It has been shown that some of the fluorinated ethane derivatives being introduced as CFC-replacements can be transformed to TFA (trifluoroacetate) in the atmosphere. Moreover, TFA is extremely stable in the environment, and this has raised questions regarding how widespread TFA is in the environment. We found that TFA is ubiquitous in precipitation: samples of rain from Ireland and Poland and snow from Canada, Sweden, New Zealand, and East Antarctica contained 1-1100 ng/L, and, studying a firn core drilled in Antarctica, concentrations of 3-56 ng/L were measured in layers formed during the 19th century. We have confirmed the preindustrial presence of significant background concentrations of trifluoroacetate in historic precipitation samples from the analysis of firn. Extensive procedures were enforced to prevent sample contamination.

Organics enriched from samples of rain, snow, and glacier ice were analyzed to determine the chemical structure of the chloroorganic compounds that were most abundant in such media. Gas chromatography with atomic emission detection (GC-AED) was used to provide an overview of the presence of volatile and extractable chloroorganics at four sites in Europe and one site in Antarctica. Real samples and isomer-specific standards were then analyzed by gas chromatography with mass-spectrometric detection (GC-MS) to identify and confirm the structure of the chloroorganics that had been detected in the GC-AED analysis. The results revealed that of the volatile chloroorganics found in the samples, dichloronitromethane, a compound not previously reported to occur in the ambient environment, was often present in the highest concentration (up to 130 ng L-1). Chlorobenzenes were detected mainly as 1,4-dichlorobenzene and minor amounts of 1,3- and 1,2-dichlorobenzene and one isomer of tetrachlorobenzene (1,2,4,5- or 1,2,3,5-tetrachlorobenzene). Chlorinated alkyl phosphates, which were normally responsible for the largest peaks in the chlorine-specific chromatograms of hexane- or ether-extractable compounds, were present as tris(2-chloroethyl)phosphate, tris(1-chloro-2-propyl)phosphate, and one of the isomers bis(1-chloro-2-propyl)(3-chloro-1-propyl)phosphate or bis(1-chloro-2-propyl)(2-chloro-1-propyl)phosphate. All of the chloroorganic compounds mentioned, i.e., dichloronitromethane, chlorobenzenes, and chlorinated alkyl phosphates, were detected at relatively remote sites in the northern hemisphere, whereas only chlorobenzenes were found in a reference sample of snow from Antarctica.

The formation of N,N-dimethylcarbamoyl chloride (DMCC) in Vilsmeier reactions (VRs) and the hydrolysis of DMCC during aqueous workup were investigated. The amount of DMCC formed was dependent on the chlorination reagent. The activity order was found to be: thionyl chloride > oxalyl chloride > phosphorus oxychloride. The concentrations of DMCC found in the tested reactions were normally at a level of 0-20 ppm. In the presence of a base the level was higher. DMCC hydrolyzed quickly under aqueous workup conditions. No more than 3 ppm of DMCC could be detected in the product after aqueous workup of the tested VR. Our results clearly indicate that by following the described procedure for VR it is perfectly safe from the health risk point of view to operate this chemistry when preparing compounds for pharmaceutical use. A very useful analytical procedure for detection and quantification of trace amounts of DMCC formed in the VR was developed. The method was based on derivatization of DMCC with ethanol to form ethyl N,N-dimethylcarbamate and analysis by GC coupled to a mass spectrometer in selected ion monitoring mode. The analytical method was selective and showed very good linearity. The limit of detection (LOD) and limit of quantification (LOQ) of DMCC using standard addition analysis with real Vilsmeier reaction matrices were determined to be LOD ) 0.2 ppm and LOQ ) 0.7 ppm.

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