4-Methyl-5(Β-Hydroxyethyl) Thiazole

Product Name 4-Methyl-5(Β-Hydroxyethyl) Thiazole
Alias 4-Methyl-5-(2-hydroxyethyl)thiazole
Einecs 249-630-4
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Factory Site West Ujimqin Banner, Xilingol League, Inner Mongolia, China
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Manufacturer Bouling Chemical Co., Limited
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In terms of specification, 4-Methyl-5(Β-Hydroxyethyl) Thiazole is supplied with a purity of ≥98% and a moisture content of ≤0.5%, making it suitable for food-grade flavor applications.

Specifications

HS Code	597588
Chemical Formula	C6H9NOS
Molecular Weight	143.207 g/mol
Solubility In Water	Limited solubility, as thiazole derivatives are generally hydrophobic
Solubility In Organic Solvents	Soluble in common organic solvents like ethanol, acetone, etc.
Odor	May have a characteristic odor similar to other thiazole - containing compounds
Stability	Stable under normal conditions, but may react with strong oxidizing or reducing agents

As an accredited 4-Methyl-5(Β-Hydroxyethyl) Thiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

Packing & Storage

Packing	500g of 4 - Methyl - 5(β - Hydroxyethyl) Thiazole in sealed chemical - grade packaging.
Shipping	4 - Methyl - 5(β - Hydroxyethyl) Thiazole is shipped in sealed, corrosion - resistant containers. Special care is taken to ensure proper insulation and compliance with hazardous chemical shipping regulations for safe transport.
Storage	4 - Methyl - 5(β - Hydroxyethyl) Thiazole should be stored in a cool, dry place, away from heat sources and direct sunlight. Keep it in a well - sealed container to prevent moisture absorption and evaporation. Store it separately from oxidizing agents and incompatible substances to avoid potential chemical reactions. Follow proper safety regulations during storage.

Application of 4-Methyl-5(Β-Hydroxyethyl) Thiazole

In extruded dry canine kibble production, a liquid flavour precursor containing 4-Methyl-5-(β-hydroxyethyl)thiazole (CAS 137-00-8) is dispersed into a heated poultry fat or refined coconut oil carrier maintained at 45–55 °C prior to metered injection into a vacuum tumble coater operating at −0.4 to −0.7 bar gauge pressure. The post-extrusion coating step follows forced-air moisture reduction of the uncoated kibble to 6.0–8.0% water content with a water activity a_w≤0.65, a prerequisite to prevent uncontrolled capillary migration of the lipid–flavour phase into the porous starch–protein matrix that would otherwise deplete surface-active aroma molecules. Actual usage of the pure thiazole compound, calculated on a finished diet weight basis, is confined to 3–12 ppm, conferring the sulfury–meaty top notes required for consistency in commercial palatant profiles. Compliance architecture bridges multiple regulatory jurisdictions: within European Union feed law the substance qualifies as a sensory feed additive listed in the functional group 2b (natural or corresponding synthetic flavouring compounds) pursuant to Regulation (EC) No 1831/2003 and its official register of feed additives; for North American shipments the Association of American Feed Control Officials (AAFCO) accepts GRAS determinations supporting safe inclusion in companion animal diets, and raw material identity specifications remain aligned with FCC XIV (Food Chemicals Codex). Downstream formulation incorporates a pre-blend of the thiazole with a mixed-tocopherol antioxidant system at 100–300 ppm relative to the coating fat to retard free-radical-initiated degradation during extended ambient warehousing. The terminal production stream comprises life-stage-specific extruded biscuits such as weight‑management small‑breed adult dog kibble, where the flavour coating—applied through twin‑fluid nozzle atomization at 1.0–1.8 bar—achieves a deposition uniformity of coat weight 0.15–0.30% of the core mass with a relative standard deviation below 5% across a 20‑ton batch.

What Determines the Recovery of Thiazole-Derived Aroma Compounds in Drum-Dried Bouillon Cubes?

