Liquid chromatography reactions

Gas-liquid chromatography has been widely used for the identification of reaction mixtures and for the separation of heterocycles. Some typical conditions are shown in Table 34. 

Epichlorhydrin (ECH) detection starts with detecting epoxide cycle using hydrochloric acid in combination with sodium chloride the reaction product - 1,3-dichlorhydrin - is extracted in diethyl ether and concentrated by removing the latter. Gas-liquid chromatography with a flame-ionization detector is used to detect glycerin 1,3-dichlorhydrin. The sensitivity of the method is 0.01 mg/dm. ... 

Gas liquid chromatography of similar hydrogenation reaction mixtures on a 6 foot column, packed with 3.1% S.E. 30 supported on Diatoport S, at 150°C., showed that the proportion of the D-gluco to l-ido isomers formed was in the ratio of approximately 70 30 whereas in methanol and using palladium as catalyst the ratio was 96 4. 

High-pressure liquid chromatography (HPLC) is used to separate and purify the products of laboratory reactions. 

Liquid chromatography. 432 Lithium, reaction with alkynes, 269-270... 

The reaction mixture is cooled, diluted with 100 mL of sat. aq NaCI and extracted with four 50-mL portions of Ei,0. The combined ethereal extracts are washed with 50 ml. of sat. aq NaCI, dried, filtered and concentrated to a volume of a few milliliters. 20 ntL of petroleum ether arc added to precipitate the soluble salts. The mixture is filtered through a silica gel column (petroleum ether)and purified by medium-pressure liquid chromatography yield 360 mg (65%). 

Liquid chromatography 58 a-Lithiosulphinyl carbanions 829 a-Lithiosulphones, reactions of 1058 a-Lithiosulphoxides NMR spectra of 600 reactions of 596-598 LUMO energies 1048, 1049... 

More recently, the reaction advancement of resole syntheses (pH = 8 and 60°C) was monitored using high-performance liquid chromatography (HPLC), 13C NMR, and chemical assays.55,56 The disappearance of phenol and the appearances of various hydroxymethyl-substituted phenolic monomers and dimers have been measured. By assessing the residual monomer as a function of reaction time, this work also demonstrated the unusually high reactivity of 2,6-dihydroxymethyl-phenol. The rate constants for phenolic monomers toward formaldehyde substitution have been measured (Table 7.6). 

Table 5.2 Selected-reaction monitoring (SRM) transitions nsed for MS-MS detection of the pesticides studied in the systematic investigations on APCI-MS signal response dependence on eluent flow rate. Reprinted from J. Chro-matogr.. A, 937, Asperger, A., Efer, J., Koal, T. and Enge-wald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science...

Figure 5.65 LC-UV and LC-MS-MS (multiple-reaction monitoring (MRM)) traces from the analysis of a enzymatically digested solution of 100 p,g salmon testes DNA (for nomenclature, see text). Reprinted by permission of Elsevier Science from Comparison of negative- and positive-ion electrospray tandem mass spectrometry for the liquid chromatography-tandem mass spectrometry analysis of oxidized deoxynucleosides , by Hua, Y., Wainhaus, S. B., Yang, Y., Shen, L., Xiong, Y., Xu, X., Zhang, F., Bolton, J. L. and van Breemen, R. B., Journal of the American Society for Mass Spectrometry, Vol. 12, pp. 80-87, Copyright 2000 by the American Society for Mass Spectrometry.

Figure 5.67 Reconstructed ion chromatograms for Idoxifene and internal standard (ds-Idoxifene using LC-ToF-MS for (a) double-blank human plasma extract, (b) extract of blank human plasma containing internal standard (IS), and (c) control-blank human plasma spiked with Idoxifene at 5 gml , the LOQ of the method. Reprinted from 7. Chromatogr., B, 757, Comparison between liquid chromatography-time-of-flight mass spectrometry and selected-reaction monitoring liquid chromatography-mass spectrometry for quantitative determination of Idoxifene in human plasma , Zhang, H. and Henion, J., 151-159, Copyright (2001), with permission from Elsevier Science.

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