Sciencemadness Discussion Board - Phenol from toluene

Phenol from toluene

helzblack - 1-11-2024 at 05:52

I know I can get this from salicylic acid, but I am trying to make bakelite, in my ever quest to make really cheap moulds (cheaper than buying epoxy resin by the bulk).

Assume a price of 25$ per kg for epoxy resin.

Currently I can get formaldehyde for 2.5$ a kilo. Toluene at 7$ per liter.

I can also get Sodium benzoate at 2.5% per kilogram.

If I could turn the toluene to phenol it would be very cheap.

The moulds are not going to be used for anything that is supposed to be edible or anything like that.

How can I cheaply transform the toluene into phenol?

[Edited on 1-11-2024 by helzblack]

Keras - 2-11-2024 at 03:04

There is no cheap way to do this.

Oxidise toluene to benzoic acid using potassium permanganate then reduce it to alcohol using sodium borohydride. Neither of those are cheap, nor easy to source, for the latter.

If you don’t have access to sodium borohydride, it’s even worse. You'd have to decarboxylate benzoic acid to benzene, using sodium hydroxide on sodium benzoate, then nitrate your benzene, reduce nitrobenzene to aniline, then use sodium nitrite to get a diazonium salt that would be hydrolysed at 60 °C to give phenol. Definitely doable, but quite an endeavour!

[Edited on 2-11-2024 by Keras]

unionised - 2-11-2024 at 04:28

How different is cresol formaldehyde resin from Bakelite?
Not taking the methyl group off might make things easier.

Sulphonation followed by hydrolysis is probably the least bad option on a "home chemistry" scale and it still sucks.

Texium - 2-11-2024 at 06:02

Quote: Originally posted by Keras

Oxidise toluene to benzoic acid using potassium permanganate then reduce it to alcohol using sodium borohydride. Neither of those are cheap, nor easy to source, for the latter.

If sodium borohydride could reduce carboxylic acids, that would give you benzyl alcohol and get you no closer to phenol. But it wouldn’t even reduce it anyway.

Keras - 2-11-2024 at 06:47

Quote: Originally posted by Texium

Quote: Originally posted by Keras

Oxidise toluene to benzoic acid using potassium permanganate then reduce it to alcohol using sodium borohydride. Neither of those are cheap, nor easy to source, for the latter.

If sodium borohydride could reduce carboxylic acids, that would give you benzyl alcohol and get you no closer to phenol. But it wouldn’t even reduce it anyway.

Drat, you’re right. :/
I don’t agree. Sodium borohydride can reduce carboxylic acids when used with zinc chloride. See below.

Screenshot 2024-11-02 at 15.46.37.png - 245kB

helzblack - 2-11-2024 at 07:07

Quote: Originally posted by unionised

How different is cresol formaldehyde resin from Bakelite?
Not taking the methyl group off might make things easier.

Sulphonation followed by hydrolysis is probably the least bad option on a "home chemistry" scale and it still sucks.

Anything that produces a plastic resin that is neither just a goopy slimy mess, nor a fragile brick, is fine by me as long as it is cheap.

Texium - 2-11-2024 at 07:14

Quote: Originally posted by Keras

Drat, you’re right. :/
I don’t agree. Sodium borohydride can reduce carboxylic acids when used with zinc chloride. See below.

Yes, there are many of these compound reagents of sodium borohydride with various metal salts that are capable of reducing esters or carboxylic acids. But your first post stated sodium borohydride alone, which would not touch a carboxylic acid.

bnull - 2-11-2024 at 12:19

It depends on your "cheapness" standards. If it involves an initial investment on suitable^* equipment that you intend to use for a long time or until it has paid itself, I'd say it is feasible with a lot of caveats. And an extensive research, of course. Patents, papers, old books.

You want to convert an inflammable, toxic (less toxic than benzene but still toxic) substance into another inflammable, toxic substance. Safety first, try small scale, don't use open flames, use PPE, do an extensive research etc.

The process is toluene->benzoic acid->phenol. It involves the least amount of steps and, consequently, intermediates^**.

Oxidation of toluene to benzoic acid. There are several ways to oxidise toluene to benzoic acid. @Keras suggested permanganate as oxidiser. If I were to do the procedure, I'd go with electrochemical oxidation or air oxidation. Electricity and air are cheap (it depends on the country, of course). With appropriate equipment, you can even have a batch converter where you feed toluene and remove benzoic acid/benzoates.
Decarboxylation of benzoic acid or benzoate. This one may be quite tricky. Reduction of benzoic acid yields benzyl alcohol, which is a step back, not a step forward in the synthesis. Oxidative decarboxylation of benzoic acid or inorganic benzoates yields phenol. If I'm not mistaken (someone correct me if needed), when using sodium benzoate, you need temperatures around 400 °C; with copper (ii) benzoate as catalyst and benzoic acid as substrate, the required temperature is about 150 °C lower (250-280 °C). I find the latter interesting because I love copper salts.