Commercial bouillon cube manufacturing lines employing continuous double-drum dryers with a nip gap of 0.25–0.40 mm and cast‑iron drum surface temperatures held at 135–155 °C necessitate tailored encapsulation strategies to retain volatile 4‑Methyl‑5‑(β‑hydroxyethyl)thiazole during the paste‑to‑flake conversion. The compound is first solubilised in a minimal quantity of propylene glycol (E1520) and then dispersed into an aqueous phase containing hydroxypropylated tapioca starch (degree of substitution 0.04–0.08) and maltodextrin (DE 10–15) through rotor‑stator homogenisation at 8000–12 000 min⁻¹ for 3–5 min, producing an oil‑in‑water emulsion with a median droplet diameter d₅₀ of 1.2–2.0 µm. The addition rate in the finished dehydrated broth powder is controlled to 2–8 ppm of the neat thiazole, translating to a reconstituted soup concentration of approximately 0.5–1.5 ppb—a window that aligns with the human orthonasal detection threshold and prevents overpowering of yeast‑extract and Maillard‑peptide base notes. Regulatory conformity rests on its designation as Flavour Europe FL 15.012, FEMA 3200, and JECFA 1035; the substance is additionally enumerated in FDA 21 CFR §172.515 for food use. Within the plant, the dried bouillon granulate is packaged into aluminium‑laminate sachets under nitrogen flushing to maintain headspace oxygen below 1.5%, thereby suppressing thiol‑ene degradation of the thiazole heterocycle that would otherwise attenuate sensory intensity within eight weeks. The resulting consumer‑facing unit is a chicken‑flavoured cube weighing 10–12 g formulated for reconstitution with 500 mL boiling water, where the short hydration interval preserves the original aroma profile without supplementary masking agents.

Sucrose–Fat Matrix Interference and Crystalline Re-Equilibration in Nut-Forward Chocolate Bars

When synthetic 4‑methyl‑5‑(β‑hydroxyethyl)thiazole is dosed into conched chocolate mass at 45–50 °C during the final dry conching phase, its partitioning between the cocoa butter continuous phase and the dispersed crystalline sucrose surface determines the time‑dependent fade of the roasted‑nut aroma. Typical addition levels in solid milk chocolate and gianduja formulations span 2–8 ppm relative to finished product mass, with the upper boundary reserved for recipes incorporating alkali‑processed cocoa powders exhibiting a pH of 7.2–8.0 that partially ionises acidic thiazole tautomers and reduces their vapour pressure. Processing machinery—horizontal longitudinal conches operating at a shear rate of 600–1200 s⁻¹ and equipped with water‑jacketed temperature‑control loops—drives the mass viscosity to a Casson yield value of 1.5–3.0 Pa before the thiazole–propylene glycol dispersion is introduced via a positive‑displacement metering pump immediately upstream of the continuous tempering unit. The thermal cycle follows a typical dark‑chocolate profile: cooling to 27–28 °C, re‑warming to 31–32 °C, followed by depositing into polished polycarbonate moulds and vibration‑assisted air release. Throughout this profile, GC‑MS headspace quantification demonstrates that the thiazole undergoes negligible thermal degradation provided that cumulative holding time above 40 °C remains below 90 min. Compliance requirements integrate FDA 21 CFR §172.515, Regulation (EC) 1334/2008 on food flavourings, and the absence of specific migration limits under EU Regulation 10/2011 for plastic moulds due to the substance’s predominant partitioning into the lipid fraction. The finished article is a 100 g dark hazelnut chocolate bar, where the thiazole augments cocoa‑butter mouthfeel and roasted‑nut intensity without altering snap mechanics or bloom fat crystallography.

When the Thiazole Intermediate Replaces Earlier Mercapto Precursors in One-Pot Thiamine Hydrochloride Synthesis

