2-Methylbenzothiazole

Coffee and Nut Savoury Notes Achieved at Sub-ppm Addition Levels

At use levels of 0.5–2 ppm in finished foodstuffs, 2-Methylbenzothiazole delivers a potent roasted coffee, hazelnut, and cooked-meat top note that is difficult to replicate with pyrazine-only architectures. The material is listed as a permitted synthetic flavouring substance under FDA 21 CFR §172.515 and holds FEMA GRAS 3201 status, with a European registration documented in the Union List of Flavouring Substances (FL-no 15.016). In a typical liquid savoury flavour concentrate intended for retorted meat analogues, the compound is first dissolved in triacetin or propylene glycol at a concentration of 0.1–0.5 wt%, then blended with 2-acetylthiazole, 2,5-dimethylpyrazine, and a maltol carrier before high-shear homogenisation at 3,000 rpm for 15 minutes. When encapsulated via spray-drying using a modified starch–gum arabic wall system (inlet temperature 180–195 °C, outlet 85–95 °C), the payload retention exceeds 92 % after 12 months in aluminium-laminated foil at 25 °C. Terminal products span dry coffee whitener powders, liquid nut-flavour emulsions for plant-based beverages, and heat-stable process flavours for extrusion-cooked snacks.

How Thiazole Orange Derivatives Enable High-Resolution Flow Cytometry

2-Methylbenzothiazole serves as the heterocyclic electrophore precursor in the one-step synthesis of asymmetric cyanine dyes structurally related to Thiazole Orange. In a documented laboratory-scale procedure later validated for 2 kg batch production, 2-methylbenzothiazole is quaternised with methyl tosylate in acetonitrile at 60 °C to yield the N‑methyl‑2‑methylbenzothiazolium salt; subsequent condensation with 4‑methylquinoline-2-thione in the presence of triethylamine generates a fluorophore exhibiting an absorption maximum at 501 nm and a Stokes shift of 23 nm. While no harmonised pharmacopoeial monograph exists for the bulk dye, batches destined for diagnostic reagent formulation are released against a ≥ 98 % purity specification by HPLC-UV at 254 nm and endotoxin limits of ≤ 0.25 EU mg⁻¹ in accordance with ISO 13485:2016 design-control principles. The molar ratio of 2-methylbenzothiazole to methyl tosylate is maintained at 1 : 1.05; excess quaternising agent is extracted with ethyl acetate before the condensation step. Terminal product formats include lyophilised fluorophore-Oligonucleotide conjugates shipped in single-use vials and ready-to-use 500 nM staining solutions in PBS validated for BD FACSCanto™ and Cytek® Aurora platforms.

When Anti-Parasitic APIs Demand a Thiazole Heterocycle Backbone

Several veterinary anthelmintic candidates in the benzimidazole-thiazole class employ 2-methylbenzothiazole as the C-2 building block. In one patent-documented route to a thiabendazole analogue, 2-methylbenzothiazole is subjected to Vilsmeier–Haack formylation at 0–5 °C to install a 5-formyl substituent while leaving the methyl group intact; the aldehyde is then condensed with 4‑cyanothiosemicarbazide under acidic catalysis. The synthesis is executed in multipurpose glass-lined reactors compliant with ICH Q7 Section 5.1 equipment design, with all stages monitored by in-process HPLC against impurity thresholds of ≤ 0.15 % for any single unknown entity. Residual hydrazine, a Class 5 genotoxic impurity per ICH M7(R2), is controlled to ≤ 1.5 ppm through a resin-scavenging step prior to the final crystallisation from isopropanol-water. The methyl group at the 2-position remains unreacted throughout the sequence, differentiating this scaffold from the more common 2‑unsubstituted benzothiazole intermediates. Terminal drug substances derived from this intermediate are formulated as oral drenches or feed premixes, and the intermediate itself is typically shipped under nitrogen in HDPE drums with a certificate of analysis referencing USP <231> heavy-metals limits.

