Phenole

[frogfot]

It seems like many fun experiments require phenole and it is quite unavailable, I can't even order it from chem supplyers... though thats not an important part, lets focus on it's preparation.

Most organic books describes dangerous process where they first sulfonates benzene with conc H2SO4 and then sulfonate group is substituted with hydroxide by melting together sulfonate salt and NaOH at freaking 325*C!! (detailed procidure is described below)
I wouldn't do this even if phenole was really needed..

Another procidure seems a bit more friendly where they decompose diazonium salt of benzene in water.
First, they convert aniline to it's sulfate salt (with H2SO4):
C6H5-NH2 + H2SO4 --> [C6H6-NH3]SO4H

excess of H2SO4 makes nitrous acid required in diazotisation:
2NaNO2 + H2SO4 --> 2HNO2 + Na2SO4

diazonium salt forms (should not be that dangerous in proper conditions):
[C6H5-NH3]SO4H + HNO2 --> [C6H5-N2]SO4H + 2H2O

and finally, above salt is decomposed in water when heated:
[C6H5-N2]SO4H + H2O --> C6H5OH + N2 + H2SO4
(detailed procidure described below)

Now, second method sounds much more promicing, but aniline is nearly as hard to get as phenole. But, I'm quite sure it can be made easily, though I made only few tests and only half way in.. All book methods I had recall for reduction of nitrobenzene, and there we'll need benzene again.. So, I thoat of another way..
First we prepare benzamide from methyl benzoate and ammonia and then convert it to aniline by action of aqueous hypochlorite, heres overall path:
C6H5COOMe --> C6H5CONH2 --> C6H5NH2

First reaction is partially tested, where I used 25% aqueous ammonia, homemade methyl benzoate and ethanole as solvent. After reacting at room temp for a day, HPLC showed presence of benzamide (several percent), however alot of the methyl benzoate had decomposed and there were also traces of ethyl benzoate. So, next try would be to use methanole as solvent instead of ethanole and keep everything as dry as possible to prevent water catalysing decomposition of methyl benzoate.
All precursors sofar are easy to get/prepare/dry. Dry methyl alcohol can be ubtained even from pyro supplyer and methyl benzoate is easily prepared from benzoic acid:
C6H5COOH + MeOH -H2SO4-> C6H5COOMe + H2O (for example Vogel got the detailed procidure)

In next benzamide experiment I'll pass dry NH3 gas through a mixture of methyl benzoate and methanole. This should go nicely, though if not, it would be nice to hear other ways to benzamide. I came to think of decomposition of ammonia benzoate by heat, it should work since the reaction mechanism is similar to decomposition of ammonia acetate when we prepare acetamide..

Back to aniline. Second step to aniline is a bit more doubtful.. There I wanna act by hypochlorite on benzamide this should also work since reaction mechanism is also similar to when we prepare methyl amine from acetamide. Heres the not so detailed mechanism (based on reaction with NaOBr instead of NaOCl):

first one H on amide is substituted by Cl:
R-CO-NH2 + NaOCl --> R-CO-NHCl + NaOH

the resulting partially acidic H is then removed by hydroxide:
R-CO-NHCl + NaOH --> R-CONa=NCl + H2O

R group jumps over to N (since NCl can leave easily):
R-CONa=NCl --> CO=N-R NaCl (draw this on paper to get better understanding)

and finally water attacks carbonyl:
R-N=C=O + H2O --> R-NH2 + CO2

This reaction path is mentioned with acetamide as example though I don't see why -R couldn't be -C6H5. -CH3 and -C6H5 seems also have quite similar electronegativity. I suspect that amide of the later will give less yield since it's harder for big -R groups to make intermolecular "jumps" such that in third reaction (jump from C to N).

