Sciencemadness Discussion Board

PREPERATION OF ACIDS FROM ALKALI SALTS

SHADYCHASE54 - 17-1-2011 at 19:23

HELLO OUT THERE I AM A NEW MEMBER BUT A LONG TIME READER. I AM A NOVICE CHEMIST LEARNING VIA TEXT AS WELL AS TRIAL AND ERROR. I REALIZE THIS IS A RATHER ELEMENTARY QUESTION SO IF IT ANNOYS ANYONE DONT BOTHER YOURSELF BY RESPONDING HOWEVER HELP WOULD BE APPRECIATED.

I AM INTERESTED IN PREPARING FORMIC ACID FROM SODIUM FORMATE (ELEMENTARY I KNOW?) TO DETERMINE THE REQUIRED AMOUNT OF ACID IS IT MERELY A MATTER OF MATCHING THE TWO MOLE TO MOLE? TAKING INTO ACCONT THE ACIDS CONCENTRATION OF COURSE? THANKS IN ADVANCE FOR ANY RESPONCE.

mr.crow - 17-1-2011 at 19:33

PLEASE STOP SHOUTING

SHADYCHASE54 - 17-1-2011 at 19:40

HA I AM MERLY LAZY NOT LOUD HENCE THE LACK OF EXCLAMATION POINTES BUT THANK YOU MONSIEUR CROW

psychokinetic - 17-1-2011 at 19:41

THE SHIFT KEY IS OVER TO THE LEFT.

You don't have to yell just because we're really far away ;).

And yes, I do believe you need a mole to mole ratio.

EDIT: It's on wikipedia o.o'
Quote:
It can also be obtained by reacting chloroform with an alcoholic solution of sodium hydroxide.

CHCl3 + 4NaOH → HCOONa + 3NaCl + 2H2O

or by reacting sodium hydroxide with chloral hydrate.

C2HCl3(OH)2 + NaOH → CHCl3 + HCOONa + H2O

The latter method is, in general, preferred to the former because the low aqueous solubility of CHCl3 makes it easier to separate out from the sodium formate solution, by fractional crystallization, than the soluble NaCl would be.

For commercial use, sodium formate is produced by absorbing carbon monoxide under pressure in solid sodium hydroxide at 160 °C.

CO + NaOH → HCOONa



[Edited on 18-1-2011 by psychokinetic]

SHADYCHASE54 - 17-1-2011 at 19:49

THANKS PSYCHOKINETIC I DO APPRECIATE THE CONFORMATION TRULY.

Magic Muzzlet - 17-1-2011 at 19:51

I think he wants to make formic acid from the sodium formate, but the question is quite unclear to me. In this case I'm thinking you need some sulfuric acid and distill like nitric acid from KNO3, probably an excess of H2SO4. An easier method I would think is oxalic acid and glycerin, also giving you allyl alcohol. 2 products at once, beautiful! ;)

SHADYCHASE54 - 17-1-2011 at 20:14

YES I DO INFACT REQUIRE SOME FORMIC ACID BUT THE QUESTION WAS A GENERAL QUESTION FOR THE PREPERATION OF ANY ACID FROM ITS RESPECTIVE ALKALI SALT. WOW WHAT A RUN ON, ANYWAY I REALLY DIG THE ADVICE, ESPECIALLY THE, "OXYALIC ACID + GLYCEROL= FORMIC AND ALLY" HOW VERY ELEGANT THANKS AGAIN.

SHADYCHASE54 - 17-1-2011 at 20:26

I AM REALLY INTERESTEDIN THE FORMENTIONED SYNTH. (OXYALIC+GLYCERINE= ALLY ALCOHOL AND FORMIC ACID) COULD YOU OR SOMEONE ELABORATE ON THE PARTICULARS OF THIS REACTION? I ASSUME I WOULD REFLUX THE TWO REACTANTS THEN FRACTION THE PRODUCT. WHAT TEMP. AND DURATION WOULD BE REQUIRED.

DJF90 - 17-1-2011 at 20:28

Don't use sulfuric acid unless you want to gas yourself with CO!

