Sciencemadness Discussion Board

Need to make magnesium citrate

acetone - 13-5-2013 at 09:17

Can I make magnesium citrate by neutralizing magnesium oxide/magnesium hydroxide with citric acid?

chemcam - 13-5-2013 at 09:32

Quote: Originally posted by acetone  
Can I make magnesium citrate by neutralizing magnesium oxide/magnesium hydroxide with citric acid?


You will get magnesium citrate and water by adding citric acid to magnesium hydroxide. This is a very basic question(excuse the pun) why not google it?

EDIT: Magnesium citrate can also be purchased over the counter in the pharmacy section of any store; it is sold as a laxative.

[Edited on 5-13-2013 by chemcam]

Hexavalent - 13-5-2013 at 11:51

Yes.

Mg(OH)2 + C6H8O7 → C6H6MgO7 + 2H2O

MgO + C6H8O7 → C6H6MgO7 + H2O


[Edited on 13-5-2013 by Hexavalent]

chemcam - 13-5-2013 at 12:05

I think citric acid is C6H8O7.

Hexavalent - 13-5-2013 at 12:23

Ah yes, I knew something didn't look quite right. Thanks for pointing that out, I'll update the equations accordingly.

AJKOER - 13-5-2013 at 13:58

I have observed that adding aqueous ammonia to a solution of MgSO4 (from dissolving Epsom Salt in water), forms a fine white suspension of Mg(OH)2, which requires filtering:

MgSO4 + 2 NH3 + 2 H2O --> Mg(OH)2 (s) + (NH4)2SO4

so you can make your own Mg(OH)2 if so inclined.

acetone - 13-5-2013 at 16:07

Thanks guys. Can zinc citrate be made in a similar way? Neutralizing Zinc hydroxide with citric acid?

AJKOER - 13-5-2013 at 17:07

Quote: Originally posted by acetone  
Thanks guys. Can zinc citrate be made in a similar way? Neutralizing Zinc hydroxide with citric acid?


Try slowly dissolving Zn in a solution of H2O2 and Citric acid.

Alternately, add Zn powder to Bleach (NaOCl) to make ZnO:

Zn + NaOCl --> ZnO (s) + NaCl

Wash the Zinc oxide, and then attempt to slowly dissolve in aqueous Citric acid.

Alternate preparations, dissolve Zn in a strong acid to form a soluble salt, and then use NaOH to precipitate Zn(OH)2, but do not use an excess of NaOH. Dissolve the Zn(OH)2 in Citric acid.

Caution: Unless you are absolutely certain there are no traces of heavy metals in your Zinc metal source, I would not recommend internal consumption of any Zn compound you have created.

[Edited on 14-5-2013 by AJKOER]

acetone - 14-5-2013 at 03:07

Quote: Originally posted by AJKOER  

Caution: Unless you are absolutely certain there are no traces of heavy metals in your Zinc metal source, I would not recommend internal consumption of any Zn compound you have created.


You correctly read my mind.

[Edited on 14-5-2013 by acetone]

blogfast25 - 14-5-2013 at 04:35

Zinc powder probably dissolves in citric acid quite easily, use an excess zinc. Because of its structure the three dissociation constants (pKa) are remarkably close, much closer than for other triprotic acids.

Bezaleel - 14-5-2013 at 05:33

But since both the base and the acid are weak, will the reaction run to completeness? Or will the solution be turbid and retain some unreacted hydroxide and acid?

blogfast25 - 14-5-2013 at 09:01

http://www.chemicalbook.com/ChemicalProductProperty_EN_CB113...

So zinc citrate exists, here as a dehydrate. You would definitely use an excess of acid in this case (using zinc hydroxide or zinc carbonate), to prevent acid citrates to form. After that, the zinc citrate and excess acid would presumably be separated by crystallisation.

DubaiAmateurRocketry - 17-5-2013 at 06:05

Is Magnesium Citrate flammable ?

Finnnicus - 17-5-2013 at 06:53

No, it is not flammable! A quick google could give you that.

