2,4-Dimethyl-5-Acetylthiazole
|
HS Code |
486301 |
| Chemical Formula | C7H9NOS |
| Molecular Weight | 155.22 g/mol |
| Appearance | Colorless to pale yellow liquid |
| Odor | Characteristic, sulfur - like, nutty odor |
| Boiling Point | Approx. 210 - 212 °C |
| Density | 1.132 g/cm³ (at 20 °C) |
| Solubility In Water | Insoluble |
| Solubility In Organic Solvents | Soluble in many organic solvents like ethanol, ether |
| Flash Point | Approx. 92 °C |
| Vapor Pressure | Low vapor pressure at room temperature |
As an accredited 2,4-Dimethyl-5-Acetylthiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 500g of 2,4 - Dimethyl - 5 - Acetylthiazole packaged in a sealed glass bottle. |
| Shipping | 2,4 - Dimethyl - 5 - Acetylthiazole, a chemical, is shipped in properly sealed, corrosion - resistant containers. Shipment follows strict safety regulations for handling and transporting chemicals to ensure secure delivery. |
| Storage | 2,4 - Dimethyl - 5 - Acetylthiazole should be stored in a cool, dry, and well - ventilated area. Keep it away from heat sources, open flames, and strong oxidizing agents. Store in a tightly sealed container to prevent evaporation and contact with air, which could potentially lead to degradation. It is advisable to store it in a dedicated chemical storage facility following safety regulations. |
Chocolate mass alkalised to pH 6.8–7.2 develops a characteristic flatness in the roasted-burnt spectrum; 2,4-Dimethyl-5-Acetylthiazole is introduced at 0.5–1.5 ppm (calculated on the finished conched mass) to restore pyrazine-coupled depth without contributing the raw-beany side notes associated with overuse of 2,4-dimethylthiazole. The compound is pre-dispersed in anhydrous cocoa butter or fractionated PGPR at a 1:99 dilution and injected through a metering pump into the conche during the final 25–35 min of dry conching, where the mass temperature is held below 62 °C. Elevating the conching temperature above 68 °C for more than 12 min after addition leads to a measured loss of thiazole through volatilisation and, in systems with residual moisture above 0.8 %, hydrolytic ring-opening that generates sulfanyl ketone by-products detectable by GC-O as rubbery off-notes. The addition protocol is compatible with three-roll refiners and horizontal Bühler EcoNova-type conches with closed hoods operating at low-fat pre-mix viscosity < 3.5 Pa·s. Regulatory acceptance is covered under EU Regulation 1334/2008 (flavouring substance FL 15.006), FEMA 3267 (GRAS), JECFA 1035, and China GB 2760 (code S0398), with a maximum use limit in plain chocolate typically set at 2 mg/kg in the European flavouring database. Terminal products include 70 % dark chocolate couverture, filled tablets, and compound coatings for confectionery centres. Production-scale quality control uses SPME-GC-MS monitored against an internal standard of 2-isobutyl-3-methoxypyrazine, with a retention time window of ±0.03 min acceptance criterion. A batch-to-batch purity specification of ≥ 98.5 % by GC area normalisation is enforced because earlier field experience demonstrated that the presence of 2-methyl-5-acetylthiazole isomer at ≥ 1.2 % shifts the sensory profile towards a phenolic-medicinal character unacceptable in cocoa applications.