Well, if this works aniline could be simply converted to phenole as mentioned above. (and in detiled bookmethod below)

------------------------------ Procidures

Now, here are the two procidures I could leach from my books that I mentioned above:

Phenole from benzene (reference: Laboratory practicum of precursors and pigments, L.N.Nikolenko, 2:ed, 1965)

Sulfonating benzene
In 0,5 l iron pot with refluxer and dropping funnel place 220 g (120 ml) H2SO4*H2O. Add drop by drop 90 ml (78 g, or 1 mol) benzene in a period of 30-60 min. While adding benzene make sure to keep temp below 70-75*C.
When all benzene is in, slowly raise temp to 105-110*C and while keeping it there stirr for 4 h. All benzene will react.
Reaction mixture is poured into 0,5 l water while stirred well. Solution is heated to boiling and neutrolised with CaCO3 until no CO2 is evolved (pH >5,5). Solution is filtered, washed with 200 ml warm water 30-40*C.
Then, 110 g crystolline or 47 g anhydrous NaHSO4 is added followed by 18 g NaHCO3.
Solution is filtered from precipitated CaCO3, and evaporated preferrably under vacuum until solid salt shows up.
Precipitate is filtered and dryed at 100-105*C. Ubtained sodium benzosulfonate salt will contain 7 % sodium sulfate.

Phenole from sulfonate salt of benzene
Place 150 g NaOH and 50 ml water into 0,5 l iron pot. Pot is slowly heated on flame to 290-295*C, avoiding large foaming. While stirring, add in small portions, fine powder of above prepared sulfonate salt. Addition speed is addjusted to not let temp drop below 290*C. When all salt is in, raise temp to 325*C during 30 min. Mixture is stirred at this temp for 40 min.
While mix is hot, pour it out on an iron plate. When it cools down, crush it and dissolve in 1 liter water, while heating.
Solution is heated to boiling, neutrolised by 50% H2SO4 and filtered at 50-70*C. While filtrate is still hot, add conc HCl until pH is 2-3. Phenole is extracted 3 times with benzene (200 ml benzene totally will be required).
Product is destilled at atmospheric pressure, fraction of 178-180*C is collected.
Yield is 70-75 g (75-80% from theoretical), freezing temp 38*C.

Phenole from aniline (reference: Practicum of organic chemistry, N.D.Prjanishnikov, 4:ed, 1956)

Place 50 ml water in 300-500 ml beaker and while stirring add 10 ml conc H2SO4 (0,18 mol). While solution is still hot, slowly while stirring add 9,3 g (0,1 mol) of freshly destilled aniline. Mix is cooled to room temp and 70 g crushed ice is added. On cooling, there will precipitate hydrogen sulfate salt of aniline, it will not affect next step of synthesis.
To the cooled reaction mix that should be at about 0*C add slowly, while stirring vigorously, a solution of 7,5 g (0,11 mol) NaNO2 in 30 ml water. When big ammount of nitrite have been added, reaction mix is checked by a iodine/starch paper(Note1). If indicator shows blue after a while since the last addition of nitrite, reaction is compleate.
Ubtained solution of diazonium salt is transferred to 500 ml roundbottomed flask and heated at 40-50*C in water-bath until nitrogen stops evolving.
Phenole is then destilled with water steam.
Destillate is saturated by fine powdered NaCl and phenole is extracted several times by diethyl ether. Organic phase is dryed by CaCl2 and solvent is destilled away. Phenole is then destilles with short air destiller.
Yield is 6-7 g. mp 42,3*C: bp 182,1*C

Note1:
Iodine/starch paper
Heat a solution of 0,5 g starch in 100 ml water until it gets wallpaper glue consistency, add 1 g KI.
Soak filtering paper in prepared solution and dry it. After cut paper in strips and store in airtight jar.

------------------------------ Procidures end

Ok, diazotisation synthesis sounds to be very promicing, But steam destillation in the end sounds to be much of work, one could simply extract product with, say, ethylacetate or other similar widely available solvent. That is if reaction mix is properly neutrolised..

