Two polymorphs of 5-cyclohexyl-5-ethylbarbituric acid and their packing relationships with other barbiturates.
Polymorph (Ia) (m.p. 474 K) of the title compound, C(12)H(18)N(2)O(3), displays an N-H...O=C hydrogen-bonded layer structure which contains R(6)(6)(28) rings connecting six molecules, as well as R2(2)(8) rings linking two molecules. The 3-connected hydrogen-bonded net resulting from these interactions has the hcb topology. Form (Ib) (m.p. 471 K) displays N-H...O=C hydrogen-bonded looped chains in which neighbouring molecules are linked to one another by two different R(2)(2)(8) rings. Polymorph (Ia) is isostructural with the previously reported form II of 5-(2-bromoallyl)-5-isopropylbarbituric acid (noctal) and polymorph (Ib) is isostructural with the known crystal structures of four other barbiturates.
Institute of Pharmacy, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
Thomas
T
Gelbrich
Institute of Pharmacy, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
Isabella
I
Meischberger
Institute of Pharmacy, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
Ulrich J
UJ
Griesser
D001463:Barbiturates / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D003510:Cyclohexanes / Q000737:chemistry*; D006860:Hydrogen Bonding; D015394:Molecular Structure
C000599232:5-cyclohexyl-5-ethylbarbituric acid; D001463:Barbiturates; D003510:Cyclohexanes; C032232:barbituric acid
barbiturates; crystal structure; hcb topology; hot-stage microscopy; hydrogen bonding; isostructurality; polymorphism