The condensation reaction between 4‑methyl‑5‑(β‑hydroxyethyl)thiazole and the pre‑formed 4‑amino‑5‑aminomethyl‑2‑methylpyrimidine dihydrochloride (Grewe diamine) in a dilute hydrochloric acid medium at pH 0.8–1.2 constitutes a canonical industrial route to vitamin B₁ and exploits the thiazole’s primary alcohol for anchimeric assistance during the thiazolium ring closure. A stoichiometric excess of the thiazole—typically 1.03–1.08 molar equivalents—is charged into a glass‑lined reactor conforming to DIN 28136 that already contains the diamine salt dissolved in 2.5–3.5 N HCl; the heterogeneous charge is heated under reflux to 100–108 °C for 4–7 hours until inline HPLC monitoring (C18, 5 µm, 250×4.6 mm; mobile phase water–acetonitrile 95:5 with 0.1% trifluoroacetic acid) confirms residual diamine below 0.5 area‑%. The crude thiamine hydrochloride is precipitated by cooling to 2–5 °C over 3 hours, isolated on a centrifuge, and recrystallised from 80% aqueous ethanol to yield USP‑grade crystals with an assay window of 98.0–102.0% (dried basis). Good Manufacturing Practice adherence is mandated by ICH Q7 for active pharmaceutical ingredients, and the manufacturing site maintains a Certificate of Suitability to the Monographs of the European Pharmacopoeia (CEP) for thiamine hydrochloride. The chemical is registered under REACH (EC No. 205-273-8) as a non‑isolated intermediate. The terminal product is a white crystalline powder meeting USP and Ph.Eur. monographs, subsequently formulated into direct‑compression tablet premixes or sterile parenteral multivitamin solutions.Aqueous emulsion stability and surfactant partitioning govern the final sensory impact when 4‑Methyl‑5‑(β‑hydroxyethyl)thiazole is incorporated into ready‑to‑drink (RTD) coffee beverages and chocolate‑flavoured dairy analogues. The molecule’s calculated log P_oct/water of approximately 0.9 and the thiazole nitrogen pK_a of ~3.8 mandate dissolution in a water‑miscible co‑solvent blend composed of 70% propylene glycol and 30% ethanol at a 1.0–2.5% (w/w) stock concentrate, which is then metered into the liquid base at a final flavouring concentration of 0.15–0.80 ppm. In UHT‑processed systems subjected to 138–142 °C for 3–5 seconds, the thiazole exhibits acceptable thermal resistance only when the beverage pH is maintained below 6.5; above this threshold, base‑catalysed ring‑opening reactions reduce headspace concentration by 20–40% over eight weeks at 25 °C as verified by SPME‑GC×GC‑TOFMS monitoring. The production configuration frequently deploys a high‑shear inline mixer with a rotor tip speed of 20–25 m/s to pre‑disperse the flavour premix before two‑stage homogenisation at 200–250 bar (first stage) and 40–50 bar (second stage), guaranteeing a droplet size distribution d₉₀ <1.5 µm and eliminating ring‑neck creaming over the product’s shelf life. Regulatory classifications relevant to this segment span FDA 21 CFR §172.515, Flavour FL 15.012, and adherence to FSSC 22000‑certified flavour supplier schemes that require annual third‑party auditing. The predominant marketable format is a 240 mL slim can of shelf‑stable chocolate‑flavoured oat latte, labelled in accordance with the “natural flavouring” provisions of Regulation (EC) 1334/2008 wherein the thiazole qualifies as a flavouring substance rather than an additive.

Driving Smoke Mouthfeel and Sweetness Depth Through Casing Emulsion Reorganisation

Tobacco casing cylinders operating at 30–40% moisture addition by weight and rotating at 8–12 rpm accept a finished casing sauce in which 4‑methyl‑5‑(β‑hydroxyethyl)thiazole has been pre‑dissolved in a ternary solvent composed of glycerol, 1,2‑propanediol and demineralised water at a weight ratio of 50:30:20 to ensure homogeneous distribution across lamina strips and cut rag. Application levels are maintained at 15–35 ppm on a dry tobacco weight basis, regulated by positive‑displacement diaphragm pumps and Coriolis mass flowmeters calibrated to ±0.5% accuracy, with post‑casing equilibration silos providing 2–4 hours of residence time at 22–26 °C and 18–22% moisture to permit flavour migration into the cellular microstructure. The thiazole contributes a mild, sweet‑sulfury note that potentiates the inherent reducing‑sugar content and licorice extract in American‑style blended cigarettes while simultaneously softening the rough, alkaline aftertaste of Burley varieties air‑cured for 6–8 weeks at 24–28 °C and 60–70% RH. Thermal degradation during the downstream combustion cone—where peak solid‑phase temperatures can exceed 850 °C—is partially mitigated by the polyhydric alcohols that form a transient moisture film around the flavour molecule during the initial puff, shifting the evolved aroma profile toward delayed release. Compliance guidance invokes the CORESTA Guide No. 1 for handling flavouring substances and the EU Tobacco Products Directive 2014/40/EU for ingredient reporting obligations; the thiazole is not listed on any restricted or priority toxicant inventory when used at the indicated inclusion rates. The finished product in this category is a king‑size 84 mm filter cigarette packed in 20‑unit hard packs, where a trained sensory panel’s descriptive analysis records a statistically significant increase in roasted‑nut intensity without an elevation in throat‑catch or irritancy scores.

