Author Topic: How to make PTSA from 30% H2SO4  (Read 2114 times)

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acx01b

  • Guest
How to make PTSA from 30% H2SO4
« on: May 18, 2004, 07:23:00 PM »
sorry to open a new subject.... more visible like that...

I tried electrolysis of my 32% H2SO4:

Graphite electrode where H2 is formed is not destroyed.

Electrode where O2 is formed:
1st time Graphite electrode: destroyed
2nd time Cu: same
3rd time Al: same

i dont even try Fe, Zn and Sn/Pb, will be destroyed i guess!

i could find an Ag electrode, but that's all.

do you think Ag would work ?
do you have other ideas ? other way than electrolysis?

i cant do any distillations, but i read somewhere h2so4(aq)could just be boiled.

what concentration can i get then ?

i have some dried MgSo4, can i use it to make conc. H2SO4 ?

tks by advance

Nicodem

  • Guest
UTFSE or just boil it off
« Reply #1 on: May 18, 2004, 08:10:00 PM »
other way than electrolysis?

Make your life easy and just boil the water off. Stop when it gets fuming H2SO4 vapors (I guess that would bee somewhere above 250°C). This will get it concentrated enough for TsOH preparation if you will use a Dean-Stark trap.

what concentration can i get then ?

That depends on how high you will lett the boiling temperature rise and if you will use a vacuum pump or not. If you use a vater pump and value your life don't forget the water trap. Generaly it should not bee a problem to get a concentration of 85% or more.

PS: Please bee careful. Playing with boiling H2SO4 is not for the clumsy and careless. Wear all the protection you can.


acx01b

  • Guest
...
« Reply #2 on: May 18, 2004, 08:22:00 PM »
ok

a flask, a pipe on it, the pipe goes in a cold red-methyl solution.

when the redmethyl goes red, i stop boiling

:-)

BUT I NEED TO KNOW SOMETHING BEFORE TRYING:
can my flask (pyrex) EXPLODE ????
(i guess the tube cannot xplode because it is not supposed to contain some boiling conc. h2so4)

can i even try with a pyrex test tube (will it explode?)????

Nicodem

  • Guest
a flask, a pipe on it, the pipe goes in a cold
« Reply #3 on: May 18, 2004, 09:45:00 PM »
a flask, a pipe on it, the pipe goes in a cold red-methyl solution.

And what if a suckback occurs?  ::)
Let the flask bee open. Believe me, when the H2SO4 vapors start coming out you will notice it without problems. :-[

can my flask (pyrex) EXPLODE ????

Sure it can. This can always happen so don't use a flame to heat and preferably put the flask on a silica bath over an electric stowe. Make sure you don't forget the boiling chips and just stay far away!
Actually, it usually boils just nicely all the way up.


acx01b

  • Guest
i just have gaz flamm :-( (methane)
« Reply #4 on: May 18, 2004, 11:05:00 PM »
i just have gaz flamm :-( (methane)

aluminium paper (dont know if it is the good word) around the flaks or the test tube, good / or bad idea?


anyway i'll try tonight with winter clothes and big glasses, with 10 ml, so i hope to be still alive tomorrow to tell you!!! :p)

acx01b

  • Guest
Heeelp!!!!!
« Reply #5 on: May 20, 2004, 11:53:00 PM »
i slowly distillated my 30% h2so4 (about 70mL), i got about 40mL of water + h2so4.

the acid in the flask became brown, and then TOTALLY black like petrol....

i am gonna try to calculate the concentration of the acid obtained with some NaOH and Ph paper,

BUT THE IMPORTANT thing is that i tried to mix 3mL of the acid with 1mL toluene, and no reaction happened... :-(

the 2 phases are still there....... :-(

Nicodem

  • Guest
the acid in the flask became brown, and then...
« Reply #6 on: May 21, 2004, 07:40:00 AM »
the acid in the flask became brown, and then TOTALLY black like petrol....

