2.4.5-Methylthiazole
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HS Code |
989765 |
| Chemical Formula | C5H7NS |
| Molecular Weight | 113.18 g/mol |
| Appearance | Colorless to pale yellow liquid |
| Odor | Foul - smelling |
| Boiling Point | 147 - 148 °C |
| Density | 1.05 g/cm³ (at 20 °C) |
| Solubility In Water | Slightly soluble |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, ether |
| Flash Point | 44 °C |
As an accredited 2.4.5-Methylthiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 500g of 2,4,5 - Methylthiazole packaged in a sealed, chemical - resistant bottle. |
| Shipping | 2.4.5 - Methylthiazole is shipped in well - sealed, corrosion - resistant containers. Shipment adheres to strict chemical transport regulations, ensuring safety during transit to prevent any leakage or hazard. |
| Storage | 2,4,5 - Methylthiazole should be stored in a cool, dry, well - ventilated area away from heat sources and ignition sources. It should be kept in a tightly closed container, preferably made of materials resistant to corrosion. Store it separately from oxidizing agents and other incompatible substances to prevent potential chemical reactions. |
Certain manufacturing lines running continuous compounding for modified atmosphere packaging (MAP) films have documented batch-to-batch olfactory intensity variation exceeding ±12% when 2,4,5-trimethylthiazole is dosed using gravimetric feeders lacking liquid temperature control at the hopper throat. The root cause was traced to transient viscosity shifts in the neat compound above 28°C, altering drip rate into the side-stuffer at L/D 44. A jacketed feed line maintained at 18–20°C with a Coriolis mass flow meter feedback loop reduced the coefficient of variation to under 3.2% across 72-hour runs on a Berstorff ZE 90A twin-screw extruder. For thin-gauge (≤35 µm) LLDPE sealant webs intended for cooked poultry, the addition of 0.08–0.15 wt% 2,4,5-trimethylthiazole masterbatch (5% active on EVA carrier, MI 2.0) into the outer sub-layer of a three-layer blown film lowers the seal initiation temperature by approximately 4°C compared to a neat sealant control due to slight plasticization. However, migration into food simulants under conditions specified in Regulation (EU) No 10/2011, Annex V (simulant D2, 60°C for 10 days) must remain below the total specific migration limit of 10 mg/dm². Trials confirm that coextrusion with a 5 µm pure nylon MXD6 barrier layer eliminates quantifiable migration into simulant while preserving the characteristic roasted-allium note in the packaged product.A Pyrazine-Free Process Flavor Block for Enzyme-Modified Dairy BasesReaction flavor developers formulating enzyme-modified cheese (EMC) pastes with high lipolysis indices often encounter off-notes derived from Maillard-derived pyrazines that clash with the desired creamy-sulfurous profile of aged cheddar or Parmesan replacers. By replacing a pyrazine-dominant top note with 2,4,5-trimethylthiazole at 0.04–0.09% of the finished paste after lipase deactivation (85°C for 20 min), the volatile profile shifts toward a burnt-nutty, cocoa-like underlay without introducing green-pepper off-character. The compound is dispersed in a minimum quantity of propylene glycol (1:8 ratio by weight) and added post-enzymolysis under vacuum (−0.92 bar) to prevent oxidative dimerization; headspace analysis via SPME-GC-MS confirms that over 85% of the added thiazole survives into the final paste. A documented failure mode occurs when the paste is homogenized above 55°C in the presence of residual active lipase, causing a rapid decline in the perceived odor unit contribution of the thiazole due to protein-thiol binding. Production-scale batches (nominal 1,200 kg) in Stephan UMC-5 cutters consistently achieve a target sensory score within 0.7 points on a 15-point QDA scale when the thiazole is the sole heterocyclic modifier, avoiding the antagonistic suppression observed between methylthiazoles and 2-acetylpyridine.Odor-Masking Mechanism in Low-VOC Architectural Primers Aimed at Post-Renovation Occupancy TimelinesWater-based styrene-acrylic primers formulated for quick-return interior painting (4-hour recoat, 24-hour occupancy) must suppress the characteristic ammonia and monomer traces released from the coalescing film without relying solely on non-volatile coalescents that compromise block resistance (ASTM D4946, ≥7 rating). Introducing 0.025–0.05% 2,4,5-trimethylthiazole on total