At What Point Does 2,4-Dimethyl-5-Acetylthiazole Outperform 2-Acetylthiazole in Beefy Process Flavours?In thermally generated meat-like reaction flavours where a roasted-crusty top note is required rather than the fresh-sulfury character of 2-acetylthiazole (FEMA 3328), 2,4-dimethyl-5-acetylthiazole demonstrates a cleaner, longer-lasting impact at 2–8 ppm in the reconstituted bouillon base. The compound is not introduced into the Maillard reactor vessel because the combination of 110–125 °C heating, pH 5.0–5.8, and the presence of cysteine and thiamine generates competing thiazole-derived cross-products that consume the acetyl moiety. Instead, the flavouring is dissolved in propylene glycol (USP/EP) at a 10 % w/w stock solution and post-dosed into the cooled hydrolysate (≤ 55 °C) immediately before high-shear mixing and subsequent spray-drying. A production-scale APV Anhydro or Niro spray tower with rotary atomiser (wheel speed 16 000–22 000 rpm) is used; inlet air temperature is maintained at 175–185 °C and outlet at 85–95 °C, with a feed total solids of 42–48 %. Retention of 2,4-dimethyl-5-acetylthiazole through the dryer is 72–78 % when the carrier matrix is a 2:1 blend of gum arabic and OSA-modified starch (nOSA starch); replacing the gum arabic with maltodextrin DE 10–15 reduces retention to approximately 58–64 %, a drop confirmed by full-evaporation headspace analysis. Finished applications include dry soup and sauce mixes, noodle seasoning sachets, and retorted wet pet foods where post-processing flavour fade must be compensated. A notable incompatibility arises when the dry blend contains nitrite-cured ingredients: residual free nitrite reacts with the thiazole ring in the presence of trace moisture (aw > 0.35) to form pink-coloured nitroso-thiol adducts, causing both colour formation and aroma quenching. For such matrices, encapsulation in hydrogenated vegetable oil flakes through chill-roll solidification is recommended, delaying flavour release until the heating step in the consumer’s kitchen. The absence of soluble copper ions (> 0.05 ppm) in the process water is verified because copper-catalysed oxidation converts the thiazole into its corresponding sulfoxide and sulfone, which carry a harsh, metallic sensory character.Instant Coffee Powder Aroma Reconstitution and Masking of Processed NotesSpray-dried and freeze-dried soluble coffee products suffer substantial loss of low-boiling sulfur aroma constituents during extraction and thermal concentration; the roasted, slightly nutty character of 2,4-dimethyl-5-acetylthiazole is employed at 0.3–3.0 ppm relative to dry powder mass to rebuild headspace authenticity. The flavouring is emulsified into a cold-water phase (12–18 °C) containing 5–10 % gum acacia and 0.5 % lecithin, then plated onto agglomerated coffee powder in a continuous fluidised-bed dryer-glommerator operating with inlet air at 55–65 °C and a bed temperature not exceeding 38 °C. Volatile recovery data from a Glatt GPCG 3.1 laboratory unit show that when the addition is made after the granulation phase instead of before, retention increases from 61 % to 84 % because the thiazole-bearing droplets are absorbed into existing porous agglomerates with reduced steam-distillation loss. The organoleptic impact is assessed under ISO 4120:2004 triangle-test conditions against a reference standard of freshly brewed 100 % Arabica coffee; a panel of 24 trained assessors could not distinguish the flavoured prototype at 1.2 ppm. The compound is typically blended with 2-furfurylthiol acetate, 2,3-pentanedione, and 4-vinylguaiacol to create a balanced roast-and-smoke profile for 3-in-1 coffee mixes packed under nitrogen-flushed aluminium laminate. Packaging under ambient atmosphere accelerates thiazole oxidation: a headspace oxygen content above 1.2 % by volume reduces the sensory shelf life from 12 to 4 months at 25 °C. Consequently, modified-atmosphere packing with residual oxygen below 0.5 % and a water vapour transmission rate of the film below 0.5 g/m²/24h (38°C, 90 % RH) is specified in OEM co-packing agreements.The Thiazole Is Added Post-Grinding in Peanut Butter to Replicate Fresh-Roasted Aroma Lost During Vacuum DegassingIndustrial nut butter processing involves roasting peanuts at 160–170 °C for 20–30 min, followed by two-stage grinding in a Urschel Comitrol or colloid mill and vacuum treatment at −0.6 to −0.8 bar to remove dissolved air for shelf-life stabilisation. The vacuum step strips out a significant portion of the freshly roasted character; 2,4-dimethyl-5-acetylthiazole is dosed at 0.2–1.5 ppm directly into the holding tank after the deaerator, where the product temperature is 48–52 °C, ensuring dissolution in the oil phase without flash evaporation. The addition is performed with an in-line static mixer (Sulzer SMX-type with 6–8 elements) placed downstream of the dosing port to achieve a coefficient of variation in concentration below 5 % across a 2 000 kg batch. The compound’s log P of approximately 2.3 favours partitioning into the peanut oil fraction, which slows its migration into the headspace and provides a sustained release during mastication. Under FDA 21 CFR 172.515, the substance is fully permitted as a synthetic flavouring agent for direct addition; GMP-based usage is self-limiting because concentrations above 2.5 ppm begin to impart an undesirable coffee-toned bitterness detectable by a R-index sensory panel. Finished goods include stabilized creamy and chunky peanut butter packed in PET jars with induction-seal liners, as well as sesame paste (tahini) analogues where the thiazole masks the raw legume notes of hydrogenated soy protein extenders. One documented processing constraint arises when heated recirculation loops exceed 65 °C for more than 8 hours during clean-in-place deviations: the acetyl group undergoes α-cleavage under these conditions, producing dimethylthiazole with a character that contrasts sharply with the target roasted peanut profile.