Anyway, comments, suggestions are welcome. Maby there are even simpler synthesis ways to phenole..

[vulture]

Ever thought of the decarboxyaltion of salicylic acid?

Check TNP aspirin process.

[knowledgehungry]

Using Conc H2SO4 on Aspirin gives you phenol IIRC.

[frogfot]

I've seen that procidure, but for some reason they don't sell pure aspirin here (swe).. I have only access to those 500 mg tablets which are darn expencive.

Btw, I will try this to see the yields.. or maby someone have already measured theese (yields of phenole from aspirin)?
Also, maby there are different reaction conditions that will give better yields. For example, IMO, the acetyl group could be taken away faster with an alkali..
Then I read in org chem book that some decarboxylations on aromatics is carried out on heating in presence of powdered Cu. I don't think that H2SO4 have any role in decarboxylation (atleast when I tryed to draw mechanism), or?

[T_Pyro]

The synthesis of aniline via Hofmann degradation of amide that you spoke of sounds ineresting (and promising). The last step, however, "and finally water attacks carbonyl", IIRC, is actually:
R-N=C=O + 2OH- -> R-NH2 + CO32-

Another method of preparation of amiline would be the nitration of benzene to obtain nitrobenzene, and subsequent reduction using Sn + HCl to give aniline. I'm not sure of the experimental conditions, though, apart from the fact that heating is required.

[vulture]

[QUOTE]For example, IMO, the acetyl group could be taken away faster with an alkali..
[QUOTE]

Quite the contrary, the acetyl function is hydrolized in water bij accepting H+. Acid will make it go faster.

H2SO4 enormously speeds up decarboxylation. Otherwise very strong heating is necessary which will often decompose the molecule.

[T_Pyro]

I came across an interesting procedure for the preparation of phenol, which is supposed to be the method for the preparation of nearly all the phenol produced today. This method starts with 2-phenylpropane (cumene). 2-phenylpropane is converted by air oxidation into 2-hydroperoxy-2-phenylpropane, which is converted by aqueous acid into phenol and acetone.
http://www.che.rochester.edu/Courses/CHE286/cumene_rearrangement.gif
(Image from this page (http://www.che.rochester.edu/Courses/CHE286/bisphenol_a.htm))

[Marvin]

I would be bothered the conc acid might sulphonate the ring. I'm also a little bothered you arnt forming the acid itself with a seperate step, I'm not sure this will succeed.

I'd probably start with either asprin or methyl salicylate, add caustic soda to hydrolyse/form the salts, add HCl to ppt and distill the salicylic acid from powdered pumace,glass or sand to produce phenol. Several older books recommend the distilling process to decarboxylate.

[frogfot]

Quite the contrary, the acetyl function is hydrolized in water bij accepting H+. Acid will make it go faster.

I assumed OH- catalysed "deacetylation" would go faster because it have less steps in mechanism than H+ catalysed, I dunno :rolleyes:

Thats a nice way, T_Pyro, I like idustrial process. On some search, cumene seems to be used as thinner for paints (maby as substitute/addition to toluene, which would be easy to get/separate). Time to visit some stores :)

Btw, isn't lignine a cheap phenol derevative.. I got access to 23 books about wood processing, gonna check them out when there will be more free time..

Marvin, I checked bp of salicylic acid and it sublimes at 76*C, how can it then be thermally decomposed at atmospheric pressure. Do you mean that pumace/glass etc will somehow prevent sublimation, or did I misunderstand something? (destill with excess HCl?)

I've checked Vogel for sulphonation of phenol where they place 2 -SO3H on a phenol. Reaction is carried out with conc H2SO4 at 100*C, so, now I'm also worrying about sulphonation of final product :(
How about using catalytic ammounts of H2SO4, since sulphonation is reversible, there will be enough H2SO4 during whole decarboxylation.
Or, how about refluxing with HCl, maby it will have same decarboxylation effect..

