Pentafluorobenzyl tertiary amines

Antihistaminics, being tertiary amines, are analysed after reaction with an analogous reagent [566] with pentafluorobenzyl chloroformate a derivative is formed with a high ECD response and good GC properties, e.g., on OV-17. Hucker and Miller [567] subjected amitriptyline and other tertiary amines to exhaustive methylation and analysed the products from the reaction (Hoffman). Whereas the initial substances gave considerable tailing on 3% of QF-1, the derivatives provided sharp and symmetric peaks. 

As an alternative to the potassium salt, tertiary amines and tetra-alkylammonium salts have been used instead. The acids, e.g. the dried residue from a serum extraction, are treated with an acetonitrile solution of pentafluorobenzyl chloride and di-isopropylethylamine, in a 3 1 molar ratio, at 40 °C for 5 minutes. The reaction mixture is blown dry with nitrogen if necessary the esterification may be repeated (96). lndole-3-acetic acid was similarly esterified, but using acetone as solvent and N-ethylpiperidine as the cation and reaction for 45 minutes at 60 °C [97). Tetrabutylammonium hydrogen sulphate (0.1 mmol) was converted to the hydroxide with sodium hydroxide (0.2 mmol) and added to the dried acids in a serum extract with 1 ml of methylene chloride and 20 pi of pentafluorobenzyl bromide. The mixture was vigorously shaken for 30 minutes and blown down to dryness with nitrogen, and the esters were extracted into hexane for HPLC [98,99). 

Pentafluorobenzyl- chloroformate 2.16.1 Derivatization of tertiary amines for ECD-GLC analysis and mass spectrometry Convenient introduction of fluorine when perfluoro acid chlorides or anhydrides cannot be used... 

Pentafluorobenzyl chloroformate has been used for the direct GC determination of tertiary amines (122, 123]. The method seems to be an improvement over the original [124] time-consuming procedure for the derivatization of these substances. 

Chloroformates are useful analytical reagents for primary, secondary, and tertiary amines. The reaction of these reagents with amines can be performed easily, and the resultant carbamate derivatives are suitable for GC analysis. The carbamate derivatives obtained from primary and secondary amines are determined selectively and sensitively by GC-MS and -BCD. After dealkylation, tertiary amines are derivatized to carbamates in the same manner for primary and secondary amines. The carbamate derivatives obtained with pentafluorobenzyl chloro-formate are determined with high sensitivity by GC-ECD. Chloroformates also react with phenols, thiols, imidazoles, as well as amines. 

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