Sciencemadness Discussion Board - What to do with diphenyl carbonate?

What to do with diphenyl carbonate?

woelen - 19-8-2006 at 13:11

I could pick up 1 kilo!!

of Acros reagent grade diphenyl carbonate in a still sealed bottle for just EUR 4, and I could not let this go past me for this mad price

This compound has formula (C6H5)2CO3, structure is:

(C6H5O)2C=O, in fact it is the carbonate "ester" of phenol and carbonic acid.

Now, I'm wondering, are there any interesting things I can do with this? For this small amount of money I took the risk of buying an uninteresting chemical, but I expect that some of you will be able to point me in the direction of some fun/interesting experiments with this compound. Any ideas?

[Edited on 19-8-06 by woelen]

hinz - 19-8-2006 at 14:21

I think it's useful for "phenylations" like dimethyl carbonate is useful for methylations. Geneally it shold behave like organic sulfates and other alkylation or phenylation agents.
Here is a good article for dimethylcarbonate:

http://www.iupac.org/publications/pac/2001/pdf/7307x1117.pdf...

Diphenylcarbonate should behave similar. An interesting experiment could be to phenylate toluene to triphenyl methane CH(C6H5)3, which is a strong acid (due conjugation with phenyl group) The diphenyl carbonate doesn't phenylate it to tetraphenyl methane due steristic reasons, the forth phenyl group would use to much space. More about that you could find in Peter Sykes "Mechanism in Organic Chemistry" ( My favorite Organic Chemistry lecture

)

The reaction should proceed like that:

2C6H5-CH3+2(C6H5O)2C=O ==> 2C6H5-CH2-C6H5+C6H5OH+CO2

2C6H5-CH2-C6H5+2(C6H5O)2C=O ==>2C6H5-CH-(C6H5)2+C6H5OH+CO2

I only hope toluene is acidic enough to get phenylated completly.

BTW: Would it possible to get also some of that nice stuff, are you able to ship it around europe. 4Euro for one kilo of it a too good price.

Edit: With water it should give phenol and benzene, also quite useful, what would happen if I would add HCl without a lewis acid, theoretically it could give phenol and chlorobenzene, both quite useful.

[Edited on 19-8-2006 by hinz]

The_Davster - 19-8-2006 at 14:54

I remeber Bromic was doing some experiments trying to make organic carbonates, he should know about these. I remember that their toxicity is absurdly low, which seems contradictory now that hinz mentioned that they can be methylating agents. I have never heard good things about methylating agents.

With reaction with hydrohalic acids you could get whatever halobenzene you want!

Nicodem - 20-8-2006 at 00:09

Quote:

Originally posted by hinz
I think it's useful for "phenylations" like dimethyl carbonate is useful for methylations. Geneally it shold behave like organic sulfates and other alkylation or phenylation agents.
[...]
Diphenylcarbonate should behave similar.
[...]
I only hope toluene is acidic enough to get phenylated completly.
[...]
Edit: With water it should give phenol and benzene, also quite useful, what would happen if I would add HCl without a lewis acid, theoretically it could give phenol and chlorobenzene, both quite useful.

In no way can diphenyl carbonate behave as a 'phenylating agent'. Even phenyl tryflate can only be used as an electrophile in quite extreme conditions so you can forget about the carbonate ester. Aryl groups are very different from alkyl groups in their chemical behavior and you can’t generalize like this.

Toluene itself is not acidic enough for reaction with any known alkylating reagent.

Hydrolysis of diphenyl carbonate gives phenol only, which is probably the most useful product you can get from it, especially since there is quite some discussion on phenol production on this forum.

woelen - 28-10-2006 at 04:58

I tried to make phenol from the diphenylcarbonate, but it simply does not work. The best I obtain is a faint phenolic odor, but no detectable quantities otherwise (e.g. the test with iron(III) did not show any phenol).

I added diphenylcarbonate to a strongly alkaline aqueous solution, hoping that it would hydrolyse to phenol and sodium carbonate. I boiled for a while. The only thing I get is that the diphenylcarbonate melts. It does not dissolve in water. The hot liquid has a faint phenolic odour, that's all

.

