Mercaptobenzothiazole

Mercaptobenzothiazole

Names
IUPAC name 1,3-Benzothiazole-2(3H)-thione
Identifiers
CAS Number	149-30-4
ChEBI	CHEBI:34292
ChemSpider	608157
EC Number	205-736-8
Jmol 3D model	Interactive image
KEGG	C14437
PubChem	697993
InChI InChI=1S/C7H5NS2/c9-7-8-5-3-1-2-4-6(5)10-7/h1-4H,(H,8,9) Key: YXIWHUQXZSMYRE-UHFFFAOYSA-N InChI=1/C7H5NS2/c9-7-8-5-3-1-2-4-6(5)10-7/h1-4H,(H,8,9) Key: YXIWHUQXZSMYRE-UHFFFAOYAK
SMILES c1ccc2c(c1)[nH]c(=S)s2
Properties
Chemical formula	C7H5NS2
Molar mass	167.25
Appearance	solid
Melting point	177-181 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

2-Mercaptobenzothiazole (MBT) is an organosulfur compound with the formula C₆H₄NSCSH. The molecule consists of a benzene ring fused to a 2-mercaptothiazole ring. It is used in the vulcanization of rubber.^[1]

Synthesis and reactions

It is produced by the reaction of 2-aminothiophenol and carbon disulfide:

C₆H₄(NH₂)SH + CS₂ → C₆H₄NSCSH + H₂S

It oxidizes to give the disulfide called MBTS. Upon oxidation in the presence of secondary amines, it gives sulfenamide derivatives. One commercially useful example is 2-morpholinodithiobenzothiazole (MBSS), which is used as an accelerator in the vulcanization of rubber.

Uses

Using MBT, rubber vulcanizes with less sulfur and at milder temperatures, both factors give a stronger product. This effect was reported in 1921 by workers at Pirelli and at Goodyear Tire & Rubber.^[1]

The compound has also been used in the past in the gold-mining industry to "float" the gold from ore residue as part of the extraction process.^[2]

Safety

Studies have identified it as a potiential human carcinogen.^[3][4] In 2016, it was identified by the World Health Organization as a human carcinogen.^[5]

It causes allergic contact dermatitis.^[6] The derivative morpholinylmercaptobenzothiazole is a reported allergen in protective gloves, including latex, nitrile, and neoprene gloves.^[7]

It becomes air-borne as a result of wear on car tires, and is able to be inhaled.^[8]

References

1. Hans-Wilhelm Engels, Herrmann-Josef Weidenhaupt, Manfred Pieroth, Werner Hofmann, Karl-Hans Menting, Thomas Mergenhagen, Ralf Schmoll, Stefan Uhrlandt “Rubber, 4. Chemicals and Additives” in Ullmann's Encyclopedia of Industrial Chemistry 2004, Wiley-VCH, Weinheim. doi:10.1002/14356007.a23_365.pub2
2. CABASSI, PAJ et. al (November–December 1983). "The improved flotation of gold from the residues of Orange Free State ores" (PDF). Journal of the South African Institute of Mining and Metallurgy 83 (11): 270–276. ISSN 0038-223X.
3. T. Sorahan (April 2009). "Cancer risks in chemical production workers exposed to 2-mercaptobenzothiazole". Occup Environ Med 66 (4): 269–273. doi:10.1136/oem.2008.041400.
4. National Toxicology Program scientists (May 1988). "NTP Toxicology and Carcinogenesis Studies of 2-Mercaptobenzothiazole (CAS No. 149-30-4) in F344/N Rats and B6C3F1 Mice (Gavage Studies).". Natl Toxicol Program Tech Rep Ser. 232: 1–172. PMID 12732904.
5. Chris Graham (February 28, 2016). "Chemical found in babies' dummies and condoms 'probably causes cancer'". The Telegraph. Retrieved February 29, 2016.
6. Gillian de Gannes, Sayali Tadwalkar, Aaron Wong, and Nino Mebuke (2013), British Columbia Fails to Meet the North American Screening Standards: What are the Implications for Workers with Allergic Contact Dermatitis? (PDF), WorkSafeBC
7. Rose, R.F.; Lyons, P.; Horne, H.; Wilkinson, S.M. (2009), "A review of the materials and allergens in protective gloves", Contact Dermatitis 61 (3): 129–137, doi:10.1111/j.1600-0536.2009.01580.x
8. Avagyan, R.; Sadiktsis, I.; Bergvall, C.; Westerholm, R. (2014), "Tire tread wear particles in ambient air—a previously unknown source of human exposure to the biocide 2-mercaptobenzothiazole", Environmental Science and Pollution Research 21 (19): 11580–11586, doi:10.1007/s11356-014-3131-1