If Cigarette Filler Is Subjected to Expanded Tobacco Processing, the Casing Solution Containing 2,4-Dimethyl-5-Acetylthiazole Must Be Applied Post-Expansion to Avoid Pyrolytic Loss.In Virginia-type and American-blend cigarettes, the compound imparts a dry, nutty, and slightly woody casing note that bridges the cocoa and maple syrup nuances from other top-dressing components. A typical application rate ranges from 5 to 30 ppm on cut-filler weight, delivered as a 0.5–1.2 % solution in a 70:30 (v/v) ethanol–water mixture sprayed through air-atomising nozzles in a rotating casing drum (rpm 12–18, jacket temperature 32–38 °C). When the filler is processed through an expansion tower with superheated steam at 280–340 °C, nearly 80 % of any thiazole applied beforehand is destroyed or stripped within the first 3 seconds of expansion; therefore, injection downstream of the tumble dryer is mandatory. Transfer efficiency into mainstream smoke, determined under ISO 3308:2012 smoking conditions with a Borgwaldt RM20H rotary machine, averages 8–12 %, which requires back-calculation of the filler loading to achieve a target smoke delivery in the 0.05–0.15 μg/cigarette range that yields a perceptible but not dominant roasty note. Compliance with EU TPD 2014/40/EU is product-specific: because 2,4-dimethyl-5-acetylthiazole can contribute a characterising flavour, its use in EU-member-state cigarettes must be assessed via the established sensory evaluation panel procedure to verify that the resulting product does not exhibit a “clearly noticeable smell or taste other than tobacco.” In markets outside the EU, where no characterising-flavour ban applies, the restriction does not exist, and the substance is listed on tobacco manufacturers’ approved-flavour directories alongside related heterocyclics. The terminal cigarettes are usually tested for tip-staining and filter ventilation integrity with Cerulean SM450 linear smoke machines before packaging in soft-cup or hinged-lid packs with inner foil lamination to < 0.5 cm³/m²/24h oxygen transmission rate.In the construction of niche gourmand fragrances, 2,4-dimethyl-5-acetylthiazole contributes a dry, nutty-coffee facet distinct from the lactonic sweetness of coumarin and the caramelic warmth of maltol. It is almost exclusively used in the concentrate at 0.01–0.2 % w/w, diluted further in the finished Eau de Parfum to < 0.001 % (10 ppm), where it imparts a subtle roasted dimension to accords built around tonka bean, sandalwood, and immortelle. The neat material is first prepared as a 10 % solution in dipropylene glycol (DPG) or triethyl citrate to improve handling accuracy; the pre-dilution is then introduced into the alcoholic perfume matrix at 15–20 °C under gentle propeller agitation (60–90 rpm) following the pre-maceration of natural absolutes. No significant Schiff-base formation is observed with aldehyde top notes at acidic pH, but contact with undiluted cinnamic aldehyde or vanillin in powder pre-mixes leads to gradual thiazole adduct formation, generating a heavy, sweet-balsamic modification that alters the diffusion profile. Photostability testing under a Q-SUN Xe-3 xenon arc chamber following protocol adapted from ICH Q1B demonstrates 92 % intact compound after 24 hours in a clear glass bottle; amber-coloured borosilicate packaging is nevertheless specified to limit UV-induced ring scission. Skin sensitisation assessment aligns with the IFRA QRA approach: while no IFRA Standard specifically restricts this molecule, a dermal induction threshold of 100 μg/cm² is provisionally applied based on read-across from 2-isopropyl-4-methylthiazole, and the typical leave-on exposure falls three orders of magnitude below this level. Finished products include Eau de Parfum, scented pillar candles with 3–5 % fragrance load in paraffin-soy wax blends, and reed diffusers where the compound provides a bridge between green-woody and oriental-gourmand vectors without turning into the sweet-fruity territory that would conflict with sandalwood-musk drydowns. |
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Designated by CAS 38205-64-0 and FEMA 3267, 2,4-dimethyl-5-acetylthiazole belongs to the alkyl-substituted acetylthiazole family whose sensory trajectory veers sharply from the popcorn-like signature of unsubstituted 2-acetylthiazole toward a deeply roasted, coffee- and meat-centric character. A pale yellow to amber liquid at 20 °C, it solidifies below approximately 8 °C and can be restored to homogeneity by warming to 30–35 °C under nitrogen without detectable ester cleavage. Typical bulk specifications reference a minimum purity of 98.0% (area-%) by gas chromatography with flame-ionization detection on a polar stationary phase (e.g., polyethylene glycol, film thickness 0.25 µm); the principal impurity is the de-acetylated 2,4-dimethylthiazole, analytically controlled below 0.5%. Physical constants reported across current production lots cluster around a refractive index (nD20) of 1.5160–1.5190 (ISO 280:1998), a relative density (d2020) of 1.048–1.058 (ISO 279:1998), and a boiling range of 108–112 °C at 1.33 kPa (10 mmHg). The flash point, determined by Pensky-Martens closed cup per ASTM D93-20, typically measures 93 °C, placing the compound in a combustible liquid class that necessitates storage below 40 °C and separate handling from strong oxidizers.
