3,5-diethyl-1,2,4-trithiolane

Also heterocyclic flavour molecules can be formed from renewable resources. 3,5-Diethyl-1,2,4-trithiolane is an important molecule for onion flavours and can easily be prepared from propanal obtained by biotransformation and hydrogen sulflde (Scheme 13.17). A meat flavour molecule like thialdine [dihydro-2,4,6-trimethyl-l,3,5(4H)-dithiazine] can be prepared from acetaldehyde isolated from molasses and ammonium sulflde (Scheme 13.18). The bacon flavour substance 2,4,6-triisobutyl-5,6-dihydro-4H-l,3,5-dithiazine can be prepared from isovaleraldehyde prepared from essential oils and ammonium sulfide (Scheme 13.19). 

Tetrafluoro-l,2,3-trithiolane 189 was synthesized by the reaction of sulfur with tetrafluoroethene. At elevated temperature, tetrafluoroethylene reacts with the complex S4(Sb2Fi 1)2 with the formation of perfluoro-3,5-dimethyl-3,5-diethyl-1,2,4-trithiolane 190. ... 

British Industrial Biological Research Association, 1976) is at least 190 000 times the estimated daily intake of 3,5-diethyl-1,2,4-trithiolane when used as a flavouring agent. 

For 3,5-diethyl-1,2,4-trithiolane (No. 1686), the NOEL of 1.9 mg/kg bw per day for the structurally related substance 3,5-dimethyl-1,2,4-trithiolane (No. 573) from a 91-day study in rats (British Industrial Biological Research Association, 1976) provides an adequate margin of safety (at least 190 000) in relation to currently estimated levels of intake of this substance from use as a flavouring agent. 

Fourteen members of this group of flavouring substances, ethane-1,1 -dithiol (No. 1660), 4-mercapto-2-pentanone (No. 1670), diisopentyl thiomalate (No. 1672), cis- and frans-mercapto-p-menthan-3-one (No. 1673), 2,4,6-trithiaheptane (No. 1684), ( )-2,8-epithio-c/s-p-menthane (No. 1685), mixture of 3,6-diethyl-1,2,4,5-tetrathiane and 3,5-diethyl-1,2,4-trithiolane (No. 1687), ( )-3-(methylthio)heptanal (No. 1692), ethyl methyl disulfide (No. 1693), ethyl propyl trisulfide (No. 1695), methyl isopentyl disulfide (No. 1696), butyl ethyl disulfide (No. 1698), allyl propyl disulfide (No. 1700) and bis(1-mercaptopropyl)sulfide (No. 1709), have assay values of <95%. Information on the safety of the secondary components of these 14 compounds is summarized in Annex 5 (Summary of the safety evaluation of secondary components for flavouring agents with minimum assay values of less than 95%). The secondary component of diisopentyl thiomalate, diisopentyl thiotartronate, is expected to share the same metabolic fate as the primary substance. The secondary components of frans-mercapto-p-menthan-3-one, piperitone (No. 435) and a-terpineol (No. 366), are expected to undergo rapid absorption, distribution, metabolism and excretion and were evaluated at previous... 

Diethyl-1,2,4-trithiolane (No. 1686) was evaluated by the Committee at the present meeting. It was concluded that 3,5-diethyl-1,2,4-trithiolane was not a safety concern at current levels of intake. 3,5-Diethyl-1,2,4-trithiolane is anticipated to undergo oxidation and subsequent elimination in the urine or reduction to the free dithiol (Nelson Cox, 2000). Dipropyl trisulfide (No. 585) was evaluated by the Committee in 1999. It was concluded that dipropyl trisulfide was not a safety concern at current levels of intake. 

Tirey et al. (1993) evaluated the degradation of phorate at three different temperatures. When oxidized at temperatures of 200, 250, and 275 °C, the following reaction products were identified by GC/MS ethanol, ethanethiol, methyl mercaptan, 1,2,4-trithiolane, 1,1-thiobisethane, 1,1 -(methylenebis(thio))bisethane, 1,3,5-trithiane, 0,0-diethyl-5-pentenyl phosphorodithioic acid, ethylthioacetic acid, diethyl disulfide, 2,2 -dithiobisethanol, ethyl-(1-methylpropyl) disulfide, sulfur dioxide, carbon monoxide, carbon dioxide, sulfuric acid, and phosphine. 

The most important sulfur heterocycles with a five-membered ring and three sulfur atoms are the diastereomeric 3,5-dialkyl-1,2,4-trithiolanes 6. The dimethyl derivatives (6, R - Me) have been found in various cooked foods, such as mushrooms (41), boiled beef (42) commercial beef extract (43), boiled antarctic krills (44), red algae (45), and several model systems containing a source of sulfur (2,19,29), The diethyl derivative (6, R - Et) was identified by Ledl (33) and by Sultan, with propionaldehyde as the starting material. The dipropyl and diisopropyl derivatives (6,... 

Scheme 13.17 Formation of 3,5-diethyl-l,2,4-trithiolane from acetaldehyde...

Trithiolanes have received increasing attention since the identification of diastereomeric 3,5-dimethyl-l,2,4-trithiolane in the volatiles of boiled beef (13). The parent 1,2,4-trithiolane is a component of Shiitake mushrooms (14) and red algae (15). In addition to 3,5-dimethyl-l,2,4-trithiolane, Kubota et al. (16) identified 3-methyl-5-ethyl-l,2,4-trithiolane and 3,5-diethyl-l,2,4-tri-thiolane in both syn and anti forms in boiled Antarctic Gulls. Both compounds were described as garlicky. Flament and co-workers (17) reported the identification of 3-methyl-5-ethyl-l,2,4-trithiolane and 3-methyl-5-isopropyl-l,2,4-trithiolane in a commercial beef extract. ... 

Cysteine may react with carbonyls to yield flavor compounds (e.g., trithiolanes) or be decarboxylated to give cysteamine, deaminated to provide a-keto-3-thiopro-pionic acid or degraded to free HjS. While each of these pathways may yield significant aroma compounds, the formation of free H2S is particularly important. H2S is a flavor compound in its own right and also is very reactive with carbonyls and free radicals to form very potent aroma compounds (e.g., ethyl sulfide, diethyl disulfide, amyl mercaptan, and 3-methyl-2-butenethiol). 

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