Sciencemadness Discussion Board - What to do with styrene?

What to do with styrene?

Linus1208 - 7-5-2022 at 04:29

So I have lots of styrofoam laying around and I was thinking about depolymerising it to make styrene. Just because it would be a fun project.

But it would be kind of stupid to have the styrene laying around until it just polymerises.
I also thought about oxidizing it to benzoic acid with KMnO4 and making benzene from it, but I only can order a limited amount of KMnO4 per year and I don't have that much of it.

Is there an easier way to convert it to benzene, or some other interesting EU-compatible things I could do with it?

SplendidAcylation - 7-5-2022 at 05:23

I too have been interested in the potential fun projects involving styrene.

You could convert it to styrene oxide:
http://www.sciencemadness.org/talk/viewthread.php?tid=15284#...

That is an epoxide, so you could do some fun things with that, perhaps react it with a nucleophile such as ammonia, to obtain the amino-alcohol (two isomers?), or with base to obtain phenyl ethylene glycol (1-phenyl-1,2-ethanediol).

Grignard reagents can also add to episodes, although I'm not sure where the Grignard would add to an unsymmetrical epoxide.

You could also hydrate styrene, ending up with 1-phenylethanol (not quite as interesting as 2-phenylethanol aka phenethyl alcohol)

You could do a hydrohalogenation to obtain 1-bromo-1-phenylethane, or try an anti-Markovnikov addition to obtain phenethyl bromide.

There was a thread on here about ozonolysis of styrene to obtain phenylacetaldehyde but I'm not sure if that's too easy.

I'm looking forward to hearing what other peoples' responses are!

BTW Styrofoam might not be the easiest thing to depolymerize unless you have some way of reducing its volume by removing the air somehow.

I would rather not waste KMnO4 in oxidising styrene, but that's just my view, haha, I'd be looking for a cheaper oxidiser

DraconicAcid - 7-5-2022 at 08:58

Removing the air from styrofoam is easy- mix it with acetone. That gives you a somewhat intractable lump, but if you're just heating it to depolymerize it, the heat will remove any acetone before the reaction starts.

Keras - 7-5-2022 at 09:00

You can synthesise phenethyl alcohol which is the main component of rose perfume.

Mateo_swe - 9-5-2022 at 07:21

You can get benzene from sodium benzoate and sodium hydroxide both found in any food store.
See here
http://www.sciencemadness.org/talk/viewthread.php?tid=325

Nilered has a video about the procedure here:
https://www.youtube.com/watch?v=X10VZeQmFDo

I have done it and it works well using a paintcan as dry distilling vessel (dont use glass).

Fantasma4500 - 9-5-2022 at 16:17

iirc you can turn styrene oxide - or just styrene into benzaldehyde by passing it over heated Al2O3

ah, here goes
p.styrene heated --> styrene
styrene + alumina catalyst + O2, air --> styrene oxide/benzaldehyde
SO/Benzaldehyde + NaClO --> Benzaldehyde

redhot copper wire might also work for this, it catalyses (with airflow) alcohols to aldehydes, its a bit more tedious with higher boiling liquids though.

SplendidAcylation - 11-5-2022 at 06:36

Quote: Originally posted by Antiswat

iirc you can turn styrene oxide - or just styrene into benzaldehyde by passing it over heated Al2O3

ah, here goes
p.styrene heated --> styrene
styrene + alumina catalyst + O2, air --> styrene oxide/benzaldehyde
SO/Benzaldehyde + NaClO --> Benzaldehyde

redhot copper wire might also work for this, it catalyses (with airflow) alcohols to aldehydes, its a bit more tedious with higher boiling liquids though.

That'd be awesome if it worked!

I'm a bit sceptical of that final stage; Benzaldehyde oxidises really easily to benzoic acid with unselective oxidisers like hypochlorite.

I have tried a number of times to oxidise benzyl alcohol to benzaldehyde using NaOCl, supposedly high yielding according to a paper somewhere, but it really isn't very effective in my experience; It seems to result in a mixture of benzyl alcohol, benzaldehyde, and benzoic acid, the smell of benzaldehyde is immediately evident, though!

