3-thienyl mercaptan

3-Thienyl mercaptan, also known as 3-mercaptothiophene, is an organosulfur compound characterized by a thiophene ring with a mercapto group at the 3-position. Its molecular formula is C₄H₄S₂, and it belongs to the class of sulfur-containing heterocyclic thiols. The compound exhibits a distinctive meaty, cooked meat, and garlic-like odor at very low concentrations, making it valuable for flavoring purposes. It appears as a clear liquid with a moderate molecular weight near 116.2 g/mol and is primarily sourced through synthetic organic methods involving thiophene derivatives. Detailed chemical information is accessible via public repositories like PubChem.

3-Thienyl mercaptan naturally occurs in trace amounts within cooked meat aromas and is synthetically produced for use as a flavoring agent. Its prominent sulfurous and meaty odor contributes to enhancing savory notes in food formulations. The compound finds application across multiple food categories, including dairy, fats and oils, edible ices, confectionery, bakery products, and beverages. Regulatory evaluation according to FEMA (US) and EFSA (EU) standards acknowledges its controlled use levels, supporting its inclusion in flavor formulations under specified thresholds. These evaluations ensure its use aligns with safety guidelines for flavoring substances derived from chemical group assessments of related thiazoles, thiophenes, and thienyl derivatives.

3-Thienyl mercaptan presents with a molecular weight of approximately 116.2 g/mol and a molecular formula of C₄H₄S₂. It has a flash point around 58 °C (137 °F), indicating moderate flammability. Its estimated log P value of 2.1 reflects moderate lipophilicity, which influences its solubility and partitioning behavior. The compound's specific gravity ranges between 1.248 and 1.254 at 25 °C, and the refractive index is between 1.617 to 1.623 at 20 °C, showing its optical characteristics. Vapor pressure measures about 1.761 mmHg at 25 °C, reflecting moderate volatility. It exhibits solubility in alcohol and limited water solubility, with an estimated water solubility around 750 mg/L at 25 °C. These physicochemical traits impact formulation strategies where volatility, solubility, and odor release are critical factors.

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Safety information

Hazards identification
Classification of the substance or mixture
GHS Classification in accordance with 29 CFR 1910 (OSHA HCS)
None found.
GHS Label elements, including precautionary statements
Pictogram
Hazard statement(s)
None found.
Precautionary statement(s)
None found.
Oral/Parenteral Toxicity:
Not determined
Dermal Toxicity:
Not determined
Inhalation Toxicity:
Not determined

Safety in use information

Category:
flavoring agents
Recommendation for 3-thienyl mercaptan usage levels up to:
	not for fragrance use.
Maximised Survey-derived Daily Intakes (MSDI-EU):		0.011 (μg/capita/day)
Modified Theoretical Added Maximum Daily Intake (mTAMDI):		78 (μg/person/day)
Threshold of Concern:		90 (μg/person/day)
Structure Class:		III
Food categories according to Commission Regulation EC No. 1565/2000 (EC, 2000) in FGE.06 (EFSA, 2002a). According to the Industry the "normal" use is defined as the average of reported usages and "maximum use" is defined as the 95th percentile of reported usages (EFSA, 2002i).
Note: mg/kg = 0.001/1000 = 0.000001 = 1/1000000 = ppm.
		average usage mg/kg	maximum usage mg/kg
Dairy products, excluding products of category 02.0 (01.0):		0.20000	1.00000
Fats and oils, and fat emulsions (type water-in-oil) (02.0):		0.10000	0.50000
Edible ices, including sherbet and sorbet (03.0):		0.20000	1.00000
Processed fruit (04.1):		0.20000	1.00000
Processed vegetables (incl. mushrooms & fungi, roots & tubers, pulses and legumes), and nuts & seeds (04.2):		-	-
Confectionery (05.0):		0.20000	1.00000
Chewing gum (05.3):		-	-
Cereals and cereal products, incl. flours & starches from roots & tubers, pulses & legumes, excluding bakery (06.0):		0.10000	0.50000
Bakery wares (07.0):		0.20000	1.00000
Meat and meat products, including poultry and game (08.0):		0.10000	0.20000
Fish and fish products, including molluscs, crustaceans and echinoderms (MCE) (09.0):		0.10000	0.20000
Eggs and egg products (10.0):		-	-
Sweeteners, including honey (11.0):		-	-
Salts, spices, soups, sauces, salads, protein products, etc. (12.0):		0.10000	0.50000
Foodstuffs intended for particular nutritional uses (13.0):		0.20000	1.00000
Non-alcoholic ("soft") beverages, excl. dairy products (14.1):		0.10000	0.50000
Alcoholic beverages, incl. alcohol-free and low-alcoholic counterparts (14.2):		0.20000	1.00000
Ready-to-eat savouries (15.0):		0.50000	2.00000
Composite foods (e.g. casseroles, meat pies, mincemeat) - foods that could not be placed in categories 01.0 - 15.0 (16.0):		0.10000	0.50000

Safety references

European Food Safety Athority(EFSA):Flavor usage levels; Subacute, Subchronic, Chronic and Carcinogenicity Studies; Developmental / Reproductive Toxicity Studies; Genotoxicity Studies...

European Food Safety Authority (EFSA) reference(s):

Flavouring Group Evaluation 21: Thiazoles, thiophene, thiazoline and thienyl derivatives from chemical group 29. Miscellaneous substances from chemical group 30. (Commission Regulation (EC) No 1565/2000 of 18 July 2000) - Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in contact with Food (AFC) View page or View pdf

Flavouring Group Evaluation 76, (FGE.76)[1] - Consideration of sulphur-containing heterocyclic compounds evaluated by JECFA (59th meeting) structurally related to thiazoles, thiophene, thiazoline and thienyl derivatives from chemical group 29, miscellaneous substances from chemical group 30 evaluated by EFSA in FGE.21 - Scientific Opinion of the Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food View page or View pdf

Flavouring Group Evaluation 21, Revision 1 (FGE.21Rev1): Thiazoles, thiophene, thiazoline and thienyl derivatives from chemical group 29 Miscellaneous substances from chemical group 30 View page or View pdf

Flavouring Group Evaluation 93 (FGE.93): Consideration of sulphur heterocyclic evaluated by JECFA (68th meeting) structurally related to thiazoles, thiophene, thiazoline and thienyl evaluated by EFSA in FGE.21Rev1 (2009) View page or View pdf

Scientific Opinion on Flavouring Group Evaluation 21, Revision 2 (FGE.21Rev2): Thiazoles, thiophene, thiazoline and thienyl derivatives from chemical group 29. Miscellaneous substances from chemical group 30. View page or View pdf

Scientific Opinion on Flavouring Group Evaluation 21, Revision 3 (FGE.21Rev3): Thiazoles, thiophenes, thiazoline and thienyl derivatives from chemical groups 29 and 30 View page or View pdf

Scientific Opinion on Flavouring Group Evaluation 21, Revision 4 (FGE.21Rev4): Thiazoles, thiophenes, thiazoline and thienyl derivatives from chemical groups 29 and 30 View page or View pdf

Scientific Opinion on Flavouring Group Evaluation 21, Revision 5 (FGE.21Rev5): Thiazoles, thiophenes, thiazoline and thienyl derivatives from chemical groups 29 and 30 View page or View pdf

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thiophene-3-thiol

Chemidplus:0007774734