Is there any way, in which I could make phenol from this compound? I have 1000 grams of it, unlocking the phenol from it would be a very good use for it, otherwise I just have a fairly dull chemical, which does not dissolve, nor react.

[Edited on 28-10-06 by woelen]

YT2095 - 28-10-2006 at 05:12

you could send some to me and I can try to make this Ellusive Phenyl Oxalate ester I`ve been trying to synth for over a month now

Just a thought

chromium - 28-10-2006 at 05:20

Quote:

Originally posted by woelen
I tried to make phenol from the diphenylcarbonate, but it simply does not work. The best I obtain is a faint phenolic odor, but no detectable quantities otherwise (e.g. the test with iron(III) did not show any phenol).

I added diphenylcarbonate to a strongly alkaline aqueous solution, hoping that it would hydrolyse to phenol and sodium carbonate. I boiled for a while. The only thing I get is that the diphenylcarbonate melts. It does not dissolve in water. The hot liquid has a faint phenolic odour, that's all

Try to boil it in fairly concentrated solution of NaOH or if this does not work, use NaOH dissolved in ethylene glycol.

Nicodem - 28-10-2006 at 09:40

Quote:

Originally posted by woelen
I added diphenylcarbonate to a strongly alkaline aqueous solution, hoping that it would hydrolyse to phenol and sodium carbonate. I boiled for a while.

This is not a ionic reaction. It takes time and efficient stirring, especially if biphasic. You should let it reflux for at least several hours in 20-30% NaOH. Perhaps it would be best to let it reflux in 20% HCl so that you would avoid the neutralization step (the hydrolysis is over when no more CO2 evolves). Mind that phenol does not crystallize unless dry, so don't forget to dry the extract with Na2SO4 or MgSO4. You will also have to recrystallize it in order to remove impurities.

hinz - 28-10-2006 at 13:16

With HCl half of the product will be phenyl chloride by the SNi mechanism, (like the chlorination with thionyl chloride) so I you have to boil the product afterwards with hydroxide to get it hydrolysed. At least it will be a mixture of phenyl chloride and phenol, maybe there are few OH- that attack it also. I would rather take dil. H2SO4 like in the acid catalysed ester hydrolysis, since it isn't a nucleophile

[Edited on 28-10-2006 by hinz]

a.jpg - 14kB

Rosco Bodine - 28-10-2006 at 17:10

Wonder if melting it with sulfur would lead to an interesting fuel component , which could be mixed with an oxidizer like potassium chlorate or perchlorate ?

Sulfonating and then nitrating it could be interesting also ,
probably giving picric acid .

[Edited on 29-10-2006 by Rosco Bodine]

Nicodem - 28-10-2006 at 22:55

Woelen, the attached paper "Hydrolysis of Simple Aromatic Esters and Carbonates" (JOC, 27, 3717-3720) will give you an idea whether the hydrolysis is faster with bases or acids. I don't have the time to read it so I can't say. Of course, they used a cosolvent since they had to have a monophasic system (due to kinetic studies) but the hydrolysis will proceed without a cosolvent as well, it will just take more time. In any case it seems you will have to let it reflux at least 8h to be sure.

Quote:

Originally posted by hinz
With HCl half of the product will be phenyl chloride by the SNi mechanism, (like the chlorination with thionyl chloride) so I you have to boil the product afterwards with hydroxide to get it hydrolysed.

No, I'm sorry to say but your hydrolysis pathway makes no sense. In no way can chlorobenzene form. Diphenyl carbonate is phenol ester and not some ordinary alcohol ester, so nucleophilic substitution of the –OH group is absolutely and categorically out of play (unless we would be dealing with extremely electron poor phenols like picric acid, etc. – but even then HCl would not be enough).
Besides the impossibility of the last stage, your proposed mechanism fails already at every stage since it assumes the non existence of the solvent (this is something that must never be neglected, especially when the solvent is H2O).

Quote:

Originally posted by Rosco Bodine
Sulfonating and then nitrating it could be interesting also, probably giving picric acid.

Diphenyl carbonate is less nucleophilic, meaning that it is less activated for nitration. You would need slightly harsher conditions for a trinitration to occur (in other words: you would not have to worry of creating only tar, as with plain phenol). More interestingly, the lower activation means you can selectively mononitrate it and hydrolyse in one pot (for example: like in US4788346).

