DOSY Plus Selective TOCSY: An Efficient NMR Combination for Analyzing Hydrogenation/Hydrogenolysis Mixtures of Biomass-Derived Platform Compounds

Abstract

Analyzing the mixtures obtained from hydrogenation or hydrogenolysis reactions of biomass-derived platform chemicals is challenging work. With the development and improvement of NMR techniques, the NMR spectrometer proves to be an alternative and highly efficient piece of equipment for the rapid analysis of complex mixtures without the need for tedious purification. Herein, diffusion-ordered spectroscopy (DOSY) is applied in analyzing four model mixtures, which consist of the reactants and products from hydrogenation/hydrogenolysis reactions of biomass-derived platform chemicals. The results show that the DOSY technique can pseudoseparate most components in the model mixtures. The 1D selective gradient TOCSY technique is used as a supporting tool in the cases where the DOSY technique cannot clearly distinguish between the components of the mixtures. This is generally a problem when components in the mixture have very similar diffusion coefficients or severe overlap of peaks. The results show that DOSY and 1D selective gradient TOCSY techniques make a strong combination for complex mixture analyses.

Pure Shift NMR: Application of 1D PSYCHE and 1D TOCSY-PSYCHE Techniques for Directly Analyzing the Mixtures from Biomass-Derived Platform Compound Hydrogenation/Hydrogenolysis

“…18−20 Considerable progress has been made in the mixture analysis of the biomass catalytic conversion by NMR, e.g., of phenol hydrogenolysis products. 21 However, in some cases, there are severe limitations in analyzing complex systems using conversional one-dimensional (1D) 1 H or 13 C NMR techniques due to the extensive overlap of proton couplings and signals. Recently, pure shift NMR, a novel technique without 1 H− 1 H proton coupling, has been introduced to resolve the crowded and overlapped signals by suppressing homonuclear couplings.…”

“…Nuclear magnetic resonance (NMR) spectroscopy is a widely used and importantly nondestructive technique in all branches of chemical research. The technique is commonly used for compound identification, quantification, and structural analysis of complex mixtures. − Considerable progress has been made in the mixture analysis of the biomass catalytic conversion by NMR, e.g., of phenol hydrogenolysis products . However, in some cases, there are severe limitations in analyzing complex systems using conversional one-dimensional (1D) 1 H or 13 C NMR techniques due to the extensive overlap of proton couplings and signals.…”

Cross-Polymerization between the Typical Sugars and Phenolic Monomers in Bio-Oil: A Model Compounds Study

“…Bio-oil is a condensable liquid produced from the pyrolysis of biomass. − It has a complicated composition, including a wide variety of compounds such as monosugars, sugar oligomers, monophenolics, pyrolytic lignin, etc. − These organics contain high oxygen content, high molecular mass, and various reactive oxygen-containing functionalities, , which make these organics very reactive toward polymerization. , Thus, bio-oil has to be upgraded via cracking , or hydrodeoxygenation to produce biofuels with desirable heating value and thermal stability. Coking is one of the most serious issues during the hydrotreatment of bio-oil, as it leads to the blockage of reactor and deactivation of catalysts. , Nevertheless, from another aspect, bio-oil can be used as a feedstock for production of carbon materials via polymerization …”

“…1−3 It has a complicated composition, including a wide variety of compounds such as monosugars, sugar oligomers, monophenolics, pyrolytic lignin, etc. 4−6 These organics contain high oxygen content, high molecular mass, and various reactive oxygen-containing functionalities, 7,8 which make these organics very reactive toward polymerization. 9,10 Thus, bio-oil has to be upgraded via cracking 11,12 or hydrodeoxygenation 13 to produce biofuels with desirable heating value and thermal stability.…”

Diffusion Analysis on Complex Mixtures under Adverse Magnetic Field Conditions by Spatially-Selective Pure Shift-Based DOSY

“…Benefiting from the intrinsic property of noninvasive measurements, diffusion-ordered NMR spectroscopy (DOSY) provides an effective tool for “virtually” separating components by tracking specific diffusion coefficients of individual components in an acquired 2D NMR plane and for smartly studying their kinetic behaviors without invasion and damage of detected samples. Therefore, in some investigation cases when the physical isolation is hardly necessary or achievable, DOSY remains a suitable choice for resolving intact mixtures and has been widely applied to various fields. − …”