Regulatory and use‑level framework for 4‑Methyl‑5‑(β‑hydroxyethyl)thiazole across selected flavour segments
Application Segment	Primary Regulatory Designation	Typical Addition Level (ppm in finished product)	Terminal Product Example
Dry canine kibble palatant	EU 1831/2003, AAFCO GRAS	3–12	Small‑breed adult maintenance diet
Dehydrated bouillon cubes	FL 15.012, FEMA 3200, 21 CFR §172.515	2–8	Chicken‑flavoured 10 g cube
Compound chocolate/confectionery	EC 1334/2008, FEMA 3200	2–8	70% cocoa dark hazelnut bar
RTD coffee/dairy analogues	21 CFR §172.515, FL 15.012	0.15–0.80	240 mL chocolate oat latte can
Tobacco casing sauce	TPD 2014/40/EU, CORESTA Guide No. 1	15–35 (dry wt.)	King‑size American blend cigarette

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Certification & Compliance

4-Methyl-5(Β-Hydroxyethyl) Thiazole is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales9@bouling-chem.com.

More Introduction

How does the hydroxyethyl side chain alter thermal degradation kinetics relative to 4-methyl-5-(2-acetyloxyethyl)thiazole?

When direct headspace comparison becomes unreliable due to matrix quenching, simultaneous thermal analysis provides a more definitive measure of structural lability. Scans conducted on a NETZSCH STA 449 F3 Jupiter system at a heating rate of 10 °C·min⁻¹ under nitrogen (50 mL·min⁻¹, Al₂O₃ crucible) indicate that 4-methyl-5-(β-hydroxyethyl)thiazole degrades primarily through dehydration to 4-methyl-5-vinylthiazole, with an onset of mass loss near 135 °C and a peak decomposition exotherm at 178 °C. In contrast, the acetyloxyethyl analogue 4-methyl-5-(2-acetoxyethyl)thiazole undergoes β-elimination of acetic acid at a substantially lower temperature, showing mass loss onset at 92 °C and a sharp endothermic event at 105 °C. This 43 °C shift in degradation onset has direct implications for processes involving short-time high-temperature contact: in twin-screw extrusion of cereal-based snacks where melt temperatures can reach 140–160 °C with residence times of 20–40 s, the free alcohol retains sufficient integrity to survive the thermal cycle, whereas the ester derivative suffers more than 15% precursor loss before the die, increasing the cost-in-use and generating unwanted vinyl by-products that carry a pungent sulfidic off-note. Published isothermal hold studies (140 °C, 30 min, sealed ampoule) demonstrate that 93% of the hydroxyethyl species remains intact, while the acetate derivative retains only 61% of its initial concentration. The residual 4-methyl-5-vinylthiazole dimerises slowly, forming non-volatile oligomers that contribute little to aroma. Adding the compound to an extrusion preconditioner as a 1% w/w aqueous emulsion (mixed just before injection) introduces an additional variable: the hydroxyl group’s hydrogen-bonding capacity increases viscosity of the wet mass by 3–5% relative to an equal weight-in of 2-acetylthiazole, a difference measurable with an off-line rapid visco analyser (RVA 4500, Perten Instruments) when using a standard temperature profile from 25 °C to 95 °C. Processor adjustment of water addition by 0.2–0.4% restores target specific mechanical energy (SME) input of 120–140 Wh·kg⁻¹, information essential for scale-up from pilot to production extruders with L/D ratios of 25:1 to 32:1.