Edit:

I mentioned earlier the addition of a Grignard reagent to styrene oxide, I've since found out that the Grignard will add to the least substituted carbon, so:

R-MgX + styrene oxide ---> C6H5-CH(OH)-CH2-R

(Quench stage not included in above unbalanced reaction)

[Edited on 11-5-2022 by SplendidAcylation]

Fantasma4500 - 11-5-2022 at 20:15

well H2CrO4 i can also attest works for benzyl alcohol, and with either careful timing or adding in additional reagents youre supposedly able to stop it quite accurately at the aldehyde

karlos³ - 12-5-2022 at 10:53

Regarding aminoalcohols, i made fepradinol, halostachine and their N-ethyl analogue easily from styrene oxide, its just important you keep the amine in excess always and add the epoxide slowly.
Little amine like methylamine require an excess of ideally at least 4eq., though, but with isobutanolamine for fepradinol, I just used equimolar quantities.

Tsjerk - 12-5-2022 at 13:39

Quote: Originally posted by Antiswat

well H2CrO4 i can also attest works for benzyl alcohol, and with either careful timing or adding in additional reagents youre supposedly able to stop it quite accurately at the aldehyde

As you can attest, please enlighten us with the how to!

Fantasma4500 - 12-5-2022 at 23:35

Tsjerk
very easy. mix it lol
theres also some H2SO4 in it, not sure if that does anything- but it gets warm right away, upon standing you get benzoic acid- i suppose dumping in some hexane after a bit of time would get you benzaldehyde in hexane, then just distill off the hexane
if you fancy driving a bit, then you might be able to buy 1000L 30% H2CrO4 solution and more, check reagents and acquisition

Tsjerk - 13-5-2022 at 00:24

Quote: Originally posted by Antiswat

Tsjerk
very easy. mix it lol
theres also some H2SO4 in it, not sure if that does anything- but it gets warm right away, upon standing you get benzoic acid- i suppose dumping in some hexane after a bit of time would get you benzaldehyde in hexane, then just distill off the hexane
if you fancy driving a bit, then you might be able to buy 1000L 30% H2CrO4 solution and more, check reagents and acquisition

Mix it lol would be the summary of any write-up, literally. Please detail the procedure a bit more so your post will bear meaning. Reaction conditions are a minimum, yields as well. Without you could as well have posted nothing.

Linus1208 - 23-5-2022 at 03:22

Quote: Originally posted by SplendidAcylation

BTW Styrofoam might not be the easiest thing to depolymerize unless you have some way of reducing its volume by removing the air somehow.

I was thinking about either carefully melting it and squishing it down, or just dissolving it in acetone (I have 300ml of Acetone I accidentally contamined with iron(III) compounds, so I can't use it for other stuff either way).

Quote: Originally posted by SplendidAcylation

I would rather not waste KMnO4 in oxidising styrene, but that's just my view, haha, I'd be looking for a cheaper oxidiser

That's what I was thinking to. I only know one shop that sells it in germany, and they only sell a limited amount of it per year and person.

Linus1208 - 23-5-2022 at 05:53

Quote: Originally posted by Antiswat

So you're saying styrene can be oxidized with Al2O3 catalyst and air to a mix of SO and Benzaldehyde.
And SO will be oxidized to benzaldehyde with NaClO? That would be great.

I'm not sure if the benzaldehyde would oxidize further to benzoic acid, as NaClO is not a very selective oxidizer. Either way I would have planned to oxidize it to benzoic acid either way so I wouldn't really care.

Fantasma4500 - 24-5-2022 at 01:27

MnO2 may also work- it does work to turn benzyl alcohol into benzaldehyde, unsure if it requires oxygen for this
if you have a bulk you could try using lower than 30% HClO3, this will also form some chlorinated stuff but its very easily affordable to make in big amounts, above 30% it becomes dangerous to work with

H2CrO4 can effectively turn benzyl alcohol into benzoic acid if left to stand for a bit

if you want concentrated NaClO, pool chlorinating agents usually react with NaOH to form concentrated NaClO

Hexabromobenzene - 24-5-2022 at 09:07

Phenylacetic acid from styrene
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
Chloroacetophenone and styrene chlorohydrin from styrene
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