OP may I ask what you need these salts for? :)

acetone - 22-5-2013 at 18:09

Quote: Originally posted by Finnnicus  
No, it is not flammable! A quick google could give you that.

OP may I ask what you need these salts for? :)


Well I was thinking about consuming them. I've heard that magnesium citrate is a good supplement for calming down an anxious nervous system.

DraconicAcid - 23-5-2013 at 08:22

Quote: Originally posted by acetone  
Quote: Originally posted by Finnnicus  
No, it is not flammable! A quick google could give you that.

OP may I ask what you need these salts for? :)


Well I was thinking about consuming them. I've heard that magnesium citrate is a good supplement for calming down an anxious nervous system.


If you're planning on consuming it, I'd be very wary about using any non-food-grade chemicals to make them (because I'm paranoid that way). Since magnesium citrate is going to be a strong electrolyte in water (very few things act as decent ligands to magnesium), you could probably just dissolve a small amount of Epsom salts in orange juice and drink the mixture. You get your magnesium ions and your citrate, and they're not going to stay together in solution anyway, so they don't really need to start out together.

acetone - 23-5-2013 at 09:04

After all your warnings I'm nervous about consuming them. I think I'll go to the chemist to get a more purer form of reagents. It will be expensive but worth the cost probably. Then I'll remake the citrate.

ParadoxChem126 - 24-5-2013 at 08:17

Can't you buy the stuff at the drugstore? It's sold as a solution that you could probably boil down.

blogfast25 - 24-5-2013 at 09:14

Quote: Originally posted by ParadoxChem126  
Can't you buy the stuff at the drugstore? It's sold as a solution that you could probably boil down.


'Human consumption grade' magnesium products are expensive (as all 'supplements') and often don't really contain much of anything.

I'd go with DA's idea and use Epsom Salt. If you're concerned about trace contaminants in crude Epsom, consider that MgSO4 has fairly strong temperature-solubility dependence and can be 'thermally' recrystallized easily. After couple of recrystallisations your product is probably purer than some pharma grades. Add some citric acid ('beer grade' e.g.) and Bob's your uncle. Bear in mind that it is a laxative.

[Edited on 24-5-2013 by blogfast25]

acetone - 26-5-2013 at 09:50

Just found out that magnesium oxide does not dissolve in citric acid but magnesium hydroxide does.

Random - 5-6-2013 at 15:07

How much of it you really need as a laxative? I reguralry consume mg citrate supplements.

ddG - 2-12-2013 at 11:23

Quote: Originally posted by blogfast25  
Quote: Originally posted by ParadoxChem126  
Can't you buy the stuff at the drugstore? It's sold as a solution that you could probably boil down.


'Human consumption grade' magnesium products are expensive (as all 'supplements') and often don't really contain much of anything.

I'd go with DA's idea and use Epsom Salt. If you're concerned about trace contaminants in crude Epsom, consider that MgSO4 has fairly strong temperature-solubility dependence and can be 'thermally' recrystallized easily. After couple of recrystallisations your product is probably purer than some pharma grades. Add some citric acid ('beer grade' e.g.) and Bob's your uncle. Bear in mind that it is a laxative.

[Edited on 24-5-2013 by blogfast25]


Sorry for reviving an old thread. I've been doing this lately, and wasn't comfortable reacting MgSO4 with Citric Acid directly, as I figured the SO4 has to go somewhere, and it would probably end up in my product as various sulfate/sulfite/sulfide contaminants. I've been reacting MgSO4 with NaHCO3 or Na2CO3, filtering out the insoluable MgCO3, washing it, and then reacting it with food grade citric acid. If you use NaHCO3, you will end up with Mg(HCO3)2 in the solution, which will only precipitate out upon heating the solution to its boiling point, and driving out the excess CO2, which is a pain. At any rate, I'm thinking that the above is giving me a purer product, thanks to the insolubility of the MgCO3, and the ease with which CO2 byproduct is driven from the magnesium citirate product.

