p-toluenesulfonic acid

[Chromic]

Paratoluenesulfonic acid (aka p-tosic acid)

Added 5.0g toluene (1 equiv), 16.4g 94% H2SO4 (3 equiv) to a 50ml flask. Toluene layer went to the top of the flask. Dropped in a stir bar, fitted with a condenser, started stirring, heated to get a gentle reflux (~110C) of 1 drop/sec. 40 minutes passed and the reflux had stopped, the layer of toluene was gone. Easy reaction, nothing to it!

I added 5ml water down the condenser, allowed the flask to cool slowly to room temp, nice crystals of p-tosic acid form. How do I separate them without a sintered glass buncher funnel? Or, would changing this to 1 equiv H2SO4 make tosic acid? (obviously with some 2- & 3- isomers, but that doesn't matter much as it's just going to be used as an acid catalyst, impurities don't bother me much)

[Antoncho]

hmmm... this is very interesting - so, you say that tosic acid is insoluble in aq. H2SO4?? This is really a surprise, i thought, since tosic acid is so water-soluble,... eh...

Well anyway - i suggest you just decant the liquid as much as possible and wash the crystals w/ conc. HCl several times, and then dry over H2SO4/NaOH as described.

Antoncho

[Chromic]

It seems that tosic acid hydrate isn't soluble in ~80% H2SO4, however I did notice that tosic acid does dissolve in 98% H2SO4. (crystals will not form in the above synthesis until the addition of water)

My HCl is only 31%, and I can't decant the crystals, the whole thing is sort of a slush... I'm tempted to try reacting this 1:1. I really want the crystals and don't care about the purity (so long as it's around 80+%) Maybe I should experiment more and post less.    (but I love posting...)

[terbium]

(crystals will not form in the above synthesis until the addition of water)
Yes, this is the same as the procedure in Vogel. He dries the crystals by spreading them on an unglazed porcelain plate.

[Chromic]

Reacting 1:1 toluene to sulfuric acid doesn't work, it gives off lots of SO2. I guess it must be making p-cresol. Trying to get the crystals from spreading out on a porcelin plate didn't work well, I guess I'll have to buy a sintered glass buchner funnel.

[terbium]

I guess I'll have to buy a sintered glass buchner funnel.
Or buy some of the Whatman glass fiber filter disks that I keep touting and use them on your Buchner in place of paper filter disks.

Here is the procedure for p-toluenesulfonic acid from Vogel:
(comments in italics are mine)

Use

Use the apparatus employed for Di-n-butyl ether (a round bottom flask fitted for reflux and with a Dean-Stark water trap). ... Place 87 g (100 ml) thiophene free toluene and 37 g (20 ml) of concentrated sulphuric acid (92 per cent H2SO4 by weight) in the 250 ml ... flask and heat to gentle boiling. When 9 ml of water have been collected in the Dean_Stark trap (4-5 hours), stop heating. The water is derived partly from the reaction (6.25 ml) and partly from the sulphuric acid. Add 6.3 ml of water to the cold contents of the flask; crystallization then occurs. Spread the resulting solid on a porous tile and press well with a glass stopper; toluene and o-toluenesulphonic acid are thus removed. Dissolve the residual solid (47 g) in about 22 ml of water and saturate the solution with hydrogen chloride gas; use any convenient device (e.g., a small funnel) to prevent "sucking back." After several hours the acid crystallises out as colourless prisms. Filter rapidly through a sintered glass funnel, wash with a little concentrated hydrochloric acid, and dry in a vacuum desiccator charged with stick potassium hydroxide and calcium chloride. The yield is 35 g, m.p. 105-106° (sealed tube).

[Dr_Sister]

chromic - its a fuckin mess, i triied to recrysttallize that mushy shit from ipa, and it alot of work to make more mushy shit, i triied washing with toluene, ha! But i have a suspicion that n-butyl alcohol might have a more appropriate solublty curve, but know what, i think fuck it, just distill the stuff, BP 140C next time right out of the rxn flask.

and if you reflux 1st your toluene and drip in the H2SO4 (2 equivalents), you control rxn with stirring and its over in 15 min. then toss the H20 down condenser until it stops trying to reflux out finito! and if you don't decant quik after it goes solid (not slush) really fast .

fun though
7.10.01

[Chromic]

It boils at 140C and 20mmHg.