Before pyrolysis styrofoam need to smelt. Can of paint from stell can be used as retort. Pyrolysis 1 kg storofoam gives about 0.5 kg styrene after redistillation and collection fraction 140-150C
Pyrolysis polystyrene is endothermic reaction and it rate depends on heat rate. Time pyrolysis can vary from 30-40 minutes and some days. It depends from power of heater

[Edited on 24-5-2022 by Hexabromobenzene]

Linus1208 - 24-5-2022 at 14:31

Quote: Originally posted by Antiswat

if you want concentrated NaClO, pool chlorinating agents usually react with NaOH to form concentrated NaClO

Does this work for the pool chlorinating agents based on TCCA and DCCA? Because I have lots of it, so I don't need to buy the whole store shelf of chlorine bleach.

And is the reaction basically instant or does it take some time?

Hexabromobenzene - 25-5-2022 at 03:06

Quote: Originally posted by Linus1208

Quote: Originally posted by Antiswat

if you want concentrated NaClO, pool chlorinating agents usually react with NaOH to form concentrated NaClO

Yes, you can use TCCA. Styrene practically does not react with chlorinating agents in alkaline and neutral pH. But in an acidic medium (hydrochloric acid or a mixture of sulfuric acid and sodium chloride), when heated, the reaction is very rapid and there are minutes and seconds. It is exothermic and reagents must be added in portions

The main product of the reaction of styrene chlorohydrin. With an excess of Chroloacetophenone and dichroloacetophenone.

You can use also sodium chlorate.

But for the synthesis of benzoic acid from styrene, other reagents are needed. Nitric acid, permanganates, chromates.

Also hydrogen peroxide with fe3O4 nanopatricles(can be prepared from feso4 fecl3 and naoh) if boiled with styrene gives benzlaldehyde

[Edited on 25-5-2022 by Hexabromobenzene]

Fyndium - 29-5-2022 at 12:25

The synthesis of styrene oxide works great.

Quote: Originally posted by Keras

You can synthesise phenethyl alcohol which is the main component of rose perfume.

Do you have any references to this synthesis in a lab environment?

Keras - 30-5-2022 at 01:04

Quote: Originally posted by Fyndium

The synthesis of styrene oxide works great.

Quote: Originally posted by Keras

You can synthesise phenethyl alcohol which is the main component of rose perfume.

Do you have any references to this synthesis in a lab environment?

Yes, cf. attached PDF. Replace the cyclopentene with styrene and sodium perborate with sodium percarbonate.

I intend to try this next weekend. Will post a report.

Attachment: Hydroboration.pdf (1MB)
This file has been downloaded 280 times

[Edited on 30-5-2022 by Keras]

Fyndium - 30-5-2022 at 03:05

I would be very glad if you'd post a report of your process. I looked up for this synthesis a long time ago, but sort of buried it due to not finding any lucrative material.

Keras - 30-5-2022 at 03:06

Quote: Originally posted by Fyndium

I would be very glad if you'd post a report of your process. I looked up for this synthesis a long time ago, but sort of buried it due to not finding any lucrative material.

I’ll keep you posted, pinkie promise

Amos - 30-5-2022 at 04:53

The hydration of styrene gives 1-phenylethanol, which in addition to smelling nice, can easily be oxidized to acetophenone, which is used to provide cherry or almondlike fragrances. Perhaps more useful is that it's also a useful building block in organic chemistry(often being used for Grignard reactions) and a very promising catalyst for the decarboxylation of amino acids to their amines of 1 less carbon. These in turn are incredibly useful to a home chemist.

Keras - 30-5-2022 at 05:07

Quote: Originally posted by Amos

The hydration of styrene gives 1-phenylethanol…

That would require a simple addition with HBr (non-radical addition), followed by a SN with NaOH, no?

Texium - 30-5-2022 at 05:38

Quote: Originally posted by Keras

Quote: Originally posted by Amos

The hydration of styrene gives 1-phenylethanol…

That would require a simple addition with HBr (non-radical addition), followed by a SN with NaOH, no?

No, just boiling in water with a catalytic amount of sulfuric acid.

Keras - 30-5-2022 at 06:10

Quote: Originally posted by Texium

No, just boiling in water with a catalytic amount of sulfuric acid.

Ah, right. But isn't phosphoric acid more suitable for that?