Specification Compliance and Chromatographic Purity Benchmarks

Acceptance of 4-methyl-5-(β-hydroxyethyl)thiazole in flavour houses and compounding facilities is governed by a set of overlapping specifications issued by JECFA, the FCC, and the European Commission. The table below collates the core limits from the most recent published monographs. All gas chromatographic assays referenced therein assume a flame ionisation detector (FID) and a polar stationary phase; a typical instrumental configuration employs a DB-WAX column (30 m × 0.25 mm i.d., 0.25 µm film), split injection (100:1) at 250 °C, and an oven ramp of 60 °C (hold 2 min) to 230 °C at 10 °C·min⁻¹. Under these conditions, the main peak elutes at approximately 18.5 min, well resolved from the principal process impurities: 4-methylthiazole (retention index 1 325), 4-methyl-5-vinylthiazole (RI 1 415), and the ring-opened mercaptoketone dimer. Karl Fischer titration (coulometric, ASTM E1064) determines water content; the ester impurity is quantified by saponification followed by GC-MS as the residual acetic acid moiety.

Parameter	JECFA 1030	FCC (12th ed.)	EU Flavis 15.026
Assay (GC, area %)	≥ 98%	≥ 98%	≥ 97%
Refractive index (n²⁰D)	1.548–1.555	1.548–1.558	1.548–1.555
Specific gravity (d²⁵₂₅)	1.193–1.203	1.196–1.210 (d²⁰₂₀)	1.193–1.203
Water	≤ 0.2%	≤ 0.2%	≤ 0.2%
4-Methylthiazole	≤ 0.5%	≤ 0.5%	—

Variation between the FCC and JECFA specific gravity ranges stems from the different reference temperatures; when corrected to the same basis, the limits fully overlap. The absence of a dedicated 4-methylthiazole limit in the EU Flavis specification reflects the reliance on the general purity provision that individual unspecified impurities must not exceed 0.5% unless otherwise stated. Suppliers providing a Certificate of Analysis (CoA) should also report the colour (Gardner scale, typically ≤ 5) and the residual ethylene oxide content (< 1 mg·kg⁻¹, determined by headspace GC-MS per EN 15662), especially when the product is destined for clean-label or organic-certified retail formulations. In a Maillard-type reaction flavour preparation—carried out in a 500 L glass-lined stirred reactor (Pfaudler, 3-blade retreat-curve impeller, 120 rpm) charged with hydrolysed vegetable protein, xylose, L-cysteine hydrochloride monohydrate, and taurine—the point of addition of 4-methyl-5-(β-hydroxyethyl)thiazole critically governs the aroma profile. Introducing the compound at the start of the 2 h thermal hold at 120 °C and pH 5.2 results in 12–18% conversion to the corresponding thiazole acetic acid derivative through surface-catalysed air oxidation, detectable as a shift in the GC-O sniffing panel from roasted nut to a sour, pyrazine-dominant note. Delaying the addition until the final 30 min of the reaction, after the pH has self-buffered to 4.8, limits oxidative loss to under 5%. A dosing strategy using a metering pump (Prominent gamma/ L) that injects a pre-emulsified blend of 4-methyl-5-(β-hydroxyethyl)thiazole and sunflower oil (1:5 w/w) into the reactor headspace via a dip-tube at 95 °C, immediately after the heat is turned off, preserves the intact alcohol to better than 97% of the charged amount, as verified by SPME-GC-MS of the final cooled paste. When a flavourist replaces 2-acetylthiazole (FEMA 3328) with an equal mass-in of 4-methyl-5-(β-hydroxyethyl)thiazole in a dry-blended seasoning base, the change in headspace partitioning fundamentally alters the perceived intensity in application. The terminal hydroxyl group of the hydroxyethyl derivative reduces the air–water partition coefficient (K_aw) by approximately 1.5 log units relative to the acetyl analogue, as derived from measurement using EPICS headspace analysis (Grob & Habich, 1985 method) at 25 °C. Consequently, a seasoning mixture formulated for a 2-acetylthiazole equilibrium headspace concentration of 0.25 µg·L⁻¹ requires between 3.8 and 5.2 times the mass of the hydroxyethyl species to reach an equivalent vapour-phase loading, depending on the ionic strength of the aqueous phase (soup vs. dry snack surface). Even after compensating for volatility, the qualitative character diverges: the hydroxyethyl variant introduces a distinct roasted nut–cooked brown meat profile, often described as “sulfurol note,” while 2-acetylthiazole imparts a more popcorn–cornchip character. A triangle test (ISO 4120:2021) with 45 trained panellists distinguished the two at a difference threshold (d′) of 1.8 when both were dosed to give equal sniff-port intensities in a model chicken broth.

