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Updated: Aug 9, 2026

Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example
Published on: November 18, 2015
Reactions of p-coumaric acid with nitrite: product isolation and mechanism studies
J L Torres y Torres1, J P Rosazza
1Division of Medicinal and Natural Products Chemistry and Center for Biocatalysis and Bioprocessing, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA.
Abstract:
p-Coumaric acid (1) is an abundant plant phenolic acid, a dietary chemoprotectant, and an antioxidant. The chemoprotective properties of 1 were demonstrated in vitro by its reaction with NaNO(2) in H(2)O over a range of pH values. The reaction pathway of 1 with nitrite is dependent on pH. 4-Hydroxybenzaldehyde (3, 16%), 1',4-dihydroxybenzeneacetaldehyde oxime (5, 59%), and 4-hydroxy-1'-oxo-benzeneacetaldehyde aldoxime (7, 26%) and 7-hydroxy-1,2(4H)-benzoxazin-4-one (11, 6%) were each formed at pH 2, whereas 4-(2-oxido-1,2,5-oxadiazol-3-yl)phenol (13) was formed at pH 3 (6%) and pH 7 and 10 (both 1%). Products were isolated and characterized by NMR and MS spectral analyses. Formation of benzoxazinone (11) requires the 4-phenolic functional group and the conjugated propenoic acid side chain of p-coumaric acid. The mechanism for nitrosation at pH 2 was examined by reacting 1 in H(2)(18)O/NaNO(2).
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