Then your acid is not sulphuric acid or it contains impuritues. Or maybe you simply used boiling chips that dissolved (break a tea cup and use the ceramic chips). You should buy pure 30-35% sulphuric acid used to refill bateries. When concentrated it remains completely colorless.

the 2 phases are still there....... :-(

Then how do you know that no reaction happened? Who told you that toluene dissolves in H2SO4?


acx01b

  • Guest
it is some pure h2so4 for bateries !!!
« Reply #7 on: May 21, 2004, 05:38:00 PM »
it is some pure h2so4 for bateries !!! (it is written on the bottle: pure acid...32%)

i didnt use any boiling chips.
so what should happen when mixing with the toluene?

it is the H2SO4 which should be dissolved in the toluene ?

Nicodem

  • Guest
If it was really pure than it should not ...
« Reply #8 on: May 21, 2004, 06:44:00 PM »
If it was really pure than it should not became dark. You might consider buying another one from a different manufacturer.

i didnt use any boiling chips.

You like playing with your life, don't you? ::)

When mixing with the toluene nothing special happens. You get two layers, H2SO4 is the lower one. The toluene layer slowly gets a little yellow or dark. If you would let it stay for a few days it would probably get black.
Why do you think something special should happen?


acx01b

  • Guest
if i like playing with my life.....
« Reply #9 on: May 22, 2004, 08:40:00 PM »
if i like playing with my life..... nope lol...

my toluene (just mixed with the maybe conc. h2so4) didnt get any colour, its still quite clean.
So what is the magic word to make PTSA from toluene and the H2SO4 I made ? I hope it will be then possible to separate the PTSA from the black stuffs of the acid..


tks by advance bro...

acx01b

  • Guest
just to say that i mixed 0.5gram powdered NaCl
« Reply #10 on: May 22, 2004, 11:10:00 PM »
just to say that i mixed 0.5gram powdered NaCl with 2mL of my conc. H2SO4: and big reaction happened (MgSO4 crystallization, and a few HCL gaz), reaction that doesn't happen with my 30% H2SO4.

i know that HCL conc. = 50% weight.
so i know now that my H2SO4 is more concentrated in H+ than muriatic 50% is.

hypo

  • Guest
total nonsense
« Reply #11 on: May 22, 2004, 11:16:00 PM »
> i know that HCL conc. = 50% weight.

not at atmospheric pressure, no.

> so i know now that my H2SO4 is more concentrated in H+ than muriatic 50% is

no, you don't.

measure the density. or titrate against NaOH.


acx01b

  • Guest
that my h2so4 react with nacl is a good point...
« Reply #12 on: May 22, 2004, 11:52:00 PM »
that my h2so4 reacts with nacl is a good point no?
it means that it is quite conc.

acx01b

  • Guest
oK. new things happened: i have mixed about 20
« Reply #13 on: May 23, 2004, 05:44:00 AM »
oK.

new things happened:

i have mixed about 20 mL toluene with the 30mL of conc. acid i got, and i very slowly refluxed it WITHOUT stirring!

i have let it refluxing about 2x10min, and then 6x5 min.
every time i have let the mixt cooling with external cooling, i could see cristallization in the toluene phase.

after the last 5min, i have let it cooling 10min, then i opened the flask (hard because still hot), and with a 2mL pipet (lol) i extrated the toluene phase while it was still hot. 15min after reflux stopped, i had 90% of my toluene phase in a test tube, with some (black, petrol like) H2SO4. I heated the test tube for 2min (crystals completely dissolved), and with the same 2mL pipet I extracted my toluene phase to a glass.

now i have a glass with some cristallized ptsa (mono, di, trihydrate ?) in toluene (16mL).

So I HAVE MY ANSWER NOW, IT IS VERY EAZY (WITH REFLUX EQUIPMENT) TO MAKE SOME NON-DRIED PTSA FROM 30% H2SO4 AND TOLUENE.

but how to dry the ptsa is another step....
and evaluating yields another one too!

acx01b

  • Guest
THEN: i just finished reading all the 106...
« Reply #14 on: May 23, 2004, 06:20:00 AM »
THEN:
i just finished reading all the 106 posts you can find by typing "tosic acid" in the search page, and i didnt find anyone teaching clearly how to make dried ptsa from ptsa cristallized in toluene.