Magic Muzzlet - 17-1-2011 at 20:29

There is lots of info in many places look on this forum, google, lambdasyn possibly versuchschemie.de. It is basically straight to distillation if i remember correctly. :)

SHADYCHASE54 - 17-1-2011 at 20:31

THANKS

DDTea - 17-1-2011 at 23:46

Quote: Originally posted by psychokinetic  
THE

Quote:
It can also be obtained by reacting chloroform with an alcoholic solution of sodium hydroxide.

CHCl3 + 4NaOH → HCOONa + 3NaCl + 2H2O

or by reacting sodium hydroxide with chloral hydrate.

C2HCl3(OH)2 + NaOH → CHCl3 + HCOONa + H2O

The latter method is, in general, preferred to the former because the low aqueous solubility of CHCl3 makes it easier to separate out from the sodium formate solution, by fractional crystallization, than the soluble NaCl would be.

For commercial use, sodium formate is produced by absorbing carbon monoxide under pressure in solid sodium hydroxide at 160 °C.

CO + NaOH → HCOONa



[Edited on 18-1-2011 by psychokinetic]


I wonder if there's some limit to the chloral hydrate route (besides cost--this seems like a dumb route): chloroform can be deprotonated by strong bases, forming a water-soluble cation--this has screwed up more than one alkaloid extraction for people unaware of this.

EDIT: and for the love of God, the flying spaghetti monster, or the whatever you believe in or don't believe in, turn off caps-lock--it's painful to read!

[Edited on 1-18-11 by DDTea]

woelen - 18-1-2011 at 05:20

SHADYCHASE54 : I do not ask to turn of caps lock, but I REQUEST it. From now on I want to see normal text, complete with punctuation and correct use of capital letters. if not, then this thread is good for detritus.

ScienceSquirrel - 18-1-2011 at 07:42

I doubt that making formic acid or worse allyl alcohol is a candidate for an experiment by a novice chemist working on his own.
Formic acid in the presence of concentrated sulphuric acid can decompose to form carbon monoxide, a deadly and insiduous gas, and allyl alcohol is a powerful lacrymator.

[Edited on 18-1-2011 by ScienceSquirrel]

The_Davster - 18-1-2011 at 08:28

Years and years ago I prepared sodium formate from chloroform and sodium hydroxide and I can attest it works well, but is rather slow at room temp.

SHADYCHASE54 - 19-1-2011 at 14:55

Ok, ok and ok i submit. I realize I am a newbie on this system and to fend off potential austracism i will fawn in the shadow of wollen. Truly i have found his comments on other forums, in some cases, invaluable. regarding Science Squirrel's coment suggesting caution, i appreciate your concern and rest assured I am very careful before ever moving from the notebook to the lab; before I ever procced i painstakingly study/query texts, internet, patent or more educated friends.
Thank you to everyone who commented it was helpful.

ScienceSquirrel - 19-1-2011 at 15:19

Quote: Originally posted by SHADYCHASE54  
Ok, ok and ok i submit. I realize I am a newbie on this system and to fend off potential austracism i will fawn in the shadow of wollen. Truly i have found his comments on other forums, in some cases, invaluable. regarding Science Squirrel's coment suggesting caution, i appreciate your concern and rest assured I am very careful before ever moving from the notebook to the lab; before I ever procced i painstakingly study/query texts, internet, patent or more educated friends.
Thank you to everyone who commented it was helpful.


Austracism is truly horrible.
You get to live in a country where all the men are named Bruce and all the women are named Sheila.
All the grub is cooked on a barbie, which is a skinny model of a woman made out of plastic, and served with a tinny, a can of freezing cold beer! :D
Depending on where you live, you have camels, crocs, cane toads, kangas, funnel webs, eight of the ten most poisonous snakes in the world, blue ringed octopi and more to contend with.
Apart from that you have a whole continent occupied by less than the population of almost every European country, dark skies with unforgettable star scapes, the Great Barrier Reef and miles of deserted beaches.