Investigations into the Natural Occurrence of 1-Phenylethyl Acetate (Styrallyl Acetate)

So far, the occurrence of the flavor constituent 1-phenylethyl acetate in a natural source has not been unambiguously confirmed. The present work provides the detailed identification of 1-phenylethyl acetate from clove (Syzygium aromaticum (L.) Merr. & L.M. Perry) buds. In addition, HS-SPME-GC/MS analysis revealed further occurrence of 1-phenylethyl acetate in cocoa pulp and grape hyacinth flowers. A total of 15.2 g of essential oil was recovered from 7.2 kg of clove buds by simultaneous distillation-extraction (SDE) followed by vacuum distillation. The distillate obtained was fractionated by silica column chromatography, whereby a significant enrichment of 1-phenylethyl acetate was achieved. The fraction containing the target analyte was further purified by preparative HPLC (prep-HPLC), resulting in a final purity of ~93.0% yielding a total of 1 to 2 mg of 1-phenylethyl acetate. Identification of the isolated compound was achieved by gas chromatography with mass spectrometry, infrared spectroscopy, enantioselective gas chromatography, isotope ratio mass spectrometry, and nuclear magnetic resonance spectroscopy. Enantioselective GC/MS analysis revealed an enantiomeric excess of 60% (1S)-(-)-1-phenylethyl acetate in the isolate. The δ13CV-PDB value of 32.5 ± 0.5‰ was in accordance with C3 plants and those of other constituents found in genuine clove extracts.