Unwanted alkylation during direct methylation of fatty (di)acids using tetramethyl ammonium hydroxide reagent in a Curie-point pyrolysis unit

New pyrolytic and spectroscopic data on Orgueil and Murchison insoluble organic matter: A different origin than soluble?

“…Van den Berg and Boon (2001) showed that aqueous TMAH produces fewer by-products with carboxylic (di)acids than methanolic TMAH. In our experiments we didn't observe such phenomena, probably due to the lower reactivity of chondritic IOM when compared with the carboxylic (di)acid standards used by Van den Berg and Boon.…”

The analysis of European lacquer: optimization of thermochemolysis temperature of natural resins

“…A first group of markers (2,3,12,13,14,16,19,23,27, indicated with ° in figure 2) perform well at all temperature programs (UFD, 350, 480, 550°C). Differences between them are minimal.…”

“…Unwanted side reactions, including isomerization, elimination and nitrogen incorporation, have been frequently observed in thermochemolysis with TMAH as alkylation reagent [14,19,[23][24][25][26][27][28][29], with solvent type, excess of TMAH and temperature being identified as influencing factors. Water as solvent for the TMAH is suggested to perform better than methanol but limited solubility of resins and a long drying time are important counter arguments [26,27,30]. Excess of TMAH favors side reactions by increasing both alkalinity and availability of reactive nitrogen groups in the reaction [26][27][28].…”

“…Water as solvent for the TMAH is suggested to perform better than methanol but limited solubility of resins and a long drying time are important counter arguments [26,27,30]. Excess of TMAH favors side reactions by increasing both alkalinity and availability of reactive nitrogen groups in the reaction [26][27][28]. Most clearly, however, high thermochemolysis temperature has been proven to enhance the occurrence of unwanted side products [14,19,25,26].…”

Comparison between off-line and on-line derivatisation methods in the characterisation of siccative oils in paint media

“…Thermally assisted derivatisation gas chromatography/ mass spectrometry (GC/MS) has proved to be a suitable technique without the need of any preliminary treatment [6][7][8][9][10], even if with this method additional compounds are obtained in the GC profile [8,13]. The formation of polyunsaturated fatty acid isomers as conjugated transtrans isomers in oils, for example, has been attributed to base catalysed and thermally induced isomerisation of unsaturated fatty acids [8].…”