Rubidium formate

Structural formula
General
Surname	Rubidium formate
other names	Rubidium methanoate
Molecular formula	CHO 2 Rb
Brief description	hygroscopic white powder
External identifiers / databases
CAS number 3495-35-0 EC number 624-445-0 ECHA InfoCard 100.153.035 PubChem 23673641 Wikidata Q2171583
properties
Molar mass	130.48 g · mol -1
Physical state	firmly
Melting point	170 ° C
solubility	soluble in water
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 315-319-335 P: 261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Rubidium formate is the rubidium salt of formic acid with the constitutional formula Rb (HCOO).

Extraction and presentation

Rubidium formate can be produced from rubidium hydroxide and formic acid by the salt formation reaction .

${\displaystyle {\ce {RbOH + HCOOH -> HCOORb + H2O}}}$

The synthesis from rubidium carbonate and formic acid with the evolution of carbon dioxide is also possible.

${\displaystyle {\ce {Rb2CO3 + 2HCOOH -> 2HCOORb + CO2 ^ + H2O}}}$

Rubidium formate is also produced from rubidium hydride and carbon dioxide .

${\displaystyle {\ce {RbH + CO2 -> HCOORb}}}$

properties

Rubidium formate exists in two different crystal structures. The phase transition takes place at 363 K.

Lattice parameters of the various modifications of rubidium formate
Temperature range	Crystal system	a [pm]	b [pm]	c [pm]	β
up to 363 K	orthorhombic	922.9	463.0	740.8	-
over 363 K	monoclinic	465.52	465.28	751.70	97.610 °

Rubidium formate occurs as a hemihydrate at room temperature . Below 16.5 ° C it exists as a monohydrate, above 51 ° C as an anhydrate . The solubility of rubidium formate in water is described in the table below.

Solubility of HCOORb in water (given in g HCOORb in 100 g saturated solution)
Temperature [° C]	3.3	7.8	9.5	14.0	16.3	28.3	43.6	49.9	60.8	101.7
Amount of HCOORb [g]	78.86	80.71	81.37	83.59	84.61	83.60	87.77	89.23	90.06	93.89

Rubidium formate is thermally stable up to 245 ° C. When heated further, it decomposes, initially with hydrogen being split off, rubidium oxalate is formed , which then breaks down into rubidium carbonate and carbon monoxide .

${\displaystyle {\ce {2HCOORb ->[\Delta] (COO)2Rb2 + H2 ^}}}$

${\displaystyle {\ce {(COO)2Rb2 ->[\Delta] Rb2CO3 + CO ^}}}$

There is also an acidic rubidium formate with the formula RbH (HCOO) ₂ , which is converted into neutral rubidium formate in the range from 50 to 195 ° C. with elimination of a molecule of formic acid.

Individual evidence

1. ^ "Catalog Handbook of Fine Chemicals", Verlag Aldrich Chemical Co., 2000, p. 1470. ( limited preview in the Google book search)
2. ↑ ^{a b c} data sheet rubidium formate from AlfaAesar, accessed on May 26, 2010 ( PDF )(JavaScript required) .
3. ↑ D. Leonesi, G. Berchiesi, A. Cingolani: "Electric Conductivity in Molten Binaries of Alkali Formates and Acetates", in: J. Chem. Eng. Data , 1975 , 20 (1), pp. 31-32; doi : 10.1021 / je60064a026 .
4. ↑ ^{a b} Data sheet Rubidium formats from Sigma-Aldrich , accessed on April 22, 2011 ( PDF ).
5. ^ NV Sidgwick, JAHR Gentle: "The solubilities of the alkali formates and acetates in water" in J. Chem. Soc., Trans. 1922 , 121 , pp. 1837-1843 doi : 10.1039 / CT9222101837
6. ↑ R. Abegg, F. Auerbach: Handbuch der inorganic Chemie. Verlag S. Hirzel, Vol. 2, 1908. P. 425. Full text
7. ^ "A Text-Book of Inorganic Chemistry", Forgotten Books, ISBN 978-1-4510-0469-4 . P. 209. ( limited preview in Google Book search)
8. ↑ SD Hamann, E. Spinner: The effect of pressure on the infrared spectra of the formats of the alkali and alkaline earth metals. In: Australian Journal of Chemistry. 30, 1977, p. 957, doi : 10.1071 / CH9770957 .
9. ^ ^{A b} Y. Masuda, W. Morita, A. Yahata, Y. Yukawa: "Structural studies on the phase transition of rubidium formats", in: Thermochimica Acta , 1998 , 318 , pp. 39-43; doi : 10.1016 / S0040-6031 (98) 00327-X .
10. ↑ ^{a b} Aterton Seidell: "Solubilities Of Organic Compounds Vol - I", S. 1429. Full text
11. ^ ^{A b} Journal of general chemistry of the USSR, English translation, Volume 52, Issues 4–6, p. 1063. ( limited preview in Google book search)
12. ^ T. Meisel, Z. Halmos, K. Seybold, E. Pungor: "The thermal decomposition of alkali metal formats" in Journal of Thermal Analysis and Calorimetry 1975 , 7 (1). Pp. 73-80. doi : 10.1007 / BF01911627