Dehydration (cyrstallization) into hexahydrate is easy. Further dehydration of Fe(NO3)3.6H2O is not a simple process, and can be performed only with compounds which very reactive towards water such as N2O5. But a mixture or products can be waited depending on the reaction conditions.

If you want to prepare anhydrous Fe(NO3)3, it is possible in the reaction of Fe2(CO)9 or Fe3(CO12) with N2O4 at 0 .degree.C. Interestingly, Fe(CO)5 gave NO[Fe(NO3)4]. (Chem. Comm. (LOndon), 1968(20), 1208.

Dehydration (cyrstallization) into hexahydrate is easy. Further dehydration of Fe(NO3)3.6H2O is not a simple process, and can be performed only with compounds which very reactive towards water such as N2O5. But a mixture or products can be waited depending on the reaction conditions.

If you want to prepare anhydrous Fe(NO3)3, it is possible in the reaction of Fe2(CO)9 or Fe3(CO12) with N2O4 at 0 .degree.C. Interestingly, Fe(CO)5 gave NO[Fe(NO3)4]. (Chem. Comm. (LOndon), 1968(20), 1208.

Thank you laszlo for your answer. Since I have about 500gr of Fe(NO3)3*9H2O your second solution is not yet practical. However, I think more and more about a trap design maybe using NaOH/KOH pellets before the pump in the vacuum oven to keep the equipment and me safe.

Dear Yair,

I have a feeling, that anhydrous Fe(NO3)3 cannot be prepared from hydrated one. Perhaps mixign this salt with N2O5 can lead to anhydrous salt and exces sof N2O5 can be remoevd as gaseous nitrous oxides. However formation of nitrosonium nitratoferrates cannot be excluded completely.

I have an experience with other salts - perhaps you can try it - refluxing the hydrated salts with triethylorthoformate led to ethyl formate and ethanol. I did it with zinc salts, but the oxidation ability or iron(III) might distrub this reaction. Perhaps it is wort trying to do.

Dear Laszlo thanks again. As an expert (more than me) I fully accept your answer. I assume that for my application which I cannot yet expose I will need to accept realty.

I need an iron salt powder to mix with other solids without sticking together. the only problem is to aim to the molar ratio I aspire.

Live long and prosper...

László is right - Fe(NO3)3 is strong oxidant and not eazy available.

Maybe you need convenient form for cell experiments - check Fe(III) citrate

http://www.mpbio.com/product.php?pid=02195181&country=176

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0081250

Thanks Andrei.

Although Fe(III)Ac is available the price for commercial application is to large. Since no biology is involved, thus purity is not a major issue I will look for other non-halogenated iron salts as sulfide or hydroxide.

What about adding some molecular sieves?

@Melanie

Heating under vacuum is more effective desiccant as compared with molecular sieves ( at 200C and oil-pump vacuum, 3A molecular sieves quickly lose all water ).