title: Chip-based on-line nanospray MS method enabling study of the kinetics of isocyanate derivatization reactions.
abstract: The reaction of propyl isocyanate (2), benzyl isocyanate (3), and toluene-2,4-diisocyanate (4) with 4-nitro-7-piperazino-2,1,3-benzoxadiazole (1) to yield the corresponding urea derivatives 5 was carried out in a continuous flow glass microfluidics chip. Real-time monitoring of the derivatization reactions was done by electrospray ionization mass spectrometry, making use of a recently reported modular chip-MS interface. Rate constants of 1.5 x 10(4), 5.2 x 10(4), and 2.4 x 10(4) M(-1) min(-1) were determined for 2, 3, and 4, respectively. Using macroscale batch conditions, the rate constants are 3-4 times lower. The faster on-chip kinetics is attributed to the more efficient molecular diffusion in the micrometer-sized channel.
authors.affiliation: Laboratory of Supramolecular Chemistry and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Monica
authors.initials: M
authors.lastname: Brivio
authors.forename: Andre
authors.initials: A
authors.lastname: Liesener
authors.forename: R Edwin
authors.initials: RE
authors.lastname: Oosterbroek
authors.forename: Willem
authors.initials: W
authors.lastname: Verboom
authors.forename: Uwe
authors.initials: U
authors.lastname: Karst
authors.forename: Albert
authors.initials: A
authors.lastname: van den Berg
authors.forename: David N
authors.initials: DN
authors.lastname: Reinhoudt