[Chromic]

Since distilling tosic acid isn't quite possible for me, could I dissolve it into DCM (does it even dissolve well? I've read it dissolves into ether, alcohol, water, etc), then just pour off the H2SO4. Evaporate the DCM, and get my tosic acid?

Would this work? (and if so, could I just store the tosic acid dissolved in DCM?)

[Aurelius]

try dissolving some in DCM- if it works, do as you suggested above.  before storage, however, you should probably recrystallize your product, then dissolve in fresh DCM.

[Chromic]

Ok. I'm still struggling with this. I've tried reacting toluene to sulfuric acid at:

toluene:sulfuric (molar, apx weight:weight tho since MW is similar)
1:3 - works fine
1:2.5 - works fine
1:2 - sulfur dioxide, stopped rxn
3:1 - (as suggested by Vogel) sulfuric dioxide, stopped rxn

I can't stand to breath in the SO2, plus I think it's an indication that the tosic acid is forming 4-methyl-phenol.

The DCM idea didn't work well. Tosic acid didn't move to the DCM layer. Does anyone have any other suggestions? I'm thinking about trying 80% H2SO4 with 3 eq. toluene... is that the right idea, or is there something else I could be doing?

[Chromic]

Nope... 3 equiv 80% toluene isn't working well either, looks like I need a dean-stark trap to use that method. There's a purple toluene layer, and a burgandy H2SO4 layer... doh. The only method so far to work well is 3 equiv 95% H2SO4, 1 equiv toluene.

[Vibrating_Lights]

Chromic_  Are you dreamin what i think you dreamin
VL-

[Chromic]

Not yet. I need decent quality p-tosic acid first.

[Vibrating_Lights]

Someone please help this man. 
Chromic- It looks so easy doesn't it.
VL_

[Chromic]

I'm really at a loss here. I don't have a sintered glass funnel... frig.

[terbium]

I am at a loss to. Procedures from Vogel always work as stated. Do you have crap starting materials? I am guessing that you do because you report a purple color.

[Chromic]

Hey, 3 equiv of toluene does work! My problem was not performing the distillation slow enough. If it is done very slowly there is hardly any SO2 formed.

So, my question is... should I boil off all the toluene to get solid tosic acid or use filter paper in a buchner to filter the mixture? (there is solids)

[Rhodium]

The text below is taken from a japanese patent abstract, and it tells how to produce p-toluenesulfonic acid monohydrate, the product of commerce, which I believe is much easier to isolate than the anhydrous sulfonic acid. It would soon pull that water molecule out of the air anyway.

Toluene is reacted with 80-98% sulfuric acid at 2-4 molar ratio at the boiling point of the toluene and the resultant reaction solution is cooled to about 60°C. Water in an amount corresponding to 0.75mol based on 1 mol p-toluenesulfonic acid in the reaction solution is then added to crystallize monohydrate crystals of p-toluenesulfonic acid while cooling the reaction mixture to 20-60°C. The above-mentioned crystals are subsequently separated to provide a filtrate.

[UTFSE]

are you all sure that SO3 isn't required to make this?

maybe I am thinking of tosyl chloride.
OTEECEE & meeeee!!!!

[Chromic]

SO3 isn't needed. The synthesis gave me a wet brown sludge, but it's definitely the sulfuric-acid-free tosic acid that I needed to use an a catalyst! The synth is very easy once everything is spelled out.

Summary:
3 equiv toluene, 1 equiv acid, stir bar. Slowly refluxed (<<1 drop/sec) for a few hours, the biphasic solution turned brown, and towards the end I decided to distill off about 1 equiv of toluene thinking that I might distill it to dryness (but decided against it). Instead of completing the distillation to dryness the solution was filtered (using saran wrap to press down the solids). There remained a bunch of brown sludge comprised of mostly tosic acid crystals.

Lovely!

[PrimoPyro]

We look forward to a future formal writeup with yields.  

Congratulations, Chromic!  

                                                   PrimoPyro
The Water Will Be Your Only Mirror

[GlaseIs]

This would be the dehydration of the diol to form MDP2P in the Oxone method right? Hopefully this works a lot better than H2SO4. Looking forward to a writeup
On the 6th day God created man. On the 7th day, man returned the favor.

