Author Topic: Benzaldehyde from styrene? (Read 407 times)

Helgoland · « **on:** July 14, 2010, 07:03:44 PM »

Hi, I'm Helgoland, I'm new here (this is my first post, I hope I don't break any rules). I don't own a lab and can't do any experiments (I would if I could)
I posted at WD but I like this board better (no flattering, don't get me wrong)

Now, the actual topic:
I wonder whether styrene (from polystyrene decomposition) could be turned into benzaldehyde-you'd ''only'' have to cleave that double bond.
Ozonisation would be my first guess, but it's supposed to be complicated and give bad yields.
Epoxidation and cleavage of the glycol is too troublesome, I think.
The best option would probably be electrolytical oxidation http://www.erowid.org/archive/rhodium/chemistry/isosafrole.electro.html (YAY I can UTSE) (not so YAY I couldn't find a better reference)
Just think styrene instead of isosafrole, benzaldehyde instead of piperonal, (meth)amphetamine instead of MD(M)A.

Is there a special thread for ideas bound to be never tried? I couldn't find it

embezzler · « **Reply #1 on:** July 14, 2010, 07:52:25 PM »

It is possible however it doesnt look pretty as the attached article illustrates:

Benzaldehyde synthesis via styrene oxidation by O2 over TiO2 and TiO2/SiO2

Liang Niea, Ke Ke Xina, Wen Sheng Lia and Xiao Ping ZhouCorresponding Author Contact Information

Abstract

Styrene was oxidized by molecular oxygen over TiO2 and TiO2/SiO2 for the formation of benzaldehyde. In the absence of catalyst at 100 °C and 10 atm O2, polystyrene is the major product. Over the catalysts, the oxidation of styrene is enhanced with benzaldehyde and formaldehyde being the major whereas phenylacetaldehyde, acetophenone, styrene oxide, benzoic acid, and polymer being the minor products. The polymerization of styrene was initiated by the radicals formed in the oxidation reaction. The addition of radical inhibitor nitrobenzene and/or the employment of a catalyst of high specific surface area can promote the termination of the radicals, and hence improve the selectivity of benzaldehyde.

Keywords: Benzaldehyde; Styrene oxidation; TiO2; TiO2/SiO2 catalyst

Evilblaze · « **Reply #2 on:** July 14, 2010, 08:03:51 PM »

There is an article on erowid what is about this:

http://www.erowid.org/archive/rhodium/chemistry/benzaldehydes.kmno4.html

Quote

1. Reductant (1 mmol) and KMnO4/alumina reagent (4.65 gr) were stirred in DCM overnight.
2. Reductant (1 mmol), Amberlite IR-120/H2) (1.17 g) and KMnO4 (0.49 g) were stirred in DCM 10-40 min.
3. Reductant (1 mmol) and KMnO4/alumina (4.65 g) were stirred in DCM for 4 hours.
4. Reductant (1 mmol) and KMnO4/alumina reagent (4.65 g) were stirred in DCM for 10-40 min.

If the reductant is styrene the reaction will yield benzaldehyde in 90%.

Good luck(:

Helgoland · « **Reply #3 on:** July 14, 2010, 08:24:37 PM »

Damn I messed up! But thanks for the replies.

I think I saw the Rhodium article before-DCM might be a problem for some, though.
The other one I just saw as well. First page on Google... I don't UTSE so well after all, apparently. Sounds sweet-I'm thinking TiO₂ from sunmilk right now

Here's an article on using a palladium catalyst for the reaction. Solvent is water, but the catalyst isn't that pretty...
http://www.rsc.org/publishing/journals/gc/article.asp?doi=b900807a

I still like electrolysis. Nice and clean! Another solvent might be good, I (and probably many other people as well) don't have MeCN lying around. Someone interested in testing stuff out?

Helgoland

Sedit · « **Reply #4 on:** July 14, 2010, 09:23:16 PM »

Not sure about the mechanism here but Acetonitrile may be replaced with DMSO in this instance. As well the Pt may be replaced with Lead electrods possibly.