Texium - 30-5-2022 at 08:13

Either will work

Keras - 30-5-2022 at 09:00

Quote: Originally posted by Texium

Either will work

Ether will work :p

Pun aside, how do you mix styrene with water? You use a surfactant? A phase-transfer catalyst such as TBAB? Use a steam bubbler into styrene?

[Edited on 30-5-2022 by Keras]

Keras - 7-6-2022 at 01:30

Quote: Originally posted by Fyndium

I would be very glad if you'd post a report of your process. I looked up for this synthesis a long time ago, but sort of buried it due to not finding any lucrative material.

So, I had finally some time to try out that experiment.

40 mL of tetrahydrofuran + 5 g of styrene (~ 50 mmol) + 0.76 g of sodium borohydride (~ 20 mmol) are placed in a 250 mL r.b.f. on a magnetic stirrer. I was a big moron, I didn't use a funnel to shove the borohydride in, and a few milligrams of it got stuck in the neck. That didn't matter much, because it is in excess, but as a matter of principle it was bad. The r.b.f is placed in an ice-bath (optionally ice-salt) a Claisen adapter is mounted atop of it with, on the one side, a pressure-equalised dropping funnel and, on the other side, a condenser whose output is fed to a bubbler (Drechsel bottle) filled with mineral oil. The dropping funnel is filled with a solution of 2.91 g of iodine in a bit less of 10 mL of tetrahydrofuran (the original recipe calls for 15 mL, but I only have 10 or 50 mL dropping funnels, so I went for 10 mL).

The dropping funnel is stoppered and set to about one drop every five seconds. Stirring is started. Each drop of the iodine solution causes a brief yellow colouring that promptly (1, 2s) fades. The formation of borane results in hydrogen being generated, but the bubbler never really bubbles, either because the volume generated is minimal, or because the simultaneous cooling of the flask keeps the volume in check. The iodine coloration persists a bit more towards the end of the addition, but always fades after several seconds.

Once all the iodine solution has been added, the ice bath is removed and the reaction is allowed to carry on for 90 min at r.t. The solution is clear, and there’s no visible change.

After 90 min, a new ice bath is set, the flask is allowed to cool (~ 10 min) and everything atop the flask is dismantled. 25 mL of distilled water are dropped into the r.b.f in four or five portions, each addition resulting in a brief fizz of hydrogen as the excess hydride decomposes. Then 5 mL of a 3 M NaOH (= 0.6 g of NaOH) is added, followed almost immediately by 6 g of sodium percarbonate ca. This seems to be an excess to what is needed. Logically, there could be no more than 50 mmol of final product, so 60 mmol of hydrogen peroxide is enough to completely oxidise the intermediate, and that’s what the original recipe goes for, but under the form of sodium perborate. Since each mole of sodium percarbonate contains 3 moles of hydrogen peroxide, 20 mmol is probably enough. I’m not entirely sure, though.

Note that the sodium carbonate contained in the sodium percarbonate might also be basic enough for the oxidation to work without adding sodium hydroxide. I wasn't certain, however, so I stuck to the original procedure.

After 2 or 3 min the temperature of the flask steadily rises and reaches about 25 °C as the oxidation proceeds. The original recipes says the reaction is over when all the perborate has dissolved. In this case, there was too much sodium carbonate for the 25 mL of water to dissolve completely so I had to watch the thermometer. After 15 min or so the temperature drops again, and I took that as the signal the reaction was over. At the end of the oxidation reaction, the solution turns yellow, then brown, meaning that the iodide ions are oxidised back into iodine, and that seems to be another clue that all the boron complex has been oxidised. I’m, however, still wondering if there was hydrogen peroxide enough – solubility of sodium percabonate is given to be slightly less than 1 mol/L, so 25 mL cannot dissolve more than 25 mmol. Can hydrogen peroxide be ‘leeched’ out of the compound in solid form, I have no idea. It might be best to increase the volume of water (say, 35 mL instead of 25 mL) to be on the safe side, though the oxidation of iodine could be a telltale that there was hydrogen peroxide enough.

