first C, H goes to the 4th. Remaining electrons move to 2-3 position, making a double bond between 2nd and 3rd C.
[Edited on 21-5-2019 by Pumukli]
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Assured Fish
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Anti markovnikov addition is what you want, All you use is an organic acid peroxide as part of your addition.
Your major product would be 1,4 dihalo butane however minor products like 1,3 and 2,3 dihalobutane will still occur and thus fractional distillation
would need to be a workup step.
I was gonna ask where you managed to aquire butadiene but it would seem its possible to make it from ethanol.
https://en.m.wikipedia.org/wiki/Butadiene
Perhaps this could be a potential route to 1,4 dibromobutane, then again butadiene is rather toxic.
Sufficiently advanced science is indistinguishable from madness.
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draculic acid69
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So if benzoic acid anhydride peroxide is added to the mix would that lead to 1,4 product?
Butadiene can be made from thermal pyrolysis of abs plastic also acrylonitrile and styrene if I'm not mistaken.also I think they're using old tyres to
make crude butadiene and acrylonitrile by shredding and thermal pyrolysis.i reckon tyres - butadiene - 1br,2butene and other isomers - n & sec
butanols as biofuels.
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draculic acid69
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Back to the point anyway.so one would need an organic acid peroxide like Benzoic acid anhydride peroxide? Would this be sufficient or something else?
One would need at least two eq of hbr at least.woulb an excess be beneficial or detrimental? would high temp still be needed?how much acid peroxide
would need to be added? Would it just be a catalytic amount like 1/10th of a mole per mole reactants?
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Pumukli
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Yes, dibenzoil-peroxide would probably work. Anti-Markownikov additions go along radical pathway so they require radical initiators (e.g. organic
peroxides).
I don't want to hijack your thread, but the method you choose, starting from butadiene seems a bit awkward.
Butadiene is not easily accessible (as someone already commented), and synthesizing it also a "bit" clumsy.
For each of his own but I'd rather start from tetrahydrofuran than from either old tyres or ethanol.
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John paul III
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Would the radical initiator method still work if I used H2SO4 as catalyst? Also, could organic acids be used if one wouldn't mind getting esters along
the alcochol?
[Edited on 22-5-2019 by John paul III]
[Edited on 22-5-2019 by John paul III]
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draculic acid69
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Esters wouldn't be formed until after the alcohol is made if going through the hbr pathway.you talk of using h2so4 does this lead to alcohol w/out
going through bromo compounds?
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John paul III
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Quote: Originally posted by draculic acid69  | | Esters wouldn't be formed until after the alcohol is made if going through the hbr pathway.you talk of using h2so4 does this lead to alcohol w/out
going through bromo compounds? |
H2SO4 is what is most often used in alkene hydration according to high school teachers and most videos on the mechanism. I thought you mentioned HBr
at first because it could afford better selectivity with temperature control. Now, if the radical initiated anti markovnikov substitution is the
solution, I thought why not use cheaper H2SO4 instead of HBr. I read that phosphoric acid also works, so maybe the bar can be lowered even further to
carboxylic acid, altough it's probably better to stick to H2SO4/H3PO4.
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draculic acid69
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H2so4 would be ideal,much cheaper and easier than hbr.
So do you have any butadiene to try this on or are we staying in the realm of theory?
Just wikied 1,3 butadiene and it boils a -4.4'c how high would the the temp need to be to do the h2so4 of hbr rxn's? would it need to be done under
pressure like in a sealed bomb?
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John paul III
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| Quote: Originally posted by draculic acid69 | H2so4 would be ideal,much cheaper and easier than hbr.
So do you have any butadiene to try this on or are we staying in the realm of theory?
Just wikied 1,3 butadiene and it boils a -4.4'c how high would the the temp need to be to do the h2so4 of hbr rxn's? would it need to be done under
pressure like in a sealed bomb? |
Im going to try getting butadiene by passing ethanol vapour in a steel tube heated between 400 - 450°C packed with MgO. I think the only practical
way would be to liquify butadiene and try the reaction in the liquid phase
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draculic acid69
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Sounds difficult to handle.do you have a vacuum and gas bottle to store your product.do you have experience working with gasses?
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CuReUS
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Why don't you just hydrolyse THF  ? -https://www.masterorganicchemistry.com/reaction-guide/acidic...
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John paul III
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I was certain it only worked with HBr or HI. That's what originally wanted to (to cleave the THF with H2SO4), but then i watched this video (https://youtu.be/qX0AaP1wRz4) and i was under impression that only halogen acids would work.
Thank you, this is much simpler, safer and has much more chance of a success. Still it's neat to know a route from such an ubiquitous chemical as
ethanol 
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Boffis
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Slightly off topic so I apologize but can you do the reverse reaction? 1,4-butandiol to 1,3-butadiene? That would be much more useful to me.
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Assured Fish
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| Quote: Originally posted by Boffis | | Slightly off topic so I apologize but can you do the reverse reaction? 1,4-butandiol to 1,3-butadiene? That would be much more useful to me.
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Sure, elimination of the halide with sodium methoxide or elimination of the alcohol with heat and H2SO4 or H3PO4.
I dont know how well the elimination of the alcohol works though as i have never seen a practical write up or demondtration or performed it myself.
https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alcohols/Reactivity_of_Alcohols/Elimination_Reactio
ns_of_Alcohols
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