Issues I forsee is the formed BnO oxidising as well forming Benzoic acid or polymerizingwith the styrene. Or the syrene itself polymerizing before the reaction is complete.

Tsathoggua · « **Reply #5 on:** July 14, 2010, 09:58:14 PM »

DCM can be bought easily enough, and it can be distilled from paint stripper, just dilute it and do not distill to dryness or else you end up with disgusting solid polymeric crap in there which is hard to get out of a flask.

Helgoland · « **Reply #6 on:** July 15, 2010, 01:51:29 PM »

Okay, I looked at the papers you all posted, I looked at the paper I posted, and then I remembered something I had seen in the Rhodium archive:
http://www.erowid.org/archive/rhodium/chemistry/epoxidation.non-metal.html

It says here that ClO^- can be used to epoxidate alkenes without a metal catalyst-all that's needed is a bit of KBr.
The solvent is water in combination with a co-solvent: tert-BuOH or MeCN.

The epoxide could then be hydrolysed and the diole cleaved either electrolytically or with Ca(OCl)₂

(look at the paper in my first post). A two-phase system is needed to prevent oxidation if the benzaldehyde.

Perhaps these two could be merged into one reaction? Water/tert-BuOH as aqueous, benzene (or some other solvent, does it dissolve tert-BuOH?) as the organic phase, OTC oxidant, OTC (I think) catalyst, environmentally friendly --- it sure would be great.

Helgoland

Sedit · « **Reply #7 on:** July 15, 2010, 03:49:07 PM »

Quote from: Helgoland on July 15, 2010, 01:51:29 PM

The epoxide could then be hydrolysed and the diole cleaved either electrolytically or with Ca(OCl)₂ (look at the paper in my first post). A two-phase system is needed to prevent oxidation if the benzaldehyde.

The Ca(OCl)₂ is used for the formation of the chlorohydrine as a source of the ClO- ion. The KBr is mearly a source for the Br- ion to form insitu the more reactive BrO- ion. As long as the PH is kept at a high level then the added source of OH- causes instant epoxidation of the formed intermediate halohydrin thru the elimination of H₂O.

You seem to state in the first post that epoxidation of the Styrene and cleavage of the glycol is to troublesome yet thats what the paper you linked to is easing up by causing cleavage of the Glycol in an electrochemical cell of NaOH to yeild, in 99% I might add, the corrisponding aldahyde.

Synthesis would require a reaction of Styrene with Ca(OCl)₂ with catalytical amounts of KBr or NaBr and a Basic workup to yeild the glycol. Further reacting this glycol in a non partioned electrochemical cell containing NaOH would yeild the BnO.

Sedit · « **Reply #8 on:** July 16, 2010, 02:42:39 AM »

I have read that part but it does not make much sence to me. That would seem to suggest that an excess of Ca(OCL)_{2_{should proceed styrene all the way to the aldahyde and I don't see this happening in a single pot reaction.}}

Helgoland · « **Reply #9 on:** July 16, 2010, 12:07:49 PM »

Quote

Hence, the product 1 migrates into the benzene layer so that overoxidation of 1 can be avoided.

I think this makes a one-pot reaction impossible: All styrene would migrate into the organic layer and be protected from oxidation just like the aldehyde

In my first post I was thinking about glycol cleavage by lead tetraacetate which didn't seem so good to me. If it can be done with hypochlorite, though, do you think this procedure has a future?

Helgoland

Sedit · « **Reply #10 on:** July 18, 2010, 05:30:03 PM »

The Clorohydrine is made with acidic Ca(OCl)2, a basic workup of this yeilds the glycol.

ausser_betrieb · « **Reply #11 on:** July 20, 2010, 04:09:22 PM »

To cleave the Ether to a glycol does not seem too hard.