It may end up reasonably cheap (I don't think so) or prohibitively expensive. At least you gain some knowledge in the process. What is cheap for industry isn't necessarily so for individuals.

*: I mean well welded stuff that has been welded by a professional welder, for example; no DIY crap made by inexperienced personnel.
**: I vaguely remember one process involving benzonitrile, which was made by the action of TCCA and ammonia over benzoic acid.

Keras - 2-11-2024 at 23:35

Quote: Originally posted by Texium

Quote: Originally posted by Keras

Drat, you’re right. :/
I don’t agree. Sodium borohydride can reduce carboxylic acids when used with zinc chloride. See below.

Fair enough. You'd need lithium aluminium hydride probably. Yet, I find it nice that properly 'enhanced' by the addition of mundane compounds, sodium borohydride can achieve almost the same results as lithium aluminium hydride, which is way more difficult to source and dangerous to handle.

Keras - 2-11-2024 at 23:39

Quote: Originally posted by bnull

Oxidation of toluene to benzoic acid.
Decarboxylation of benzoic acid or benzoate.

Another possible route starts from benzoic acid → benzamide → aniline (Hoffman rearrangement) → phenol.
The advantage of this path is that it doesn’t require heat.

[EDIT]That’s not strictly true. Benzamide is purportedly made by dehydration of ammonium benzoate, obtained by mixing benzoic acid and ammonia (or urea?). Strangely, that’s something I attempted twice with very little success. The benzamide I have was made by reacting ammonia with benzoyl chloride.

[Edited on 3-11-2024 by Keras]

Hexabromobenzene - 5-11-2024 at 05:34

Cheapest method of synthesis phenol from polycarbonate(compact discs and others).
First, hydrolysis of your plastic in boiling ethylene glycol with the addition of soda and then heat up to 300C bisphenol and as aspirin. You are half a mixture of phenol and 4 isopopenylphenol that are easily divided by distillation
Ethylene glycol can be easy recycled again
You can also directly heat polycarbonate with zinc chloride

helzblack - 6-11-2024 at 05:19

Quote: Originally posted by Hexabromobenzene

Cheapest method of synthesis phenol from polycarbonate(compact discs and others).
First, hydrolysis of your plastic in boiling ethylene glycol with the addition of soda and then heat up to 300C bisphenol and as aspirin. You are half a mixture of phenol and 4 isopopenylphenol that are easily divided by distillation
Ethylene glycol can be easy recycled again
You can also directly heat polycarbonate with zinc chloride

Thanks! This is very useful!
I found this paper covering the first reaction. https://pubs.acs.org/doi/pdf/10.1021/ie8010947

But do you know the reaction conditions for the second one? Only heat to 300C that's it?

Edit: Nevermind https://pubs.rsc.org/en/content/articlelanding/2004/gc/b3135...

[Edited on 6-11-2024 by helzblack]

[Edited on 6-11-2024 by helzblack]

RU_KLO - 6-11-2024 at 06:20

Found this,

BE CAREFULL .- Explotion risk

https://www.sciencedirect.com/science/article/abs/pii/S09504...

Explosibility, flammability and the thermal decomposition of Bisphenol A, the main component of epoxy resin
Maciej Celiński, Monika Sankowska
PII: S0950-4230(16)30240-6
DOI: 10.1016/j.jlp.2016.08.024
Reference: JLPP 3312
To appear in: Journal of Loss Prevention in the Process Industries

One of the main products, other than water and carbon oxides was phenol (retention time 16,83 min).The highest quantity was generated at a temperature of 300oC. Releasing large amounts of phenol during thermal degradation at low temperature can cause a rapid combustion of its fumes due to the relatively low flashpoint (79oC) and an auto-ignition temperature of (595oC) This also explains the disappearance of phenol at the higher temperature of the furnace.
Raising the furnace temperature results in increased generation of 4-isopropylphenol up to 750oC. The thermal degradation of Bisphenol A was also accompanied by small amounts of dodecane, 4-(1-methylethyl)phenol at 500oC, 1,4-benzoquinone and hydroquinone at 750oC

yobbo II - 6-11-2024 at 10:47

Could urea formaldehyde resin be made and used instead?

helzblack - 8-11-2024 at 13:30

Quote: Originally posted by yobbo II

Could urea formaldehyde resin be made and used instead?

But is so brittle, I would like to make it tougher