Abstract
Degradation processes of N-methylmorpholine-N-oxide monohydrate (NMMO), cellulose and cellulose/NMMO solutions were studied by high performance liquid chromatography (HPLC) and electron spin resonance (ESR) spectroscopy. Kinetics of radical accumulation processes under UV (λ = 248 nm) excimer laser flash photolysis was investigated by ESR at 77 K. Beside radical products of cellulose generated and stabilized at low temperature, radicals in NMMO and cellulose/NMMO solutions were studied for the first time in those systems and attributed to nitroxide type radicals ∼CH2–NO•–CH2∼ and/or ∼CH2–NO•–CH3∼ at the first and methyl •CH3 and formyl •CHO radicals at the second step of the photo-induced reaction. Kinetic study of radicals revealed that formation and recombination rates of radical reaction depend on cellulose concentration in cellulose/NMMO solutions and additional ingredients, e.g., Fe(II) and propyl gallate. HPLC measurements showed that the concentrations of ring degradation products, e.g., aminoethanol and acetaldehyde, are determined by the composition of the cellulose/NMMO solution. Results based on HPLC are mainly maintained by ESR that supports the assumption concerning a radical initiated ring-opening of NMMO.
Similar content being viewed by others
References
Ayscough PB, Thomson C (1962) Electron spin resonance spectra of alkyl radicals in γ-irradiated alkyl halides. Trans Faraday Soc 58:1477–1494
Buijtenhuijs FA, Abbas M, Witteveen AJ (1986) The degradation and stabilization of cellulose dissolved in N-methylmorpholine-N-oxide (NMMO). Papier 40:615–619
Chanzy H, Nawrot S, Peguy A, Smith P, Chevalier J (1982) Phase behaviour of the quasiternary system N-methylmorpholine-N-oxide, water and cellulose. J Polymer Sci 20:1909–1924
Doering H (1956) Carboxylgruppenbestimmungen in Zellstoffen mit Komplexon. Papier 10:140–141
Ferris JP, Gerwe RD, Gapski GR (1967) Iron-catalysed dealkylation of trimethylamine oxide. J Am Chem Soc 89:5269–5275
Fessenden RW, Schuler RH (1965) ESR spectra and structure of the fluorinated methyl radicals. J Chem Phys 43:2704–2712
Firgo H, Eibl K, Kalt W, Meister G (1994) Kritische Fragen zur Zukunft der NMMO-Technologie. Lenz Ber 9:81–89
Guthrie JT, Manning CS (1990) The cellulose/N-methylmorpholine-N-oxide/H2O system: degradation aspects. In: Kennedy JF, Phillips GO, Williams PA (Hrsg.) (eds) Cellulose Sources and Exploitation. Ellis Horwood, New York, pp 49–57
Holmberg RW (1969) ESR study of H•CO in single crystals of formic acid at 77K. J Chem Phys 51:3255–3260
Hon NS (1976) Formation of free radicals in photoirradiated cellulose. VIII. mechanisms. J Polym Sci Polym Chem Ed 14:2497–2512
Konkin A, Wendler F, Roth H-K, Schrödner M, Meister F, Heinze T, Aganov A, Garipov R (2006a) Electron spin resonance study of radicals generated in cellulose/N-methylmorpholine-N-oxide solutions after flash photolysis at 77 K. Magn Reson Chem 44:594–605
Konkin A, Wendler F, Meister F, Roth H-K (2006b) Characterisation of radical processes in solutions of lignocellulose in direct solvents by electron resonance spectroscopy. In Proceedings 9th European Workshop on Lignocellulosics and Pulp EWLP, Vienna, 27–30 August 2006
Lang H, Laskowski I, Lukanoff B, Schleicher H, Mertel H, Franz H, Taeger E (1986) Untersuchungen an Lösungen von Cellulose in N-Methylmorpholin-N-Oxid (MMNO). Cell Chem Technol 20:289–301
Meister F, Vorbach D, Niemz F, Schulze T, Taeger E (2003) High-Tech-Cellulose-Funktionspolymere nach dem ALCERU®-Verfahren. Mat-wiss u Werkstofftech 34:262–266
Michels C, Maron R, Taeger E (1994) Besonderheiten des im TITK entwickelten Aminoxidprozesses. Lenz Ber 9:57–60
Rosenau T, Potthast A, Kosma P, Chen CL, Gratzl JS (1999) Autocatalytic decomposition of N-methylmorpholine-N-oxide induced by Mannich intermediates. J Org Chem 64:2166–2167
Rosenau T, Potthast A, Sixta H, Kosma P (2001) The chemistry of side reactions and byproduct formation in the system NMMO/water/cellulose (Lyocell-process). Prog Polym Sci 26:1763–1837
Rosenau T, Potthast A, Hofinger A, Sixta H, Kosma P (2002a) Instabilities in the system NMMO/water/cellulose (Lyocell-process) caused by Polonovski type reactions. Holzforschung 56:199–208
Rosenau T, Potthast A, Sixta H, Kosma P (2002b) Radicals derived from N-methylmorpholine-N-oxide (NMMO): structure, trapping and recombination reactions. Tetrahedron 58:3073–3078
Rosenau T, Potthast A, Adorjan I, Hofinger A, Sixta H, Firgo H, Kosma P (2002c) Cellulose solutions in N-methylmorpholine-N-oxide (NMMO)—degradation processes and stabilizers. Cellulose 9:283–291
Szabolcz O (1961) Eine kolorimetrische Methode zur Bestimmung der reduzierenden Carbonylgruppen in der Cellulose. Papier 15:41–44
Taeger E, Franz H, Mertel H (1985) Probleme der schwefelkohlenstofffreien Verformung von Zellulose zu textilen Zellulosefäden mittels N-Methylmorpholin-N-oxids. Formeln Fasern Fertigware 4:14–22
Wendler F, Graneß G, Heinze T (2005a) Characterization of autocatalytic reactions in modified cellulose/NMMO solutions by thermal analysis and UV/VIS spectroscopy. Cellulose 12:411–422
Wendler F, Kolbe A, Meister F, Heinze T (2005b) Thermostability of Lyocell dopes modified with surface-active additives. Macromol Mat Eng 290:826–832
Wendler F, Graneß G, Büttner R, Meister F, Heinze T (2006) A novel polymeric stabilizing system for modified lyocell dopes. J Polym Sci Pol Phys 44:1702–1713
Acknowledgment
The authors wish to express their gratitude to one of the anonymous reviewers whose remarks greatly help to improve the article. Financial support by the German Federal Ministry for Education and Research (BMBF) under contract No. 94/02 is gratefully acknowledged.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Konkin, A., Wendler, F., Meister, F. et al. Degradation processes in the cellulose/N-methylmorpholine-N-oxide system studied by HPLC and ESR. Radical formation/recombination kinetics under UV photolysis at 77 K. Cellulose 14, 457–468 (2007). https://doi.org/10.1007/s10570-007-9140-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10570-007-9140-1