wet weight after the let-down stage in a Cowles dissolver shifts the olfactory perception threshold of the drying film. The thiazole’s vapor pressure (calculated at ~0.38 mmHg at 25°C) places it in a window where it volatilizes primarily during the early flash-off plateau (0–25 minutes post-application), simultaneously with the most objectionable amine compounds. Headspace evaluation employing ASTM D6679-13 (Tenax TA sorbent tubes, TD-GC-MS) in a 22 m³ environmental chamber at 0.5 ACH confirms that the thiazole moiety masks the isobutyl-isobutyrate marker of latex instability without forming detectable nitrosamine derivatives under ambient nitrogen dioxide levels typical of urban interiors (≤60 ppb), a path of degradation previously flagged in amine-based masking technologies.When 2,4,5-Trimethylthiazole Replaces Thiazolidine Derivatives in High-Temperature Cured Silicone SealantsAcetoxy-cure silicone sealants applied at thicknesses exceeding 12 mm in confined vertical joints (e.g., parking deck expansion lanes compliant with ASTM C920, Class 50) frequently exhibit center-of-bead porosity if the tin catalyst load is pushed to accelerate through-cure, compromising movement capability above ±35%. A reformulation approach substitutes the commonly used amine-thiazolidine scavenger with 0.2–0.4 phr 2,4,5-trimethylthiazole pre-dissolved in the methyltrimethoxysilane crosslinker phase prior to base polymer addition. The methyl substitution pattern at the 2-, 4-, and 5-positions sterically shields the nitrogen during the exothermic condensation step, delaying premature catalyst deactivation that normally occurs at 120°C+ in continuous static mixer barrels with a 9-element geometry. Full-depth cure through 15 mm sections exposed to 50°C at 95% RH is achieved 18–22% faster than the control formulation without increasing the Shore A hardness drift (maintained within ±3 points post-cure). An operational boundary exists: when the thiazole is combined with zinc-based adhesion promoters added above 0.8 phr, the resulting chelation effect reduces available reactive sites and triggers deep-section reversion observable as a thermoplastic inner layer after 14 days of water immersion (ASTM D471 Reference Fuel B/isopropanol testing).Ester-based dielectric fluids in hermetically sealed power conversion equipment (IEC 61099 compliance) require stabilization packages resistant to copper-catalyzed oxidation during sustained operation at hot-spot temperatures of 110°C. An effective non-amine additive package employs 0.15–0.30% 2,4,5-trimethylthiazole as a multifunctional species with two distinct protection pathways. First, it coordinates with dissolved copper ions (Cu⁺/Cu²⁺) through the thiazole nitrogen, forming a transient complex that inhibits the propagation step in the radical chain oxidation of oleate esters, as measured by a 28% extension in the Oxidation Induction Time (OIP, ASTM D2112-15) vs. an unblended ester reference. Second, at the copper–ester interface under nitrogen blanketing, the thiazole undergoes a slow decomposition releasing ≤80 ppb sulfur-containing fragments detectable via ASTM D3227 fluorescent X-ray, effectively passivating the copper surface against further ion leaching. The dosing must be precisely controlled: below 0.10%, passivation diminishes, while above 0.45%, the sulfur release accelerates to corrosive levels for silver-alloy wire bonds used in adjacent power module interconnects. In forced-circulation ester test loops (200 L/h) simulating filter pump operation, differential pressure across 3 µm absolute-rated cellulose cartridges remains stable for 1,800+ hours, confirming no thiazole-induced polymeric degradation or sludging.A Kinetic Limitation in Linerless Self-Adhesive Label Coatings by Hot-Melt ProcessingLinerless label constructions printed via UV-flexo and subsequently melted in a slot-die coater onto release-coated PET belts must survive the re-melt phase inside thermal printer platen rollers (direct thermal printhead temperatures pulsing to 320°C for <15 ms) without charring or releasing aldehydic volatiles that fog the printhead. Addition of 0.10–0.22 wt% 2,4,5-trimethylthiazole into a styrene-isoprene-styrene (SIS, diblock content 25%) hot-melt formulation decreases the thermo-oxidative chain scission rate during the standing melt phase in the coating die, as tracked by a 9% narrower molecular weight distribution measured via GPC (polystyrene standards) in samples held at 