Attachment: Hydrolysis of Simple Aromatic Esters and Carbonates.pdf (398kB)
This file has been downloaded 677 times

vulture - 29-10-2006 at 15:23

It can be used to detect radical species in a reaction. IIRC it turns blue upon addition to an organic solvent which is dry and contains some sodium/potassium. Any trace of water or any other radical quenching agent and it won't do that.

YT2095 - 27-1-2007 at 06:35

this may be of use, I`m trying it now as I type, should take about a week to get a reasonable result with a 40 hour half-life.

2.2.3
Stability in Water
Diphenyl carbonate hydrolyses in the presence of water forming phenol and carbon dioxide. In a
preliminary study on the abiotic degradation of diphenyl carbonate in water the test substance had a
half-life (t1/2) of 73.5 h at 23 °C (Bayer AG, 2000c).
Due to the above mentioned result a study on the abiotic degradation of diphenyl carbonate
according to the Directive 92/69/EEC, C.7, was performed. It was concluded that at pH 7 a half-life
(t1/2) of 39.9 hours at 25 °C was expected (Bayer AG, 2001).

I did the NaOH thing, there`s nothing appreciable happening there either.

I fear to do this Properly, it`s simply a Patience game.

YT2095 - 30-1-2007 at 06:52

update, a few days, and there is definately Gas bubbles being liberated inside the flask, I have an airlock on the flask (water based) but as yet I can`t smell any Phenol odour?

the temp is kept at average 30c.

a further thought occurred to me, if I raise the PH a little this May help the reaction along, But I don`t want to force compounds, I figured Calcium hydroxide may be an ideal, it`s unlikely to react with the Phenol directly and ruin it, but it will shift the PH and become reasonable inert calcium Carbonate that I can filter out later with ease to leave my dissolved Phenol.

does this sound Viable?

Nicodem - 30-1-2007 at 09:46

What exactly are you doing or trying to achieve? I have a very hard time following what you are up to.

YT2095 - 30-1-2007 at 09:59

quite simply DPC in water, to hydrolize to Phenol and CO2.

it has a half life of ~40 hours in water at STP, with excess water the Phenol is soluble also, the air lock is there to allow the CO2 out but not the phenol or water.

Nicodem - 30-1-2007 at 10:21

I still don't get it. What is wrong with the normal methods?

YT2095 - 30-1-2007 at 10:53

again, quite simple, I don`t have a large amount of this material to risk low yields and/or losses (7.5g to be exact).

and so, the most Simple procedure is preferable here, also I lack certain apparatus required for more complex methods, as you can see, my hand is Forced somewhat towards more Mundane means of obtaining this result.

YT2095 - 4-3-2007 at 03:35

a Month+ later I just looked at my Long-Term experiments shelf and I have Phenol growing up the insides of the test tube!

I made a 50/50 mix of DPC and NaOH (by volume) and 10x that amount of water, it was then heated until all dissolved and melted, then allowed to cool and dust covered and put away for storage, all the water has evaporated leaving phenol crystals all up the inside of the test tube.

now I just need to think of a way to isolate the phenol from the Sodium salt, Water`s out of the question, perhaps 100% EtOH?

I think next time I`ll powder these crystals rather than use them as the flake form.

Nicodem - 4-3-2007 at 04:01

You can not have phenol there after you used excess NaOH for the hydrolysis. Utmost you have a mixture of moist NaOH, Na2CO3 and sodium phenolate. You need to acidify, extract the phenol, wash the extract, dry over Na2SO4 or MgSO4 and remove the solvent. Beware that phenol is hygroscopic so you can not just acidify with HCl and filter the precipitate.

YT2095 - 4-3-2007 at 04:15

I`m inclined to agree, although the Smell is Very phenolic, I`ve just covered it in pure EtOH and little to non dissolved, when I just read your post I added a few drops of 30% HCl and there was Plenty of fizzing (I assume it`s CO2).

the excess NaOH is probably all Carbonate now as the crystals up the inside of the tube were all bone dry.
I`m hoping as the Phenol from the Phenolate gets trapped quite nicely in the EtOH now leaving NaCl crystals at the bottom.

it may also be worth noting that my attempt at just the Water and DPC left with an airlock on the radiator for a month did very little beyond a trace smell of Phenol, so this "40 hour half life" doesn`t seem to work all that well in practice, I wouldn`t reccomend it to anyone.

