Sciencemadness Discussion Board

Sodium formate

jamit - 14-11-2014 at 10:20

Does anyone have any experience in the uses for sodium formate?

I just acquired a 50lb bag and I'm not sure what to do with it. Does anyone want to buy some from me?

chemrox - 14-11-2014 at 10:47

I'll take a Lb.

Dr.Bob - 14-11-2014 at 11:31

It is useful for transfer hydrogenations (use formate instead of H2 to reduce things over Pd/C), and also as a formic acid source.

I thought having a few pounds was a lot. That is a lot of formate.

jamit - 15-11-2014 at 01:26

I agree with you Bob, 50lb, that is a lot of formate. I'm not trying to make money in selling it... I rather do a trade for something others need for something I don't have.

chemrox -- if you want to buy a lb u2u me or we can do a trade.

dr bob -- what do you mean, "use it as a formic acid source"? Are you saying that sodium formate can be turned into formic acid, say by adding sulfuric acid and doing a distilation? or something else? Can you explain. thanks.

[Edited on 15-11-2014 by jamit]

Metacelsus - 15-11-2014 at 05:49

If the sulfuric acid is concentrated, it will make carbon monoxide, so be careful.

jamit - 15-11-2014 at 15:39

Quote: Originally posted by Cheddite Cheese  
If the sulfuric acid is concentrated, it will make carbon monoxide, so be careful.



Thank you for that info, I'll keep that in mind.

Chemosynthesis - 16-11-2014 at 06:27

Quote: Originally posted by jamit  

dr bob -- what do you mean, "use it as a formic acid source"? Are you saying that sodium formate can be turned into formic acid, say by adding sulfuric acid and doing a distilation? or something else? Can you explain. thanks.
This is correct. Formic acid has a pKa of 3.77, which is above that of sulfuric acid (−3 and 1.99 for the diprotic). Additionally, it has a boiling point of 100.8 °C, which is below sulfuric acid's, allowing distillation. Add in equinormal amounts of sulfuric acid and your formate salt then distill the formic acid from your sodium formate mix.

jamit - 17-11-2014 at 08:30

Quote: Originally posted by Chemosynthesis  
Quote: Originally posted by jamit  

dr bob -- what do you mean, "use it as a formic acid source"? Are you saying that sodium formate can be turned into formic acid, say by adding sulfuric acid and doing a distilation? or something else? Can you explain. thanks.
This is correct. Formic acid has a pKa of 3.77, which is above that of sulfuric acid (−3 and 1.99 for the diprotic). Additionally, it has a boiling point of 100.8 °C, which is below sulfuric acid's, allowing distillation. Add in equinormal amounts of sulfuric acid and your formate salt then distill the formic acid from your sodium formate mix.


But will this also produce carbon monoxide as mentioned by Cheddite Cheese?

[Edited on 17-11-2014 by jamit]

gdflp - 17-11-2014 at 09:50

Only reasonably concentrated formic acid will do that. Sulfuric acid at high concentrations is strong enough to dehydrate the formic acid to it's anhydride, CO, but at lower concentrations this will not occur. Similar to how concentrated sulfuric acid and potassium permanganate will form manganese heptoxide, but dilute sulfuric acid and potassium permanganate will form permanganic acid.

jamit - 17-11-2014 at 10:21

Quote: Originally posted by gdflp  
Only reasonably concentrated formic acid will do that. Sulfuric acid at high concentrations is strong enough to dehydrate the formic acid to it's anhydride, CO, but at lower concentrations this will not occur. Similar to how concentrated sulfuric acid and potassium permanganate will form manganese heptoxide, but dilute sulfuric acid and potassium permanganate will form permanganic acid.


So 98% sulfuric acid added to sodium formate will produce CO gas and formic acid, which I can distill off using a condenser?

But at what concentration of sulfuric will it not produce CO? 70% 35%. Any idea?

gdflp - 17-11-2014 at 10:28

No, 98% will produce mostly CO, very little formic acid will be formed. I'm not sure of the concentration of sulfuric acid required, you could test it by putting a small amount in a test tube, adding a pinch of sodium formate and watching for off gassing. Remember the toxicity of carbon monoxide.