[gfinetin]

Hi there people!

I just finished searching this forum about "Sodium Ascorbate" and found that u can make that salt by mixing baking soda and Ascorbic Acid, but didn't found how to do that.. I have to add 1 part Ascorbic Acid, 1 part baking soda and 1 part water? And how to make powder out of that? Just to heat it? Willn't high temp. damage the salt?

Thanks,

Gfinetin..

[lavoisier]

Ascorbic acid is said to be sensitive to oxidation by atmospheric oxygen, and this is probably even more true for the salt (due to the negative charge). So I guess you need to protect it from air.
Once it's dry it should be fine, though.

Concerning the quantities, you need to use parts in weight which are proportional to the molecular weight of the reagents and to their stoichiometry. Water of course doesn't really count, as long as you have enough to keep everything homogeneous.
In this case one equivalent of acid reacts with one of base, so look for the MW's of NaHCO3 and ascorbic acid, and that's it.

For drying the salt, I guess the method of choice would be freeze-drying (i.e. freezing the solution of the salt and then putting it into a high-vacuum chamber). Water is removed without melting, and the solid (maybe a hydrate?) is left.

If you don't have access to this equipment, you can probably find a water-miscible solvent in which sodium ascorbate is insoluble (isopropanol? ethanol? I'm just guessing), and just add it to your aqueous solution to precipitate the salt.

You may try and have a look at the Merck Index and/or at www.uspto.gov (US patent office); a patent may exist which describes the manufacturing process of ascorbates.

[DavidW]

Do you need the dry powder form?  Or is the sodium ascorbate going to be used in water anyway?

I recently needed to use sodium ascorbate in a reaction that took place in water.  I couldn't find any sodium ascorbate in my lab, but I did find ascorbic acid.  So what I did was, I added 1 mol of ascorbic acid to 1 mol of sodium hydroxide in water.  I then used the resulting sodium ascorbate solution for my reaction, and it worked fine.

[lavoisier]

I chechek on MerckIndex, and there is in fact a preparation of dry Sodium Ascorbate in US Patent US2442005 by Holland. He uses NaHCO3 in water, room T, and then precipitates the salt with isopropanol. He gives warnings about the very quick oxidation of both the acid and salt in contact with air.

So even if you don't need it dry, keep it under inert atmosphere!

[mkaplan4]

It really depends on the reaction conditions for which you are using the ascorbate. For instance, in copper(I) catalyzed formation of triazoles you add sodium ascorbate to reduce copper, and the preparation of the ascorbate is simply taking equal equivalents of NaHCO3 and ascorbic acid and adding a little bit of water, so you get the CO2 evolution.

[firassh2000]

u should protect the 5,6 OH by acetone to make Isopropylidene derivative and use sod.hydroxide to give u the salt