180°C for 60 minutes under static air. The thiazole preferentially scavenges peroxy radicals formed on the isoprene midblock at the 1,2-vinyl unsaturation sites, sites previously verified via FTIR peak depletion at 910 cm⁻¹. This reduces the common defect of visible char fibers in the adhesive meniscus region during wide-width (330 mm) intermittent coating; a Maxcess precision gap coater running 55 m/min line speed recorded a 72% reduction in char pickup area on the backing roll over a 12-hour continuous run compared to a conventional BHT/phosphite system.In the high-speed tape cassette assembly of radial tire building (stage-two belt and tread package assembly), a solvent-based neoprene cement containing a tackifying alkylphenol resin requires a transient open time of 35–45 seconds before ply application onto the extruded tread. The evaporation rate of the toluene/hexane solvent blend must be modulated without entering the explosive lower limit band monitored by continuous LEL sensors set at 10% of the published value. 2,4,5-Trimethylthiazole functions here not as a reactive participant but as a high-boiling (>160°C) polar modifier that forms transient hydrogen bonds with the phenolic -OH groups of the resin, temporarily elevating the effective viscosity at the surface microlayer by approximately 12% (measured by a Brookfield RVDV-II+ with T-bar spindle at 2.5 rpm). This delays the solvent’s capillary escape into the underlying carcass rubber (a practical limit derived from DIN 53350 solvent retention tests). The critical process limit is maintaining a thiazole-to-resin solids mass ratio strictly between 1:90 and 1:65; lower ratios yield no measurable open-time extension, while a ratio exceeding 1:55 causes bond-line porosity after vulcanization at 175°C for 8 minutes in segmented mold presses, attributable to thiazole decomposition voids detectable via phased-array ultrasonic scanning above 1.5 mm equivalent depth.
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In industrial flavor and fragrance compounding, the heterocyclic compound 2,4,5-trimethylthiazole (CAS 13623-11-5, molecular formula C₆H₉NS) functions as a high-impact aroma chemical delivering roasted, nutty, and cocoa-like organoleptic notes at exceptionally low dosage thresholds. The compound is manufactured via cyclocondensation of acetamide with phosphorus pentasulfide and aldehydes, followed by fractional distillation under reduced pressure to achieve olfactory purity. Commercial specifications typically define a minimum assay of 98.0% (GC-FID, area normalization), with isolated isomer content ≤ 1.5%. The product is a clear to pale yellow liquid with a density of 1.013–1.019 g/cm³ at 20°C (ASTM D4052-22) and a refractive index nD20 of 1.503–1.508 (ASTM D1218-21). Unlike the simpler monomethyl thiazoles, the 2,4,5-trisubstituted pattern suppresses undesirable sulfurous rubber notes while amplifying the roasted character central to cooked meat and chocolate simulations.
Process flavorists working on thermally treated meat or cocoa replacers encounter a persistent challenge: balancing sulfur impact with clean, non-distractive tonal character. The 2,4,5-trimethyl isomer addresses this through steric shielding of the thiazole sulfur, which reduces the vapor-phase sulfidity gradient measured by headspace GC-olfactometry. In Maillard model systems heated to 125°C at pH 5.5, 2,4,5-trimethylthiazole generates a flavor dilution (FD) factor of 256–512 for nutty/roasted notes, whereas 2-acetylthiazole under identical conditions yields FD 64–128 accompanied by a distinct popcorn-sulfur character. Comparative intensity-concentration curves, developed using aroma extract dilution analysis (AEDA) per standard practice in flavor chemistry, show that replacing 2-acetylthiazole with 2,4,5-trimethylthiazole at 0.05–0.2 ppm (as consumed) eliminates the need for masking agents like maltol that are otherwise required to suppress the popcorn note. 2-Isobutylthiazole, a common tomato-leaf aroma contributor, differs structurally through its 2-alkyl side chain and exhibits a green-caramel profile wholly orthogonal to the roasted matrix; blending trials at a pilot-scale savory flavor house demonstrated that even 5% fortuitous cross-contamination between these two thiazoles destabilized target profiles across three production batches. Thus, the 2,4,5-trimethyl substitution provides a sensory vector not duplicated by mono- or 2-functionalized thiazoles.
