Spectroscopic studies of methylglyoxal in water and dimethylsulfoxide

Competitive Adsorption of Substrate and Solvent in Sn‐Beta Zeolite During Sugar Isomerization

“…In an experiment where the amount of substrate was increased to DHA/Sn=10, we found that the reaction went to completion in about 10 h (Figure 2). In this case, we observed an additional signal at δ =205 ppm owing to pyruvaldehyde, a known intermediate in the reaction from DHA to LA 29. We also evaluated the performance of Sn‐MCM‐41 at room temperature (Figure S2) and confirmed that its intrinsic reaction rate is significantly lower than that of Sn‐Beta‐HF in line with recently reported results 30.…”

Gas-phase water-mediated equilibrium between methylglyoxal and its geminal diol

“…The ν δ 13 and ν δ 14 could also have a contribution from tetrol OH stretching vibrations which all fall near to those of MGD, making it difficult to distinguish or model them. In solution, the ratio of diol to tetrol is approximately 60∕40 (23). Although this ratio has not been measured for the gas phase, at much lower water concentration in our gas-phase experiments we expect MGD to be favored over the tetrol.…”

“…MG has both an aldehydic and ketonic C ¼ O and it was determined computationally that the aldehydic C ¼ O is more favorably hydrated in solution (ΔG ¼ −1.4 kcal mol −1 ) than the ketonic C ¼ O (ΔG ¼ þ2.5 kcal mol −1 ) (21). In solution, MG is present primarily as MGD (60% diol to 40% tetrol) with the aldehydic group forming a geminal diol (21,23). MGD has a lower vapor pressure than MG, which allows the molecule to partition more easily into the particle phase, lending to the formation of SOA.…”

“…For example, laboratory studies of MG hydration performed using theoretical (21) and spectroscopic techniques (14,(22)(23)(24) suggest that in aqueous environments MG can become hydrated to form methylglyoxal diol (MGD) via reaction 1 and undergo further reactions to form oligomers (14,21,24). Like other aldehydes and ketones in aqueous solution, MG hydrates through proton addition to the aldehyde carbonyl and reaction to form MGD (21)(22)(23)(25)(26)(27). MG has both an aldehydic and ketonic C ¼ O and it was determined computationally that the aldehydic C ¼ O is more favorably hydrated in solution (ΔG ¼ −1.4 kcal mol −1 ) than the ketonic C ¼ O (ΔG ¼ þ2.5 kcal mol −1 ) (21).…”

Metilglioxal: uma toxina endógena?

“…115 O espectro de absorção do metilglioxal em vários solventes, como água e acetona, foi descrito primeiramente por Woo e Chang (1945). Eles concluíram que o metilglioxal em água gera uma forma hidratada, 116 a qual já havia sido proposta por Neuberg e Schor (1927), através de estudos de espectroscopia de absorção UV-Vis.…”