Low-Field NMR Spectroscopy on Solid Dispersions A Flow Injection Method for End-Point Control of Azo Couplings for Industrial Pigment Production
- Global demand for pigments is expected to increase to around 13.4 million tons per year by 2030, representing approximately $22 billion – 5% of which will be azo pigments as the main organic pigments. Azo pigments, i.e., especially the azo bridge required for them, are almost exclusively produced in technology by the so-called azo coupling reaction in large-scale approaches on the scale of 50–100 cubic meters. Among other things, one of the reasons why large-scale production itself is still essentially discontinuous is the lack of analytical methods for a continuous azo pigment synthesis.
In an azo coupling process, an aromatic amine is diazotized to form the diazonium compound (diazo compound), which then reacts with a coupling component, i.e., "couples". A slight excess of the coupler is desired for the end of the reaction, which stoichiometrically consumes the remaining (harmful) diazo compound, i.e., below 500 ppm. This is carried out with a manual spotting reaction of aGlobal demand for pigments is expected to increase to around 13.4 million tons per year by 2030, representing approximately $22 billion – 5% of which will be azo pigments as the main organic pigments. Azo pigments, i.e., especially the azo bridge required for them, are almost exclusively produced in technology by the so-called azo coupling reaction in large-scale approaches on the scale of 50–100 cubic meters. Among other things, one of the reasons why large-scale production itself is still essentially discontinuous is the lack of analytical methods for a continuous azo pigment synthesis.
In an azo coupling process, an aromatic amine is diazotized to form the diazonium compound (diazo compound), which then reacts with a coupling component, i.e., "couples". A slight excess of the coupler is desired for the end of the reaction, which stoichiometrically consumes the remaining (harmful) diazo compound, i.e., below 500 ppm. This is carried out with a manual spotting reaction of a fast-binding coupler.
To carry out continuous azo coupling, care must be taken to ensure that the actual coupling reaction proceeds as rapidly as possible, i.e., preferentially, compared with possible side reactions. Reliable measuring methods are thus a decisive criterion for the useful performance of a continuous azo pigment synthesis. An analytical online procedure is difficult due to several limitations at once: solid dispersions extremely limit the range of reproducible analytical procedures. In addition, the appearance of a signal (e.g., excess of a starting material) in the ppm range must be reliably detected against the matrix background.
The back-titration method and benchtop NMR spectroscopy were used to overcome these problems. We present a feasibility study for a suitable process analysis with benchtop NMR spectroscopy on disperse systems for equimolar dosing of the "diazotization" or "coupling" sub-step in azo coupling, which was carried out in cooperation with a chemical company. This could replace tedious manual spotting…
Autor*innen: | Klas MeyerORCiD |
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Weitere Person: | P. Gräßer, S. Kern, Michael MaiwaldORCiD |
Dokumenttyp: | Posterpräsentation |
Veröffentlichungsform: | Präsentation |
Sprache: | Deutsch |
Jahr der Erstveröffentlichung: | 2023 |
Organisationseinheit der BAM: | 1 Analytische Chemie; Referenzmaterialien |
1 Analytische Chemie; Referenzmaterialien / 1.4 Prozessanalytik | |
DDC-Klassifikation: | Naturwissenschaften und Mathematik / Chemie / Analytische Chemie |
Freie Schlagwörter: | Benchtop NMR; Dispersions; Process Analytical Technology; Process monitoring |
Themenfelder/Aktivitätsfelder der BAM: | Chemie und Prozesstechnik |
Chemie und Prozesstechnik / Chemische Charakterisierung und Spurenanalytik | |
Veranstaltung: | SMASH Small molecule NMR conference 2023 |
Veranstaltungsort: | Baveno, Italy |
Beginndatum der Veranstaltung: | 17.09.2023 |
Enddatum der Veranstaltung: | 20.09.2023 |
Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |
Datum der Freischaltung: | 26.09.2023 |
Referierte Publikation: | Nein |