When incorporated into fine fragrance accords, 2,4,5-trimethylthiazole operates strictly as a trace top-note modulator confined to 0.001–0.01% of the finished oil. Its high odor impact necessitates pre-dilution in triethyl citrate or benzyl benzoate to 0.1% before weighing, as neat material readily contaminates weighing vessels and surrounding air-handling units. Published specification sheets from aroma chemical distributors list an acid value ≤ 2.0 mg KOH/g (ISO 660:2020) and water content ≤ 0.2% (Karl Fischer, ISO 760:1978), with storage recommended at 2–8°C under nitrogen headspace to retard oxidation of the methyl substituents. The compound’s flash point of 54°C (ISO 2719:2016, Pensky-Martens closed cup) places it in flammable liquid Category 3 under GHS; thus, processing vessels within fragrance studios must be electrically bonded and grounded. In direct comparison with 5-methylthiazole, which imparts a sharper, more amine-like burn, the 2,4,5-trimethyl analogue demonstrates reduced Schiff-base formation with aldehydes in the concentrate, a stability advantage validated through accelerated aging at 40°C over 12 weeks in a model eau de parfum matrix (ethanol/water 80:20, v/v).
Differences from structurally related products become especially evident under thermal stress. During a standard compounding procedure where a chocolate-patchouli accord was compounded at 50°C to facilitate blending of solid base notes, a trial batch using 2,4,5-trimethylthiazole retained ≥ 96% of the original GC peak area after 2 hours, whereas a parallel batch formulated with 2,5-dimethylthiazole lost 12% to dimerization byproducts (confirmed by LC-MS). The operational boundary for exposure to ambient humidity is set at 60% RH; beyond this point, the hygroscopic impurities drawn into partially emptied drums accelerate esterification between the thiazole and trace carboxylic acids present in natural essential oils, producing off-odors detectable by a trained panel at 0.5 ppt in the headspace of a finished product. No added antioxidants are required if the drum is blanketed and re-sealed within 30 minutes after each withdrawal.
| Parameter | 2,4,5-Trimethylthiazole | 2-Acetylthiazole | 2-Isobutylthiazole |
|---|---|---|---|
| CAS | 13623-11-5 | 24295-03-2 | 18640-74-9 |
| Assay minimum (%) | 98.0 | 97.0 | 97.5 |
| Boiling point (°C) | 177–179 (1013 hPa) | 89–91 (12 hPa) | 180–182 (1013 hPa) |
| Flash point (°C) | 54 | 78 | 58 |
| Key sensory descriptor | Roasted nut, cocoa, meaty | Popcorn, roasted corn, sulfur | Green, tomato vine, galbanum |
| Typical use level (ppm in food) | 0.05–0.5 | 0.5–5.0 | 0.02–0.2 |
The substance is registered under REACH (EC No. 237-273-6) with a typical tonnage band of 1–10 tonnes per annum for the EU market. In the United States, it holds FEMA GRAS status (FEMA No. 3325) and is listed in 21 CFR §172.515 as a synthetic flavoring substance permissible for food use at levels consistent with good manufacturing practice. JECFA (No. 979) evaluated the material and established a temporary ADI of 0–0.5 mg/kg body weight. For fragrance applications, IFRA Standards do not assign a specific restriction category beyond the general quantitative risk assessment for sensitization, as the predicted dermal absorption from fine fragrance exposure at 0.01% remains below the threshold of toxicological concern. When declaring this compound on consumer product labels, the INCI designation “2,4,5-Trimethylthiazole” is mandated; the older trivial designation “nuez thiazole” may not be substituted in regulated markets. A compliance checklist referencing these standards forms part of the qualification dossier for new suppliers of the material.