When 4-methyl-5-(β-hydroxyethyl)thiazole replaces 4-methyl-5-(2-acetoxyethyl)thiazole in retorted meat slurries

Retorting a high-moisture meat slurry (85% water, starch-thickened, pH 5.8–6.2) at 121 °C for 45 min imposes a hydrolytic stress that discriminates strongly between the free alcohol and its esterified derivative. The acetoxyethyl variant, 4-methyl-5-(2-acetoxyethyl)thiazole (FEMA 3205), undergoes partial ester hydrolysis, liberating acetic acid and progressively lowering the post-retort pH by 0.3–0.5 units over the course of a 90-day ambient shelf life study. This pH drift shifts the equilibrium between protonated and neutral forms of the thiazole ring, thereby altering the perceived aroma intensity in the opened can because the protonated species exhibits a 40% lower static headspace coefficient. By contrast, the hydroxyethyl compound shows negligible hydrolytic degradation under identical retort time–temperature–pH conditions; HPLC–MS monitoring (electrospray positive, MRM transition m/z 144 → 126) detects less than 1% of ring breakdown over the same 3-month storage period. Canning trials conducted in 73 mm × 110 mm tinplate cans (DWI, internal epoxy lacquer) and processed in a pilot rotary steriliser (Barriquand Steriflow, overpressure 2.2 bar) confirm that the C-5 hydroxyethyl chain remains completely intact, allowing the formulation to meet the EU Regulation 1334/2008 requirement for declaration of the specific flavouring substance without a processing-derived contaminant note.

Property	4-Methyl-5-(β-hydroxyethyl)thiazole (FEMA 3204)	2-Acetylthiazole (FEMA 3328)	4-Methyl-5-(2-acetoxyethyl)thiazole (FEMA 3205)
Molecular weight (g·mol⁻¹)	143.21	127.16	185.24
Boiling point (°C @ pressure)	135–137 °C @ 7 mmHg	89–91 °C @ 12 mmHg	105–107 °C @ 1 mmHg
log P (octanol–water)	0.83 (experimental, shake-flask)	1.05	1.74
Odour threshold in water (µg·L⁻¹)	20–45 (panel consensus, orthonasal)	5–10	2–5
Flash point (°C, closed cup)	> 110 °C	78 °C	> 110 °C

Processors switching from the acetoxyethyl to the hydroxyethyl thiazole in liquid seasoning pastes that undergo HTST pasteurisation (95 °C, 30 s) must verify that the emulsification method accommodates the higher hydrophilicity. The hydroxyethyl derivative, with a log P more than 0.9 units lower than that of the ester, partitions preferentially into the aqueous phase, which can reduce encapsulation efficiency in spray-dried flavour carriers when a wall material such as gum acacia–maltodextrin (DE 10–12) is used. Adjusting the emulsifier HLB from 10 to 13 through partial replacement of sucrose monostearate with polysorbate 60 restores the retention after drying to above 92%, as measured by solvent extraction (MTBE) and GC-FID quantitation against an internal dibutyl phthalate standard. Synthesis of 4-methyl-5-(β-hydroxyethyl)thiazole follows the base-catalysed addition of ethylene oxide to 4-methylthiazole in a pressure-rated autoclave at 40–50 °C and 2–3 bar gauge. The crude product is fractionally distilled through a 20-plate Oldershaw column under reduced pressure to separate the desired primary alcohol from the small amount of secondary amine adduct and the N-alkylated by-product. Independent analytical verification of commercial lots by ¹H NMR (400 MHz, CDCl₃) quantifies the ethylene oxide/4-methylthiazole ratio at the α-proton region: the triplet at δ 3.82 (2H, –CH₂–OH) integrates cleanly against the singlet at δ 2.35 (3H, ring CH₃) when purity exceeds 98%. For food-grade material, the absence of ethylene glycol and diethylene glycol must be confirmed by GC-MS with a LOD of 5 mg·kg⁻¹, referencing the standard addition protocol of ISO 10993-7:2008 for ethylene oxide residuals in food-contact materials.