[psychokitty]

You might want to try to saturate the aqueous layer with sodium bisulfate or something to salt out the tosic acid.  If it has any solubility in any of the common extraction solvents, it should go to the organic layer with ease.

[Chromic]

The above method works, but the brown sludge comprised of mostly tosic acid doesn't dissolve into toluene (perhaps it's wet with water?)

The crystals do seem to dissolve OK into methanol. I was wondering if I could take the impure tosic acid and do the pinacol rearrangement by refluxing the glycol in methanol? Is this a good idea, or should I just give up and order lab grade tosic acid?

[Rhodium]

The impure tosic acid probably will work as rearrangement catalyst, but to get those desired high yields, I believe you need some fresh acid from a chem supplier.

[Chromic]

Rhod, do you think the tosic acid rearrangement will work in methanol? (or is there something critical about benzene?)

I could distill off some of the methanol and then add water and extract with DCM. Should be easy, but will it work?

[Chromic]

Foxy2, could you do a little searching on Pinacol rearrangements in alcohol? Is it possible?

[foxy2]

Check this out
Facile and fast pinacol rearrangement by AlCl3 in the solid state.
Abstract
A facile and efficient synthetic procedure for effecting the pinacol rearrangement catalyzed by AlCl3 in the absence of solvent is developed.  The rearrangement product is obtained at room temp. in a few minutes and in almost quant. yield.  Benzylic pinacols rearrange under these conditions, while aliph. pinacols do not react. 

http://www.mdpi.org/molecules/papers/60500442.pdf

I can't tell if it will yeild the desired ketone or propiophenone?  I think it will bee the right one.  Damn why didn't they do one more experiment. 

Will AlCl3 tear apart the MDO ring?

Here is something also worth looking into for ketone preparation possibilities.  Maybee even a whole new route to MDP2P from the dihalide,  if the dihalide of safrole rearranges to the ketone it would bee even better!!!

Kakis Rearrangement: A series of organic laboratory experiments.
Field, Kurt W.; Moroz, Judith S.   
Abstracts of Papers, 222nd ACS National Meeting, Chicago, IL, United States, August 26-30, 2001  (2001), CHED-426.  Publisher: ACS
Abstract
We have developed a microscale org. lab. expt. which illustrates the Kakis rearrangement and related reactions.  The Kakis reaction, which is comparable to the pinacol rearrangement, involves the silver ion promoted rearrangement of vic-dihalides to aldehydes or ketones.  For example, the reaction of 1,2-dichloro-1,1,2,2-tetraphenylethane, 1, with silver ion and water is solvent dependent.  In aq. (.apprx.1%) methanol, 1 gives 2,2,2-triphenylacetophenone almost exclusively.  However, in aq. (.apprx.11%) acetone, 1 affords near quant. yields of tetraphenylethylene oxide.  An efficient prepn. of 1 from tetraphenylethylene was also developed which eliminates the use of cylinders of chlorine and chloroform solvent.  These transformations illustrate a no. of important mechanistic processes; details of the expts. will be presented.
Those who give up essential liberties for temporary safety deserve neither liberty nor safety

[Chromic]

from that paper, "Toda found that the reaction proceeds faster and more selectively in the solid state by using organic acids like CCl3CO2H and p-TsOH [6]."

Toda, F. and Shigemasa, T. "Pinacol rearrangements in the solid state". J Chem Soc. Perkin Trans, 1, 1989, 209-211

That article sounds like it's worth reading. The more I think about it though, the more likely it seems that the rearrangement would work in methanol as it works with H2SO4/MeOH/H2O and in p-tosic/Benzene, so thoughts are that it should work in p-tosic/MeOH. I'm going to go ahead and give it a try anyways.

[Antoncho]

[drooling]...

_{/thought you'd enjoy some feeedback,}

Antoncho

[foxy2]

Ok i was going to the library anyways and i picked up.

