Two different products from the reaction of 1-aryl-5-chloro-3-methyl-1H-pyrazole-4-carbaldehyde with cyclohexylamine when the aryl substituent is phenyl or pyridin-2-yl: hydrogen-bonded sheets versus dimers

J. Orrego Hernandez, J. Portilla, J. Cobo, C. Glidewell

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Cyclohexylamine reacts with 5-chloro-3-methyl-1-(pyridin-2-yl)-1H-pyrazole-4-carbaldehyde to give 5-cyclohexylamino-3-methyl-1-(pyridin-2-yl)-1H-pyrazole-4-carbaldehyde, C16H20N4O, (I), formed by nucleophilic substitution, but with 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde the product is (Z)-4-[(cyclohexylamino)methylidene]-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, C17H21N3O, (II), formed by condensation followed by hydrolysis. Compound (II) crystallizes with Z′ = 2, and in one of the two independent molecular types the cyclohexylamine unit is disordered over two sets of atomic sites having occupancies of 0.65-14;(3) and 0.35-14;(3). The vinylogous amide portion in each compound shows evidence of electronic polarization, such that in each the O atom carries a partial negative charge and the N atom of the cyclohexylamine portion carries a partial positive charge. The molecules of (I) contain an intramolecular N-HN hydrogen bond, and they are linked by C-HO hydrogen bonds to form sheets. Each of the two independent molecules of (II) contains an intramolecular N-HO hydrogen bond and each molecular type forms a centrosymmetric dimer containing one R22(4) ring and two inversion-related S(6) rings.
Original languageEnglish
Pages (from-to)363-368
Number of pages6
JournalActa Crystallographica Section C Structural Chemistry
Volume71
Issue number5
DOIs
Publication statusPublished - May 2015

Keywords

  • Pharmaceutical compounds
  • Condensation reaction
  • Nucleophilic substitution
  • Crystal structure
  • Hydrogen bonding

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