Original scientific paper

https://doi.org/10.5562/cca3361

Cocrystals of Barbituric Acid with Alkali Metal Halides

William Clegg orcid.org/0000-0003-1643-5298 ; Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
Gary S. Nichol orcid.org/0000-0002-1597-3679 ; Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
Ashish Patel ; Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

Abstract

Barbituric acid BAH reacts with potassium, rubidium and caesium iodides in methanol, forming anhydrous BAH·MI. BAH·CsI has a different 8-fold coordination geometry from corresponding alkali metal bromides, intermediate between triangular dodecahedral and square antiprismatic. BAH·KI and BAH·RbI display features that are new for this family, with a high coordination number of 9, and with no involvement of iodide in either coordination or hydrogen bonding, its environment being six BAH molecules. BAH·NaCl·2H2O, prepared by successive treatment of BAH in water with sodium hydroxide and dilute hydrochloric acid, is isostructural with other chlorides and bromides, with 7-coordinate Na+ and a network of hydrogen bonding. Two BAH molecules are oxidatively coupled by aqueous potassium permanganate to generate 5-hydroxyhydurilic acid, isolated as a hydrated potassium salt with K+ in an unusually low 5-coordination. The folding of the BAH molecule in its full range of known crystal structures is analysed; the dihedral folding angle ranges from 0 to approximately 20 °, uncorrelated with any other particular features of the structures.

This work is licensed under a Creative Commons Attribution 4.0 International License.

Keywords

barbituric acid; alkali metals; crystal structure; cocrystals

Hrčak ID:

202768

URI

https://hrcak.srce.hr/202768

Publication date:

4.6.2018.

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