What to do with styrene?

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.

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

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

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.

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

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.

Quote: Originally posted by Antiswat

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

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 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?

Quote: Originally posted by Keras

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

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?

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

Quote: Originally posted by Amos

The hydration of styrene gives 1-phenylethanol…

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?

Quote: Originally posted by Texium

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

Quote: Originally posted by Texium

Either will work

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]

Quote: Originally posted by Tsjerk

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.

Hydration of styrene

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.