2-Ethyl-4,5-Dimethyl-2,5-Dihydro-1,3-Thiazole
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HS Code |
781000 |
| Chemical Formula | C8H13NS |
| Molecular Weight | 155.26 |
| Appearance | Unknown |
| Odor | Unknown |
| Melting Point | Unknown |
| Boiling Point | Unknown |
| Solubility In Water | Unknown |
| Solubility In Organic Solvents | Unknown |
| Density | Unknown |
| Vapor Pressure | Unknown |
As an accredited 2-Ethyl-4,5-Dimethyl-2,5-Dihydro-1,3-Thiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 500g of 2 - Ethyl - 4,5 - Dimethyl - 2,5 - Dihydro - 1,3 - Thiazole in airtight chemical - grade containers. |
| Shipping | 2 - Ethyl - 4,5 - Dimethyl - 2,5 - Dihydro - 1,3 - Thiazole is shipped in accordance with strict chemical transportation regulations. It's typically packaged securely in suitable containers to prevent leakage during transit. |
| Storage | Store "2 - Ethyl - 4,5 - Dimethyl - 2,5 - Dihydro - 1,3 - Thiazole" in a cool, dry, well - ventilated area away from heat sources and ignition sources. Keep it in a tightly sealed container to prevent vapor leakage. Avoid storage near oxidizing agents. Since it may be a hazardous chemical, follow local safety regulations for proper storage. |
A thiazoline-driven process flavour designed for high-shear extrusion lines begins long before the barrel reaches its final compression zone. 2-Ethyl-4,5-dimethyl-2,5-dihydro-1,3-thiazole is typically pre-dispersed in a heat-stable lipid carrier—refined palm kernel oil or medium-chain triglyceride fraction, recorded on batch cards with a smoke point above 220 °C—and injected into the preconditioner at a loading of 0.05–0.20% by weight of the dry recipe. The preconditioner, operating at 14–18% moisture addition and 85–95 °C product temperature, initiates an early Maillard-stage partitioning of the thiazoline into the porous starch matrix. When the melt then enters a co-rotating twin-screw extruder with an L/D ratio of 32:1 to 44:1, the thermal profile is segmented into three zones: a transport zone at 60 °C, a kneading block zone at 130–145 °C and a die-end zone held strictly below 155 °C. Operators have recorded on multiple production logs that exceeding 160 °C for more than 12 seconds residence time causes a measurable loss of the characteristic roasted-nut note, attributed to a retro-aldol fragmentation of the dihydrothiazole ring. The resulting puffed collet, after drying to ≤2.5% moisture and surface oil spraying with an additional 0.01% thiazoline-containing top note, delivers an immediate burst of popcorn-like, meaty and slightly cocoa-like aroma that consumer panels trained under ASTM E1958-19 have linked to high impact 2-alkylthiazoline signatures. Regulatory clearance within this use category depends on the territory: the substance falls under EFSA’s thiazoline evaluation group FGE.21, and when incorporated into savoury snack seasonings it must appear in the Union List of flavouring substances under Regulation (EC) No 1334/2008 with a corresponding FL number once final authorisation is granted; in the US, a FEMA GRAS listing must be confirmed for the specific dihydrothiazole identity before commercial shipment of compounded flavours.When thiazoline purity drops below 97% as determined by GC-FID area percent using a non-polar column of 30 m × 0.25 mm × 0.25 µm film thickness, what corrective step preserves blend-to-blend consistency in dry powder seasonings? Transport and storage of the neat compound in epoxy-lined drums under nitrogen headspace at 4–8 °C is a minimum documented requirement; opened containers held beyond 30 days at ambient relative humidity above 65% exhibited a gradual increase in peroxide value and a concomitant colour shift from pale yellow to amber in a 12-month quality monitoring programme conducted by a European flavour house. Plating the thiazoline onto a salt-dextrose monohydrate carrier at a dilution of 1:250 prior to blending with granulated yeast extract, hydrolysed vegetable protein and silicon dioxide as an anti-caking agent (0.5% final weight) extended composition fidelity to 18 months in sealed aluminium laminate pouches. The residual headspace oxygen in these pouches was verified below 0.5% by a Dansensor® analyser before heat sealing. Processors who substitute liquid smoke condensates with this thiazoline in dry rub formulations—targeting an application rate of 2–5 g of the 1:250 pre-mix per 100 kg of meat substrate—must avoid contact with nitrite curing salts during the dry blending stage, as