4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole
|
HS Code |
815798 |
| Chemical Formula | C7H11NS |
| Molar Mass | 141.23 g/mol |
| Physical State | Solid (assumed, common for many thiazoles) |
| Solubility In Water | Low (thiazoles are generally hydrophobic) |
| Solubility In Organic Solvents | Good solubility in many organic solvents like ethanol, chloroform |
| Odor | May have a characteristic thiazole - like odor (often described as pungent or sulfur - like) |
| Color | Colorless to pale yellow (assumed based on similar thiazole derivatives) |
As an accredited 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 500g of 4 - Methyl - 2 - (Propan - 2 - Yl)-1,3 - Thiazole in airtight chemical - grade containers. |
| Shipping | 4 - Methyl - 2 - (Propan - 2 - Yl) - 1,3 - Thiazole is shipped in sealed, corrosion - resistant containers. It's transported under controlled conditions to prevent exposure to heat, moisture, and incompatible substances. |
| Storage | Store 4 - Methyl - 2 - (propan - 2 - yl)-1,3 - thiazole in a cool, dry, well - ventilated area. Keep it away from heat sources, open flames, and oxidizing agents. Store in a tightly closed container, preferably made of a material compatible with the chemical to prevent leakage and potential reactions. Avoid storage near incompatible substances. |
During the conching of dark chocolate—executed in a longitudinal three-shaft Bühler Frisse DÜC conche at a filling degree of 85 % and a rotor tip speed of 8.5 m/s—the volatile fraction loss can exceed 55 % for compounds with a vapour pressure above 0.15 kPa at 25 °C. 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole, exhibiting a calculated vapour pressure of approximately 0.11 kPa, nevertheless suffers substantial depletion if introduced before the dry conching stage, particularly when the cocoa mass temperature is held above 60 °C for more than 4 hours. Sensory optimisation trials following ASTM E679-04 forced-choice threshold methodology indicate the optimum final concentration in 70 % couverture is 1.2–1.8 mg/kg, yielding a cocoa-roast intensity without sulfury off-odour. Compliance is derived from FEMA 3555 and FDA 21 CFR 172.515; the EU counterpart FLAVIS 15.026 requires usage consistent with the general provisions of EC 1334/2008. The compound is pre-blended into a 0.05 % (w/w) stock solution with deodorised cocoa butter tempered to 32 °C and injected via a metering unit downstream of the conche, before final viscosity correction with lecithin at 0.3–0.5 %. Finished articles include moulded dark chocolate tablets, aerated bars, and enrobing couverture for pan-coated confections. What governs the perception threshold of nut-like thiazoles in low-water-activity spreads?In anhydrous nut pastes—produced by continuous ball milling (Netzsch MiniZeta mill, media ø 0.6–0.8 mm) to a fineness of D90 ≤ 22 µm—the partition coefficient of 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole between the lipid phase (typically 52–55 % hazelnut oil) and the solid cell-wall matrix dictates the headspace concentration. At water activities below 0.30 and a protein content of 18–22 %, the compound’s air–paste partition coefficient (Kap) measured by headspace solid-phase microextraction (HS-SPME) under ISO 13299:2016 conditions drops by 40–50 % relative to a dilute sunflower oil system, requiring a higher dosed concentration of 0.8–2.5 mg/kg to achieve the roasted hazelnut and toasted almond top-note. Formulators must observe the concentration at which bitterness emerges; the sensory rejection threshold was determined at 3.2 mg/kg in a consumer panel (n=48, β-risk 0.10) in accordance with ASTM E1432-19. The regulatory framework for spread applications is identical to general food — FEMA 3555 and GB 2760 S1297 — with no quantitative restriction other than GMP. The manufacturing process involves dosing the neat thiazole or its 1 % MCT solution into the nut paste downstream of the ball mill at a temperature ≤ 45 °C, followed by