Pentafluorobenzoyl chloride PFBC

Recently, m our laboratories, an improved method for quantitative analysis of amino acids has been developed (Yeung, Baker, and Courts, manuscript in preparation). The carboxylic acid moiety IS derivahzed quantitatively by adding one drop of concentrated HCl to an isobutanol solution of the amino acids, rather than bubbling HCl gas in the conventional manner, prior to heating. Benzoyl chloride is known to be more reactive chemically than acid anhydrides, and pentafluorobenzoyl derivatives are highly sensitive to electron-capture detection (Moffat et al., 1972, Matin and Rowland, 1972, McCallum and Armstrong, 1973 Midha et al., 1979 Cristofoli et al, 1982, Nazarali et al., 1983). Pentafluorobenzoyl chloride (PFBC), therefore, was chosen to derivatize the other reactive groups of the amino acid isobutyl esters. Pentafluorobenzoylation (Fig. 7) was conducted at room temperature in aqueous conditions. 

An acyl chloride such as benzoyl chloride can react with secondary and primary amines and amino acids to form N-substituted benzamide derivatives. Analytical reagents used for precolumn derivatizations are p-nitrobenzene azobenzoyl chloride for LC-UV, o-acetylsalicyloyl chloride for LC-ECD, and 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxa-line-2-carbonyl chloride (DMEQ-COCl) and 4-(4,5-diphenyl-lf/-imidazol-2-yl)benzoyl chloride (DIB-Cl) for LC-FL, respectively. Pentafluorobenzoyl chloride (PFBC) is used as an acylating reagent for GC with electron-capture detection (Figure 4). Many of those described above can also react with hydroxyl and phenol groups. 

---