Thermochemolysis using TMAAc and TMAH reagents as means to differentiate between free acids and esters

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Abstract

The reactivity of aromatic and aliphatic esters in on-line thermochemolysis in the presence of methylation reagents was studied using model compounds. Guaiacyl and 2-nonyl palmitates were synthesised, representing aromatic and aliphatic ester bonds, respectively. These model compounds were analysed by on-line thermochemolysis using tetramethylammonium acetate (TMAAc) and tetramethylammonium hydroxide (TMAH) in order to differentiate free acids from esterified acids. The released palmitic acid with TMAH for both model compounds was close to the theoretical palmitic acid content in the model compounds, even if part of the aliphatic ester had not reacted with TMAH. The free palmitic acid content by TMAAc was one third of the theoretical value for aromatic ester and only a few percentages for aliphatic ester. The result indicated that the less basic reagent is able to hydrolyse the aromatic ester linkage to some extent, whereas the aliphatic ester remains intact. Thus, differentiation of free acids by TMAAc from the esterified acids cannot be reliably performed from matrices containing aromatic esters. It was found that transesterification due to the use of methanol as a solvent with TMAAc is an insignificant reaction in on-line thermochemolysis.
Original languageEnglish
Pages (from-to)31-35
JournalJournal of Analytical and Applied Pyrolysis
Volume103
DOIs
Publication statusPublished - 2013
MoE publication typeNot Eligible

Fingerprint

Esters
Acetates
Acids
Palmitic acid
Palmitic Acid
Methylation
tetramethylammonium
Palmitates
Transesterification
Methanol

Keywords

  • Ester bond
  • free acids
  • Py-GC/MS
  • tetramethylammonium acetate
  • tetramethylammonium hydroxide
  • thermochemolysis

Cite this

@article{16ccc4e1bd5f49b589a467c66774ac63,
title = "Thermochemolysis using TMAAc and TMAH reagents as means to differentiate between free acids and esters",
abstract = "The reactivity of aromatic and aliphatic esters in on-line thermochemolysis in the presence of methylation reagents was studied using model compounds. Guaiacyl and 2-nonyl palmitates were synthesised, representing aromatic and aliphatic ester bonds, respectively. These model compounds were analysed by on-line thermochemolysis using tetramethylammonium acetate (TMAAc) and tetramethylammonium hydroxide (TMAH) in order to differentiate free acids from esterified acids. The released palmitic acid with TMAH for both model compounds was close to the theoretical palmitic acid content in the model compounds, even if part of the aliphatic ester had not reacted with TMAH. The free palmitic acid content by TMAAc was one third of the theoretical value for aromatic ester and only a few percentages for aliphatic ester. The result indicated that the less basic reagent is able to hydrolyse the aromatic ester linkage to some extent, whereas the aliphatic ester remains intact. Thus, differentiation of free acids by TMAAc from the esterified acids cannot be reliably performed from matrices containing aromatic esters. It was found that transesterification due to the use of methanol as a solvent with TMAAc is an insignificant reaction in on-line thermochemolysis.",
keywords = "Ester bond, free acids, Py-GC/MS, tetramethylammonium acetate, tetramethylammonium hydroxide, thermochemolysis",
author = "Taina Ohra-Aho and Jarmo Ropponen and Tarja Tamminen",
year = "2013",
doi = "10.1016/j.jaap.2012.09.015",
language = "English",
volume = "103",
pages = "31--35",
journal = "Journal of Analytical and Applied Pyrolysis",
issn = "0165-2370",
publisher = "Elsevier",

}

TY - JOUR

T1 - Thermochemolysis using TMAAc and TMAH reagents as means to differentiate between free acids and esters

AU - Ohra-Aho, Taina

AU - Ropponen, Jarmo

AU - Tamminen, Tarja

PY - 2013

Y1 - 2013

N2 - The reactivity of aromatic and aliphatic esters in on-line thermochemolysis in the presence of methylation reagents was studied using model compounds. Guaiacyl and 2-nonyl palmitates were synthesised, representing aromatic and aliphatic ester bonds, respectively. These model compounds were analysed by on-line thermochemolysis using tetramethylammonium acetate (TMAAc) and tetramethylammonium hydroxide (TMAH) in order to differentiate free acids from esterified acids. The released palmitic acid with TMAH for both model compounds was close to the theoretical palmitic acid content in the model compounds, even if part of the aliphatic ester had not reacted with TMAH. The free palmitic acid content by TMAAc was one third of the theoretical value for aromatic ester and only a few percentages for aliphatic ester. The result indicated that the less basic reagent is able to hydrolyse the aromatic ester linkage to some extent, whereas the aliphatic ester remains intact. Thus, differentiation of free acids by TMAAc from the esterified acids cannot be reliably performed from matrices containing aromatic esters. It was found that transesterification due to the use of methanol as a solvent with TMAAc is an insignificant reaction in on-line thermochemolysis.

AB - The reactivity of aromatic and aliphatic esters in on-line thermochemolysis in the presence of methylation reagents was studied using model compounds. Guaiacyl and 2-nonyl palmitates were synthesised, representing aromatic and aliphatic ester bonds, respectively. These model compounds were analysed by on-line thermochemolysis using tetramethylammonium acetate (TMAAc) and tetramethylammonium hydroxide (TMAH) in order to differentiate free acids from esterified acids. The released palmitic acid with TMAH for both model compounds was close to the theoretical palmitic acid content in the model compounds, even if part of the aliphatic ester had not reacted with TMAH. The free palmitic acid content by TMAAc was one third of the theoretical value for aromatic ester and only a few percentages for aliphatic ester. The result indicated that the less basic reagent is able to hydrolyse the aromatic ester linkage to some extent, whereas the aliphatic ester remains intact. Thus, differentiation of free acids by TMAAc from the esterified acids cannot be reliably performed from matrices containing aromatic esters. It was found that transesterification due to the use of methanol as a solvent with TMAAc is an insignificant reaction in on-line thermochemolysis.

KW - Ester bond

KW - free acids

KW - Py-GC/MS

KW - tetramethylammonium acetate

KW - tetramethylammonium hydroxide

KW - thermochemolysis

U2 - 10.1016/j.jaap.2012.09.015

DO - 10.1016/j.jaap.2012.09.015

M3 - Article

VL - 103

SP - 31

EP - 35

JO - Journal of Analytical and Applied Pyrolysis

JF - Journal of Analytical and Applied Pyrolysis

SN - 0165-2370

ER -