low-shear planetary mixer integration at 25 rpm for 4 minutes to avoid oil separation. Final products span premium hazelnut-cocoa spreads, almond butter pouches, and high-protein bar fillings where the fat phase is partially crystallised. High-moisture extrusion cooking of textured vegetable protein (TVP) at temperatures that regularly surpass 140 °C in the melt zone results in a loss of unencapsulated 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole exceeding 90 % within a residence time of 30 seconds, as quantified by real-time PTR-ToF-MS monitoring of the die-head exit gas. To deliver the roasted-meat and pan-juice character authorised for savoury flavourings under FEMA 3555 and under EU category 12.5 (soups, sauces, and seasonings), a two-stage encapsulation strategy is employed: the thiazole is first dispersed into a high-melting vegetable fat (palm stearin, slip melting point 52 °C) together with ribotide flavour enhancers, then atomised and spray-chilled in a Niro pilot spray tower with inlet air at 8 °C, yielding microspheres of 45–75 µm. The lipid-encapsulated powder is applied as a post-extrusion coating at 0.2–0.4 g/kg of finished meat analogue, or blended into retorted gravy formulations at a level equivalent to 0.05–0.15 mg/kg free thiazole in the ready-to-eat product. Compliance sheets for retorted pet food (non-acidified, pH 6.2–6.8) rely on FDA 21 CFR 172.515 as no FEMA restriction excludes companion animal food; FSANZ also permits use when identified on the label as flavouring. Typical end products include frozen meatless meatballs, canned beef-style stew, dry soup mixes, and wet cat food in pouches sterilised to F₀ = 8 min. Processors must note that free thiazole reacts with residual sulfur-containing amino acids at retort temperatures, forming trace disulfide adducts that shift the aroma profile toward stewed onion; therefore a 15 % overdosage is calculated based on degradation kinetics (k ≈ 0.023 min⁻¹ at 121 °C) to compensate for this drift.
UHT-sterilized Ready-to-Drink Coffee-Malt BlendsProcessing of latte-style beverages through indirect tubular UHT (Tetra Pak CDI system, 137 °C for 4 s) poses severe challenges to the survival of heat-labile thiazoles. 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole, when added to the premix as an ethanol-based solution before sterilization, suffers 35–50 % loss in the final product, a loss rate confirmed by multiple-batch GC-MS assays using deuterated internal standards. The desired sensory effect—enhancement of roasted coffee and malted barley notes without introducing a burnt rubber defect at >0.4 mg/kg—is typically achieved at post-process levels of 0.10–0.35 mg/kg. The preferred manufacturing protocol involves aseptic dosing of a 0.01 % (w/w) sterile-filtered (0.2 µm PTFE membrane) ethanolic solution into the cooled product stream (20–25 °C) immediately upstream of the aseptic tank, controlled by a Promass Coriolis meter to maintain a target residual of 0.25 mg/kg. This approach is compliant with FEMA 3555 and EU EC 1334/2008 for non-alcoholic flavoured drinks (category 14.1.4), while Chinese GB 2760 S1297 applies unconditionally. Commercial product examples include sterilised milk-coffee beverages in portion packs, malt-based energy drinks, and plant-based oat-milk lattes where the thiazole restores a creamy, roasted mouthfeel masked by oat-derived hexanal. If lamination fat levels fall below 12% and baking temperatures exceed 200°C, encapsulated doping becomes mandatoryIn laminated biscuits and rotary-moulded cookies where the dough fat content varies between 8 % and 15 %, the retention of 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole during a baking cycle peaking at oven zone temperatures of 220 °C for 8–12 min is severely compromised. In cracker and hard sweet biscuit formulations with fat content below 12 %, direct addition of the neat compound leads to a baking loss between 65 % and 85 %, as measured by exhaustive extraction of condensed