A monoclinic polymorph of 2-(4-nitrophenyl)acetic acid

Alan R. Kennedy, Lygia Silva De Moraes

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A new monoclinic form of 4-nitrophenylacetic acid, C8H7NO4, (I), differs from
the known orthorhombic form both in its molecular conformation and in its
intermolecular contacts. The conformation is different as the plane of the
carboxylic acid group in (I) is more nearly perpendicular to the plane of the
aromatic ring [dihedral angle = 86.9 (3)] than in the previous form (74.5). Both
polymorphs display hydrogen-bonded R2
2(8) carboxylic acid dimeric pairs, but in
(I), neighbouring dimers interact through nitro–nitro N O dipole–dipole
contacts rather than the nitro–carbonyl contacts found in the orthorhombic form.
Original languageEnglish
Article numberx161932
Number of pages3
JournalIUCr Data
Publication statusPublished - 9 Dec 2016


  • crystal structure
  • polymorphism
  • carboxilic acid
  • hydrogen bonding
  • nitro-nitro dipole interactions
  • monoclinic form
  • ortho­rhom­bic form


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