p-Menthene-8-thiol

• CAS: 71159-90-5
• Catalog Number: ACM71159905
• Category: Main Products
• Molecular Weight: 170.31
• Molecular Formula: C10H18S
• Synonyms: GRAPEFRUIT MERCAPTAN;FEMA 3700;ALPHA, ALPHA,4-TRIMETHYL-3-CYCLOHEXENE-1-METHANETHIOL;.alpha.,.alpha.-4-Trimethylcyclohex-3-ene-1-methanethiol;1-p-menthene-8-thiol;alpha,alpha,4-trimethyl-3-cyclohexene-1-methanethio;p-1-menthene-8-thiol;p-Menth-1-ene-8-thiol
• IUPAC Name: 2-(4-methylcyclohex-3-en-1-yl)propane-2-thiol
• Canonical SMILES: CC1=CCC(CC1)C(C)(C)S
• InChI Key: ZQPCOAKGRYBBMR-UHFFFAOYSA-N
• Boiling Point: 229.4ºC at 760 mmHg
• Density: 0.938 g/cm³
• Solubility: water, 5.485 mg/L @ 25 °C (est)
• Appearance: Colorless liquid with aroma and taste of grapefruit in dilute solution Visual appearance of the given substance
• Assay: 0.99
• EC Number: 280-191-7
• Exact Mass: 170.11300
• Packaging: 25 kg/DRUMS
• Refractive Index: 1.5

Case Study

Gas chromatographic separation of enantiomers of 1-p-menthene-8-thiol

Schoenauer, Sebastian, and Peter Schieberle. Journal of agricultural and food chemistry 64.19 (2016): 3849-3861.

The gas chromatographic separation of enantiomers of 1-p-menthene-8-thiol was achieved using heptyl(2,3-di-O-methyl-6-O-TBDMS)-β-cyclodextrin as an enantioselective gas chromatography chiral stationary phase. Sensory evaluation of the pure enantiomers was achieved by enantioselective gas chromatography-olfactometry. (R)-1-p-menthene-8-thiol was found to have a formative effect on the natural odor of grapefruit, while the odor of the (S)-enantiomer was weaker and non-specific.
Cyclodextrin diluted in PS 268 30 mx 0.23 mm id df 0.25 prn; carrier gas-hydrogen; column head pressure 62 kPa; injector temperature 240℃; injection 10 splitless; temperature program 100℃ for 2 min, then increase 2℃min to 200℃; detector (flame photometry) 280℃. Retention time - lp-menthene-8-thiol enantiomer, (S)R, = 23.9 min, (R)R, = 25.4 min; chiral resolution, cR, = 3.1. Column fused silica capillary coated with 30% heptyl (2,3-di-O-methyl-6-O-TBDMS)-/3-cyclodextrin solution diluted in SE 52 50 m 0.32 mm id, df 0.5 pm; carrier gas hydrogen; column head pressure 100 kPa; injector temperature 220°C, on-column injection; temperature program 50°C for 2 min, 10°C/min to 120°C, then 2°C/min to 200°C. The eluent from the chiral column was split 1:1 by a "Y" glass splitter and directed to both the flame ionization detector (FID-240°C) and the heated sniffing port. The end of an uncoated and deactivated restriction capillary (0.40 mx 0.32 mm id) was used as the sniffing port and its temperature (180°C) was controlled by mounting it on the second detector base. Eluent from the GC column (100-400°C). Each enantiomer was split 1:1 to the FID and the sniffing port to allow for direct sniffing of each enantiomer 50-200 ng Retention time 1-p-menthene-8-thiol enantiomer, ( S ) R, = 27.9. min, (R)R, = 28.5 min; cR, = 3.0.

GC/MS Determination of p-menthen-8-thiol in Fruit Juice

Goodner, Kevin L., and Carlos A. Margaria. Proceedings of the Florida State Horticultural Society. Vol. 116. 2003.

