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)

Abstract

The syntheses of several perdeuterated substances-some of them isotopically labeled ( 15 N) in addition-are described, which act as direct solvents of cellulose either on their own, such as N-methylmorpholine N-oxide (NMMO), 1-butyl-3-methylimidazolium acetate (BMIM-OAc), or 1-ethyl-3-methylimidazolium acetate (EMIM-OAc), or in combination with auxiliaries, such as N,N-dimethylacetamide (DMAc-for the cellulose solvent DMAc/LiCl). NMMO-d 11 (9) was obtained in an eight-step approach from non-labeled diglycolic acid (1) via diethylene glycol-d 8 (4) and its bis-tosylate (5), which underwent ring closure with benzylamine to N-benzylmorpholine-d 8 (6). Debenzylation, methylation and oxidation completed the synthetic sequence, which was also able to provide the 15 N-labeled product (9a) by usage of 15 N-benzylamine. DMAc-d 9 (14) was obtained from deuterated acetic acid (10) and dimethylamine-d 6 -carbon dioxide complex (13) in a solvent-free gas-solid reaction with acidic alumina as the catalyst. Employing the CO 2 -complex of 15 N-dimethylamine-d 6 afforded the 15 N-labeled product 15 N-DMAc-d 9 (14a) in a similar way. The two ionic liquids EMIM-OAc (21) and BMIMOAc (22) were obtained from imidazole in three-step sequences starting with butylation and ethylation, respectively. The resulting 1-alkyl imidazoles were purified, and subsequently methylated according to a novel protocol using dimethylcarbonate-d 6 . Addition of acetic acid-d 4 caused traceless degradation of the methylcarbonate anions and exchange for acetate. In all syntheses, the reaction steps were optimized with nonlabeled compounds towards high yields and high reproducibility before entering the ''hot runs'' with deuterated and otherwise isotopically labeled material.

Diffusion, Ion Pairing and Aggregation in 1‐Ethyl‐3‐Methylimidazolium‐Based Ionic Liquids Studied by 1H and 19F PFG NMR: Effect of Temperature, Anion and Glucose Dissolution

“…A typical NMR spectrum of the ionic liquid samples studied is shown in Figure , which shows the 1 H NMR spectrum of the [EMIM] + cation in the [EMIM][TFSI] ionic liquid together with the peak assignment, based on the data of Adelwohrer et al . previously reported.…”

“…[TFSI] ionic liquid together with the peak assignment, based on the data of Adelwohrer et al [18] previously reported. The 19 FNMR spectrumo ft he [TFSI] À anion,r eported in the ESI material, showedas ingle peak for the equivalent fluorinea toms in [TFSI] À ,i na greement with what has previously been reported.…”

Ab Initio Prediction of Proton NMR Chemical Shifts in Imidazolium Ionic Liquids

“…Since proton NMR data of high resolution could only be found for neat [C 2 mim][BF 4 ], for the analysis of calculated NMR shifts the preference was given to the literature data taken in the same solvent with a relatively low dielectric constant such as chloroform, as these NMR data are expected to be the closest to those of neat samples. For the C 2 mim-based ionic liquids coupled with the tetrafluoroborate, chloride, acetate, dicyanamide, hexafluorophosphate, and ethylsulfate anions, the NMR data came from the literature data in deuterated chloroform solutions, whereas for the ILs in combination with the trifluoroacetate and tosylate anions, the proton NMR spectra were measured in this work (for more detail see Experimental Procedures).…”

“…Chemical shifts of equivalent protons in the cation (e.g., protons in the methyl groups) were found to differ by 1 ppm on average and, therefore, were calculated as an average value. In order to be consistent with the available experimental data, the 1 H NMR chemical shifts of the ion pairs were calculated with respect to the magnetic shielding value of twelve equivalent protons in tetramethylsilane (TMS). − For the sake of consistency, absolute magnetic shielding of protons in TMS was calculated at the same levels of theory as those of the ion pairs. The geometry of TMS was optimized at the MP2/aug-cc-pVDZ level of theory.…”

Charakterisierung von Cellulasepräparationen mittels Streulicht

“…Viele Arbeitsgruppen versuchten im Laufe des letzten Jahrhunderts die Struktur der Cellulose und deren Abbau im Detail zu verstehen. Es wurden zahlreiche Modelle zur Beschreibung der molekularen Struktur von Cellulose entwickelt [1] und unterschiedliche Wege zur Auflösung [2] oder zum Abbau der Cellulosefasern zu Polysacchariden [3] vorgeschlagen. In der letzten Zeit rücken die enzymatischen Hydrolyseverfahren zunehmend in den Mittelpunkt [4].…”