Gases infrared spectra

The purity of cyclobutanone was checked by gas chromatography on a 3.6-m. column containing 20% silicone SE 30 on chromosorb W at 65°. The infrared spectrum (neat) shows carbonyl absorption at 1779 cm. - the proton magnetic resonance spectrum (carbon tetrachloride) shows a multiplet at 8 2.00 and a triplet at S 3.05 in the ratio 1 2. 

Figure 2. Infrared spectrum of methyl-trans-chrysanthemate Prepared from DL-trans-chrysanthemum acid and collected as pure ester from gas chromatograph...

Figure 4. Infrared spectrum of methyl-transrpyrethrate Prepared from pyrethric acid isolated from hydrolysis mixture of pyrethrum concentrate. Pure ester isolated by gas chromatography...

Figure 6. Infrared spectrum of cinerin II Collected from gas chromatograph after isolation from silicic acid-acetonitrile-hexane partition column...

Figure 7. Infrared spectrum of pyrethrin I Isolated after dual partition chromatography First partition column. Celite-acetonitrile-hexane Second partition column. Silicic acid-nitromethane-hexane (with 5% acetone). Corresponds to peak 3 of gas chromatographic separation of pyrethrum mixture...

Figure 10. Infrared spectrum of long-chain ester recovered from gas chromatography after hydrolysis and methylation of pyrethrum concentrate...

Figures 2 through 9 are infrared spectra of fractions collected from partition columns, gas chromatography, thin-layer chromatography, or a combination of these separation techniques. Figure 10 is the infrared spectrum of a compound isolated by gas chromatography after hydrolysis of a pyrethrum concentrate. In this case the compound is a long-chain ester. All the infrared spectra were made with a Perkin-Elmer Model 221 instrument. The following operating parameters were used. A liquid demountable cell with a 0.01-mm path length was employed.

Figure 4.22. The infrared spectrum of gas phase CO shows rotational fine structure, which disappears upon adsorption, as shown by the spectrum of CO adsorbed on an Ir/Si02 catalyst. [J.W. Niemantsverdriet, Spectroscopy in Catalysis, An Introduction (2000), Wiley-VCH, Weinheim.]...

The infrared spectrum of matrix-trapped CF2 (produced by the photolysis of difluorodiazirine, CF2N2) has been examined 28 The three fundamental vibrational frequencies were determined to be 668,1102, and 1222 cm. The intensities of the two stretching fundamentals were sufficiently strong to permit observation of the corresponding absorption of13CF2, from which the bond angle of CF2 was calculated to be approximately 108 °. The gas-phase infrared... 

The infrared spectrum of GeF2 has also been reported 10 3 It was necessary to study the matrix-isolated spectrum for two reasons. First, the examination of the ultraviolet absorption spectrum of GeF2 indicated that at least ten of the bending states were populated, and second, germanium has five abundant isotopes. These suggested that the gas phase spectrum would be broad and ill de-... 

The unique appearance of an infrared spectrum has resulted in the extensive use of infrared spectrometry to characterize such materials as natural products, polymers, detergents, lubricants, fats and resins. It is of particular value to the petroleum and polymer industries, to drug manufacturers and to producers of organic chemicals. Quantitative applications include the quality control of additives in fuel and lubricant blends and to assess the extent of chemical changes in various products due to ageing and use. Non-dispersive infrared analysers are used to monitor gas streams in industrial processes and atmospheric pollution. The instruments are generally portable and robust, consisting only of a radiation source, reference and sample cells and a detector filled with the gas which is to be monitored. 

Figure 3. Photoacoustic infrared spectrum of gaseous CO2 obtained in a microphonic PAS cell for solid samples when the operator exhaled once into the cell before closing. 100 scans, 0.5 cm-1 resolution. This illustrates the large photoacoustic signal arising from gas phase samples and the high resolution attainable.

V. Moulin, A. Schriver, L. Schriver Mazzuoli, and R Chaquin, Infrared spectrum of 2,2,2 trichloroethanol isolated in gas matrices. Ab initio optimization of conformers and potential energy calculations. Chem. Phys. Lett. 263, 423 428 (1996). 

In order to stop the reaction when the amount of monoole-finic product in the reaction mixture is highest, aliquots of the reaction mixture are removed at intervals and analyzed by infrared spectrometry or by gas chromatography. In the infrared spectrum the relative intensities of bands at 965 cm. (trans-CH=CH) and 702 cm. (m-CH=CH) are observed in successive aliquots. The reaction is stopped when the band at 965 cm.- attributable to the trans double bonds of the starting triene, has almost completely disappeared and the band at 702 cm.- (m-olefin) remains. 

An infrared spectrum can be obtained for a sample of an organic compound regardless of its physical state (solid, liquid, gas or dissolved in a solvent). Infrared radiation is passed through the sample in the spectrometer. Some wavelengths are absorbed, causing bond vibrations within the molecules. The transmitted radiation then passes to a detector where the intensity at different wavelengths is measured. An Infrared spectrum, like that shown in the diagram, is obtained. 

The various fractions of the forerun were analyzed employing a gas chromatography column packed with silicone gum, No. XE-60, suspended on Chromosorb P and heated to 248°. The components found (with the retention times indicated) were benzyl bromide (9.0 minutes), 2-methylcyclohexanone (5.3 minutes), and, in some cases, bibenzyl (22.6 minutes). The bibenzyl, formed by reaction of the benzyl bromide with the excess methyllithium, was identified from the infrared spectrum of a sample collected from the gas chromatograph. 

TG-FT-IR, Pyrolysis analyses were performed on the preliquefaction solids using thermogravimetric (TG) analysis with on-line analysis of the evolved products (including an infrared spectrum of the condensables) by FT-IR. The TG-FTIR method has been described previously (23-25). The Bomem TG/plus instrument was employed. A sample is continuously weighed while it is heated. A flow of helium sweeps the products into a multi-pass cell for FT-IR analysis. Quantitative analysis of up to 20 gas species is performed on line. Quantitation of the tar species is performed by comparison with the balance reading. 

Recently, Cooper and co-workers 74) succeeded in obtaining direct evidence for the existence of free FCIO in the gas phase. During a study of the hydrolysis of excess CIF3 in a flow reactor, a novel species was observed in the infrared spectrum showing a PQR band centered at 1032 cm . The species causing this band was found to decompose at ambient... 

The pyramidal structure of symmetry Cg for FCIO2 was also confirmed by vibrational spectroscopy. E. A. Smith et al. (271) and Arvia and Aymonino (6) reported the infrared spectrum of the gas. D. F. Smith et al. (270) studied the infrared spectrum of the gas, measured the 3501-3701 i6Q i8o isotopic shifts, recorded the Raman spectrum of the liquid, and carried out a normal coordinate analysis. The observed frequencies and their assignment are summarized in Table XIII. 

Andrews and co-workers have recently reported (5) C1- C1 and i 0- 0 isotopic shifts for the infrared spectrum of argon matrix-isolated FCIO2. Tantot (282) has studied in his thesis work the infrared and Raman spectra of the gas, the Raman spectrum of the neat liquid and of HF solutions, and the infrared and Raman spectra of the solid. 

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