EDIT:
Attempt to make benzamide wasn't that good..
Ammonia gas was dryed by solid KOH and let through a mix of 9,5 ml methylbenzoate and 19 ml methanol. After about a day reacting at room temp, HPLC showed that there was benzoic acid present... so, this means methyl benzoate decomposed because water was present :mad: dammit, thats probably air humidity.. I will not attemt same experiment nearest time.. gonna test thermal decomposition of ammonia benzoate.

[markgollum]

How is this for the synthesis of phenol?.
React sodium salicylate, (an ingredient in whistle mix for pyrotechnics) with hydrochloric acid, (cheaper than H2SO4) to make sodium chloride, and salicylic acid. Next, decarboxylate with sulfuric acid to make phenol.
Unless I am really missing something, this should be a good way to make your phenol.
(When last I checked, sodium salicylate was avalible from either pyroteck or firefox for about $15 a pound :))

[Marvin]

I am uncertain how the decarboxylation happens, but I have several books that suggest this is how it can be done and nothing to suggest the acid process. I have read the usual method of CaO/NaOH is too reactive and yeilds drop as a result and one verbal reference that the product is frequently an unapealiong tarry mass but that the yeild on purification is high 80%+ ish. Salycylic acid is made industrially from phenol by heating under pressure with carbon dioxide, which adds strength to the distilling method to my mind.

mark, not a bad idea, but the bone of contention seems to be how to decarboxylate rather than where to get the salicylic acid from. A good tip though.

[Lavoisier]

Attempt to make benzamide wasn't that good..

Water usually dosen't interfere much in theses reactions, as ammonia is a better nucleophile than water and the resulting amide more stable than the acid... perhaps you rather lost all your ammonia before it even reacted if your reaction vessel was left wide open to atmospheric conditions? it could also been caused by some KOH that would have been dragged into your mix...

I used to make acetamide this way :

I mixed ~50g ethyl acetate with ~100mL 28% aqueous ammonia under heavy stirring in a properly capped flask for 48h at room temperature. Then I distilled everything under reduced pressure (painful...). Yield was about 30g.

Now for benzamide, I would probably keep using methanol as solvent.. but with 28% aqueous ammonia, which is way more convenient to handle than gaseous ammonia...

Btw, if theses are only small amounts of benzoic acid.. why don't you simply wash your benzamide with dilute aqueous NaOH? That would get you rid of it...

I hope this help you out somewhat...

[frogfot]

Thanx. Though the only problem with water is that it decompose methylbenzoate.. You're right that aqueous ammonia is easier to handle, it was a pain in the ass to saturate solution with ammonia (btw, finall concentration was checked by titration, it had about equimolar ammount of NH3), and I've heard that this reaction should actually undergo better in more polar solvent which justifyes to use aqueous ammonia again.
I have also noticed that formation of benzamide favors over decomposition of ester with increased temperature. So I'm going to test this out by filling a soda bottle with aqueous reaction mix and monitor pressure with barometer, and heating it in water bath. Hope it wouldn't blow up :rolleyes:

Anyway, I found out that benzamide to aniline reaction can't go with help of hypochlorite :( either there are another way to drive this reaction, or, I'll just produce some benzamide to occupy another bottle..

[frogfot]

Oki, a new procidure got into my mind, which is more promicing.. again using benzoic acid.

To sum it up, we prepare meta-nitrobenzoic acid by simply nitrating it with H2SO4/KNO3 (btw, m-isomer is a probable mutagen, see MSDS). Then, it's decarboxylated by heat (possibly with Cu/Cu(I) as catalyst) to form nitrobenzene (not that healthy eather), which is then reduced to aniline by Sn/HCl or in other reducing conditions, here I'll try to find a method that uses zinc pellets (time of reaction is not critical).
Aniline is then converted to phenole as was mentioned in first post.