Process flavor formulations built on a cysteine-xylose-thiamine Maillard basis often generate an overwhelming burst of 2-methyl-3-furanthiol and alkylpyrazines that can mask the nuanced roasted-meat register sought in retorted meat analogues. Addition of 2,4-dimethyl-5-acetylthiazole at 0.2–1.5 wt% on total precursors, blended into the aqueous slurry immediately before induction heating to 100–105 °C, shifts the volatile headspace equilibrium toward the thiazole domain, suppressing the relative abundance of 2-ethyl-3,5-dimethylpyrazine by as much as 40% (based on SPME-GC × GC quantitation in a cysteine-ribose model, pH 5.2). The 5-acetyl substituent’s electron-withdrawing character retards thiazole ring oxidation during the hold phase at 105 °C for 90 minutes; this kinetic stability is a decisive advantage over 2-acetylthiazole, which thiazolidine ring-opening becomes measurable after 60 minutes in the same medium. Commercial savory bases delivered in a drum reactor with variable-frequency agitation (50 rpm, pitched-blade impeller) require gradual dosing of a 10% 2,4-dimethyl-5-acetylthiazole solution in propylene glycol via a peristaltic pump at 0.5 L·min⁻¹ to avoid localized over-concentration that can precipitate Maillard-derived melanoidin-templated agglomerates.
Seasoning blends deposited onto puffed rice or baked lentil chips with residual surface oil below 3 g/100 g create an optically transparent matrix highly penetrable by UVA radiation ( 320–400 nm), a condition that accelerates photo-oxidative cleavage of thiazole rings in structurally simpler analogues. 2-Acetyl-4-methylthiazole, exposed to 8 hours of simulated retail fluorescent lighting ( 800 lux, 25 °C), yields a dose-dependent increase in dimethyl disulfide and methional, quantified at 12–15 µg·kg⁻¹ after 72 hours. In contrast, 2,4-dimethyl-5-acetylthiazole, applied at an equivalent molar concentration of 0.02 mmol·kg⁻¹ seasoning, generates dimethyl disulfide concentrations below 1.5 µg·kg⁻¹ under identical exposure, a protective effect attributed to the additional methyl group at the 4-position increasing steric shielding of the thiazole sulfur atom and the 5-acetyl carbonyl acting as a weak internal UV filter through n→π* transitions. This photostability translates directly to an extended sensory shelf life of at least 9 months in transparent metallized pouches, validated by triangle tests (α= 0.05, β= 0.10) against foil-wrapped controls stored at 35 °C, 75% relative humidity.
Direct injection of neat 2,4-dimethyl-5-acetylthiazole into the barrel of a co-rotating twin-screw extruder (L/D 40:1, screw diameter 25 mm) is feasible only within a narrow thermal window. Processing trials on a laboratory-scale Thermo Prism 24MC with segmented screws and a melt temperature profile of 120×145×165×175×165 °C from feed throat to die reveal that, when the thiazole is introduced through a liquid injection port at the L/D 24 position, the post-die retention level of the parent compound drops by 1.8% per 10 °C increase in the final zone temperature above 175 °C, primarily due to thermal elimination of the acetyl group yielding 2,4-dimethylthiazole. At zone temperatures exceeding 190 °C, the formation of 2,4-dimethylthiazole surpasses 5% of the original thiazole load and becomes sensorially detectable as a distinct sulfidic-medicinal note. Consequently, practical formulation windows cap the melt temperature at 178 ± 3 °C for a residence time of 45–60 seconds. Using a pressurized injection assembly with a back-pressure regulator set at 2.5 MPa prevents vapor lock at the point of introduction, as the compound’s vapor pressure at 175 °C approximates 8.0 kPa. Post-extrusion loss can be partially compensated by adding 15–20% excess thiazole to the injected dose, but the cost must be weighed against downstream regulatory ceilings.