Revies of methods used for this:
Chemical Reviews 59 737 (1959)
Angewandte Chemie, International Edition in English 31 1179 (1992)

But when direct Chlorhydrine-> Glycol is possible, no need to bother with that

Buzzoff · « **Reply #12 on:** August 26, 2010, 07:36:43 AM »

Lots of ways to make Benzaldehyde. Consider the Nitration of Styrene with NaNO2 and I2.

The resultant Nitrostyrene, can then probably be refluxed with a-Methyl-Benzylamine to form the Benzaldehyde-Imine, with the release of Nitromethane as a gas. Upon hydrolysis Benzaldehyde is produced, and the starting a-Methyl-Benzylamine is recovered.

With a little diligence, both Nitromethane and Benzaldehyde, are produced from one pot.

Of course, there is too much Benzaldehyde in the world already. But, Nitromethane is less odious, and it is a versatile reagent. Some folks react it with 3.4,5-Trimethoxybenzaldehyde.

Rhodium supplies details for synthesis of Nitro-olefins via NaNO2/I2, and Shulgin gives an example of the "retro" Henry reaction, in Pihkal. Where he produces myristicin aldehyde, from
the Myristicin Nitro-Propene.

From Rhodium: http://www.erowid.org/archive/rhodium/chemistry/nitryliodide.nano2.html

From Pihkal: A mixture of 50 g 1-(3-methoxy-4,5-methylenedioxyphenyl)-2-nitropropene and 26 g racemic a-methylbenzylamine was heated on the steam bath. The mixture gradually formed a clear solution with the steady evolution of nitroethane. When the reaction became quiet, there was added a mixture of 20 mL concentrated HCl in 100 mL H2O. The reaction mixture dissolved completely, and as the temperature continued to rise there was the abrupt solidification as the formed myristicinaldehyde crystallized out. This product was removed by filtration and, when combined with a second crop obtained by the hexane extraction of the filtrate, gave 36.9 g of myristicinaldehyde. The mp of 128-129 °C was raised to 133-134 °C by recrystallization from hexane.

embezzler · « **Reply #13 on:** September 20, 2010, 07:22:50 PM »

Styrene Oxidation using Iron Nickel catalyst

I have attached 2 papers detailing the oxidation of styrene by means of a metal catalyst. Which seems (perhaps I’m misunderstanding) to give 38% yield of benzaldehyde with 100% selectivity when the catalyst (discussed below), styrene and H2O2 (2:1 ratio) are refluxed at 50 deg Celsius in acetone for 6hours.

The aldehyde should be easily separated by via the bisulphite adduct and the polymer mess discarded and solvent recycled.

The catalyst of choice (due to ease of preparation) is Iron Ferrite. This doesn’t look so bad all things considered. And no sign of the acid.

Any ideas on this it seems a fairly acceptable yield considering the reaction conditions and the cost of the reagents?

The catalyst was prepared as follows : (Guin et al 2005)

Quote

2.1.1. Synthesis of NiFe2O4, ZnFe2O4 and Ni0.5Zn0.5Fe2O4
Stoichiometric amounts of Ni(NO3)2•6H2O, Zn(NO3)2 and
Fe(NO3)3•9H2O are dissolved in doubly distilled water. The pH
of the solution was adjusted to 8 by slow addition of ammonia
solution. The reaction mixture was stirred for 1 h before trans-
ferring the contents to a 1000ml stainless steel autoclave. The
temperature of the autoclave was maintained at 230 ?C for half
an hour and then the reaction mixture was allowed to cool to
room temperature. The product formed was washed with dis-
tilled water several times, ?ltered and dried at 100 ?C for 8 h.
Similarly, NiFe2O4 was also synthesized while maintaining pH
of the starting composition at 10.

