In situ infrared analysis

Ethane-1,2-dioyl dichloride oxalyl chloride (COCOj) reacts with antimony(V) fluoride above -35 "C to form COCIF (identified by in situ infrared analysis) and SbFj. The reaction was accompanied by the generation of a small quantity of CO, and possibly COFj. Examination of the infrared spectrum during the progress of the reaction when cooled to -50 C revealed the formation of an intermediate oxocarbonium salt. The reaction was interpreted in the following terms [7] ... 

The scope for IR spectroscopic techniques for direct in-polymer additive analysis is much broader than for extracts. In many real-life cases the form of the sample as presented for analysis is not at all suitable for routine transmission spectroscopy, which would, of course, have been the only method feasible with dispersive IR instruments. Most real-life samples are much too intensely absorbing or scattering for this to be possible. Yet, this does not preclude their routine measurement with Fourier transform spectrometers with the variety of sampling modes. In situ infrared analysis has been used for a host of analytical problems, as indicated in Table 1.10. 

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. 

Melucci D. Monti D. D Elia M. Luciano G. Rapid in-situ repeatable analysis of drugs in powder form using reflectance Near-Infrared Spectroscopy and multivariate calibration. Journal of Forensic Sciences, 2012, 57, 86-92. 

Yun, K-S., Joo, S., Kim, H-J., Kwak, J., Yoon, E. (2004). Silicon micromachined infrared thin-layer cell for in situ spectroelectrochemical analysis of aqueous and nonaqueous solvent system. Electroanalysis 17 959-64. 

In situ infrared reflectance spectroscopy investigation of the oxidation reaction of ethanol appears thus as an efficient method to elucidate some mechanistic aspects of the reaction. However, the quantitative analysis of the reaction products remains difficult due to different parameters the characteristic absorption band may not be monopolar (this is the case for carbon monoxide for example) and the difficulty to obtain a quantitative relationship between infrared extinction coefficients and concentration for reaction products and by-products. 

Wetzel, D.L. and LeVine, S.M. (1998) Fourier transform infrared (FT-IR) microspectroscopy a new molecular dimension for tissue or cellular imaging dimension for tissue or cellular imaging and in situ chemical analysis. Cell. Mol Biol, 44 (1), 1-280. 

Abstract In situ spectroscopy is an important tool to characterize polymers synthesized via a precursor route. Highly conjugated polymers such as po y(p-phenylene vinylene) (PPV) and PPV derivatives are commonly prepared from a precursor polymer because the final polymers are very insoluble and intractable. Preparation in the precursor form enables the polymer materials to be cast as films. The PPV polymers are obtained from the precursor forms using a thermal elimination reaction. The exact conditions of the reaction are important as they influence the properties of the resultant polymer. The details of this thermal elimination reaction have been analyzed using thermal gravimetric analysis (TGA) coupled with infrared analysis of the evolved gas products. In situ infrared spectroscopy of the precursor films during thermal conversion to the polymers has provided further details about the elimination reaction. We have characterized PPV synthesized from a tetrahydrothiophenium monomer (sulfonium precursor route) and via the xanthate precursor route. PPV derivatives under study include poly(2,5-dimethoxy-p-phenylene vinylene) and poly(phenoxy phenylene vinylene). 

In situ infrared spectroscopy (heated cell) and TGA-IR (evolved gas product analysis) are important tools that have been used to characterize the thermal elimination reaction in the synthesis of PPV and PPV derivatives using the precursor route. A detailed understanding of the reaction is important as the conditions of the reaction influence the properties of the resultant polymer product. The mechanism of the thermal elimination reaction can be characterized using in situ spectroscopy. Both an El and an E2 mechanism appears to be operating during the thermal conversion of PPV... 

Dobson, K. D., McQuillan, A. J. (1999). In situ infrared spectroscopic analysis of the adsorption of aliphatic carboxylic acids to Ti02, Zr02, AI2O3, and Ta20s from aqueous solutions, Spectrochim. Acta A Vol. 55,1395-1405,0584-8539. 

Controlled-potential electrolysis yields a product which may be identified in situ, e.g., spectrometrically, or after isolation from the solution. In the former case, both stable and unstable products may be studied, whereas isolation is usually limited to stable compounds. The methods used for identification of the product will also depend upon the stability of that product. Electron spin resonance, ultraviolet spectrophotometry, and cyclic voltammetry have proved useful techniques for the identification of unstable (radical) species. The presence of water in the electrolyzed solution usually prevents the use of in situ infrared (but not Raman) spectrophotometric analysis, and the use of such powerful techniques as nuclear magnetic resonance and mass spectrometry is also excluded unless the product can be isolated in a reasonably pure state. 

Although, this method is questionable to measure the density of surface active sites when the reactants are not NO-NH3, th e is no doubt that this technique is the right choice to investigate the surface of those materials active on selective catalytic reduction (SCR) of nitric oxide with ammonia. In fact, 10 years later, Dumesic and coworkers [12,13] upgraded the use of NO-NH3 as probe molecules in their investigation of a series of supported vanadium on titania catalysts during DeNO c process. The authors performed TPSR (online mass spectrometric analysis of desorbed products upon heating) and in situ infrared (IR) analysis over the catalysts with preadsorbed ammonia exposed to either NO, O2, or NO + O2 mixture. 

Fourier Transform Infrared (FT-IR) Microspectroscopy. A New Molecular Dimension for Tissue or Cellular Imaging and in situ Chemical Analysis. Cellular and Molecular Biology Special Issue (1998) Vol. 44, Issue no. 1. 

Near-infrared Raman scattering can be used as a tool to perform in situ histochemical analysis. In biological applications approximately 10 ° of the incident... 

Vander Putten.E., Dehairs, E, Andre, L., and Baeyens,W. (1999). Quantitative in situ micro-analysis of minor and trace elements in biogenic calcite using infrared laser ablation— inductively coupled plasma mass spectrometry—3 critical evaluation. Anal. Chim. Acta 378(1), 263. 

Yeom and Frei [96] showed that irradiation at 266 nm of TS-1 loaded with CO and CH3OH gas at 173 K gave methyl formate as the main product. The photoreaction was monitored in situ by FT-IR spectroscopy and was attributed to reduction of CO at LMCT-excited framework Ti centers (see Sect. 3.2) under concurrent oxidation of methanol. Infrared product analysis based on experiments with isotopically labeled molecules revealed that carbon monoxide is incorporated into the ester as a carbonyl moiety. The authors proposed that CO is photoreduced by transient Ti + to HCO radical in the primary redox step. This finding opens up the possibility for synthetic chemistry of carbon monoxide in transition metal materials by photoactivation of framework metal centers. 

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