Fig. 8
Determination of the chemical structure of δ-acaridial by NMR spectroscopy. a Chemical structure of δ-acaridial showing the numbering of the individual carbon atoms, which is in accordance with its IUPAC name 2-(but-1-en-1-yl)-4-butylidene-3-(pent-2-en-1-yl)-pentanedial. Chiral centers are indicated with asterisks. b Schematic presentation of the key 1H-1H correlations observed in 2D COSY and TOCSY spectra. c Relevant regions of a 2D 1H-1H COSY spectrum recorded at 700 MHz at 274 K using 16 transients, 2 k × 340 data points, with spectral widths of 10 × 10 ppm, corresponding to a digital resolution of 7 Hz in f2 and 42 Hz in f1, resulting in a measurement time of 3 h. Positive signals are shown in red, negative ones in orange. d Corresponding regions of a 2D 1H-1H TOCSY spectrum recorded at 700 MHz at 274 K using a mixing time of 80 ms, 16 transients, 2 k × 256 data points, with spectral widths of 10 × 10 ppm, corresponding to a digital resolution of 7 Hz in f2 and 56 Hz in f1, resulting in a measurement time of 2.6 h. Negative signals are shown in grey