Synthesis of the perdeuterated cellulose solvents N‐methylmorpholine N‐oxide (NMMO‐d₁₁) and N,N‐dimethylacetamide (DMAc‐d₉)

Abstract

The synthesis of the perdeuterated cellulose solvents NMMO‐d11 (9) and N,N‐dimethylacetamide‐d9 (14) is described. NMMO‐d11 was obtained according to a five‐step approach from non‐labeled diglycolic acid (1) via diethylene glycole‐d8 (4) and its bis‐tosylate (5), which underwent cyclization with benzylamine to N‐benzylmorpholine (6). The removal of the benzyl protecting group, methylation and N‐oxidation completed the synthesis. DMAc‐d9 (14) was obtained from deuterated acetic acid (10) and dimethylamine–carbon dioxide complex (17) with acidic alumina as the catalyst according to a solvent‐free gas–solid reaction. Copyright © 2008 John Wiley & Sons, Ltd.

Synthesis of N‐methylmorpholine N‐(17O‐oxide) and N‐methylmorpholine 15N‐(17O‐oxide)

“…The synthesis approach starting from H 17 2 O(1) is shown in Figure 1. In the case of 15 N-methylmorpholine, which was available from previous work, 12 application of a large excess was not realistic. When NMM and generated hydrogen peroxide were used in a roughly equimolar ratio, the oxidation stagnated after about 40% conversion, and it was also not possible to drive the reaction to completion by higher reaction temperatures.…”

Synthesis of the perdeuterated cellulose solvents N-methylmorpholine N-oxide (NMMO-d11 and NMMO-15N-d11), N,N-dimethylacetamide (DMAc-d9 and DMAc-15N-d9), 1-ethyl-3-methylimidazolium acetate (EMIM-OAc-d14) and 1-butyl-3-methylimidazolium acetate (BMIM-OAc-d18)

“…Fully deuterated NMMO has not yet been described in the literature besides a preliminary communication (Adelwöhrer et al 2008). A good synthesis of the compound should be high yielding and highly reproducible at every step, particularly considering the generally high prices of deuterated compounds.…”

Chemical Modification of Reducing End‐Groups in Cellulose Nanocrystals

“…With much shorter T 1 relaxation rates and longer T 2 values, the pulse repetition is faster and the resolution is higher in solution‐state NMR spectroscopy. However, cellulose is not a trivial substance to dissolve and the required perdeuterated cellulose solvents are scarcely available [173] . Common ionic liquids for cellulose dissolution, such as 1‐ethyl‐3‐methylimidazolium acetate, have the disadvantage that many of their resonance signals overlap with those of the cellulose backbone.…”