Nicodem - 8-3-2007 at 11:49

Chemical degradation half lives are values true only for monophasic systems. If you have a mixture of diphenyl carbonate and water, the half life value will only be true for the diphenyl carbonate that is dissolved in water. Hence you can not generalize the half life of 40h to cases like yours. I don't even understand why you bothered when the kinetics of diphenyl carbonate hydrolysis are measured and described in the paper I posted earlier up the tread.
Sodium phenolate should smell like phenol since it partially decomposes to phenol due to the absorption of CO2 and H2O from air.

YT2095 - 9-3-2007 at 01:57

well it`s Thanks to that paper you posted, that I`ve gotten results that far outstripped the plain water method I worked on, I got 2.5g dissolved/reacted in less than 48 hours, compared to the Miligrams over a Month+

at the moment I`ve just letting all the water evaporate off to leave my Sodium Phenolate (and excess NaOH).

then I`ll add HCl dropwise until the PH is below 7 and evap again, leaving phenol and NaCl, I`ll then dissolve all the phenol in EtOH and filter off the NaCl, and evap the EtOH.

Thanks for your help and Corrections, your method is Indeed Very Viable/workable and I Will at last get some Phenol

Nicodem - 9-3-2007 at 08:56

You better stick to the workup that I suggested earlier. The one that you suggested will not give you a pure enough product and you will have a hard time crystallizing it. You should know that wet (and impure) phenol simply does not dry on air (if it crystallizes at all!).

Edit: Sticking to conventional methods is better simply because there is generally a good reason for why they are conventional.

[Edited on by Nicodem]

JohnWW - 9-3-2007 at 11:08

Thanks, nicodem, for the info. However, several browsers and download clients cannot handle https sites.

YT2095 - 23-9-2007 at 01:59

well I`m Still experimenting with DPC, and have made some simple Reflux apparatus to this with.
the NaOH soln and DPC works quite well, and after about 7 hours of reflux a clear brown liquid is seen and there`s no molten DPC floating, here:

I`ve tried using CaOH as the base, hoping that it will lock up the CO2 and so simple filtering is all that will be needed to leave Phenol water, oddly rather than the Brown color seen in the above pic, this is a salmon Pink?
here:

garage chemist - 23-9-2007 at 04:07

I dont think calcium hydroxide is a strong enough base for the hydrolysis, also some calcium phenolate would be in solution.

NaOH is really your best bet, just acidify the reaction mix and extract phenol with ether, DCM or CHCl3, dry the organic phase (MgSO4, Na2SO4) and distill off the ether to leave phenol.

YT2095 - 23-9-2007 at 04:26

the only problem is that they are both water based, I thought I`de try the Ca(OH)2 as when I add the sulphuric acid, the PPT will just stay in the filter paper leaving a phenol water mix (and maybe a trace of Sulphuric acid).
the idea was to boil off most of the water at this point since phenols BP is higher.
and then extract with a solvent.

the strange thing is that when the cold condenser pipe drips back into the hot mix, the drips are a clear brown color.
I`m thinking perhaps I should just distill the whole lot after acidifying, that way no Sulphuric or Sulphate salts are going to come over, and neither will the DPC as that`s all been converted.

phenolic water maybe a nice place to start from, I can alway put this in a bottle and forget it until I get more time.

my plans of making Diphenyl Oxalate are not possible anyway, I realise this.

