Sciencemadness Discussion Board - calcium nitrite synthesis

calcium nitrite synthesis

karandikarmv - 4-9-2003 at 21:19

i am trying to synthesis calcium nitrite.
i have taken calcium nitrate and tried to reduce it to calcium nitrite by using a reducing agent and also by thermal treatment. but i m not getting the desired product .
how about using ammonium nitrate and lime? or using sodium nitrite and lime?
is there any other way to synthesis calcium nitrite...please let me know

[Edited on 5-9-2003 by karandikarmv]

Mephisto - 5-9-2003 at 01:54

I know for sure, that there is a synthesis described in the first volume of the second edition of „Handbook of Preparative Inorganic Chemistry“ (G. Brauer, Academic Press, New York, 1963). It’s a standard reference work, so you can find it in the most libraries.

Reduction of calcium nitrate with lead didn’t work?

karandikarmv - 8-9-2003 at 00:15

Mephisto
i have checked in the book, but its not there

Mephisto - 8-9-2003 at 08:52

Sorry, I checked it too fast. So I messed up calcium nitrite with calcium nitride.

Maybe you’ve got an other process, which evolves nitrous fumes. You can lead the fumes through Ca(OH)2 and get a solution of calcium nitrite. A nice way of recycling.

Sorry for the misguidance.

karandikarmv - 8-9-2003 at 20:10

Mephisto

is the following reaction possible?
Ca(NO3)2------ Ca(NO2)2 +O2
what is the temp. at which O2 will be evolved from Ca. nitrate?
the manufactures of Ca-nitrite claim it to be 500 deg.C
i have tried the above reaction and could get some Ca.nitrite, analysed as NO2 by spectro. method, but its only ~20% conversion from nitrate to nitrite.
does recrystallisation required?
i am interested in 100%conversion of nitrate to nitrite.
i have also searched literature on the net and in library,but unable to get a complete paper.

Mephisto - 9-9-2003 at 08:37

There isn’t much source material about the synthesis of calcium nitrite. The conversion of calcium nitrate to the nitrite won’t work. Here’s what I found:

‚Calcium nitrite decomposes to calcium oxide and a mixture of nitrogen monoxide and nitrogen dioxide at temperatures as low as 250 °C.‘ That’s the reason why calcium nitrate is directly converted to calcium oxide. ‚Thermal decomposition of calcium nitrate begins at 500 °C.
Ca(NO3)2 --> CaO + 2 NO2+ 1/2 O2 DH = +369 kJ/mol‘

A recrystallistion is possible, but I haven’t the exact solubility data. Only that:

‚The nitrite can be recovered as the tetrahydrate Ca(NO2)2 · 4H2O by concentration and cooling. This product has a lower solubility than calcium nitrate tetrahydrate Ca(NO2)2· 4H2O.‘

The synthesis form Ca(OH)2 and nitrous gases yields to a technical product:

‚Calcium nitrite is formed when a mixture of gaseous nitrogen dioxide and nitrogen monoxide (OD < 50 %) is absorbed in a suspension of calcium hydroxide. This process is used to clean up the final tail gases from low-pressure nitric acid plants when no demand exists for sodium nitrate or sodium nitrite. The spent absorption liquor contains calcium nitrite and generally some calcium nitrate.‘

I hope, I could help a little bit. If you get access to a Beilstein database, you should find more.

Quoted from: [Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2002 Electronic Release (c) Wiley-VCH. Weinheim. Germany.]

[Edited on 9-9-2003 by Mephisto]

madscientist - 11-9-2003 at 12:21

http://www.sciencemadness.org/talk/viewthread.php?tid=52

karandikarmv - 17-9-2003 at 21:37

Mephisto

today i got a little success,i hope that i have got some ca- nitrite, i am trying to analyse the nitrite in calcium nitrite

the spectrophotometric method for nitrite is only for low concentration of nitrite... so i am trying the volumetric method as per ASTM using potassium permanganate and sodium oxalate

do u suggest any other method for high nitrite concentration?

Mephisto - 18-9-2003 at 03:35

Sorry, I haven’t much knowledge about volumetric analysis.

BTW, why are intersted in another method? The KMnO4 and oxalate method should be right.

kingspaz - 18-9-2003 at 06:26

would it not be possible to convert by recrystalisation?

like make some KNO2. make a hot saturated solution of Ca(NO3)2 and the KNO2 then allow to cool....KNO3 will crystalise out (i think, i have no solubility data to hand a bad memory!) then you're left with Ca(NO2)2 in solution.

Sedit - 15-3-2009 at 13:06

[moved]

[Edited on 16-3-2009 by Sedit]

Calcium Nitrite from Sodium Nitrite and Hydrated Lime

Rosco Bodine - 16-9-2010 at 09:10

Quote: Originally posted by karandikarmv

i am trying to synthesis calcium nitrite.
i have taken calcium nitrate and tried to reduce it to calcium nitrite by using a reducing agent and also by thermal treatment. but i m not getting the desired product .
how about using ammonium nitrate and lime? or using sodium nitrite and lime?
is there any other way to synthesis calcium nitrite...please let me know

[Edited on 5-9-2003 by karandikarmv]

Hopefully nobody was in a big hurry for an answer to your question

Sodium Nitrite and Lime will work . See attached patent US4294813

Attachment: US4294813 Calcium Nitrite from Sodium Nitrite.pdf (103kB)
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