Solubilities of Some Cyclohexyl Derivatives of Dialkyl 1,4-Dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-imidazol-2-yl)- 3,5-pyridinedicarboxylates (Nifedipine Analogues) in Supercritical Carbon Dioxide. Part I

Abstract

Equilibrium solubilities of five recently synthesized nifedipine analogues were measured at temperatures ranging from (328 to 348) K for bis(cyclohexyl)-1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-imidazol-2-yl)-3,5-pyridinedicarboxylates (NP1) and bis(cyclohexylmethyl)-1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-imidazol-2-yl)-3,5-pyridinedicarboxylates (NP2) and (338 to 358) K for bis(2-cyclohexylethyl)-1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-imidazol-2-yl)-3,5-pyridinedicarboxylates (NP3), bis(3-cyclohexylpropyl)-1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-imidazol-2-yl)-3,5-pyridinedicarboxylates (NP4), and bis(4-cyclohexylbutyl)-1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-imidazol-2-yl)-3,5-pyridinedicarboxylates (NP5) and in a pressure range from (12.2 to 35.5) MPa in supercritical carbon dioxide. The data were obtained by using a simple static sampling apparatus, which was tested by measuring the solubility of naphthalene in supercritical carbon dioxide. The measured solubilities were correlated using a semiempirical model. The calculated results show satisfactory agreement with the experimental data.