The crystal structures of two polymorphs of 5-ethyl-5-isoamylbarbituric acid (amobarbital)

The crystal and molecular structure of the bis(5-ethyl-5-isoamylbarbiturato)bis(imidazole) complex of nickel(II)

“…The bond lengths for the barbiturate ligand show good agreement with those reported for two polymorphs of the parent 5-ethyl-5-isoamylbarbituric acid (Craven & Vizzini, 1969). In this latter compound, the internal ring angle C(2)-N(1)-C(6) was found to have a mean value of 126.6 (3) ° while in the present complex it is 122.4 (2) °.…”

Perdeuterated biuret hydrate C2D5N3O2.(0.77D2O)

“…The puckering of the molecules of both biuret and triuret appears to result from repulsions across the pseudo-rings which arise from the formation of the intramolecular hydrogen bonds. It is of interest that the angles C(1)-N(2)-C(2) and N(2)-C(2)-N(I) are very similar to the internal ring angles C-N-C (126 °) and N-C-N (116 °) observed in the polymorphs of amobarbital (Craven & Vizzini, 1969). The barbiturate pyrimidine ring is puckered also, with torsion angles of about 6 ° .…”

Crystallization of Metastable Polymorphs of Phenobarbital by Isomorphic Seeding

“…54 Forms Pbtl-IX and Pbtl-X and Related Structures. Pbtl-IX and Pbtl-X belong to an extended group of structurally closely related barbiturates together with the following 10 forms (see also Table 2): amobarbital (Amtl), 57 two polymorphs of amytal (Amy-I and Amy-II), 58 5-ethyl-5-(3′-methylbut-2′-enyl)barbituric acid (Embl, mp 154 °C), 59 ipral (Ipr-I), phanodorm (Phd-II), 60 nembutal (Nbtl-I), sandoptal (Spt-I), and two polymorphs of soneryl (Snl-I and Snl-LT). 61,62 The crystal structures of Ipr-I, Nbtl-I, and Spt-I were determined for the first time in this study, and we also report an improved structure model for Phd-II (see Table 3).…”