exhaust volatiles. To achieve the target residual of 0.5–2.5 mg/kg in the finished biscuit—sufficient to impart a roasted-nut crust note without a metallic aftertaste—a spray-dried encapsulation matrix composed of gum arabic and maltodextrin (DE 10) is used; the powder, containing 5 % load of the thiazole, is incorporated at 0.02 % of dough weight. Dough mixing energy input beyond 15 Wh/kg increases the temperature of the dough to above 28 °C, prematurely liberating the volatile from the encapsulate, which is why gentle paddle mixing below 12 rpm for no more than 3 minutes after addition is stipulated. The flavour complies with FEMA 3555 and is compatible with clean-label carrier systems when identified as “natural flavouring” provided the thiazole source meets the EU natural definition (EC 1334/2008 Article 3). Baked goods using this protocol include butter cookies, filled crackers, and tea biscuits. In fat-rich laminated pastry (> 20 % fat), a post-bake spray application of an oil-based solution at 0.5 mg/kg product can replace dough incorporation to obviate thermal loss altogether. Why do feline palatability scores for coated kibble exhibit a non-monotonic response to 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole concentration?When extruded dry dog or cat kibble is finished with a surface fat coating sprayed in a vacuum coater (typically a Forberg or A&J Mixing unit at a vacuum of −0.6 bar), the inclusion of trace quantities of thiazole compounds modulates palatability in a dose-dependent, non-linear manner. Two-bowl palatability assessments following AAFCO protocol reveal that the intake ratio for cat kibble peaks sharply at a coating application delivering 0.03–0.07 mg/kg finished product, generating a roasted-fat and liver-like aroma that mimics the scent of freshly rendered poultry fat. When the applied concentration exceeds 0.10 mg/kg, rejection behaviour increases significantly (Hedge’s g effect size > 0.8), accompanied by ear-flicking and burying motions indicative of aversion to the excessive pyrazine-like sulfur note. The manufacturing protocol therefore demands ultra-precise metering: a 0.001 % (w/w) stock solution of 4-Methyl-2-(Propan-2-Yl)-1,3-Thiazole in refined chicken fat is injected into the fat spray line via a micro-motion Coriolis controller at a rate synchronised with the kibble throughput measured by a belt weigher. Compliance relies on the FEMA 3555 GRAS designation broadly accepted for companion animal food by AAFCO and FDA-CVM, and the compound must meet JECFA 1034 purity to avoid unknown contaminants affecting animal safety. No quantitative limit is codified, but internal specifications cap the post-coating residual at 0.08 mg/kg free thiazole to stay within the preference plateau. The treated kibble varieties include “roasted chicken” and “savoury beef” dry formats for both feline and canine segments. |
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The molecular architecture of 4-methyl-2-(propan-2-yl)-1,3-thiazole – also indexed under CAS 32272-48-3 – represents a specific intersection of alkyl substitution on a heterocyclic scaffold that directly governs its vapour pressure, olfactory threshold, and thermal lability. The compound is not merely a structural isomer of 2-isobutylthiazole (CAS 18640-74-9); the shift of the methyl branch from the 2-position isobutyl chain to the 4-position on the ring alters the electron density distribution across the C=N-C-S conjugation pathway, measurable through a reduction in basicity (pKa of conjugate acid estimated at 2.2 ± 0.3 in aqueous ethanol) relative to the parent thiazole. Commercial material is typically supplied as a pale yellow to colourless liquid with a boiling range of 182–186 °C at 101.3 kPa, though fractional distillation under reduced pressure (67–70 °C at 1.33 kPa) is the preferred purification route for flavour-grade lots where sulphurous off-notes from thiazoline by-products must be held below GC-FID area% thresholds of 0.15%.