So once the oxidation reaction is seemingly over, a sodium thiosulphate aqueous solution is added until the flask has completely lost its yellow tinge. The r.b.f is then decanted into a sep funnel. Water is heavier than tetrahydrofuran, so the organic layer sits on top. It is cloudy at first, but after 10 min or so all the water has collected below and the upper layer should be almost crystal clear. The lower layer is collected and discarded, unless you want to recover the couple of grams of iodine trapped inside, which I didn't do but is sensible given the price and difficulties to source iodine. The upper layer is collected in turn, and the solvent is removed, in my case by simple distillation with a short path apparatus. I recovered a bit more than 40 mL of tetrahydrofuran, but I let the temperature rise up to 80 °C. If I had stopped as soon as it began rising over 66 °C, I would've been nearer to 30 mL. I suspect the last 10 mL contains water, so I saved the tetrahydrofuran in a flask over calcium chloride to dry it. The lost 10 mL must've gone into the water layer, or just were lost as vapour, because distillation was pretty fast.

What remains in the flask after all the tetrahydrofuran has distilled out is several mL of a sort of syrupy compound, creamy in colour (but that might be due to leftover traces of iodine). It doesn’t smell of styrene at all, but I have a hard time qualifying it as ‘rose perfume’, though it has some overtones of it. To me, it is closer to the scent of freshly cut mushrooms. On the other hand, the hydroboration of styrene is known to be less regioselective than normal hydroborations, producing up to 20 % of 1-phenethyl alcool, which has a different smell.

PS: It is a priori easy to separate 1- from 2-phenethyl alcohol. Just put both in the freezer. 1- will solidify, and 2- remain liquid.

[Edited on 7-6-2022 by Keras]

clearly_not_atara - 7-6-2022 at 15:05

Re: subject:

https://en.wikipedia.org/wiki/Prins_reaction

Phenylpropane-1,3-diol could eliminate to hydrocinnamyl alcohol (NaHSO4, heat) and be oxidized with MnO2 to cinnamaldehyde. Seems clever.

Fantasma4500 - 8-6-2022 at 13:58

Quote: Originally posted by Tsjerk

Quote: Originally posted by Antiswat

so i found the following. 100g CrO3 in water, H2CrO4, tip this up to 300mL and you have .. 39.3% H2CrO4
this reacts with just about 100mL BnOH to form - seemingly 100mL BnH - benzaldehyde in a ration of 100 mL BnOH to 185mL 39.3% H2CrO4
this reacts basically instantly, i believe i cooled down the mixture about 3-4 times while adding it. its a very warm reaction so no need to heat on it.
this was then extracted in rounds of 3 or 4 times using hexane-heptane fraction acquired from fractionally distilling gasoline, i believe its 80-100ish fraction, 95 maybe
seperating this was rather easy, simply distill off the solvent and youre left with rather pure BnH

i have no clue how to deal with the chromium waste however. basifying it makes it entirely impossible to filter. entirely. and BnH is detectable at 0.04ppm while its slightly toxic- leaving it to dry out is not an option for me. the sludge also sucks up a bit of solvent so its inevitable that it will always keep a bit of aromatics locked up
the sludge is supposedly Cr(III) - hydroxide, chloride. i tried eliminating t he rest of the chromate by acidifying and adding EtOH which seems to react decently fast. ascorbic acid may also be used, i need to look into what FeSO4 produces with chromate ions, i recall seeing that used to reduce it into Cr(III) state- i hate throwing out waste so i hope i can find a solution for dealing with the byproducts.

Hydration of styrene

SplendidAcylation - 6-4-2023 at 01:34

Quote: Originally posted by Texium

Quote: Originally posted by Keras

Quote: Originally posted by Amos

The hydration of styrene gives 1-phenylethanol…

That would require a simple addition with HBr (non-radical addition), followed by a SN with NaOH, no?

No, just boiling in water with a catalytic amount of sulfuric acid.

I have been looking for something useful to do with styrene for a while, so I can have some excuse to make it from polystyrene I have lying around.

Do you suppose that this hydration would be as simple and effective as it seems? I wonder why no one has really discussed the preparation of 1-phenylethanol from styrene here.

Once we have 1-phenylethanol, the most obvious interesting project would be the oxidation of the secondary alcohol to the ketone, acetophenone:
http://www.sciencemadness.org/talk/files.php?pid=506841&...

[Edited on 6-4-2023 by SplendidAcylation]