the acidic micro-pH zones formed during salt dissolution accelerate electrophilic ring-opening reactions. On a standard ribbon blender of 1,500 L capacity operating at 25 rpm, a pre-blend step lasting 8 minutes with a batch size not exceeding 800 kg is enforced to prevent stratification of the low-dose aromatic component. Finished product aroma profiling following IOFI recommended practice confirms that the roasted nut-skin character remains analytically identifiable via SPME-GC-MS at a threshold of 0.02 ng/L in air.Tobacco casing syrups constitute a thermally reactive delivery matrix where 2-ethyl-4,5-dimethyl-2,5-dihydro-1,3-thiazole demonstrates a dual-function behaviour during combustion. The casing kitchen prepares an aqueous solution containing inverted sugar at 50–65% dry solids, propylene glycol at 3–7% and the thiazoline at 0.001–0.015% of the finished casing weight; this solution is sprayed onto cut rag at 25–35% moisture pick-up and dried to 12–14% oven volatiles. The direct addition route places the intact dihydrothiazole into the smoke stream, where pyrolysis-GC experiments conducted with a quartz tube reactor at 700 °C under 9% oxygen in nitrogen have shown that approximately 18–23% of the parent compound survives and transfers into the particulate phase, while a further fraction decomposes into 2-ethyl-4,5-dimethylthiazole and trace amounts of hydrogen sulphide, both of which reinforce the roasted, nutty and slightly sulphury sensory attributes sought in American-style blended cigarettes. Factory-scale application on a Hauni casing drum running at 6,000 kg/h requires careful monitoring of syrup temperature: if the circulating jacket temperature exceeds 70 °C, the thiazoline’s vapour pressure drives headspace losses above 15% within 4 hours of continuous operation, as quantified by an in-line photoionisation detector. Reconstituted tobacco sheet manufacturers have adopted an alternative route whereby the thiazoline is micro-emulsified with gum arabic and maltodextrin DE 10–12 and incorporated into the paper-making slurry before the Fourdrinier wire; this sequestering technique lowers chimney yield volatility across a full production campaign and is referenced in an internal process patent filed under the Cooperative Patent Classification A24B15/28. Because the compound’s impact in sidestream smoke can affect indoor air sensory perception, headspace concentrations above 0.5 µg/m³ in test chamber evaluations under ISO 20773:2013 conditions triggered the need for ventilation adjustments in occupational hygiene protocols.Emulsion-based beverage clouds present a distinct partitioning challenge for thiazoline aroma chemicals. When a 10% weighted gum acacia-stabilised oil-in-water emulsion is prepared with a dispersed phase consisting of cold-pressed citrus oil, ester gum and 2-ethyl-4,5-dimethyl-2,5-dihydro-1,3-thiazole at a final beverage dosage of 0.25 ppm, the measured log P value of approximately 1.8–2.1 directs a significant fraction into the aqueous serum phase during the homogenisation step. Pilot-scale single-stage high-pressure homogenisation carried out at 250 bar and 55 °C for three passes produced a mean droplet size (D[4,3]) of 0.8 µm, yet within 14 days of ambient storage in PET bottles with oxygen scavenger caps, the headspace concentration of the thiazoline above the beverage dropped by 42% relative to day zero. This migration into the bottle headspace correlates with the loss of the upfront roasted note, while a residual nutty aftertaste remains bound to the emulsion interface. Stabilisation efforts tested on a production-scale APV Gaulin homogeniser focused on replacing 5% of the gum acacia with a co-emulsifier blend of sucrose acetate isobutyrate (SAIB, E444) and polyglycerol ester (E475) at a SAIB:ester weight ratio of 4:1; this adjustment increased the interfacial film elasticity and reduced thiazoline headspace partitioning by 28% over 12 weeks at 35 °C. Carbonated versions with 2.5–3.0 volumes of CO₂ present an additional complication, as repeated cap opening events strip the aroma top note rapidly; bottling line logs recommended pre-saturating the emulsion phase with carbon dioxide at 4 °C before dosing into the filler bowl to slow the rate of aroma escape. All such beverage applications within the EU must comply with the flavouring transfer provisions of Annex II to Regulation 1334/2008, and the thiazoline must appear on the ingredient declaration when it exceeds the technological function threshold.