Toda, F. and Shigemasa, T. "Pinacol rearrangements in the solid state". J Chem Soc. Perkin Trans, 1, 1989, 209-211

Abstract
The rearrangement of PhCH(OH)C(OH)PhR1 (R1 = Ph, tolyl, anisyl, ClC6H4) to mixts. of PhCOCHPhR1 and R1CPh2CHO was catalyzed by HCl, p-toluenesulfonic acid, and CCl3CO2H.  The HCl-catalyzed rearrangement of MeCH(OH)C(OH)MePh, in a complex with a 2,2'-biphenyldicarboxamide deriv. host compd., gave MeCOCHMePh. 


They were looking at these substituted reactions in this article --> PhCH(OH)C(OH)PhR1 (R1 = Ph, tolyl, anisyl, ClC6H4). This paper is really short and doesn't really apply to pur case, except for a few short statements at the end which reference the following paper which might bee more interesting.
F. Toda, A. Kati, Y. Tagami, and T.C. Mak, Chem. Lett., 1987, 1393.

But this paper does have one very interesting thing.  They say the (dilute H2SO4 33wt% i think, under reflux at 112C)-catalyzed rearrangement of MeCH(OH)C(OH)MePh, yeilds MeCOCHMePh 48%,  (Me)2CHCOPh 29%, OCHC(Me)2Ph 5%.  Then they say that the same selectivity was observed by treating the above with p-TsOH in the solid state. 

I wonder if this same effect is occuring in the isosassy diol rearrangement to give an alpha-methylphenylacetaldehyde contaminant?

Oh yes, one other thing.  They got good rearramngement yeilds using dry HCl gas on the solids mentioned in the abstract.
Foxy

Those who give up essential liberties for temporary safety deserve neither liberty nor safety

[Chromic]

>so thoughts are that it should work in tosic/MeOH. I'm going to go ahead and give it a try anyways.

I ran a 29.6g anethole run with 300ml DCM, 13.1g NaHCO3. Added 152.1g peracetic acid (made from h2o2 and GAA that was left to sit 4 days), with 3.8g NaOAc. (heat evolved, and the smell changed to the typical glycol smell) I washed with 10% NaOH two times, went ahead with the impure tosic made from 2.4g toluene and 6.9 H2SO4 with 0.3g H2O (I figure about 4.5g tosic acid, 4.3g unreacted h2so4) in 200mL MeOH. Well, I refluxed for 30 mins, neutralized the acid, distilled off some of the methanol, flooded with water, and washed two times with 10% NaOH. The washes were clear each time. Anyways, it's sitting right now in DCM ready to be distilled and tested.

If this is ketone, it's the most unbelievably clear stuff I've seen after rearrangement. I'll keep my fingers crossed.

[Chromic]

Well, I distilled off the DCM and tested with bisulfite. Negative. I tested by trying to form the oxime. Negative.

So I distilled the oil. At 120-200C I got 5.1g forerun (more dense than water), at about 272-278C I got 22.6g. I pulled it off the heat, and maybe 3g was left in the flask. I tested the main fraction with bisulfite. Negative.

Conclusion: the main fraction is not ketone, I don't think it's the acetyl glycol as that normally smells of acetic acid after distillation, so it's most likely glycol. This fits because anethole's BP is 235, the anethole ketone is 268C, so it makes sense for the glycol to be 278C.

This means a couple things:

1) dilute tosic acid in methanol doesn't work to rearrange the glycol

2) distilling glycol does not rearrange it to ketone

This is not to say the technique doesn't work with the epoxide. Who knows? This is not to say that distilling formyl glycols does not rearrange them. Twodogs said in

Post 229901

(twodogs: "Re: Ketones from Propenylbenzenes via the di-bromides", Novel Discourse) that it works. Remember the reason Horing wanted to check out the epoxide rearrangement by boiling? It wanted to prove that the rearrangement was an intramolecular transformation (not one catalyzed by minute amounts of acid). Perhaps a small amount of H2SO4, p-tosic, or even formic acid from the formyl glycol could be used to catalyze the rearrangement.

PS. When attempting the oxime, I got some white precipitate that definitely wasn't the oxime... what is that stuff? I talked of it in other threads, perhaps some sodium sulfate or something?

PPS. The glycol withstands heat alright, it showed only a very mild discoloration after heating to ~280C for 20 minutes.

For further study: I also wonder if adding just a couple drops of sulfuric acid would bring about the rearrangement of the 20.0g. I'll have to try that!

