Furfuryl mercaptan, oxidation

Dimethoxy Phenol 3,4-Dimethyl 1,2-Cyclopen tandione 5-Ethyl 3-Hydroxy 4-Methyl 2(5H)-Furanone 3-Ethyl Pyridine Furfuryl Mercaptan Geranyl Isovalerate 2,3 -Heptandione (Z)-3-Hexenyl Butyrate (Z)-3-Hexenyl Formate Hexyl Butyrate Hexyl Hexanoate Isoamyl Isobutyrate Isobutyl Formate Isobutyl Hexanoate Linalool Oxide... 

We believe the mechanisms of the reaction are as shown in equation 9. The final step is an unusual one. The thiofurfural intermediate undergoes a redox reaction with Hydrogen Sulfide to produce Difurfuryl Disulfide and Sulfur (equation 9). The reaction is carried out in a Nitrogen atmosphere, which would preclude the facile oxidation of Furfuryl Mercaptan to Furfuryl Disulfide. 

Some of these reaction flavors occur in nature. The oxidation of mercaptans to form disulfides and other products is in part responsible for the loss of flavor from fresh roasted coffee only a short time after brewing. Furfiiryl Mercaptan is one of the most potent flavor components in coffee and is responsible for a fresh brewed coffee flavor. While it is present at only 1.55 ppm versus Furfuryl Alcohol (515 ppm) and Furfural (157 ppm), its flavor contribution is 310,014 times its flavor threshold (0.005 ppb). If there were a 100% conversion of Furfuryl Mercaptan to Diflirfuryl Disulfide, the coffee would appear to be 10 times weaker due to Difurfliryl Disulfide s flavor threshold being 0.05 ppb, or ten times weaker than Furfuryl Mercaptan (equation 10). The overall effect of this oxidation is that the coffee has lost its flavor. 

The oxidation of mercaptans can be useful to prepare other flavor molecules. Furfuryl Mercaptan and Methyl Mercaptan can be oxidized together to give Methyl Furfuryl Disulfide, a potent material useful for bread, pork and other meat products. It is also the third most active flavor material in fresh brewed coffee, being present at 0.38 ppm or 9,623 times its flavor threshold (0.04 ppb) (equation 11). 

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