Any thoughts on this? Unnecessary?

blogfast25 - 2-12-2013 at 12:08

The purity of your Mg citrate may be compromised if occlusion occurs when you precipitate the MgCO3. I don't know if MgCO3 is prone to occluding but CaCO3 for instance is quite notorious for it. Occlusion can also be reduced by precipitating from more dilute solutions.

It's probably best to test your product for sulphates with BaCl2 or Ba(NO3)2. Use a blank (distilled water) to compare your result with. The test is very sensitive for sulphates, due to BaSO4 precipitation.

There's also a basic magnesium carbonate.

[Edited on 2-12-2013 by blogfast25]

ddG - 2-12-2013 at 14:37

Quote: Originally posted by blogfast25  
The purity of your Mg citrate may be compromised if occlusion occurs when you precipitate the MgCO3. I don't know if MgCO3 is prone to occluding but CaCO3 for instance is quite notorious for it. Occlusion can also be reduced by precipitating from more dilute solutions.

It's probably best to test your product for sulphates with BaCl2 or Ba(NO3)2. Use a blank (distilled water) to compare your result with. The test is very sensitive for sulphates, due to BaSO4 precipitation.

There's also a basic magnesium carbonate.

[Edited on 2-12-2013 by blogfast25]


Love it! And I can put that into practice, as I have some BaCO3 just sittin' around, waiting to be mixed with some HCl. Thanks!

AJKOER - 3-12-2013 at 06:43

A possibly important point, this is one of those instances where the compound's names (Magnesium citrate, C6H6MgO7) is loosely applied to two possible salts. Per Wiki (http://en.wikipedia.org/wiki/Magnesium_citrate ) to quote:

"Magnesium citrate (1:1) (1 magnesium atom per citrate molecule), called below by the common but ambiguous name magnesium citrate (which can also mean magnesium citrate (3:2)), is a magnesium preparation in salt form with citric acid. It is a chemical agent used medicinally as a saline laxative..."

The other Magnesium citrate, C12H10Mg3O14, is said to be not very soluble in water and has a bitter taste (see http://en.wikipedia.org/wiki/Magnesium_citrate_(3:2) ).

Now I have experimented with Citric acid and it can form three possible Sodium citrate salts. As such, if one uses a slight excess of MgCO3, for example, the product formed may not be exclusively Magnesium citrate (1:1). I would suggest cooling to remove the unwanted less soluble Mg salt or employing an excess of Citric acid (note, per quote above: "is a magnesium preparation in salt form with citric acid" and this source (http://www.drugfuture.com/Pharmacopoeia/USP32/pub/data/v3227... ): "Oral Solution contains a dry mixture of Magnesium Carbonate, Citric Acid, and Potassium Citrate"). What is a bit disturbing is that my last source, a prescription drug preparation information site, incorrectly (?) states "magnesium citrate (C12H10Mg3O14)".

In any event, if you unwisely decide to taste your product, and it is a slightly bitter, there may be a non-lethal explanation.

[EDIT] If one adds purified MgCO3 to the Orange juice, I suspect it would be easy to overdue on the Mg, thus forming some of the bitter less soluble Magnesium citrate.


[Edited on 3-12-2013 by AJKOER]

ddG - 4-12-2013 at 07:23

Yeah, I saw that. The first time I did this, I used lemon juice for the citric acid, and I had a white, poorly-soluble precipitate that I at first assumed was the 3:2 Mag Citrate. However, additional citric acid (food grade) dissolved the precipitate with the evolution of a gas, so I think it was probably just unreacted MgCO3 or a mixture of the 3:2 and the carbonate. Using a fruit juice for the citric acid is inefficient, because the acid comprises such a small part of the juice; as a result, overdosing by mixing MgCO3 with OJ seems unlikely, as you'll have to imbibe a fair amount of unreacted carbonate, which is bitter and nasty. Either that, or drink an immense amount of juice, I guess. Either way, you'll be spending a lot of time on the potty.