Free base

Abstract: A method is disclosed for the recovery of an organic acid from a dilute salt solution in which the cation of the salt forms an insoluble carbonate salt A tertiary amine and CO 2 are introduced to the solution to form the insoluble carbonate salt and a complex between the acid and an amine A water immiscible solvent, such as an alcohol, is added to extract the acid/amine complex from the dilute salt solution to a reaction phase The reaction phase is continuously dried and a product between the acid and the solvent, such as an ester, is formed

Abstract: A series of computational methods were used to study how cytochrome P450 2A6 (CYP2A6) interacts with (S)-(−)-nicotine, demonstrating that the dominant molecular species of (S)-(−)-nicotine in CYP2A6 active site exists in the free base state (with two conformations, SRt and SRc), despite the fact that the protonated state is dominant for the free ligand in solution. The computational results reveal that the dominant pathway of nicotine metabolism in CYP2A6 is through nicotine free base oxidation. Further, first-principles quantum mechanical/molecular mechanical free energy (QM/MM-FE) calculations were carried out to uncover the detailed reaction pathways for the CYP2A6-catalyzed nicotine 5′-hydroxylation reaction. In the determined CYP2A6–(S)-(−)-nicotine binding structures, the oxygen of Compound I (Cpd I) can abstract a hydrogen from either the trans-5′- or the cis-5′-position of (S)-(−)-nicotine. CYP2A6-catalyzed (S)-(−)-nicotine 5′-hydroxylation consists of two reaction steps, that is, the hydrogen tra...

Abstract: A series of substituted tetraphenylporphyrin iron chloride complexes [RTPPFe(III)Cl, R=o/p-NO₂, o/p-Cl, H, o/p-CH₃, o/p-OCH₃] were synthesized by a novel universal mixed-solvent method and the spectral properties of free base porphyrins and iron porphyrin compounds were compared with each other. The experimental results showed that the one-pot mixed solvent method was superior to the two-step method in the yields, reaction time and workup of reaction mixtures for the synthesis of iron porphyrin compounds. The highest yields (28.7%-40.4%) of RTPPFe(III)Cl were obtained in the mixed solvents propionic acid, glacial acetic acid and m-nitrotoluene under reflux for 2 h. A detailed analysis of ultraviolet-visible (UV-vis), infrared (IR) and far-infrared (FIR) spectra suggested the transformation from free base porphyrins to iron porphyrins. The red shift of the Soret band in ultraviolet-visible spectra due to the presence of p-nitrophenyl substituents and the blue shift of Fe-Cl bond of TPPFeCl in far-infrared spectra were further explained by the electron transfer and molecular planarity in the porphyrin ring.