Novel infrared optical probes for process monitoring and analysis based on next-generation silver halide fibers

Heise, H. M.; Küpper, Lukas; Butvina, Leonid N.

doi:10.1007/s00216-003-1782-8

Cited by 20 publications

(11 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This deviation is further confirmed by a plot of the concentration ratios c phenol / c phenyl isocyanate versus reaction time (Fig. 10) [5]. Due to the equimolar consumption of phenol and phenyl isocyanate in the synthesis of the diphenyl urethane this concentration ratio is expected to remain constant during the reaction progress.…”

Section: Resultsmentioning

confidence: 61%

“…The spectroscopic measurements were performed on a Bruker IFS-28 FT-IR spectrometer (Bruker Optik GmbH, Ettlingen, Germany) equipped with an MCT detector and a diamond ATR-probe (two reflections) which was coupled to the spectrometer by a 2 m silver halide waveguide-fiber (Infrared Fiber Sensors, Aachen, Germany) [5]. Spectra were www.elsevier.com/locate/vibspec Vibrational Spectroscopy 43 (2007) 217-220 recorded in pre-selected time intervals at a spectral resolution of 4 cm À1 and 32 scans were accumulated for the improvement of the S/N-ratio.…”

Section: Instrumentationmentioning

confidence: 99%

See 1 more Smart Citation

In situ monitoring of an isocyanate reaction by fiber-optic FT-IR/ATR-spectroscopy

Friebe¹,

Siesler²

2007

Vibrational Spectroscopy

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 61%

Section: Instrumentationmentioning

confidence: 99%

In situ monitoring of an isocyanate reaction by fiber-optic FT-IR/ATR-spectroscopy

Friebe¹,

Siesler²

2007

Vibrational Spectroscopy

View full text Add to dashboard Cite

“…In contrast, infrared radiation is strongly adsorbed by quartz; hence, special infrared transmissive fibers are required. Such silver halogenide fibers have proven suitable and are now well established [35][36][37] despite their fragility and degradation over time.…”

Section: Spectroscopic Reactors and Practical Aspectsmentioning

confidence: 99%

Reaction Monitoring in Multiphase Systems: Application of Coupled In Situ Spectroscopic Techniques in Organic Synthesis

Knöpke

Bentrup

2013

Heterogeneous Catalysts for Clean Technology

View full text Add to dashboard Cite

In situ spectroscopy is the only approach to obtain reliable information on mechanisms and the role of intermediates in chemical reactions as well as on structure-reactivity relationships in catalysis [1][2][3][4][5]. Especially, in heterogeneous catalysis, the application of a variety of in situ methods has gained a lively development during the recent two decades. But also in homogeneous catalysis, as well as in catalytic multiphase systems, in situ characterization methods are increasingly applied. A survey of techniques, which are most commonly applied in gas/solid and multiphase systems and the method-specific information, is presented in Table 3.1.The vibrational spectroscopies, Raman and Fourier transform infrared spectroscopy (FTIR) provide complementary information. While FTIR spectroscopy requires groups with a permanent dipole moment, Raman spectroscopy needs groups that have polarizable bonds. As a result, certain vibrations of functional groups are active or inactive in the infrared or Raman spectra, respectively. Thus, the spectra of molecules such as water or carbon monoxide show strong bands in the infrared spectra but only very weak bands in the Raman spectra. However, this is advantageous for measurements in aqueous systems. Furthermore, bands resulting from metal-nonmetal vibrations can be observed well with Raman spectroscopy. A disadvantage of Raman spectroscopy is the possible damage or fluorescence of the sample when irradiated with Raman laser light. In particular, the analysis of condensed aromatic systems can be perturbed by fluorescence. Consequently, the combination of both methods provides comprehensive information about the vibrational state of molecules or adsorbed species.Ultraviolet-visible (UV-vis) spectroscopy gives less distinct information about the molecular structure than infrared and Raman spectroscopies. Typically, the bands appearing in UV-vis spectra are rather broad. This is because of the simultaneous excitation of rotational, vibrational, and electronic transitions. The bands appearing in the UV-vis spectra of organic molecules are prominent for chromophores. These chromophores can be small parts of the sample molecule, but in extreme cases also the complete electronic shell of the sample molecule.

show abstract

“…Flexible commercially available fiber probes based on chalcogenide fibers have also been applied for reaction studies [e.g., [6][7][8][9][10], but at temperatures above 65°C, they are fragile and not stable without active cooling. In contrast, the availability of flexible fiber probes based on silver halide material offers several inherent advantages with respect to the obtainable spectral region, the mechanical robustness, and the high temperature stability [11,12].…”

Section: Introductionmentioning

confidence: 95%

Mid-Infrared Monitoring of Gas-Liquid Reactions in Vitamin D Analogue Synthesis with a Novel Fiber Optical Diamond ATR Sensor

Bentrup

Küpper²,

Budde³

et al. 2006

Chem. Eng. Technol.

Self Cite

View full text Add to dashboard Cite

A novel mid-infrared optical sensor enabling in situ ATR measurements was applied to investigate several steps of a vitamin D analogue synthesis. The probe based on silver halide fibers coupled to a diamond prism was connected to a conventional FTIR spectrometer with internal MCT detector. All steps of the reaction were monitored by real-time in situ FTIR measurements. The steps carried out were the dissolution of SO 2 in a CH 2 Cl 2 /CH 3 OH solvent mixture as well as the addition of SO 2 to a vitamin D analogue, the subsequent ozonation of the double bond in the SO 2 addition product, and the following reduction of the formed hydroperoxide with triphenylphosphine. The dissolving process of SO 2 and the addition of SO 2 to the vitamin D analogue were monitored by changing the characteristic m as (SO 2 ) and m s (SO 2 ) modes of dissolved and incorporated SO 2 . It was found that during ozonation of the SO 2 addition product the formation of hydroperoxide is accompanied by the simultaneous formation of the corresponding aldehyde identified by the typical m(C=O) band at 1720 cm -1. Extended ozone exposure favors the formation of the corresponding acid detected by an additional carbonyl band at lower wavenumbers. During the reaction with triphenylphosphine the increasing intensity of the aldehyde band and the appearance of the m(P=O) mode of the formed triphenylphosphine oxide indicate the progressive reduction of hydroperoxide. The hydroperoxide band disappears completely during the reaction whereas the m as (SO 2 ) band remains unaffected.

show abstract

Novel infrared optical probes for process monitoring and analysis based on next-generation silver halide fibers

Cited by 20 publications

References 20 publications

In situ monitoring of an isocyanate reaction by fiber-optic FT-IR/ATR-spectroscopy

In situ monitoring of an isocyanate reaction by fiber-optic FT-IR/ATR-spectroscopy

Reaction Monitoring in Multiphase Systems: Application of Coupled In Situ Spectroscopic Techniques in Organic Synthesis

Mid-Infrared Monitoring of Gas-Liquid Reactions in Vitamin D Analogue Synthesis with a Novel Fiber Optical Diamond ATR Sensor

Contact Info

Product

Resources

About