Addition of 0.1–0.3 wt% 2-Methylbenzothiazole to a hydrotreated Group II base stock, prior to the final viscosity-index improver blend, extends the Rotating Pressure Vessel Oxidation Test induction time from 250 minutes to 410–460 minutes when measured per ASTM D2272-11. The mechanism is dual-function: the thiazole nitrogen coordinates soluble copper ions that catalyse radical generation, while the methyl group at the 2-position sterically suppresses irreversible sulphur oxidation, resulting in superior retention of the active heterocycle compared to unsubstituted benzothiazole. Formulated turbine oils for combined-cycle gas turbines additionally pass the ASTM D943-20 TOST life target of 5,000 hours to a TAN of 2.0 mg KOH g⁻¹ when 2-methylbenzothiazole is co-added with 0.5 wt% octyl-diphenylamine at a treat rate ratio of 1 : 3. Production-scale blending at 60–70 °C under a nitrogen blanket in a 20 m³ side-entry agitated vessel achieves full dissolution within 45 minutes; filtration through a 5 µm bag filter is mandatory before drumming to prevent nucleation during storage at ambient temperatures below 15 °C. The table below compares oxidation performance across three treat rates in the same Group II baseline.

Quaternisation of 2-methylbenzothiazole with 1,4-butane sultone in acetonitrile at 60 °C over 8 hours produces a zwitterionic brightener intermediate that, when added to a Watts-type nickel plating bath at 0.02–0.08 g dm⁻³, refines grain structure toward a mirror-bright finish on steel and zinc die-cast substrates. The intermediate is isolated as a white crystalline solid with a melting point of 218–221 °C and incorporated into commercial brightener packages alongside 2‑butyne‑1,4‑diol at a ratio of 1 : 5 to balance levelling and brightness. Hull cell panels run at 2 A for 10 minutes in a 267 mL cell per ASTM B456-17 show full bright range from 0.5 to 8.5 A dm⁻² without hazing when the 2-methylbenzothiazole-derived brightener is maintained at 0.05 g dm⁻³. Electroplated components subsequently pass the RoHS Directive 2011/65/EU hexavalent-chromium exclusion and achieve a minimum nickel thickness of 10 µm on automotive interior trim and sanitary fittings, tested by coulometric thickness measurement per ISO 2177:2003.

Corrosion Inhibition in Hot Hydrochloric Acid Treatment Fluids

In 15 wt% hydrochloric acid at 80 °C, 2-methylbenzothiazole at 50–200 ppm reduces the general corrosion rate of API N80 carbon steel from 98 mm y⁻¹ to 0.35 mm y⁻¹ when evaluated by linear polarisation resistance in a three-electrode autoclave per NACE TM0169-2000 Section 5. The inhibition efficiency exceeds 99.6 % at the upper concentration limit and is attributed to chemisorption of the thiazole π-electron system onto iron d-band vacancies, forming a film that persists after four hours of dynamic flow at a shear rate of 300 s⁻¹. Unlike pyridine-based inhibitors, the methyl substituent does not desorb at the elevated temperature, as confirmed by XPS data showing an unchanged N 1s peak at 399.8 eV post-exposure. Field applications in gaseated oilfield matrix-acidising treatments combine 2-methylbenzothiazole with propargyl alcohol at a synergistic ratio of 1 : 2 and a mutual solvent such as ethylene glycol monobutyl ether to prevent phase separation in concentrated brines above 150,000 ppm total dissolved solids. The formulated inhibitor is injected into the coiled-tubing stream downstream of the high-pressure pump at a rate of 2–5 L m⁻³ of neat fluid. Terminal products include pre-blended corrosion inhibitor packages supplied in IBC totes with a twelve-month re-certification interval, and acid-compatible intensifier additives for high-chloride well environments. The data below summarise inhibition performance as a function of concentration in an uninhibited 15 wt% HCl system.