Everything seems to be simple to do, I've already carried out nitration successfully (yield is drying over CaCl2), but decarboxylation step is a bit critical..
However, I found some references about aromatic decarboxylations. Most usual procidure involves heating with copper powder and quinoline.

Quinoline
http://img37.photobucket.com/albums/v113/frogfot/stuff/quinoline.png

March mentions following mechanism catalysed by an acid:

http://img37.photobucket.com/albums/v113/frogfot/stuff/decarboxylation.png

Another decarboxylation mechanism proceeds with a salt of the aromatic acid, first step is initiated by heat:

http://img37.photobucket.com/albums/v113/frogfot/stuff/decarboxylation2.png

Here, same catalysts can help reaction going. But I'm not sure yet which way would give better yields.

Now, to the catalysts.
Quinoline acts basically as H+ acceptor/donor and a solvent (since it have high boiling point).
March also tells that reaction is actually catalysed by copper (I) salts, where Cu+ stabilises the negative charge formed in second decarboxylation reaction above. Though I can't see how copper(I) would catalyse the first reaction, where no negative charge forms..

Another source (Chemical abstracts 1947, 6223) tells that decarboxylation proceeds easier if aromatic acid is stronger, this is because stronger acid have more positive aromatic ring and forming carbanion is more stabilised (one exception mentioned is chloro benzoic acid, which does not decarboxylate). Here, it pays off to decarboxylate nitrobenzene.
Reaction is also catalysed by compounds with -OH and -NH2 groups, which acts as H+ donors/acceptors in same way as N in quinoline.

"Chemical abstracts" mentions some experimental data, where 3 g o-nitrobenzoic acid, 3 g Cu bronze and 25 ml benzene is heated in an autoclave at 180*C (its decarb. temp) for 4 h, this gave 90% PhNO2.
While similarly, m-isomer gave 92% at 238*C and p-isomer gave 62% at 240*C.
I have no clue why bronze is used instead of pure copper.

Procidure requires an autoclave which I'd be afraid to use, so, I've decided to go with simple heating and use acetamide as a solvent.. acetamide have bp of 222*C, it's very stable and it's incredibly easy to prepare (in virtually any ammounts). Though it will not act as a catalyst as an amine would, though it have -NH2 group. Solvent would basically act as an heat conductor which should decrease pain in the ass by giving an even heating of whole reaction mix :)

It's also good to mention their experimental results from decomposition of H2N-C6H4-COOH, since it gives good yields even without a catalyst:
o-isomer gave 89% PhNH2 at 145*C (205*C final temp) in 4 h. (97,7% with recovery of CO2)
p-isomer gave 75% PhNH2 at 187-210*C in 4 h. (81,8% with recovery of CO2)

I'm not really sure what "with recovery of CO2" means, but I think it's basically when they carry out reaction in open, to let CO2 escape. Here is another possibility, through following path: toluene -(NO2+)-> o- and p-nitro toluene -(KMnO4)-> o- and p-nitrobenzoic acid -(Sn/HCl)-> o- and p-amino benzoic acid, and so on as in exp above. Thats a long, but fun path, most probably with decent yields.

Oh, decomposition of salicylic acid was also mentioned:
3 g salicylic acid, 3 g Cu bronze and 25 ml benzene was heated in an autoclave at 170*C for 3 h, this gave 93% PhOH. Acid alone would decompose at 205*C and at 170*C in presence of aniline. This sounds promicing (if, again, we changed out the solvent to something more available), but again, here in Sweden aspirine seems to be hard to get (anyone from swe cares to share a source?)
I got some more info about problem with sulfonation of phenole, apparently, sulpho groups can be simply removed by boiling with dilute H2SO4. So, procidure to get phenole from aspirine should be pretty simple: boil with conc H2SO4 until CO2 evolution ceases, then dilute with water and boil some more..

As for cumene, I couldn't find any solvent that contained it. Most had toluene, different types of xylene and suchalike. Gotta search more..