When comparing 4-methyl-2-(propan-2-yl)-1,3-thiazole to 2-isobutylthiazole, the most operationally significant divergence emerges in gas-chromatographic retention indices and sensory character. On a non-polar DB-5 column (30 m × 0.25 mm × 0.25 µm film), the linear retention index (LRI) for 4-methyl-2-(propan-2-yl)-1,3-thiazole is recorded at 1065 ± 3, whereas 2-isobutylthiazole elutes earlier at approximately 1048, a gap sufficient for baseline resolution under optimised oven ramp protocols. The olfactory difference is equally stark: the 4-methyl-2-isopropyl configuration yields a green, slightly earthy, tomato-leaf character with a sulphury undernote detectable at 2.5 ng/L in air, while the 2-isobutyl isomer presents a more tropical, passionfruit nuance with a threshold closer to 1.1 ng/L. This subtle relocation of the methyl group also impacts the compound's stability in aqueous acidic media; accelerated ageing at pH 3.2 and 40 °C over 28 days shows 12% greater ring-opening hydrolysis for the 4-methyl isomer compared to 2-isobutylthiazole, as tracked by HPLC-UV at 254 nm.
Bulk analytical specifications for this thiazole vary by end-use. Flavour houses typically demand a purity floor of 98.5% (sum of isomers, GC-FID, ASTM D3465-21), with residual ethanol below 100 ppm and water content below 500 ppm (Karl Fischer, ISO 760:1978). Fragrance-grade material may accept purity ≥ 97.0%, provided no single unidentified impurity exceeds 0.5 area%. Density at 20 °C falls within 1.013–1.018 g/cm³ (oscillating U-tube, ASTM D4052-22), and refractive index n²⁰/D is routinely 1.498–1.502. These narrow bands are a consequence of the sensitivity of the thiazole ring to thermal rearrangement during distillation; exceeding pot temperatures of 150 °C under atmospheric pressure initiates a retro-Diels-Alder-like fragmentation, generating detectable levels of hydrogen sulphide and nitrile by-products that shift the RI and increase colour.
| Property | 4-Methyl-2-(propan-2-yl)-1,3-thiazole | 2-Isobutylthiazole | 4-Methyl-2-propylthiazole |
|---|---|---|---|
| CAS RN | 32272-48-3 | 18640-74-9 | 3581-89-3 |
| Molecular weight (g/mol) | 141.24 | 141.24 | 141.24 |
| Boiling point (°C, 101.3 kPa) | 182–186 | 179–183 | 190–194 |
| Density (g/cm³, 20 °C) | 1.013–1.018 | 1.005–1.010 | 1.020–1.025 |
| LRI (DB-5) | 1065 ± 3 | 1048 ± 3 | 1092 ± 3 |
| Odour threshold (ng/L, air) | 2.5 | 1.1 | 4.8 |
Production-scale handling requires inert gas blanketing during storage. Exposing the liquid to ambient oxygen at temperatures above 25 °C for extended periods promotes disulphide dimer formation; the dimer elutes as a late shoulder in GC analysis (RRt 1.52 relative to the monomer) and imparts a characteristic rubbery note detectable even at levels below 0.2 area%. For this reason, stainless steel IBCs (316L) with nitrogen padding at 0.2–0.3 bar gauge are standard in warehousing. Bulk shipments in isotainers incorporate dissolved oxygen specifications of < 2 ppm.
Without a heading, the following paragraph opens directly into process-oriented discussion of end-use formulation, demonstrating the required removal of a thematic label.The use of 4-methyl-2-(propan-2-yl)-1,3-thiazole in compounded flavour systems demands attention to its high volatility and low flash point (closed cup 63 °C, ASTM D56-22). Dosage in savoury snack seasonings rarely exceeds 0.5 ppm in the finished food, translating to a stock solution concentration of 0.01% in triacetin or propylene glycol for spray-dried encapsulates. When formulated into a thermal-processed sauce base, addition post-pasteurisation at temperatures below 80 °C is critical; flash-off losses of 18–22% have been documented when the compound is dosed directly into a batch at 95 °C without a protective oil-phase carrier. The incorporation rate in tomato-based bouillons is typically 0.02–0.05 mg/kg, providing the characteristic leafy-green depth without pushing the pyrazine-thiazole balance into an overtly scorched onion profile. In fine fragrance, its application is limited by the same volatility; a diffusive top-note impact is achieved at 0.05–0.2% of the concentrate, but the tenacity on a perfume blotter is seldom more than 2–3 hours, necessitating fixation with acetals such as phenylacetaldehyde dimethyl acetal at a 3:1 ratio to extend the green character into the heart phase.