p-Menthen-8-thiol is a very potent aroma compound found in grapefruit juice. , p-menthen-8-thiol can be quantified with minimal sample and relatively short preparation time using a standard laboratory gas chromatography mass spectrometer (GC-MS). The method presented uses only 30 mL. It was determined to be as effective as a sulfur-specific detector (no difference in unknown concentration at 95% confidence level) and is able to quantify at much lower levels. A tentative detection limit of 1 ng/g was reported. Flame ionization detectors are generally not sensitive or selective enough to detect 1-p-menthen-8-thiol present in grapefruit juice (~5-100 ng g). Therefore, sulfur-specific detectors such as flame photometric detectors (FPDs), the more sensitive and more expensive pulsed flame photometric detectors (pFPDs), or sulfur chemiluminescence detectors (SCDs) are typically used to quantify this compound. The method presented here is an alternative to sulfur-specific detectors for chromatography systems. Without the need for dedicated and expensive equipment, existing GC/MS systems can be used to detect and quantify 1-p-menthen-8-thiol compounds.
These experiments used an FPD detector. The oven temperature was initially 50 °C and increased at 10 °C min to 250 °C with a constant flow rate of 1.3 mL min. The injector and detector were maintained at 250 °C. An autosampler was used to inject 2 μL of sample in splitless mode. The GC-MS conditions were identical. MS conditions were single ion monitoring (SIM) using m/z 170 with a dwell time of 200 ms and lower resolution. M/z 170 was chosen because this is the molecular weight of p-menthen-8-thiol. While m/z 121 and 136 are more abundant ions, they are common to most terpenes and are therefore less indicative of the analyte. Standards were prepared using standard dilution techniques to provide approximately 5 calibration points that approximate the levels at which the unknowns were expected to be measured. The unknowns were ethyl acetate extracts of juice purchased from a local grocery store. To prepare the grapefruit juice samples, 1000 mL of juice was extracted twice with 200 mL of ethyl acetate (400 mL total), centrifuged in a refrigerated (2 °C) ultracentrifuge (5000 rpm ~ 2600 × G) for 10 min, the organic layer removed, dried over anhydrous calcium chloride, and concentrated to approximately 4 mL using a distillation rectification apparatus. To prepare the second set of samples, 30 mL of juice was extracted twice each with 20 mL of ethyl acetate, centrifuged in a refrigerated (2 °C) Sorvall ultracentrifuge (5000 rpm ~ 2600 × G) for 10 min, the organic layer removed, dried over anhydrous calcium chloride, concentrated to approximately 4 mL using a distillation rectification apparatus, and then concentrated to 1.75 mL using a nitrogen stream at ambient temperature. The samples were repeated 5 times.

p-menthene-8-thiol participates in quantification and flavor reconstruction experiments to evaluate grapefruit juice study

Buettner, Andrea, and Peter Schieberle. Journal of Agricultural and food chemistry 49.3 (2001): 1358-1363.

Twenty-five odor-active compounds in fresh hand-squeezed juice of seedless grapefruit were quantified using stable isotope dilution assays. Calculation of the odor activity values of the odorants (ratio of concentration in juice to odor threshold in water) showed that the fruity esters ethyl 2-methylpropionate, ethyl butyrate and ethyl (S)-2-methylbutyrate, fruity, nectar lactones, as well as the grassy (Z)-hex-3-enal and metallic trans-4,5-epoxy-(E)-dec-2-enal, were the most potent fresh grapefruit juice odorants. The typical sulfurous, grapefruit-like odor qualities were mainly derived from the quinces-like, blackcurrant-like 4-mercapto-4-methylpentane-2-one and the grapefruit-like odor of 1-p-menthene-8-thiol. These findings were confirmed by reconstruction experiments simulating the aroma of fresh grapefruit juice.
Different amounts (100 mL, 1 L, or 5 L) of grapefruit juice were used for post-treatment, depending on the content of odorants in the juice; for example, 5 L of juice was necessary for p-menthene-8-thiol, while 100 mL was required for ethyl butyrate. The juice was obtained by carefully squeezing the fruit by hand using a kitchen juicer, then poured into an equal volume of saturated aqueous calcium chloride solution to inhibit the enzyme reaction, and finally added with known amounts of labeled internal standards listed in Table 1 and stirred for 30 minutes to reach equilibrium. Solvent extraction of samples and enrichment of odorants for quantification were performed as previously described. A standard curve was measured using a mixture of labeled and unlabeled reference odorants.

p-menthene-8-thiol studied by enantioselective GC-olfactometry

Lehmann, Detmar, et al. Phytochemical Analysis 6.5 (1995): 255-257.

The GC separation of p-menthene-8-thiol enantiomers was achieved using heptakis(2,3-di-O-methyl-6-O-TBDMS)-~-cyclode as an enantioselective GC chiral stationary phase. The sensory evaluation of the pure enantiomers was achieved by enantioselective GC-olfactometry. (R)-1-p-menthene-8-thiol was found to have a formative effect on the natural odor of grapefruit, whereas the odor of the (S)-enantiomer was weaker and nonspecific.
The GC column fused silica capillary was coated with a 30% solution of heptakis(2,3-di-O-methyl-6-O-TBDMS)-/3-cyclodextrin diluted in SE 52. 50 m 0.32 mm id, df 0.5 pm; carrier gas hydrogen; column head pressure--100 kPa; injector temperature--220°C, on-column injection; temperature program--50°C for 2 minutes, then increase by 10°C/min to 120°C, then increase by 2°C/min to 200°C. The eluent from the chiral column was split 1:1 by a "Y" glass splitter and directed to both the flame ionization detector and the heated sniffing port. The end of an uncoated and deactivated restriction capillary (0.40 m x 0.32 mm id) was used as the sniffing port and its temperature was controlled (180°C) by mounting it on the second detector base. Eluent from the GC column (100-400°C).

Synthetic Use

Upstream Synthesis Route 1

• 98-55-5

• 71159-90-5

Reference: [1]Journal of the Chemical Society. Perkin transactions I,1993,p. 1113 - 1118
[2]Patent: CN109796385,2019,A .Location in patent: Paragraph 0039-0103