Benzoyl chloride, derivatizing

Song P, Mabrouk OS, Hershey ND, Kennedy RT. In vivo neurochemical monitoring using benzoyl chloride derivatization and liquid chromatography—mass spectrometry. Anal Chem 2012 84 412-9. 

In analytical LC there are two primary reasons why chemical derivatization of the sample constituents would be necessary, and they are 1) to enhance the separation and 2) to increase the sensitivity of detection. Under certain circumstances, derivatization can also be used to reduce peak asymmetry, i.e. to reduce tailing, or to improve the stability of labile components so that they do not re-arrange or decompose during the chromatographic process. However, sensitivity enhancement is the most common goal of derivatization. For example, aliphatic alcohols that contain no UV chromaphore can be reacted with benzoyl chloride to form a benzoic ester. 

Another example of precolumn derivatization employed benzoyl chloride to derivatize polyamines and acetylpolyamines UV detection was used (Taibi et al., 2000). 

M. Zheng, C. Fu and H. Xu, High-performance liquid chromatographic detection of trace N-nitrosoamines by precolumn derivatization with 4-(2-phthalimidyl)benzoyl chloride. Analyst, 1993,118(3), 269-271. 

Hwang et al. developed a rapid and sensitive HPLC-UV method for the analysis of nine derivatized BAs, with benzoyl chloride as the derivatization agent. The reaction is faster than with tosyl chloride and leads to stable products with shorter elution times than do dansyl derivatives. The amines were previously extracted after acidification with TCA. The method was applied to detect BAs in fried marlin fillet, implicated in a food poisoning incident (in Taipei City in 1996) and indicated that a high level of His (84.1 mg/100 g) was present in the sample (80). 

We initially demonstrated that brain cerebrosides, galactosyl-ceramides containing hydroxy fatty acids (HFA) and nonhydroxy fatty acids (NFA), could be completely derivatized by reaction with 10% benzoyl chloride at 60°C for 1 hour (2). After removal of excess reagents by partition between hexane and alkaline aqueous methanol, the perbenzoyl derivatives were seen to separate into two completely resolved components (HFA and NFA... 

A quantitative HPLC method for the analysis of sphingolipids as their perbenzoyl derivatives was first developed for ceramides (5). Ceramides can be conveniently derivatized with benzoic anhydride in pyridine (3 hrs at 110°C) and the products formed have been utilized for the quantitative analysis of NFA and HFA ceramides in normal and Farber s disease tissue. Iwamori and Moser also utilized this procedure for the analysis of ceramides in Farber s disease urine (6). More recently Iwamori and Moser (7) established that the ceramide derivatives formed by reaction with benzoyl chloride or benzoic anhydride are analogous to those formed with cerebrosides. They also characterized the behavior... 

Polysaccharide-based CSPs also exhibit a chiral recognition for alcohols and a large number of resolutions have been reported. Chiral alcohols can usually be directly resolved with hexane containing a small amount of an alcohol as the eluent. For aliphatic alcohols, which cannot be directly resolved, their resolution is often efficiently attained as phenylcarbamate or benzoate derivatives on OD (Figure 17).85 For example, 2-butanol and 2-pentanol are completely resolved with a very high selectivity on OD as their phenylcarbamates. The derivatization of alcohols to phenylcarbamates and benzoates can be easily achieved by the reaction with phenyl isocyanates and benzoyl chlorides, respectively. In most cases, the phenylcarbamates are better resolved than the benzoates. For chiral compounds bearing phenolic hydroxy groups, the addition of a small amount of an acid to an eluent is recommended to depress its dissociation. 

Creasy (68) investigated postcolumn derivatization of A-ethyldiethanolamine and triethanolamine with benzoyl chloride in combination with APCI. Derivatization of one hydroxyl group occurred after mixing the reagent with LC eluent, and sensitivity was not affected by derivatization. A possible advantage of this method is to increase the molecular mass to remove the analyte from interferences. 

An efficient derivatization method using reagent benzoyl chloride for analysis of BAs in wine, was proposed (Paleologos and Kontominas,... 

Recently Street et al. acylated diatomaceous earth with benzoyl chloride in pyridine as a pretreatment for coating. They reported that a marked reduction in adsorption could be obtained, enabling polar compounds, such as morphine, to be gas chromatographed in nanogram amounts without derivatization. A 1000-fold improvement in chromatographic capability could be obtained, compared to the best conventional conmercial packing. 