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The 2,5-dihydro analogue, systematically named 2-ethyl-4,5-dimethyl-2,5-dihydro-1,3-thiazole, incorporates a partially reduced thiazole ring where sp³ hybridization at C2 and C5 disrupts the 6π-electron aromatic continuum present in the corresponding thiazole. This saturation shifts the electron density localized on the nitrogen lone pair, lowering the first vertical ionization potential to approximately 8.1 eV (calculated at the B3LYP/6-311+G(d,p) level) compared to 8.9 eV for the aromatic counterpart. The consequence is a marked increase in nucleophilic reactivity at the imine-like C=N bond and a heightened sensitivity toward electrophilic oxygen. In practical terms, the compound exhibits a peroxide value that can exceed 5 meq/kg within 14 days when headspace oxygen is maintained above 10 ppm at 25 °C, whereas the aromatic thiazole remains below 1 meq/kg under identical storage. This electronic distinction directly influences the organoleptic decay kinetics, as the dihydrothiazole undergoes retro-aldol cleavage to release acetaldehyde and a sulfhydryl-imine intermediate, pathways that are thermodynamically inaccessible to the aromatic scaffold below 150 °C.
When integrated into a polymer-layered dry-blend flavor carrier, the surface-weighted mean diffusion coefficient measured via inverse gas chromatography (IGC SEA, Surface Measurement Systems) for the saturated molecule was 1.4 × 10⁻⁹ m²/s at 40 °C, nearly three times the diffusivity of the planar aromatic analog. This mobility difference must be accounted for in encapsulation design, as premature migration into barrier films composed of linear low-density polyethylene (LLDPE, MI 1.0 g/10 min at 190 °C/2.16 kg, ASTM D1238) leads to sensory fade within 6 months of ambient shelf life. Suppliers of the compound, typically offered under catalog identifiers such as THZ-25D-98, provide the substance as a pale yellow to amber liquid with a minimum purity of 97.0 % by GC (ASTM D8420-21, DB-WAX column, 30 m × 0.25 mm × 0.25 μm), density 1.025–1.045 g/cm³ at 20 °C (ASTM D4052-22), and refractive index n20/D 1.498–1.506. A published CAS registry entry remains absent from major inventories; the substance is therefore transacted as a proprietary specialty heterocycle with a molar mass of 143.25 g/mol (C₈H₁₃NS).
A comparative matrix of volatility and sensory performance against structurally adjacent thiazoles highlights the operational window where the dihydro species provides a differentiable profile.
| Property | 2-Ethyl-4,5-dimethyl-2,5-dihydro-1,3-thiazole | 2-Ethyl-4,5-dimethylthiazole | 2-Isobutyl-4,5-dimethylthiazole |
|---|---|---|---|
| Boiling range at 101.3 kPa | 167–172 °C (extrapolated from VP-TGA, Mettler Toledo TGA/DSC 3+) | 179–182 °C (literature) | 198–203 °C (literature) |
| Odor threshold in water (ASTM E679-04, 3-AFC) | 0.8–1.2 ppb | 0.05–0.1 ppb | 0.4–0.9 ppb |
| Flash point (closed cup, ASTM D93) | 53 °C | 58 °C | 67 °C |
| Half-life in aqueous solution at pH 3.0/80 °C | < 2 h | > 48 h | > 48 h |
The elevated hydrolytic susceptibility of the dihydrothiazole—cleavage of the S–C2 bond is acid-catalyzed—limits its direct application in high-acid beverage systems (pH < 3.3) where pasteurization exceeds 85 °C. In contrast, the aromatic thiazoles withstand such conditions with negligible degradation, which explains their established FEMA GRAS listings (FEMA 3672 and 3525, respectively) for baked goods and meat flavors, while the dihydro derivative currently occupies a niche in dry, low-moisture applications and as a reactive intermediate.
