New Pyrazolium-carboxylates as Structural Analogues of the Pseudo-Cross-Conjugated Betainic Alkaloid Nigellicine was written by Schmidt, Andreas;Habeck, Tobias;Kindermann, Markus Karl;Nieger, Martin. And the article was included in Journal of Organic Chemistry in 2003.Safety of Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate The following contents are mentioned in the article:
Pyrazolium-3-carboxylates were examined as relatives of the betainic alkaloid nigellicine and as new examples of the sparsely populated class of heterocyclic pseudo-cross-conjugated mesomeric betaines. The title compounds were prepared in a 4-step procedure starting from EtO2CCOCH:CROH [R = Me, Ph] which were cyclized with substituted hydrazines. The resulting isomeric pyrazole esters were separated and quaternized with di-Me sulfate in the presence of nitrobenzene to pyrazolium esters. Saponification was best accomplished in diluted sulfuric acid, which resulted in the formation of the pseudo-cross-conjugated mesomeric betaines in one step. Protonation to the corresponding carboxylic acids required the treatment of the betaines with tetrafluoroboric acid in dichloromethane. The effect of neg. solvatochromism proves the charge separation in the ground state of the mols. X-ray crystallog. analyses, semiempirical calculations, and ESI mass spectrometric measurements were performed to gain knowledge about the phenomenon of pseudo-cross-conjugation. This study involved multiple reactions and reactants, such as Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate (cas: 17355-75-8Safety of Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate).
Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate (cas: 17355-75-8) belongs to pyrazole derivatives. Pyrazole is a weak base, with pKb 11.5 (pKa of the conjugated acid 2.49 at 25 °C).Pyrazole used as a ligand to prepare organometallic compounds. Pyrazole rings have been used as core components of several leading non-steroidal anti-inflammatory drugs (NSAIDs) and antihypertensive drugs. It has also been found to be useful as a bifunctional ligand for metal catalysis.Safety of Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics