Solid phase reaction infrared analysis

Infrared and Raman spectroscopy are nondestructive, quick and convenient techniques for monitoring the course of solid-phase reactions, and have therefore been widely used for the characterization of polymer supports and supported species [156-160]. In fact, the application of infrared spectroscopy in solid-phase synthesis has received much attention and has been the subject of several recent reviews [127, 128, 161-164]. Reactions involving either the appearance or disappearance of an IR-active functional group can be easily monitored using any of the IR techniques described in this section. Some beads are typically removed from the reaction mixture, then they are quickly washed and dried prior to IR analysis. Traditionally, polymer supports are diluted and ground with KBr, then conventional FT-IR analysis of the KBr disk is carried out Although this is a commonly used... 

Rahman SS, Busby DJ, Lee DC, Infrared and Raman spectra of a single resin bead for analysis of solid-phase reactions and use in encoding combinatorial libraries, J. Org. Chem., 63 6196-6199, 1998. 

The most common methods for monitoring solid phase reactions utilized in normal research laboratories are Infrared analysis of resin... 

Micro-IR spectra were used for real-time monitoring of solid phase reactions (12,15,16) and, utilizing deuterium isotope containing protecting groups, for quantitative infrared analysis of solid phase, resin-bound chemical reactions (13). 

An important tool for the fast characterization of intermediates and products in solution-phase synthesis are vibrational spectroscopic techniques such as Fourier transform infrared (FTIR) or Raman spectroscopy. These concepts have also been successfully applied to solid-phase organic chemistry. A single bead often suffices to acquire vibrational spectra that allow for qualitative and quantitative analysis of reaction products,3 reaction kinetics,4 or for decoding combinatorial libraries.5... 

The gas phase reaction proceeds very much as described for nickel carbonyl, but the product does not contain the nitrite group (10). A smoke is formed immediately the gases come into contact, but the analysis and infrared spectrum of the solid formed show it to be the oxide-nitrate Fe0(N03). It seems likely that initial reaction involves the NO2 radical, and an iron nitrite such as Fe(N02)3 may be produced initially. The oxidation-reduction properties of the ferric and nitrite ions may render them incompatible Fe0(N03) would then be left as a decomposition product. So little is known about transition metal nitrites that this must remain conjecture at present, but it may be relevant to recall that it has not yet been possible to isolate pure samples of Fe(N03)3, A1(N03)3, or Cr(N03)3. 

Spectroscopic techniques (particularly infrared, x-ray photoelectron, and x-ray absorption spectroscopy) have been applied to fill the information gap about chemical speciation and interfacial reactions of As in model and natural materials. They have been used to determine the stmcture of x-ray amorphous particles involved in interfacial reactions, to identify the types of sorption reactions occurring in simplified model systems containing As and one or more phases, and to identify the valence and speciation of predominant As species present in natural, heterogeneous materials. This chapter summarizes much of the recent spectroscopic information on arsenic speciation in minerals and other solid phases that are analogous to phases present in aquifer sediments. These data are primarily derived from analysis of synthetic samples or natural model compounds. 

Infrared and Raman spectroscopy allow direct spectral analysis of the solid phase, thus avoiding the tedious cleavage of compounds from the solid support. With diagnostic bands in starting materials or products, IR and Raman spectroscopy in general are efficient in monitoring each reaction step directly on the solid phase. 

Pivonka, D.E., Russell, K. and Gero, T., Tools for combinatorial chemistry In situ infrared analysis of solid-phase organic reactions, Appl. Spectrosc., 50 (1996) 1471-1478. 

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