[foxy2]

Do it solventless!
The diol is liquid right?
Just add the tosic acid right to it.
Those who give up essential liberties for temporary safety deserve neither liberty nor safety

[Chromic]

I wonder if adding just a couple drops of sulfuric acid would bring about the rearrangement of the glycol

Well, no that doesn't work either!!! Bisulfite gave some nice white jagged crystals (hey, it's good to be reaffirmed that the bisulfite test actually works!)... but there's obviously oil not reacting. 65% recovered of the ~20g was recovered. Distillate came across at about the same temperature range (~260-~280). Still most of it is the glycol. Damn.

OK... ONE LAST TIME... as foxy2 said, we're going to do it solventless!  

[Chromic]

Well, that was a waste of time... didn't work... it seemed that the p-tosic acid was breaking down at the high temperatures, and the distillate was murky. I guess there's good reason to stick to the references...

[Chromic]

Well, I finally am ready for another idea... how does this sound to people?

I was thinking about doing a 100mmol batch of the peracetic (glycol from 16.2g isosafrole) in 100ml toluene using 1.0g tosic (same 1% acid solution, but reduced volume than the reference in

Post 264135

(Scooby_Doo: "Ref on Isosafrole to diol via electro", Novel Discourse)).

I plan to make the tosic acid in situ as needed, by slowly refluxing 0.57g of 90% sulfuric acid in 100ml of toluene using a dean stark, when that's done, then to add the glycol and continue the reflux for 20mins. I know toluene refluxes at a higher temp but I hope everything will be OK. Then wash with 10% NaOH and distill the ketone.

Does this sound alright to everyone? Would using that huge excess of toluene stop the sulfuric acid from reacting? If so, this seems like a nice easy way OTC way to do the rearrangement. (minus the unusual piece of glass...)

[Ritter]

Chromic,

That should work just fine, however 20 minutes at reflux temp of toluene is a bit too long.  If you insist running at reflux temp, do it in a HUGE flask because when you add the glycol or formyl glycol there will be a massive effervescence and it really sucks to see your hard work sprayed onto the ceiling.  I recommend you try a temperature in the 100'C range instead of full reflux temp.  When you try this rxn for the first time you will quickly understand why I suggest this!

[Chromic]

Ok, thanx Ritter. I'm preparing the tosic acid now. I used 0.5ml sulfuric and 0.5ml water with 100ml toluene (I know that a bit of an excess, but I felt weird using any less) and am refluxing with tons of stirring and a dean stark... it seems to have the characteristic smell of tosic acid (of other runs I've done), but, there's this black sludge coating the flask. I hope it's just the dirty tosic acid dissolved in water... I hope after refluxing for a few more hours that that water in the sludge collects in the trap and the contents of the flask form some sort of homogeneous solution.

I feel so close to completing this...

[Chromic]

The contents of the flask have turned black and it looks like there's some crap "baked" to the inside of the flask. I hope I can clean the flask out OK.. I'll run it until the cloudy toluene settles in the dean stark, then see...

The dean stark trap made all the difference, it allowed the tosic acid to go into the toluene instead of staying dissolved in the small amount of water! Excellent! This stuff looks pretty nasty, but hopefully it's just a small amount of impurities... time to go prepare some isosafrole glycol.

P.S. I think if I was going to run batch after batch of the rearrangement I'd prepare a bunch of tosic acid in toluene at once, then use a bit of the solution at a time.

[hellman]

I have skimmed through your posts, and have realized there seems to be a simple component missing to your preperation of p-toluenesulphonic acid, Why are you not using HCL,

Here it is how it should read,.

RC6H5+So3-------H2so4---RC6H4So3H+H⁺

Procedure:
In a round bottom flask (50ml) fitted with a reflux condensor place pure toluene (13g, 15ml) and conc. sulphuric acid (11g, 6ml).
Boil the mixture gently for 5 minutes with frequent shaking to mix the layers.  Cool the mixture in ice water and decant and discard the upper layer (principally toluene); add conc hydrochloric acid (12ml), attach the condensor, heat gently ,just as long as necessary to obtain a clear solution and then cool, as before.
The solid that precipetates is mainly the p-acid but is contaminated with the o-isomer; filter it at the pump and repeat the crystalization to obtain the p-isomer (3-3.2 g) mp.103-105.
If the acid is still slightly deliquesent, repeat the crystallisation to obtain a pure sample, mp 105c.