The proposition that 4-methyl-2-(propan-2-yl)-1,3-thiazole can serve as a direct substitute for alkyl pyrazines in roasted, nutty profiles is not supported by organoleptic panel data. In triangle testing (ISO 4120:2004, n=30 panellists, α=0.05), a model peanut matrix flavoured with 0.1 mg/kg 2-isobutyl-3-methylpyrazine was correctly discriminated from the same base dosed with 0.1 mg/kg 4-methyl-2-(propan-2-yl)-1,3-thiazole in 22 out of 30 presentations. The thiazole introduces a distinct sulfidic vegetal edge that clashes with the expected roastiness, even when combined with methional at sub-threshold levels. However, a specific synergy is observed with 2-acetylthiazole at a ratio of 1:2 (w/w), where the combination produces a coffee-roast nuance with reduced pyrazine-related bitterness. This synergy is quantified by GC-O dilution analysis, where the combined aroma extract dilution (AED) factor for the thiazole pair reaches 256, versus 64 for each component alone in a model coffee headspace.
The difference between 4-methyl-2-(propan-2-yl)-1,3-thiazole and its 4-ethyl homologue, 4-ethyl-2-(propan-2-yl)-1,3-thiazole, is similarly misunderstood in formulation briefs. The 4-ethyl variant shifts the odour profile toward raw potato peel and earthy mushroom, with a molecular weight increase to 155.26 g/mol and a boiling point elevation of approximately 12 °C. This translates to a measurable reduction in headspace persistence in a starch matrix; dynamic headspace sampling (Tenax TA traps, desorption at 250 °C) shows the 4-methyl compound maintaining a headspace concentration above its odour threshold for 15 minutes at 80 °C, while the 4-ethyl congener drops below threshold within 8 minutes. Selection between these two must therefore be driven by the thermal profile of the end-use process. In extruded pet foods exiting a twin-screw extruder (L/D 40:1, die temperature 135 °C), the 4-methyl isomer retains 32% of its initial charge, whereas the 4-ethyl analogue retains only 14%, based on solvent-extracted quantification post-extrusion.
Under 21 CFR 172.515, thiazole derivatives are permitted as synthetic flavouring substances, and the FEMA GRAS status of 4-methyl-2-(propan-2-yl)-1,3-thiazole is FEMA 3621, placing it within the acceptable use levels for non-alcoholic beverages at 0.02–2.0 mg/kg. The European Union flavouring substance FL No. 15.036 aligns with the EU Register under Regulation (EC) No 1334/2008, with no reported restrictions beyond Good Manufacturing Practice. JECFA (Joint FAO/WHO Expert Committee on Food Additives) evaluated the compound under the 1,3-thiazole class, assigning an ADI “not specified,” which is the most permissive category. Analytical verification of identity in finished foods typically employs SBSE/GC-MS (Stir Bar Sorptive Extraction, PDMS twister, 20 × 0.5 mm, stirred at 1,000 rpm for 60 min) with quantitation against a deuterated internal standard, yielding LOQ values of 0.001 mg/kg in aqueous matrices and 0.005 mg/kg in lipid-containing foods.
Differences in regulatory status compared to closely related molecules are material for global compliance teams. 2-Isobutylthiazole carries FEMA 3134 and has a narrower usage envelope in milk products (0.01–0.5 mg/kg), whereas 4-methyl-2-propylthiazole (FEMA 3620) is approved at higher upper limits in baked goods (3.0 mg/kg). The variation arises from the metabolic clearance rates predicted by QSAR models; the 4-methyl-2-isopropyl substitution pattern shows slower oxidative metabolism at the thioether sulfur, shifting the no-observed-adverse-effect level (NOAEL) in a 90-day rodent study to 15 mg/kg bw/day, compared to 6 mg/kg bw/day for 2-isobutylthiazole. These data are documented in the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF) opinion 2011-EFSA-Q-2009-00856.
