title: Aspects of the stability of isoindoles derived from the reaction of o-phthalaldehyde-ethanethiol with primary amino compounds.
abstract: The stability of a series of fluorescent isoindoles formed under analytical conditions following the reaction of o-phthalaldehyde (OPA) and ethanethiol (ET) with a series of primary amines is reported. Increasing the bulk and degree of substitution of the isoindole N-substituent resulted in substantial increases in isoindole stability. The effects of excess reagents on isoindole stability is examined and OPA is observed to accelerate isoindole degradation whilst ET provides a stabilizing effect. Comparison with previously reported data involving the use of 2-mercaptoethanol revealed that ET clearly forms the more stable isoindole derivatives, i.e. a minimum of five-fold improved stability based on the time for 10% degradation to occur. Identification of the major degradation product together with kinetic data suggests that degradation proceeds via autoxidation.
authors.affiliation: Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS 66045, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Stobaugh
authors.forename: A J
authors.initials: AJ
authors.lastname: Repta
authors.forename: L A
authors.initials: LA
authors.lastname: Sternson