Accelerated Hantzsch electrospray synthesis with temporal control of reaction intermediates. Issue 1 (25th September 2014)

• Record Type: Journal Article
• Authors: Bain, Ryan M.; Pulliam, Christopher J.; Cooks, R. Graham
• Is Part Of: Chemical science. Volume 6:Issue 1(2015:Jan.)
• Page Start: 397
• Page End: 401
• Publication Date: 2014-09-25
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c4sc02436b
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Complex reaction sequences can be followed in electrosprayed droplets on the millisecond time scale. Abstract : Complex chemical reactions can occur in electrosprayed droplets on the millisecond time scale. The Hantzsch synthesis of 1, 4-dihydropyridines was studied in this way using on-line mass spectral analysis to optimize conditions and characterize the product mixture. Changing the distance between the nanospray source and the MS inlet allowed exploration of reaction progress as a function of droplet time-of-flight. Desolvation of the charged microdroplets is associated with transformation from starting material to intermediates and eventually to product as the distance is increased. Results of the on-line experiments require a termination step that discontinuously completes the desolvation process and allows the generated gaseous ions to be used to characterize the state of the system at a particular time. The intermediates seen correspond to those known to occur in the bulk solution-phase reaction. Off-line collection of the sprayed reaction mixture allowed the recovery of 250 mg h −1 of desired reaction product from a single sprayer, permitting characterization by NMR and other standard methods. A thin film version of the accelerated reaction is described and it could be controlled through the temperature of the collection surface.