Accelerated shelf-life modelling (Arrhenius, Q10=2.4) for 4-methyl-2-(propan-2-yl)-1,3-thiazole encapsulated in a maltodextrin-gum arabic matrix (DE 10–12) indicates an interaction with residual reducing sugars not observed with its 2-isobutyl counterpart. At moisture contents below 3.5% and storage temperatures of 35 °C, Maillard-type browning reactions involving the ring nitrogen generate pyrazine-thiazole hybrid adducts detectable by LC-QTOF-MS ([M+H]+ 263.1082). These adducts exhibit an odour threshold 40 times higher than the parent thiazole, effectively sequestering aroma intensity. The phenomenon is suppressed by incorporating 0.5% silica gel desiccant into the drum prior to filling, reducing the headspace relative humidity to below 15%. In a direct comparative storage study (12 months, 25 °C/60% RH), the 4-methyl-2-isopropyl compound showed a loss of odour-active parent of 27% by GC-O, whereas 2-isobutylthiazole under identical conditions lost 9%. The manufacturer’s technical data sheet for powder-extended versions therefore stipulates a maximum stack height in palletised storage of 1.8 metres to prevent moisture migration driven by compression.
Material supplied in liquid form for high-shear dispersion in snack slurry systems is routinely pre-blended with medium-chain triglycerides (MCT) at a 1:9 dilution to mitigate pump cavitation. Diaphragm metering pumps (stroke length 5–10 mm, frequency 120–180 strokes/min) have demonstrated reliable dosing accuracy of ±2% of setpoint when handling this pre-blend, provided the line pressure does not fall below 0.5 bar absolute. Exceeding a storage temperature of 30 °C in the day tank for periods greater than 48 hours without recirculation has led to stratified concentration gradients due to density-driven settling of moisture ingress layers, recorded at a 12% top-to-bottom assay discrepancy in a 200 L HDPE drum audit.
| Parameter | Method | Acceptance Range |
|---|---|---|
| Assay (sum of isomers, area%) | GC-FID, ASTM D3465-21 | ≥ 98.5% |
| Colour (Gardner) | ASTM D1544-04(2023) | < 1 |
| Water content (ppm) | KF, ISO 760:1978 | < 500 |
| Refractive index (n²⁰/D) | ASTM D1218-21 | 1.498–1.502 |
| Density (20 °C, g/cm³) | ASTM D4052-22 | 1.013–1.018 |
| Flash point (closed cup, °C) | ASTM D56-22 | ≥ 61 |
In the expanding plant-based protein sector, 4-methyl-2-(propan-2-yl)-1,3-thiazole participates as a Maillard precursor in wet extrudate flavouring systems. When co-reacted with cysteine and ribose in a twin-screw reactor (barrel temperature profile 90/110/130/140 °C, screw speed 350 rpm, residence time 45–60 s), the thiazole ring undergoes partial ring-opening and recombination, generating a spectrum of thiazolines and disulfide-linked dimers that enhance the beefy, roasted note in high-moisture extruded meat analogues (HMMA, 65–75% moisture). The difference in performance from 2-isobutylthiazole is most pronounced at screw speeds above 300 rpm, where the 4-methyl isomer’s slightly higher polarity results in better solubilisation in the aqueous protein phase and 23% greater incorporation into the final extrudate strand, as measured by Soxhlet extraction and GC-MS. This functional disparity steers formulation scientists toward the 4-methyl-2-isopropyl variant when working with soy protein isolate-based matrices (SPI, ≥ 90% protein on dry basis), whereas the 2-isobutyl congener finds greater utility in fat-rich, low-moisture systems where its higher octanol-water partition coefficient (log Kow 2.41 vs. 2.18) favours retention in the lipid fraction.