A number of various derivatization reactions have been used, as shown in Table 14.25. The derivatization has been carried out as off-column or on-column derivatization, mostly in order to give morphine and related alkaloids with phenolic or alcoholic hydroxyl groups better gas chromatographic properties. Especially for quantitative determination of morphine in opium or biological material such derivatization was necessary. Street et al. found, however, that the problem of adsorption of a phenolic alkaloid, such as morphine, because of "active sites" on the solid support could be solved by deactivation of the solid support by treatment of it (diatomaceous earth) with benzoyl chloride in pyridine before coating it with the stationary phase. 

Parameters such as solvent, basic medium and reaction time, affecting the derivatization of alcohols and phenols with benzoyl chloride, were investigated. End analysis was by GC with UVD . a sensitive method proposed for trace determination of phenols in water consists of preconcentration by SPE with a commercial styrene-divinylbenzene copolymer, acylation with pentafluorobenzoyl chloride in the presence of tetrabutylammonium bromide and end analysis by GC with either ECD or ITD-MS. LOD was 3 to 20 ngL for ECD and 10 to 60 ngL for ITD-MS, with 500 mL samples . Acylation with the fluorinated glutaric acid derivative 43 was proposed for determination of urinary phenols, as indicative of exposure to benzene and other aromatic hydrocarbons. End analysis by GC-MS shows strong molecular ions of the derivatives by electron ionization. The proto-nated ions are the base peaks obtained by chemical ionization. LOD was 0.5 mgL and the linearity range 0-100 mg L for phenol . 

Direct tri-0-alkylation of calix[4]arenes has been reported to lead to the syn/syn isomer using bases such as BaO, BaO/Ba(OH)2 or CaH2 in DMF " . The tribenzoate of the p-unsubstituted calix[4]arene, one of the first examples of selectively derivatized calix[4]arenes, was obtained as the anti-syn isomer (benzoyl chloride/pyridine) , while the tribenzoate of 2a obtained in toluene with iV-methylimidazole as base (70% yield) was described as the syn-syn isomer, assuming a partial cone conformation with an inverted phenol ring . Both tris(3,5-dinitrobenzoates) of 2a were obtained by acylation with 3,5-dinitrobenzoyl chloride/l-methylimidazole. While 95% of the syn-syn isomer was formed in acetonitrile, 70% of the anti-syn isomer was obtained in chloroform . 

A simultaneous way of determining ammonia including aliphatic amines, aromatic amines, and phenols in environmental samples by GC-MS method using a single derivatization reagent has been reported recently by Mishra et al. The method consisted in precolumn formation of benzoate esters and benzamides under the conditions of the Schotten-Baumann procedure with benzoyl chloride and SPE of the derivatives. The limit of detection of ammonia was 20 /rg/l when 80 ml of sample was preconcentrated, after derivatization, on a styrene divinyl benzene copolymer sorbent. 

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. 

Pyridine has also been used as the basic catalyst and chloride acceptor for benzoylation reactions. In one procedure, amines, volatile alcohols or thiols isolated by benzene extraction, are benzoylated with pyridine (1 ml) and benzoyl chloride (0.5 ml) by shaking intermittently at room temperature for several hours. The pyridine phase is extracted with 2 M HCl and the excess benzoyl chloride is hydrolysed with water for 12 hours. After shaking with 2 M sodium carbonate to remove benzoic acid, the benzene solution is dried and concentrated for analysis [144]. Aminoglycoside antibiotics are derivatized to the benzoyl derivatives in a similar reaction using 90 fi of pyridine and 10 /il of benzoyl chloride at 80 °C for 30 minutes. The pyridine is evaporated in a stream of nitrogen and excess benzoyl chloride is converted to methyl benzoate with methanol, again at 80°C, for 10 minutes. The product is cleaned up for analysis by a rather involved solvent extraction procedure [145]. 

Benzoyl chloride is the preferred derivatizing agent for polyamines, as it reacts with most of the naturally occurring diamines and polyamines. Redmond and Tseng [13] described a procedure involving the addition of benzoyl chloride to the sample suspended in an alkaline solvent. Fumiss et at. [14] recommended that following the reaction the mixture should be washed with alcohol to remove excess benzoyl chloride. Benzoylated poly-... 

Among the derivatization methods for hydroxyl groups, esterification with benzoyl chloride and its analogues... 

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. 

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