227456-27-1

Basic information

• Product Name: 3-Mercapto-2-methylpenta-1-ol
• Synonyms: 3-MERCAPTO-2-METHYLPENTANOL;3-Mercapto-2-methylpenta-1-ol;2-Methyl-3-sulfanylpentan-1-ol;3-MERCAPTO-2-METHYLPENTAN-1-OL (RACEMIC)
• CAS NO: 227456-27-1
• Molecular Formula: C6H14OS
• Molecular Weight: 134.23976
• EINECS: 927-385-6
• Product Categories: thiol Flavor
• Mol File: 227456-27-1.mol

Chemical Properties

• Boiling Point: 204.968 °C at 760 mmHg
• Flash Point: 77.762 °C
• Appearance: /
• Density: 0.96 g/cm³
• Vapor Pressure: 0.0612mmHg at 25°C
• Refractive Index: 1.472
• PKA: 10.50±0.10(Predicted)
• CAS DataBase Reference: 3-Mercapto-2-methylpenta-1-ol(CAS DataBase Reference)
• NIST Chemistry Reference: 3-Mercapto-2-methylpenta-1-ol(227456-27-1)
• EPA Substance Registry System: 3-Mercapto-2-methylpenta-1-ol(227456-27-1)

Safety Data

• Hazardous Substances Data: 227456-27-1(Hazardous Substances Data)

Usage

Chemical Properties

3-Mercapto-2-methylpentan-1-ol (racemic) is a highly odorous mercaptan with an onion or leek-like aroma. Flavor quality was reported to strongly depend on concentration.

Occurrence

Reportedly present in onion.

Preparation

Prepared by a highly diastereoselective aldol reaction using a chiral auxiliary process with further derivatization yielding the enantiopure compound.

Aroma threshold values

At low concentrations (0.5 ppb), a pleasant, meat-broth, sweaty, onion and leek-like odor can be perceived.

InChI:InChI=1/C6H14OS/c1-3-6(8)5(2)4-7/h5-8H,3-4H2,1-2H3

Upstream product

• 14250-96-5 2-methyl-2-pentenal 
• 623-36-9 (E)-2-methylpent-2-enal 
• 22236-42-6 3-(acetylthio)-2-methylpentanal 

Relevant articles and documents

3-mercapto-2-methylpentan-1-ol, a new powerful aroma compound

3-Mercapto-2-methylpentan-1-ol was first detected in a complex thermally processed flavor and finally isolated from raw onions. The chemical structure of this new compound was identified by MS and 1H NMR measurement and synthesis of the proposed structure. Sensory evaluation at different concentrations indicated that the flavor quality is strongly dependent on concentration. At low concentration (0.5 ppb) a pleasant meat broth, sweaty, onion, and leek-like odor can be perceived. On the basis of some isolation experiments and volatiles occurring in raw onions, a formation pathway is proposed. As one intermediate 3-mercapto-2-methylpentanal, another new strong flavor compound, was suggested. The presence of this compound in raw onions was confirmed by synthesis and comparison of MS and chromatographic data.

Quantitation of the Intense Aroma Compound 3-Mercapto-2-methylpentan-1-ol in Raw and Processed Onions (Allium cepa) of Different Origins and in Other Allium Varieties Using a Stable Isotope Dilution Assay

A stable isotope dilution assay was developed for the quantitation of the potent onion odorant 3-mercapto-2-methylpentan-1-ol (1) using mass chromatography and synthesized [2H 2]-3-mercapto-2-methylpentan-1-ol as the internal standard. Application of the newly developed method on onions from different origins revealed amounts between 8 and 32 μg/kg in raw onions, whereas 34-246 μg was found in sliced, stored (50 min), and then cooked onions. In extracts prepared by simultaneous steam distillation-extraction the highest concentrations of 1 were formed, amounting to > 1200 μg/kg. The much higher content of 3-mercapto-2-methylpentan-1-ol in cooked onions suggested its formation from specific, yet unkown, precursors enzymatically formed during cutting of raw onions. 1 was for the first time identified and also quantified in other Allium species such as chives, scallions, and leek, whereas surprisingly garlic and bear's garlic did not contain the aroma compound.

Synthesis and sensorial properties of 2-alkylalk-2-enals and 3-(acetylthio)-2-alkyl alkanals

Parallel synthesis was applied to prepare a series of 3-(acetylthio)-2-alkyl alkanals by Michael addition of thioacetic acid under alkaline conditions to α,β-unsaturated 2-alkyl-substituted aldehydes, which were obtained by aldol condensation of the corresponding primary aldehydes as starting materials. The target compounds were characterized in terms of GC, MS, and NMR data. The sensory properties of the odorants, such as odor quality and odor detection threshold value, were determined with a trained panel. Structure-activity relationships are discussed, suggesting that the 1,3-oxygen-sulfur functionality, required for the "olfactophore" of tropical/vegetable notes, can further be extended to the acetylthio derivatives.