Salt forms of amides : protonation of acetanilide
Jaconelli, Harry S. and Kennedy, Alan R. (2024) Salt forms of amides : protonation of acetanilide. Acta Crystallographica Section C: Structural Chemistry, 80 (Pt. 9). C80. ISSN 2053-2296 (https://doi.org/10.1107/s2053229624007332)
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Abstract
Treating the amide acetanilide (N-phenylacetamide, C8H9NO) with aqueous strong acids allowed the structures of five hemi-protonated salt forms of acetanilide to be elucidated. N-(1-Hydroxyethylidene)anilinium chloride–N-phenylacetamide (1/1), [(C8H9NO)2H][Cl], and the bromide, [(C8H9NO)2H][Br], triiodide, [(C8H9NO)2H][I3], tetrafluoroborate, [(C8H9NO)2H][BF4], and diiodobromide hemi(diiodine), [(C8H9NO)2H][I2Br]·0.5I2, analogues all feature centrosymmetric dimeric units linked by O—H⋯O hydrogen bonds that extend into one-dimensional hydrogen-bonded chains through N—H⋯X interactions, where X is the halide atom of the anion. Protonation occurs at the amide O atom and results in systematic lengthening of the C=O bond and a corresponding shortening of the C—N bond. The size of these geometric changes is similar to those found for hemi-protonated paracetamol structures, but less than those in fully protonated paracetamol structures. The bond angles of the amide fragments are also found to change on protonation, but these angular changes are also influenced by conformation, namely, whether the amide group is coplanar with the phenyl ring or twisted out of plane.
ORCID iDs
Jaconelli, Harry S. and Kennedy, Alan R.![ORCID logo](/images/orcid_16x16.png)
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Item type: Article ID code: 90050 Dates: DateEvent1 September 2024Published8 August 2024Published Online23 July 2024AcceptedSubjects: Medicine > Pharmacy and materia medica > Pharmaceutical chemistry
Science > Chemistry > Physical and theoretical chemistryDepartment: Faculty of Science > Pure and Applied Chemistry Depositing user: Pure Administrator Date deposited: 26 Jul 2024 09:58 Last modified: 01 Sep 2024 03:00 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/90050