|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||85.12 g·mol−1|
|Boiling point||116 to 118 °C (241 to 244 °F; 389 to 391 K)|
|Acidity (pKa)||2.5 (of conjugate acid) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Thiazole, or 1,3-thiazole, is a heterocyclic compound that contains both sulfur and nitrogen; the term 'thiazole' also refers to a large family of derivatives. Thiazole itself is a pale yellow liquid with a pyridine-like odor and the molecular formula C3H3NS. The thiazole ring is notable as a component of the vitamin thiamine (B1).
Thiazoles are members of the azoles, heterocycles that include imidazoles and oxazoles. Thiazole can also be considered a functional group. Oxazoles are related compounds, with sulfur replaced by oxygen. Thiazoles are structurally similar to imidazoles, with the thiazole sulfur replaced by nitrogen.
Thiazole rings are planar and aromatic. Thiazoles are characterized by larger pi-electron delocalization than the corresponding oxazoles and have therefore greater aromaticity. This aromaticity is evidenced by the chemical shift of the ring protons in proton NMR spectroscopy (between 7.27 and 8.77 ppm), clearly indicating a strong diamagnetic ring current. The calculated pi-electron density marks C5 as the primary site for electrophilic substitution, and C2 as the site for nucleophilic substitution.
Thiazoles are found in a variety of specialized products, often fused with benzene derivatives, the so-called benzothiazoles. In addition to vitamin B1, the thiazole ring is found in epothilone. Other important thiazole derivatives are benzothiazoles, for example, the firefly chemical luciferin. Whereas thiazoles are well represented in biomolecules, oxazoles are not. It is found in naturally occurring peptides, and utilised in the development of peptidomimetics (i.e. molecules that mimic the function and structure of peptides).
Commercial significant thiazoles include mainly dyes and fungicides. Thifluzamide, Tricyclazole, and Thiabendazole are marketed for control of various agricultural pests. Another widely used thiazole derivative is the non-steroidal anti-inflammatory drug Meloxicam. The following anthroquinone dyes contain benzothiazole subunits: Algol Yellow 8 (CAS# [6451-12-3]), Algol Yellow GC (CAS# [129-09-9]), Indanthren Rubine B (CAS# [6371-49-9]), Indanthren Blue CLG (CAS# [6371-50-2], and Indanthren Blue CLB (CAS#[6492-78-0]). These thiazole dye are used for dyeing cotton.
Various laboratory methods exist for the organic synthesis of thiazoles. Prominent is the Hantzsch thiazole synthesis is a reaction between haloketones and thioamides. For example, 2,4-dimethylthiazole is synthesized from thioacetamide and chloroacetone. Another example  is given below:
Thiazoles are generally form via reactions of cysteine, which provides the N-C-C-S backbone of the ring. Thiamine does not fit this pattern however. Several biosynthesis routes lead to the thiazole ring as required for the formation of thiamine. Sulfur of the thiazole is derived from cysteine. In anaerobic bacteria, the CN group is derived from dehydroglycine.
Alkylation of thiazoles at nitrogen forms a thiazolium cation. Thiazolium salts are catalysts in the Stetter reaction and the Benzoin condensation. Deprotonation of N-alkyl thiazolium salts give the free carbenes and transition metal carbene complexes.
Alagebrium is a thiazolium-based drug.