Hope that next time I'll have some experimental results..

(heh, and I finally got an account on photobucket :) )

EDIT:
Dammit, on a bit rethinking, I checked MSDS sheets of nitrobenzene and aniline, both seems to be pretty evul compounds.. so theres the catch :(
Before attempting this experiment, one should probably make a fumehood and place where one can handle theese compounds and wash equipement (don't wanna do this in kitchen..)
See MSDSs here:
http://ptcl.chem.ox.ac.uk/MSDS/NI/nitrobenzene.html
http://ptcl.chem.ox.ac.uk/MSDS/AN/aniline.html

Also any idea if nitrobenzene can explode on heating? They say "wide explosion limits"..

[T_Pyro]

I read the MSDS's you mentioned regarding nitrobenzene and aniline, but I really don't think it's as bad as the MSDS states. We use aniline for organic analysis in our college chem lab, and I don't think they'd allow us to handle it if it was so dangerous! One of my experiments in the lab also involved the nitration of benzene, and my teacher didn't say anything when I took her permission... By saying "heating" of nitrobenzene, what temperature range are you talking about? I know that it's stable even at 70o - 80oC.

Regarding cumene:
Here's a hypothetical method for the preparation of cumene: http://img34.photobucket.com/albums/v104/T_Pyro/Cumene-preparation.gif

EDIT:
Sorry, the last diagram I'd posted was downright wrong. Anyway, here's the actual diagram. Only isopropyl alcohol is required, but the sulfuric acid will have to be concentrated to produce the required secondary carbocation. No need for grignard reagent after all (phew!).

Just got another idea:
You could react aniline with NaNO2 and conc. HCl, and then add water to hydrolyse the diazo compound to get phenol.

[frogfot]

Well, pretty high heating, I thoat if nitrobenzene could be destilled away from resulting goo after decarboxylation of nitrobenzoic acid. It have bp of 210,9*C.. it would probably get much higher since I'm planning on using gas burner.
Anyway, on other thoat, nitrobenzene could be skipped if -NO2 was reduced while it is in nitrobenzoic acid, as mentioned preveously (wahoo, so much possibilities!!)

Thats an interesting prep of cumene. And its sure much safer than melting sulfonated benzene with NaOH :)
As for grignard, I got pure Mg, and acetone could be easily dryed, methylchloride seems to be easily prepared (one book describes procidure that uses MeOH, conc. HCl and ZnCl2). But preparing grignard of a gas seems to be a bit troublesome..
I think there should be isobutanole as solvent in usual stores.

[frogfot]

While I was searching books for some info about reduction of nitrobenzoic acid, I found an interesting synth that basically makes phenole in one step by thermal decomposition of copper benzoate.

This is apparently an industrial process where they use toluene as precursor and yield is above 73% with regard to toluene!!! (buts comes later) I checked out this closer, and got two references to (Journal of Organic Chemistry 1961, 26, 3144) and a US patent 2,727,926. The first mentioned this method and the second reference basically tells everything (patent is free on http://www.uspto.gov/patft/index.html).

Procidure sounds simple, they melt a mixture of benzoic acid (solvent/reactant) and copper benzoate ("catalyst"). Owing to patent, the ammount of copper should be from 1 to 5% from total weight. A stream of steam and air is bubbled through reaction mix and phenole is destilled away. Some benzoic acid is destilled too, but in patent they use a reflux column that separates benzoic acid and phenole, which lets the former to go back into reaction vessel. Actually, during experimenting, I found this refluxing column to be the major problem, explained further.

