Natural Abundance 2H Nuclear Magnetic Resonance Study of the Origin of 2-Phenylethanol and 2-Phenylethyl Acetate

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The site-specific natural abundance deuterium distribution of raspberry ketone 3 obtained through a variety of methods has been determined through (2)H NMR spectroscopy. This technique provided a means of distinguishing between "natural" raspberry ketones biogenerated from 4-hydroxybenzalacetone (2), obtained from 4-hydroxybenzaldehyde of extractive botanical origin and acetone produced by sugar fermentation by reduction using baker's yeast and other microorganisms, and other raspberry ketone samples obtained in different "non-natural" ways. Of natural origin is also a commercial sample obtained in an unspecified manner. A mechanistic interpretation has been proposed to explain the difference of site-specific deuterium content between the examined samples.

mentioning

confidence: 99%

Natural Abundance ²H Nuclear Magnetic Resonance Study of the Origin of Raspberry Ketone

Fronza¹,

Fuganti²,

Guillou³

et al. 1998

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“…On the basis of the present experiments, sample 6 has to be considered natural and biogenerated from 2. Thus, as in the case of 2-phenylethanol (Fronza et al, 1995b) and n-hexanol (Fronza, 1996), the origin of samples of 1 can be clearly defined by the present technique, in particular taking account the mechanistic aspects of their biogeneration from defined precursors to explain the extent of deuterium labeling.…”

Section: Resultsmentioning

confidence: 96%

Natural Abundance ²H Nuclear Magnetic Resonance Study of the Origin of (Z)-3-Hexenol

Barbeni¹,

Cisero²,

Fuganti³

1997

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The origin of 11 samples of (Z)-3-hexenol was studied by SNIF-NMR measurements. The results show a possible distinction between synthetic and extractive materials and those biogenerated from linolenic acid by enzymic fragmentation at position 13 of the carbon framework of the 13-hydroperoxide obtained by the action of oxygen in the presence of lipoxygenase, followed by baker's yeast-mediated reduction of the intermediate (Z)-3-hexenal. Particularly significant to this end result are the deuterium contents at relevant positions of (Z)-3-hexenol, such as 3+4 and 1. The results suggest that one sample might be a mixture of materials of extractive origin with those obtained by biodegradation from linolenic acid. Keywords: (Z)-3-Hexenol; naturality; SNIF-NMR; biogeneration

“…d Sites 4 and 6 are magnetically equivalent. e Different ranges of values have been measured in several commercial samples ( , ).…”

Section: Resultsmentioning

confidence: 99%

Isotopic Criteria in the Characterization of Aromatic Molecules. 2. Influence of the Chemical Elaboration Process

Martin

Heck

Djamaris-Zainal

et al. 2006

Most valued natural aromatic molecules can be substituted by their low-cost chemical counterparts. Isotopic methods, which offer the most powerful tool to infer the origin of a molecule, are applied to the characterization of a large number of chemical aromatic species. Isotopic affiliation between precursors and products is investigated in several types of reactions: oxidation of benzyl chloride and benzyl alcohol and hydrolysis of benzylidene chloride and cinnamaldehyde. The isotopic parameters strongly depend not only on the type of process but, for a given process, on the experimental conditions of the reaction. Kinetic isotope effects occurring in several formylation reactions are estimated. It is shown that, in the drastic experimental conditions of many industrial processes, the benzenic hydrogen atoms may be affected by exchange phenomena. Consequently, the site-specific isotopic parameters of the ring fragment of chemical species are usually much less stable than those of the corresponding natural molecules biosynthesized in mild environments. The isotope ratios of substituents such as CH3, CH2Cl, and CHO are more resistant to exchange and provide useful criteria for characterizing both the raw materials and the process. It is shown in particular that radical hydrogen abstraction in toluene to produce benzyl chloride induces relatively moderate fractionation effects. In contrast, oxidation reactions frequently produce strong fractionation effects. In particular, industrial direct oxidation of toluene into benzaldehyde is characterized by deuterium enrichments at the formyl site, which may exceed 900 ppm. Taking into account the large magnitude and high variability of many fractionation effects occurring in chemical reactions, the isotopic fingerprint may provide unambiguous criteria, not only for excluding a natural origin and characterizing the type of process, but also for differentiating molecules synthesized by a given process in different industrial contexts. The isotopic fingerprint may therefore be used by manufacturers as a powerful label for characterizing their production batches.