rubidium oxalate

Rubidium carbonate and oxalic acid react to form rubidium oxalate:{{Cite journal |last1=Giglio |first1=E. |last2=Loreti |first2=S. |last3=Pavel |first3=N. V. |date=May 1988 |title=EXAFS: a new approach to the structure of micellar aggregates |url=https://pubs.acs.org/doi/abs/10.1021/j100321a032 |journal=The Journal of Physical Chemistry |language=en |volume=92 |issue=10 |pages=2858–2862 |doi=10.1021/j100321a032 |issn=0022-3654|url-access=subscription }}

:{{chem2|Rb2CO3 + H2C2O4 → Rb2C2O4 + H2O + CO2↑}}

Rubidium oxalate can also be obtained via the thermal decomposition of rubidium formate:{{Cite journal |last1=Meisel |first1=T. |last2=Halmos |first2=Z. |last3=Seybold |first3=K. |last4=Pungor |first4=E. |date=February 1975 |title=The thermal decomposition of alkali metal formates |url=http://link.springer.com/10.1007/BF01911627 |journal=Journal of Thermal Analysis |language=en |volume=7 |issue=1 |pages=73–80 |doi=10.1007/BF01911627 |s2cid=93705025 |issn=0022-5215|url-access=subscription }}

:{{chem2|2 HCOORb → Rb2C2O4 + H2↑}}

From an aqueous solution, rubidium oxalate crystallizes as a monohydrate {{chem2|Rb2C2O4*H2O}} in the monoclinic crystal system.{{Cite book |last1=Ans |first1=Jean d' |url=https://books.google.com/books?id=oWjEKDnsJgEC&pg=PA686 |title=Taschenbuch für Chemiker und Physiker |last2=Lax |first2=Ellen |date=1998 |publisher=Springer |isbn=978-3-540-60035-0 |language=de}} and is isomorphic to potassium oxalate monohydrate {{chem2|K2C2O4*H2O}}.{{Cite journal |last=Pedersen |first=B. |date=1966-03-01 |title=The equilibrium hydrogen–hydrogen distances in the water molecules in potassium and rubidium oxalate monohydrates |url=https://scripts.iucr.org/cgi-bin/paper?S0365110X66000951 |journal=Acta Crystallographica |volume=20 |issue=3 |pages=412–417 |doi=10.1107/S0365110X66000951 |issn=0365-110X|doi-access=free}} Two forms of the anhydrous form ({{chem2|Rb2C2O4}}) exist at room temperature: one form is monoclinic and isotypic to caesium oxalate ({{chem2|Cs2C2O4}}), the other is orthorhombic and isotypic to potassium oxalate ({{chem2|K2C2O4}}).{{Cite journal |last1=Dinnebier |first1=Robert E. |last2=Vensky |first2=Sascha |last3=Panthöfer |first3=Martin |last4=Jansen |first4=Martin |date=2003-03-10 |title=Crystal and molecular structures of alkali oxalates: first proof of a staggered oxalate anion in the solid state |url=https://pubmed.ncbi.nlm.nih.gov/12611516 |journal=Inorganic Chemistry |volume=42 |issue=5 |pages=1499–1507 |doi=10.1021/ic0205536 |issn=0020-1669 |pmid=12611516}} Freshly prepared anhydrous rubidium oxalate initially contains mainly the monoclinic form, but this slowly transforms irreversibly into the orthorhombic form.{{Cite thesis |title=Konformationsaufklärung anorganischer Oxoanionen des Kohlenstoffs und Festkörpersynthesen durch Elektrokristallisation von Ag3O4 und Na3BiO4 |url=http://elib.uni-stuttgart.de/handle/11682/6557 |date=2004 |degree=doctoralThesis |language=de |first=Sascha |last=Vensky}} In 2004, two more high-temperature forms of rubidium oxalate were discovered.{{citation|author=Robert E. Dinnebier, Sascha Vensky, Martin Jansen, Jonathan C. Hanson|date=2005-02-04|doi=10.1002/chem.200400616|issue=4|pages=1119–1129|periodical=Chemistry - A European Journal|title=Crystal Structures and Topological Aspects of the High-Temperature Phases and Decomposition Products of the Alkali-Metal Oxalates M₂[C₂O₄] (M=K, Rb, Cs)|volume=11|pmid=15624128}}