I have to learn more about transesterification before I try making it, so that`s yet another Adventure for me

unionised - 23-9-2007 at 05:02

I think phenol will steam distill over with the water.
I also don't see what's wrong with
1 boil it with NaOH (which is cheap, water soluble and a very strong base)
2 Acidify with HCl/H2SO4/ whatever's cheap and easy.
3 Extract with ether or DCM (pet ether won't work in case you wondered)
4 Dry and
5 Distill off the solvent.
(6, if you are feeling brave distill the phenol)

YT2095 - 23-9-2007 at 05:07

I have Di-ethyl ether (aka Engine Start), but isn`t that water soluble?
how would I do step 3?

also it`s worth noting that, the Ca(OH)2 does work rather well, but it does need more hours under reflux, it still stays salmon pink, but gets deeper pink, and ppt in there is no longer pure white as it when 1`st added, that is actually Flesh tone, I could sell the crap to the Avon Lady

garage chemist - 23-9-2007 at 05:36

You can't boil off water from phenol water, the phenol will boil off first! Its a classic example of steam distillation.

Diethyl ether is only slightly water soluble, its used as an extraction solvent in the organic laboratory very often. The only important thing is to dry the ether extract, since diethyl ether dissolves quite a bit of water.

Alternatively, you could steam distill the phenol after acidifying with H2SO4. That way you get pure phenol water as the distillate, which will give colorless phenol upon extraction with ether.
The brown color is due to autooxidation and metal complexes of the phenol, phenol is very prone to discoloration.

You dont even have to lead in steam to do the steam distillation, you can just distill off most of the water from the acidified solution. You will likely see two phases in the receiver at the beginning, one of them is ca. 90% phenol with some water dissolved, the other is water with some phenol dissolved.

YT2095 - 23-9-2007 at 06:10

ok, I`ll do that, and stop when I notice the second phase, I think 90% is a great place to start from.

edited to add:
I just acidified the mixture here, I used 5ml of 98% H2SO4 (seemed silly adding More Water by using diluted acid), it got quite hot even though it was added dropwise, and stunk of Phenol, quite a remarkable Color change though! Here:

as you can see the ppt is Pure white now and the liquid is a light yellow/orange.

now it`s Filtered, Here:

[Edited on 23-9-2007 by YT2095]

Nerro - 23-9-2007 at 11:30

Am I really missing something or is hydrolysis using aqeous HCl also an option? The carbonate should be converted into CO2 and two equivalents of phenol. I noticed the mechanism by Hinz but frankly it makes no sense at all. The predominant nucleophile would be water which means that there would be carbonic acid and phenol formed. Also it makes no sense at all to let the nucleophile (Cl- in his case...) attack the C on the phenylring rather than the "carbonyl-C" of the carbonate. Even in the case that a stray chloride ion would act as the nucleophile the product would almost instantaneoulsy be hydrolysed by all the water. Sulphuric acid would do the job equally well and even make the work-up easier as all you need is CaCO3 or Ca(OH)2 to get rid of the sulphate.

Why do you guys prefer to use a base?

The_Davster - 23-9-2007 at 11:50

I have observed diphenyl carbonate decompose to phenol before, during heating at over 100C for 24h in methane sulfonic acid. After 24h the condenser above the hot solution/melt was absolutly full of long phenol crystals.

The methanesulfonic acid could perhaps be replaced with conc. H2SO4 and heated with diphenylcarbonate for a day with a condenser or coldfinger above it to collect the phenol. Nice thing is the anhydrous conditions allow the pretty phenol crystals to form.

YT2095 - 24-9-2007 at 05:10

I`v had the DPC crystalise into needles when I`v had to turn off the heat (I can`t be in here all the time during reflux), and they look really nice, but are Very delicate too.

well I`v started distilling the phenol soln as shown in my last post here:

ignore the stacked tin cans, I don`t have a propper jack yet.

and this is the distilate, you`ll note it`s quite clear and not at all yellowish, and it Reeks of Phenol! here:

there doesn`t seem to the 2 phases though? as the distilation is nearly complete now.

YT2095 - 26-9-2007 at 02:41

just an interesting factoid I never knew until just and thought I`d share it here (the more advanced chemists can ignore this).

I stopped the process at the phenolic water stage and bottled it, I tested the PH with universal indicator paper (ph1-11 range) and it`s not at all as acidic as I thought it would be, the paper color hardly changed at all from Neutral!

I added a few drops in to a testube that contained equal amounts of 50% H2SO4 and 40% HNO3, after a few seconds the liquid went bright red and clear, there were also some yellow flakes form (very tiny and floating).
so it shows that there is Definitely good phenol in there as it made Mono and maybe even a little bit of Di nitrophenol.