Irprestige 21 ftir

Beads contained in a sealed plastic bag were crushed into a fine powder using a hammer. The powder was analysed using an infrared spectrometer (Shimadzu IRPrestige-21 FTIR) using 20 scans for transmittance at the highest resolution setting, and transmittance was analysed using IRsolution 1.3 software (Shimadzu). The spectra were compared with published data for Baltic amber [17 (link)] after adaptation using the WebPlotDigitizer v3.21 tool.

Fourier transform infrared (FT-IR) spectroscopy was performed in a model IR Prestige 21-FTIR Shimadzu equipment (Tokyo, Japan).

The reagents 4-fluro-3-nitroaniline, triethylamine (Et₃N), acetic anhydride, chloroacetyl chloride, chloroform, and ethanol were purchased from Merck/Sigma-Aldrich^® (Darmstadt, Germany). The recrystallization technique was used to purify the compound and its purity was confirmed from the melting point measurement using the MQAPF-302 (Microquímica, São Paulo, Brazil) apparatus. A Shimadzu spectrometer model IRPrestige-21 FT-IR (Barueri, São Paulo, Brazil) with an attenuated total reflection (ATR) accessory produced the infrared (IR) spectrum. The hydrogen and carbon nuclear magnetic resonance (NMR) spectra were obtained from a Bruker Avance 400 apparatus. The hydrogen spectra (¹H) were obtained at the frequency of 400 and 500 MHz using deuterated solvents chloroform (CDCl₃) and dimethylsulfoxide (DMSO). The carbon spectra (¹³C) were obtained at the frequency of 101 and 126 MHz using deuterated solvents chloroform (CDCl₃) and dimethylsulfoxide (DMSO). The chemical distances (δ) were generated in parts per million (ppm) and in Hertz (Hz) the coupling constants (J) were determined.

All reagents and solvents were purchased from Sigma-Aldrich and were used without further purification. Silica gel matrix, with fluorescent indicator 254 nm, was used in analytical thin-layer chromatography. The reaction and purification were monitored by TLC. All evaporations were performed under reduced pressure. Yields refer to chromatographically and spectroscopically (1H and 13C NMR) homogeneous material. IR spectra are reported in wavenumbers (cm-1) and were recorded on an IR Prestige-21 FTIR (Shimadzu, Kyoto, Japan) spectrophotometer using attenuated total reflectance (ATR). High-resolution mass spectrometry (HRMS) analysis was performed by direct infusion in the mass spectrometer using electrospray ionization with a quadrupole time-of-flight analyzer on a microTOF-QII ESI-TOF (Bruker Daltonics, Billerica, MA, USA) mass spectrometer. Nuclear magnetic resonance (NMR) experiments were performed in a Bruker Avance III HD instrument (400 MHz for 1H and 100 MHz for 13C) using CDCl₃ as solvent and TMS as the internal standard. Chemical shifts are expressed as d values in parts per million (ppm) from TMS (0 ppm) and coupling constant (J) in hertz (Hz). Abbreviations to denote the multiplicity of a particular signal are s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), and sl (signal large).