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SUMMARY: Carboxymethylcellulose (CMC) was prepared in a completely heterogeneous procedure in an isopropanol/water slurry and the influence of the reaction conditions on the pattern of functionalization within the anhydroglucose repeating unit as well as due to the formation of the four main repeating units (i. e. unfunctionalized, mono-, di-, and tricarboxymethylated) was checked. The concentration of aqueous sodium hydroxide solution, which is used to activate the cellulose, was varied in the range from 8 to 30% at reaction times from 2 to 6 h at 55 8C. The reaction with sodium monochloroacetate leads to the highest degree of substitution (DS CMC ) of 1.24 at a NaOH concentration of 15% and 5 h reaction time. Using a lye concentration of 30%, no influence of the reaction time between 2 h and 6 h was found.From 1 H NMR spectroscopical studies it was concluded that both the concentration of the alkali hydroxide solution and the reaction time influence the partial DS CMC at positions O-2 and O-6, while position O-3 shows the lowest reactivity in any case, independent of the reaction conditions used. With increasing lye concentration, carboxymethylation occurs preferably at O-6. Information about the content of the differently functionalized repeating units can be obtained by chromatographic analysis after complete depolymerization of the polymer chains. Surprisingly, in any product synthesized a statistic content of the building units of the polymer was found even at low activation of cellulose.ZUSAMMENFASSUNG: Carboxymethylcellulose (CMC) wurde durch vollständig heterogene Synthese in einer Isopropanol/Wasser-Suspension hergestellt und der Einfluß der Reaktionsbedingungen auf das Funktionalisierungsmuster innerhalb der Anhydroglucose-Wiederholungseinheiten und bezüglich der Bildung der vier wesentlichen Polymerbausteine (unsubstituiert bzw. mono-, di-und tricarboxymethyliert) beurteilt. Die zur Aktivierung der Cellulose eingesetzte wäßrige Natriumhydroxid-Lösung wurde im Konzentrationsbereich von 8 bis 30% und Reaktionszeiten von 2 bis 6 h bei 55 8C variiert. Bei der Umsetzung mit Natriummonochloracetat wurde der höchste durchschnittliche Substitutionsgrad (DS CMC ) von 1,24 bei einer NaOH-Konzentration von 15% und 5 h Reaktionszeit erreicht. Wird 30proz. NaOH-Lösung eingesetzt, findet man keinen Einfluß der Reaktionszeit im untersuchten Bereich von 2 bis 6 h mehr.Aus 1 H NMR-spektroskopischen Untersuchungen geht hervor, daß sowohl die Konzentration der Alkalihydroxidlösung als auch die Reaktionszeit die partiellen DS-Werte an den Positionen O-2 und O-6 beeinflussen, während die Position O-3 in allen Fällen die geringste Reaktivität aufweist. Mit steigender Laugenkonzentration wird die Carboxymethylierung am O-6 bevorzugt. Aussagen zum Gehalt der unterschiedlich funktionalisierten Wiederholungseinheiten konnten durch chromatographische Analyse nach vollständiger säurehydroly-tischer Depolymerisation der Polymerketten gewonnen werden. In allen hergestellten Produkten liegt überra-schenderweise sogar bei geringer A...

Carboxymethylcellulose (CMC) was prepared in a completely heterogeneous procedure in an isopropanol/water slurry and the influence of the reaction conditions on the pattern of functionalization within the anhydroglucose repeating unit as well as due to the formation of the four main repeating units (i. e. unfunctionalized, mono‐, di‐, and tricarboxymethylated) was checked. The concentration of aqueous sodium hydroxide solution, which is used to activate the cellulose, was varied in the range from 8 to 30% at reaction times from 2 to 6 h at 55°C. The reaction with sodium monochloroacetate leads to the highest degree of substitution (DSCMC) of 1.24 at a NaOH concentration of 15% and 5 h reaction time. Using a lye concentration of 30%, no influence of the reaction time between 2 h and 6 h was found. From 1H NMR spectroscopical studies it was concluded that both the concentration of the alkali hydroxide solution and the reaction time influence the partial DSCMC at positions O‐2 and O‐6, while position O‐3 shows the lowest reactivity in any case, independent of the reaction conditions used. With increasing lye concentration, carboxymethylation occurs preferably at O‐6. Information about the content of the differently functionalized repeating units can be obtained by chromatographic analysis after complete depolymerization of the polymer chains. Surprisingly, in any product synthesized a statistic content of the building units of the polymer was found even at low activation of cellulose.

For the first time, carboxymethyl starch (CMS) samples with a very high degree of substitution (DS CM ϭ 2.1) were synthesized by multistep carboxymethylation under heterogeneous reaction conditions in methanol/water with sodium hydroxide and monochloroacetic acid as an etherifying agent. The stepwise increase in the total DS CM value gradually decreased with an increasing DS CM value of the starting polymer. The determination of the functionalization pattern of CMS by 1 H-NMR spectroscopy after chain degradation indicated a high preference for

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