This catalyst is then used to convert styrene to benzaldehyde:

Quote

Solvent : Acetone
Styrene Conversion (%) : 38.4
Selectivity : Benzaldehyde 100%
Catalyst NF
Temperature: 50 Deg Celsius
Time 6hr
H2O2 : Styrene ratio: 2:1

Styrene oxidation by H₂O₂ using Ni-Gd ferrites prepared by co-precipitation method
Catalysis Communications 2007. Vol 8. pp 1521 1526
R. Ramanathan, s. Sugnunan

Abstract
Gadolinium substituted nickel ferrites were prepared by co-precipitation method using NaOH at pH 14 at room temperature. Spinel phase formation was identi?ed by taking the XRD pattern. DRIFT, TG, BET surface area and pore volume measurements, SEM and EDAX were the other characterization techniques used. Mossbauer analysis was performed to ?nd out the site distribution of iron.
Under optimized conditions, the prepared spinels were selectively forming benzaldehyde by the oxidation of styrene. Hydrogen peroxide was used as the oxidant. E?ect of reaction temperature, reaction time, styrene to hydrogen peroxide molar ratio and e?ect of solvent medium were also studied.

Keywords: Spinel; Co-precipitation; Styrene oxidation; Cation distribution of spinels

A simple chemical synthesis of nanocrystalline AFe₂O₄ (A = Fe, Ni, Zn): An efficient catalyst for selective oxidation of styrene
Journal of molecular catalysis A. 2005. Vol 242 pp 26-31
Debanjan et al.

Abstract:
Nanosized spinel ferrite (AFe2O4, A=Ni, Fe, Zn) catalysts are prepared by ‘bottom-up’ approach, i.e. ?rst forming the nanostructured building blocks and then assembling them into the ?nal material with average particle size of 7–12 nm and surface area of 80–100m2 /g. The synthesized nanocrystallites were characterized by thermal analysis, powder X-ray diffraction, transmission electron microscopy and inductively coupled plasma (atomic emission spectroscopy) technique for evaluating phase, structure and morphology and stoichiometry. These materials were found to be very good catalysts for the oxidation of styrene to benzaldehyde in the presence of hydrogen peroxide. Of the several catalysts tried, magnetite (Fe3O4) has shown to have the best catalytic activity for the above reaction. The effects of solvent medium used, styrene:hydrogen peroxide molar ratio, reaction temperature, time and reaction atmosphere required for the complete conversion of styrene to benzaldehyde were also studied. Based on our ?ndings, a plausible mechanism involved in the catalytic reaction is proposed.
Keywords: Nanoparticles; Spinel ferrites; Catalyst; Styrene; Oxidation

Vesp · « **Reply #14 on:** September 20, 2010, 08:59:07 PM »

excellent post, looks like it will work to me and seems pretty practical. I can't wait till others chime in about this - I am interested to hear what others think about its feasibility.

embezzler · « **Reply #15 on:** September 20, 2010, 09:37:29 PM »

The chemical availability make the yields worthwhile and there is no benzoic acid so it could be a nice method.

Here are a few related threads for styrene oxidation from science madness:

http://www.sciencemadness.org/talk/viewthread.php?tid=14503
http://www.sciencemadness.org/talk/viewthread.php?tid=6513
http://www.sciencemadness.org/talk/viewthread.php?tid=1752#pid17194
http://www.sciencemadness.org/talk/viewthread.php?tid=7641&page=2#pid93584

solidstone · « **Reply #16 on:** October 27, 2010, 05:16:23 AM »

I was looking at various methods for polystyrene pyrolysis.

An easy method seems to be iron pellets and polystyrene in the microwave: http://

I was also curious about this article : http://www.ncbi.nlm.nih.gov/pubmed/16649270
they use a bed of sand for the pyrolysis of polystyrene to styrene oil.

Would it be best to utilize a solvent(which solvent), or would using SiO2 be more desirable.

I've been reading about styrene to P2P at http://www.sciencemadness.org/talk/viewthread.php?tid=1752#pid27915

I'm just curious if anyone has recommendations for the procedure of pyrolysis of polystyrene other then what can be found in vague patents.