Where this product diverges critically from other thiazole derivatives is in its classification under China’s GB 2760-2014 for food additives; 2,4,5-trimethylthiazole is coded as S0859 with an approved use range in candy and bakery fillings at maximum levels of 37 mg/kg. By contrast, 2-ethyl-4-methylthiazole (S0860) is restricted to 5 mg/kg in the same categories due to a lower no-observed-adverse-effect level. This regulatory asymmetry reflects the 2,4,5-isomer’s higher olfactory potency, which enables effective sensory contribution at mass fractions that impose less toxicological load. Quality control laboratories in flavor importing companies routinely cross-check COA data against the GB specifications for residue solvents (using HS-GC-MS per GB 5009.262-2016), particularly cyclohexane and toluene residues which, if detected above 10 ppm, result in automatic batch rejection.
A production-scale consideration in multi-purpose flavor manufacturing facilities involves the cleaning validation protocol after processing 2,4,5-trimethylthiazole. Due to its tenacious odor, even a 0.001% carryover into a vanilla extract batch can produce a detectable off-note. Swab samples analyzed by GC-Sniff port are required to show no perceivable thiazole character after a validated triple-rinse cycle with heated peracetic acid (0.5%, 60°C, 20 minutes). Published data for this specific configuration is limited, but internal validation reports from contract compounders indicate that dedicated stainless-steel (316L) transfer piping with electropolished inner surfaces (Ra ≤ 0.8 µm) is preferred to avoid the adsorption/desorption hysteresis observed with polymer gaskets.
In a departure from the typical stability profile of 2-substituted thiazoles under UV exposure, 2,4,5-trimethylthiazole exhibits a photodegradation quantum yield measured at 0.012 in hexane at 254 nm, nearly an order of magnitude lower than 2-methylthiazole, which yields 0.11. This difference is attributed to the alkyl substitution at both the 4- and 5-positions that quenches excited-state ring-opening pathways. Consequently, the product is suitable for clear glass packaging in applications such as beverage flavor bases that are processed under ambient lighting without requiring darkened tunnels, provided the base contains at least 0.5% natural tocopherols as a radical scavenger to complement the inherent photostability.
Thermal processing conditions encountered in retorted filled pastries (121°C, 15 psi, 30 minutes) erase most top-note imparting chemicals through steam distillation, yet 2,4,5-trimethylthiazole partitions selectively into the lipid phase of the filling (log Pow = 2.42, measured by shake-flask method per OECD 107) and retains 40–60% of its initial added mass after the retort cycle, compared with less than 5% retention for 2-acetylthiazole under identical conditions. This differential is exploited in the formulation of shelf-stable coconut-caramel fillings where a pronounced nutty character must survive the thermal lethality stage. Pilot plant trials using a scrape-surface heat exchanger feeding a rotary piston filler set at a fill temperature of 85°C documented that a 2,4,5-trimethylthiazole dose of 0.15 ppm in the uncooked filling delivered an after-retort roasty note equivalent to a 2.5 ppm addition of 2-acetylpyrazine, the latter requiring an off-label usage rate that would exceed its established regulatory ceiling. The selection of this thiazole over pyrazine alternatives therefore maintains organoleptic fidelity within statutory bounds, a critical requirement when the product is distributed in markets with strict positive-list legislation, such as the EU (Regulation (EC) No 1334/2008 Annex I).
Processing window restrictions are narrow: if the filling’s pH falls below 4.2 (measured at 25°C with a glass electrode), the rate of acid-catalyzed ring-opening increases by a factor of 3.5 over neutral systems, as documented by HPLC monitoring of the mercaptan degradation product. In fruit-acidulated fillings for confectionery applications, the compound must be encapsulated in a melt-extruded carbohydrate matrix (dextrin-maltodextrin blend, Tg 58°C) prior to incorporation; otherwise, the protonation of the thiazole nitrogen accelerates degradation, producing hydrogen sulfide at concentrations above the sensory threshold of 0.01 mg/m³ in the pack headspace. The encapsulation step involves twin-screw extrusion (L/D ratio 40:1, barrel temperature profile 110–130–150–140°C) and requires the active content to be limited to 5 wt% of the granule to prevent plasticization and sticking on the die face.