Crystal data of the different forms of rubidium oxalate

The standard enthalpy of formation of the crystalline rubidium oxalate is 1325.0 ± 8.1 kJ/mol.{{Cite journal |last1=Masuda |first1=Y. |last2=Miyamoto |first2=H. |last3=Kaneko |first3=Y. |last4=Hirosawa |first4=K. |date=February 1985 |title=The standard molar enthalpies of formation of crystalline rubidium and cesium oxalates |url=https://linkinghub.elsevier.com/retrieve/pii/0021961485900680 |journal=The Journal of Chemical Thermodynamics |language=en |volume=17 |issue=2 |pages=159–164 |doi=10.1016/0021-9614(85)90068-0|url-access=subscription }}

The decomposition of rubidium oxalate with the release of carbon monoxide and subsequently carbon dioxide and oxygen takes place at {{cvt|507–527|C|F K}}.

:{{chem2|Rb2C2O4 → Rb2CO3 + CO↑}}

:{{chem2|Rb2CO3 → Rb2O + CO2↑}}

:{{chem2|2 Rb2O → 4 Rb + O2↑}}

In addition to the neutral rubidium oxalate {{chem2|Rb2C2O4}}, there is also an acidic salt, rubidium hydrogen oxalate with the formula {{chem2|RbHC2O4}}, which is isomorphic to potassium hydrogen oxalate {{chem2|KHC2O4}}{{Cite journal |last=Piccard |first=Julius |date=1862 |title=Beitrag zur Kenntniss der Rubidiumverbindungen |url=https://onlinelibrary.wiley.com/doi/10.1002/prac.18620860163 |journal=Journal für Praktische Chemie |language=de |volume=86 |issue=1 |pages=449–460 |doi=10.1002/prac.18620860163 |issn=0021-8383}} and forms monoclinic crystals,{{Cite book |last=Watts |first=Henry |url=https://books.google.com/books?id=va0EAAAAYAAJ&pg=PA264 |title=A Dictionary of Chemistry and the Allied Branches of Other Sciences |date=1866 |publisher=Longmans, Green, Longman, Roberts & Green |language=en}} and an acidic dioxalate with the formula {{chem2|RbHC2O4*H2C2O4}}, which exists as a dihydrate, has a density of 2.125 g/cm³ at 18 °C and a solubility of 21 g/L at 21 °C.{{Cite book |last1=Abegg |first1=Richard Wilhelm Heinrich |url=http://archive.org/details/handbuchderanor09koppgoog |title=Handbuch der anorganischen Chemie |last2=Auerbach |first2=Friedrich |last3=Koppel |first3=Ivan |date=1905 |publisher=Leipzig, S. Hirzel |others=University of California}}

Upon evaporation of a solution in hydrogen peroxide, rubidium oxalate forms a monoperhydrate of the formula {{chem2|Rb2C2O4*H2O2}}, which forms monoclinic crystals that are relatively stable in air.{{Cite journal |last1=Pedersen |first1=Berit F. |last2=Seip |first2=Hans M. |last3=Santesson |first3=Johan |last4=Holmberg |first4=Pär |last5=Eriksson |first5=G. |last6=Blinc |first6=R. |last7=Paušak |first7=S. |last8=Ehrenberg |first8=L. |last9=Dumanović |first9=J. |date=1967 |title=The Crystal Structure of Potassium and Rubidium Oxalate Monoperhydrates, K2C2O4.H2O2 and Rb2C2O4.H2O2. |journal=Acta Chemica Scandinavica |language=en |volume=21 |pages=779–790 |doi=10.3891/acta.chem.scand.21-0779 |issn=0904-213X|doi-access=free}}

Rubidium oxalate reacts with hydrogen fluoride to form a hydrofluoridate salt ({{chem2|RbHC2O4*HF}}):{{Cite journal |last1=Weinland |first1=R. F. |last2=Stille |first2=W. |date=1903 |title=Ueber die Anlagerung von Krystallfluorwasserstoff an Oxalate und an Ammoniumtartrat |url=https://onlinelibrary.wiley.com/doi/10.1002/jlac.19033280205 |journal=Justus Liebig's Annalen der Chemie |language=de |volume=328 |issue=2 |pages=149–153 |doi=10.1002/jlac.19033280205}}

:{{chem2|Rb2C2O4 + 2 HF → RbHC2O4*HF + RbF}}

{{reflist}}

{{Rubidium compounds}}

{{Oxalates}}

Category:Rubidium compounds

Category:Oxalates