Under EU Regulation 1334/2008, 2,4-dimethyl-5-acetylthiazole appears on the Union List of flavouring substances with FL-no. 15.001, assigned to chemical group 30 (thiazoles, thiazolines, and thiazolidines). The JECFA evaluation ( 56th meeting) concluded a “no safety concern at current estimated dietary intake,” resulting in an ADI “not specified,” a status mirrored by the FEMA GRAS determination 3267, which lists average maximum use levels of 5 ppm in meat products, 3 ppm in soups, and 2 ppm in snack foods. Batch authentication relies on isotopic ratio mass spectrometry (IRMS, ¹³C/¹²C) to distinguish natural-identical material from fermentation-derived batches; a δ¹³C value of −30.2 ± 0.5 ‰ is typical for fully synthetic product. Excessive 2,4-dimethylthiazole carryover detected above 0.8% in the final distillate indicates incomplete acylation during manufacture and correlates with a perceptible degradation in olfactive brightness, prompting rejection under internal release specification IS-FT-442.
A cold-storage regimen of 2–8 °C in sealed, epoxy-phenolic lined steel drums (200 kg net) under a nitrogen headspace (O₂ < 0.2%) limits the annual peroxide value increase to less than 0.5 meq·kg⁻¹. Once a drum is opened, the recommended maximum period of use is 60 days with daily nitrogen re-blanketing; beyond this interval, a peroxide value exceeding 1.0 meq·kg⁻¹ has been associated with a chlorine-bleach off-odor in diluted aqueous solutions. Blends with amine-containing seasonings or alkaline hydrolyzed vegetable protein pastes (pH > 7.5) must be avoided, as the 5-acetyl carbonyl can undergo imine formation at ambient temperature, rendering the thiazole non-volatile and sensorially inert within 48 hours.
The table below juxtaposes 2,4-dimethyl-5-acetylthiazole against three structurally proximate thiazole derivatives frequently considered interchangeable in savory compositions. Each row highlights the divergence in olfactive quality, potency, and thermal robustness that results solely from altering the position and number of methyl and acetyl substituents on the thiazole nucleus.
| Parameter | 2,4-Dimethyl-5-acetylthiazole | 2-Acetylthiazole | 2-Acetyl-4-methylthiazole | 2,4,5-Trimethylthiazole |
|---|---|---|---|---|
| FEMA No. | 3267 | 3328 | 3209 (as a mixture) | 3325 |
| Odor description | Roasted, meaty, coffee, nutty | Popcorn, bread crust, toasted grain | Musty, cocoa, burnt sugar | Cocoa, peanut, earthy |
| Odor threshold in water (ppb) | ~1 | ~10 | ~34 | ~1.5 |
| Boiling point (°C, at 10 mmHg) | 108–112 | 89–91 | 95–98 | 65–67 (8 mmHg) |
| Log P (est.) | 1.97 | 0.95 | 1.46 | 2.35 |
| Retort stability (121 °C, water, 30 min) | > 92% retention | 75–80% retention | 82–88% retention | > 90% retention (volatile loss) |
The higher log P of 2,4-dimethyl-5-acetylthiazole relative to 2-acetylthiazole drives faster partitioning into fats, making it a superior top-note anchor in high-fat snack coatings where aqueous-phase evaporation would otherwise strip the more polar congener during frying. Conversely, in clear broth applications where hydrophilicity is paramount, 2-acetylthiazole’s lower log P yields more consistent release; 2,4-dimethyl-5-acetylthiazole can be pre-dispersed in lecithin-citric acid esters to improve cloud stability. The marked improvement in retort retention over 2-acetylthiazole directly enables its use in shelf-stable wet pet food gravies processed in rotary hydrostatic retorts (e.g., JBT system, sterilizing value F₀= 5.0), whereas the unsubstituted analogue falls below the detectable flavor threshold after sterilization, requiring post-process re-dosing.
| Test | Specification | Reference Method |
|---|---|---|
| Appearance | Pale yellow to yellow liquid, free of sediment | Visual, 25 °C |
| Purity (GC, area-%) | Min. 98.0% | IS-FT-441 (30 m × 0.25 mm × 0.25 µm Carbowax, FID) |
| 2,4-Dimethylthiazole | Max. 0.5% | IS-FT-441 |
| Water content | Max. 0.3% | ISO 760:1978 (Karl Fischer) |
| Refractive index (nD20) | 1.5160–1.5190 | ISO 280:1998 |
| Relative density (d2020) | 1.048–1.058 | ISO 279:1998 |
| Acid value (mg KOH/g) | Max. 2.0 | ASTM D664-18e1 |
