RadicallyStabilized - 3-6-2023 at 03:22
Hi!
I wonder whether magnesium bisglycinate can be conveniently prepared from glycine and other magnesium salts (citrates, carbonate, chloride, sulfate or
oxide), ideally quite pure.
Does anyone have an idea?
Have a nice weekend, RS
Tsjerk - 3-6-2023 at 08:06
Do you have magnesium hydroxide?
RadicallyStabilized - 4-6-2023 at 04:58
Not currently but I could get some.
Then simply mix solutions stoichiometrically and evaporate the result?
KoiosPhoebus - 22-6-2023 at 08:07
That would be the easiest way to go about it. Note that it may take a while due to
the very low solubility of magnesium hydroxide - I'd recommend leaving it stirring for a good hour before trying to evaporate it. Additionally
magnesium hydroxide is more soluble at colder temperatures and hence I wouldn't heat it until the reaction is complete, to accelerate the complexation
by maintaining a high pH.
Another alternative, if you can't find magnesium hydroxide or oxide, is to first react calcium hydroxide with glycine, and then react the resulting
calcium bisglycinate with magnesium sulphate. Glycine has greater affinity for magnesium and will complex it over calcium; meanwhile the non-complexed
calcium ions will react with the sulphate anion and precipitate as calcium sulphate.
I wouldn't advise using magnesium citrate as the citrate anion is itself a chelating agent for magnesium. In fact, citrate is actually a stronger
chelating agent for magnesium, with a stability constant (log K) for the MgCitrate species of 3.43 versus 1.66 for the MgGly+ species (at 25 deg C,
0.1 M ionic species). Even magnesium bisglycinate (Mg(Gly)2) has a log K of just 2.26 (at 25 deg C, 3.0 M ionic species - a greater concentration of
ionic species can somewhat lower log K).