Infra-red absorption spectra of pyrylium salts

Anion exchange capacity of biochar

“…Oxonium heterocycles present in the biochar samples ought to be evident in FTIR spectra by a C-O + stretching band. The C-O + stretch exhibits strong absorbance in the 1600-1640 v max /cm −1 region in model compounds, with decreased energy of vibration observed in compounds of greater substitution 28 and was observed at 1622 v max /cm −1 in the spectrum of 2,4,6triphenylpyrylium hydrogensulfate (Fig. S1 †).…”

Isotope exchange of active methyl hydrogens. III. Preparation of 2, 4, 6‐tri‐d3‐methylpyridine, 3, 5‐di‐d3‐methylphenol, 3, 5‐di‐d3‐methyl‐2‐acetylfuran, and 4, 6, 8‐tri‐d3‐methylazulene, from 2, 4, 6‐tri‐d3‐methylpyrylum perchlorate

“…The I.R. spectrum of I was reported previously (13). These data evidence clearly that the methyl groups are deuterated in all compounds I-V. A detailed discussion of the infrared spectra of compounds I-V and of compounds VII and VIII (R = Ph or Et) (14) will be published separately.…”

Enriching and Quantifying Porous Single Layer 2D Polymers by Exfoliation of Chemically Modified van der Waals Crystals

“…Because of the limited signal‐to‐noise ratio of the spectra, the conversion could not be determined with high precision, but was estimated to be >90 %. In infrared spectroscopy, measured in attenuated total reflectance (ATR), parent pyrylium tetrafluoroborate and parent pyridine show characteristic signals at 1620 cm −1 and 1595 cm −1 , respectively . As these signals are virtually unchanged in the above model studies (see Supporting Information), they were taken as an indication for the proposed chemical reaction and as a measure for conversion.…”

“…In infrared spectroscopy, measured in attenuated total reflectance (ATR), parent pyrylium tetrafluoroborate and parent pyridine show characteristic signals at 1620 cm À1 and 1595 cm À1 ,respectively. [26] As these signals are virtually unchanged in the above model studies (see Supporting Information), they were taken as an indication for the proposed chemical reaction and as am easure for conversion. Figure 4d shows the corresponding spectral regions (full spectra:F igure S12).…”