Colorimetric monitoring of solid-phase aldehydes using 2,4-dinitrophenylhydrazine.
A simple and rapid method to achieve colorimetric monitoring of resin-bound aldehydes, based on ambient temperature reaction with 2,4-dinitrophenylhydrazine (DNPH) in the presence of dilute acid, has been developed as an adjunct to solid-phase organic synthesis and combinatorial chemistry. By this test, the presence of aldehydes is indicated by a red to dark-orange appearance, within a minute. Alternatively, resins that are free of aldehydes or in which aldehyde functions have reacted completely retain their original color. The DNPH test was demonstrated for poly(ethylene glycol)-polystyrene (PEG-PS), aminomethyl polystyrene (AMP), cross-linked ethoxylate acrylate resin (CLEAR), and acryloylated O,O'-bis(2-aminopropyl)poly(ethylene glycol) (PEGA) supports and gave results visible to the naked eye at levels as low as 18 micromol of aldehyde per gram of resin.
Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
Simon K
SK
Shannon
George
G
Barany
D000179:Acrylates / Q000032:analysis / Q000737:chemistry; D000447:Aldehydes / Q000032:analysis* / Q000737:chemistry; D003124:Colorimetry / Q000379:methods*; D006834:Hydrazines / Q000737:chemistry; D007202:Indicators and Reagents; D007659:Ketones / Q000737:chemistry; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000032:analysis / Q000737:chemistry; D011137:Polystyrenes / Q000032:analysis / Q000737:chemistry; D012117:Resins, Synthetic / Q000032:analysis / Q000737:chemistry; D012997:Solvents / Q000737:chemistry
D000179:Acrylates; D000447:Aldehydes; D006834:Hydrazines; D007202:Indicators and Reagents; D007659:Ketones; D011137:Polystyrenes; D012117:Resins, Synthetic; D012997:Solvents; C446799:dinitrophenylhydrazine; C103390:polyethylene glycol-polystyrene; D011092:Polyethylene Glycols