Now, to the reactions that explain why air and steam is needed. First copper benzoate decomposes from heat, at 200-250*C:

2Cu(C6H5COO)2 --> C6H5COOC6H5 + 2CuC6H5OO + CO2

Formed copper(I)benzoate oxidises in presence of oxygene to regenerate copper(II)benzoate:

2CuC6H5OO + 2C6H5COOH + 1/2O2 --> 2Cu(C6H5COO)2 + H2O

The ester formed in first equation decomposes in presence of water:

C6H5COOC6H5 + H2O --> C6H5OH + C6H5COOH

Net reaction is following:

C6H5COOH + 1/2O2 --> C6H5OH + CO2

Since water formed in second equation will partially evaporate, external water is supplyed in form of steam to maintain full decomposition of phenyl benzoate ester.

I experimented a little with this myself. Apparatus used was a reaction flask with short air condencer and recieving flask, all in glass. A car tier pump was pumping air through 50-70*C water and produced "steam" was let by a copper pipe to the bottom of reaction flask where I melted 2 parts of benzoic acid and 1 part of copper salt. Heating was done by a gas burner and in further tests by a heat gun (set at 300*C).
Reaction went nice though condencer stuffed up pretty fast by benzoic acid (heating reduction didn't help much). A product was ubtained, that smelled phenole though most of it was composed of benzoic acid and its phenolic ester. I guess that supplyed steam wasn't enough to break down the ester.

Here comes the main catch, even if temp of reaction is kept below bp of benzoic acid, it still destills over to some extent (prolly with water steam). In industry they solve this easy by using a reflux column as mentioned previously. It basically returns all acid back into reaction vessel. But this does not sound simple at all... column temp must be maintained at mp of acid and thats not the only problem. Screw the column..
One could always extract phenol from the final solid desillate but main problem still remains: this destillate taps the condencer over short operation time.
Also, while experimenting I found out what phenol does on the skin.. :) Apparently, first, skin numbs and then appears a white burn.. Just in case I had tight goggles all the time.

Anyway, patent mentions that reaction could be also done with sodium or potassium benzoates, preferrably with CuSO4 as catalyst in aqueous conditions. This process is described in first reference I gave. Though there, they carry out reaction under pressure, which is tedious.. conversion is not full either.

One thoat was to decompose copper benzoate together with sodium benzoate as in method mentioned in beginning (with steam and air), but mp of benzoate salt is above 300*C which is kinda too high. Most probably, this will give low yield with alot of tar residue and probably higher benzene output. I've tryed to melt the salt and it started to char over the time..
I beliave reaction would be a bit different, specially oxidation of copper(I) salt:

2CuC6H5OO + 2C6H5COONa + 1/2O2 + H2O --> 2Cu(C6H5COO)2 + 2NaOH

Together, giving following net reaction:

C6H5COONa + 1/2O2 --> C6H5ONa + CO2

Sodium salt of phenoxide would remain in reaction mix, waiting to be extracted.. it would be probably partially decomposed, but still, we wouldn't need any reflux column nor air condencer with funky glass equipement. But I'll currently stop experimenting with this process.

I still have a hope of the other 5 step process mentioned in previous posts, though some difficulties came up.. like, o-nitrobenzoic acid didn't want to be oxidised by KMnO4, only p- isomer could :( However, the rest of steps have pretty good yields. Not looking on that darn oxidation, one could get up to 30% yield of phenol with regard to toluene. One solution would be to separate the o- and p- nitrobenzoic acids, then oxidising only the p- isomer. But what the hell would I do with the o- isomer..?!?! (although it smells funny :p it's toxic, I know)
Maby anyone knows some reaction conditions that would oxidise both isomers in the same batch? As I see it, the o- nitro isomer cann't be oxidised because the partially negative nitro group doesn't let the oxidiser to come close to the methyl group. So, maby oxidiser should be small, neutral or positive charged and ofcaurse strong. (I have currently a ready batch of nitrotoluene..)

Anyway, when I'm finished with all steps I'll present all procidures.

Btw, I have made a google search and found a phenol discussion on SciMad where copper process was mentioned. Also, someone decarboxylated aspirine just by melting it, ubtaining 77% yield. Though there was no further experimental data..