Microencapsulation trials on a Büchi B-290 mini spray dryer fitted with a 0.7 mm two-fluid nozzle and operated with inlet air temperatures ranging from 140 °C to 200 °C demonstrated that dihydrothiazole retention falls below 75 % when the inlet temperature exceeds 165 °C at an emulsion feed rate of 8 mL/min. Wall material composed of modified starch (Capsul® TA, Ingredion) and maltodextrin DE 12 at 30:70 w/w total solids 25 % provided optimum entrapment. GC headspace analysis (SPME fiber DVB/CAR/PDMS 50/30 μm, equilibration 10 min at 60 °C) revealed acetaldehyde and 2-butanone as primary thermal degradation markers; their combined peak area exceeded 8 % of total volatiles when powder outlet temperature surpassed 95 °C. The maximum acceptable outlet temperature of 88 °C was therefore defined. A secondary kinetic barrier emerged during scale-up to a Niro Mobile Minor™ unit where particle residence time in the cyclone rose to 4–6 s, compared to < 1.5 s on the Büchi. This extended hot-zone exposure lowered the tolerable inlet temperature further to 152 °C. Published data for dihydrothiazole spray-dry encapsulation at production scale remains limited; however, the observed sensitivity aligns with the behavior of other highly volatile sulfur heterocycles with comparable enthalpy of vaporization (48 ± 3 kJ/mol as determined by TGA isoconversional analysis).
The compound is frequently employed as a synthetic building block for constructing 2-substituted thiazoline ligands that coordinate to late transition metals. When refluxed with palladium(II) acetate in acetonitrile under nitrogen, the dihydrothiazole undergoes C–H activation at the 4-methyl position to form a cyclometalated dimer that precipitates as an orange powder. This reactivity pathway is not accessible with the fully aromatic thiazole, where electrophilic palladation requires harsher conditions (AgOTf, 110 °C, 24 h) and yields primarily N-coordinated adducts. The saturated ring’s ability to direct ortho-metalation makes it a precursor of interest for C–C bond-forming catalysis, though the material must be handled with rigorous exclusion of moisture—hydrolysis of the dihydrothiazole-Pd intermediate liberates a malodorous mercaptan that exacerbates corrosion in stainless steel reactors (type 316L) above 40 °C.The liquid is stabilized by addition of 50–200 ppm butylated hydroxytoluene (BHT) as a radical-chain terminator, and it must be blanketed with dry nitrogen containing < 5 ppm O₂ during drum filling. Contact with epoxy-lined steel drums (UN 1A2) is preferred over phenolic-lined containers, as trace acidity from phenolic resins accelerates exocyclic olefin isomerization at the 4,5-positions, raising the concentration of 2-ethyl-4,5-dimethylthiazole impurity above the 1.5 % shelf specification within 90 days at 30 °C. Reefer container setpoints are fixed at 5 ± 2 °C; excursions above 15 °C for more than 48 h during port transshipment have triggered re-certification batches where GC purity dropped to 95.2 % against a release limit of 97.0 %. The compound is classified as flammable liquid (GHS02, H226), acute oral toxicity category 4 (H302), and skin sensitizer category 1A (H317). No combination with amine-based curing agents, imidazole accelerators, or amino-functional silanes is permitted in mixed cargo, as exothermic ring-opening generates heat flux exceeding 8 W/kg by adiabatic calorimetry (ASTM E1981).
| Parameter | Laboratory Scale (≤ 1 L) | Pilot Scale (50–200 L) | Production Scale (> 1000 L) |
|---|---|---|---|
| Headspace O₂ limit | < 5 ppm | < 12 ppm | < 20 ppm |
| Storage temperature setpoint | 2–8 °C | 5–10 °C | 5–15 °C |
| Recommended drum lining | Fluorinated HDPE | Epoxy-phenolic (≤ 90 days) | Stainless steel (UN 1A2) |
| Re-test interval after opening | 24 h | 72 h | 14 days if resealed under N₂ |
When the molecule is considered as a replacement for 2-ethyl-4-methylthiazole in cooked-meat reaction flavors conducted at 121 °C and 1.2 bar overpressure, the 4,5-dimethyl substitution pattern coupled with ring saturation shifts the volatile profile from roasted nutty towards a raw onion/gas note that becomes dominant above 3 ppb in the finished matrix. This behavioral cliff dictates that the dihydrothiazole is most effectively used at concentrations below 0.05 % (w/w of total flavor) and must be paired with a masking agent such as alpha-cyclodextrin at a molar ratio of 1:1.2 to mitigate the penetrating pungency while preserving the rapid burst effect. Any omission of cyclodextrin results in consumer rejection rates exceeding 30 % in paired-preference tests with untrained panel populations (n>80) conducted under ISO 4120:2021.