If This is what you have been doing, forget this post.

Hellman

IQ is the rate of logic, as Wisdom increases logic, fear & compromise decrease to reveal objectivity

[Chromic]

Thanks for the post, but I don't have conc HCl (just the whimpy 31%).

Making tosic acid in toluene has worked fine though as I posted (the dean stark is necessary!). The flask was easy to clean too. Some crystals have precipitated from the toluene over the last few days tho (odd?). Anyways, I'm just waiting for some peracetic acid to form, then I'll get on with the epoxidation, then rearrangement and let you all know.

Hopefully this means an increase in everyone's yields.  

[Rhodium]

You can most likely use 31% HCl, conc HCl is only 5% stronger. Just adjust for the different concentration.

[foxy2]

Just gass the 31% HCl and make it concentrated, thats not too hard is it?
Those who give up essential liberties for temporary safety deserve neither liberty nor safety

[hellman]

Just to see , duh,duh, duh, duh,
The rearrange done like this,
Eagerly awaiting the tosic acid rearrangement news,.

Im not a newbee- arrrrgggghhhhhhh
IQ is the rate of logic, as Wisdom increases logic, fear & compromise decrease to reveal objectivity

[Chromic]

Some detail is in

Post 344100

(Chromic: "OTC tosic acid rearrangement SUCCESS!", Methods Discourse). I've got the oxime in the freezer, it doesn't look like it has fully crystallized yet. Perhaps it won't. I'll vac filter tomorrow and let everyone know.

[Bwiti]

CN1201776
Abstract
A process for synthesizing p-cresol by direct alkali fusion of p-toluenesulfonic acid includes such technological steps as preparing p-toluenesulfonic acid by sulfonating reaction of toluene on sulfuric acid, direct alkali fusion of p-toluenesulfonic acid with fused sodium hydroxide to obtain cresol sodium, acidifying it with SO2 to obtain coarse cresol and then separating to obtain p-cresol. Itsadvantages include no need of neutralization step, less consumption of energy and raw materials, short reaction time reduced by 4/5, and high output rate increased by 10%.
---------------------
  I found the above patent at

http://gb.espacenet.com/

, but it's only the abstract. Anyone know where to find the complete specification? Peace!
Love my country, fear my government.

[Osmium]

Can you read chinese?
Because if you don't that patent won't be of any use to you.
I'm not fat just horizontally disproportionate.

[SPISSHAK]

There was an infrared pen I noticed at fryes electroncs the other day that you use to scan froiegn documents and it hooks up to the usb port in youtr computer.
It has a dictonary of 35 languages you download from thier website and it automatically translates whatever you scan.
Looks like one you bees with money should buy one for such uses, and offer a translating service to all of us.
BTW it costs $ 200.00

[Bwiti]

No, I can't read mandarin, smart ass. I just thought I'd throw it out here just in case there's an english text article floating about somewhere, or maybe there are equivalents. I can't find any other patents that are geared specifically towards the production of p-tosic acid, just halogenated stuff.

  For whatever it’s worth, p-tosic acid’s soluble in DMSO

”Other suitable organosulfonic acids will be readily apparent to the skilled of the art. The most preferred organosulfonic acid is para-toluene sulfonic acid (p-TsOH), in view of its wide commercial availability, low cost, and high solubility in the sulfoxide solvents of the invention.”

http://l2.espacenet.com/espacenet/viewer?PN=US4304681&CY=gb&LG=en&DB=EPD

UPDATE: Check this out;

http://l2.espacenet.com/espacenet/viewer?PN=US4242275&CY=gb&LG=en&DB=EPD

Another;

http://l2.espacenet.com/espacenet/bnsviewer?CY=gb&LG=en&DB=EPD&PN=US3458449&ID=US+++3458449A1+I+

More;

http://l2.espacenet.com/espacenet/bnsviewer?CY=gb&LG=en&DB=EPD&PN=US2841612&ID=US+++2841612A1+I+

http://l2.espacenet.com/espacenet/bnsviewer?CY=gb&LG=en&DB=EPD&PN=US2828333&ID=US+++2828333A1+I+

  Peace!

Love my country, fear my government.