1: do i need to filter ??? (i hope no! big yield loosing in these scales!)
2: i have read like 5 or 6 times: << PTSA monohydrate is refluxed with a water trap (dean stark) in toluene, to get dried ptsa >>

why ? toluene wont form an azeotrope with the water ?
ptsa wont be vapourized ?

in fact i just want to know:
in the water trap, i will get some toluene and a few water ? or will i only get some water?

and finally: thinking about just stirring the ptsa monohydrate-toluene with 5grams MgSO4 is stupid ?
(if some 50+ % h2so4 doesnt make the ptsa dried, dried powdered mgso4 cannot too)

Nicodem

  • Guest
Read before doing experiments
« Reply #15 on: May 23, 2004, 03:25:00 PM »
OK, don't get offended, this is only a suggestion, also for the sake of your physical health:

Go in the library, take some good books about theoretical as well as preparative chemistry and read them thorougly.


acx01b

  • Guest
ty vm for suggestion, but you cannot answer me
« Reply #16 on: May 23, 2004, 10:17:00 PM »
ty vm for suggestion, but you cannot answer me instead of ???

because i'm probably not a pro of chemistry, but i didn't fail in making ptsa monohydrate from 30% h2so4 !  so why not to try to make dried ptsa ???? so close to succeed!!!!!!!!!!!!

i'll read some books this summer

Nicodem

  • Guest
Yes, yes
« Reply #17 on: May 24, 2004, 08:18:00 PM »
ty vm for suggestion, but you cannot answer me instead of ???

I would answer your questions if I would understand them. Instead of asking a question, all you do is asking a lot of useless questions and questioning the answers when there is no need for it. Besides, if you wanted instructions on how to concentrate H2SO4 and make tosic acid why didn’t you post in the Newbee forum? More people with experience on this would bee able to take some time and answer. What exactly is your main question? Instead for asking for tips and instructions all you do is question the well established preparation of TsOH×H2O and loosing time with what you could readily found out by yourself with an excursion to the library. Like here, look:

why ? toluene wont form an azeotrope with the water ?
ptsa wont be vapourized ?

in fact i just want to know:
in the water trap, i will get some toluene and a few water ? or will i only get some water?

and finally: thinking about just stirring the ptsa monohydrate-toluene with 5grams MgSO4 is stupid ?


- Toluene and most water inmishelable solvents form azeotropes (benzene, hexane, CHCl3 etc.).
- Tosic acid does not evaporate and why should it?
- In a Dean-Stark trap you will get water at its bottom (water has higher density than toluene - this is why this trap works).
- Trying to dry a hydrate by forming another hydrate is not feasible. MgSO4 does bind water, but so does TsOH, meaning that even if TsOH×H2O would give up some water it would never give up all the water (thermodynamic equilibriums). This is not really a feasible way to get anhydrous tosic acid.

OK enough, I guess you don't need pure tosic acid, so this will do:

Follow the usual procedure for the sulphonation of toluene (like described in Organikum or whatever other preparative book). At the end of the reflux (with a Dean-Stark trap!) separate the toluene layer while still relatively hot (>60°C) so that no tosic acid crystallizes out. This is best done simply decanting the above layer off. Then distill this toluene fraction, reuse the distilled toluene to extract the remaining black H2SO4 phase by heating and mixing them for a few minutes. Decant again in the distilling flask and repeat. Doing this three or four time should bee enough. In the distillation flask you will bee left with brown tosic acid contaminated with some toluene, o-toluenesulphonic acid, H2SO4 and other stuff. This waxy stuff will solidify on cooling. This product is very crude and dirty but it will do just fine for most uses. If you took care to cleanly separate the toluene fractions from the black sulphuric acid fraction, you might bee lucky and see the TsOH crystallize.

This was checked and is as simple as it can bee done.

so close to succeed!!!!!!!!!!!!

Yeah, and don’t forget the damn boiling chips again or you will end up in an emergency room with your face unrecognizable from hot sulphuric acid burns! No serious chemist ever forgets boiling chips, not even if he is distilling water.


hypo

  • Guest
read this
« Reply #18 on: May 24, 2004, 08:48:00 PM »
this should contain all you need:

Post 389646

(Antoncho: "Toluenesulfonic acid - tips and tricks.", Methods Discourse)


> No serious chemist ever forgets boiling chips, not even if he is distilling water.

??? who the heck distills without magstirrer ???


acx01b

  • Guest
if rhodium wants to put the posts in newbee...
« Reply #19 on: May 24, 2004, 11:57:00 PM »
if rhodium wants to put the posts in newbee forum np no difference for me!

tyvm for the time u took to anwer.