2-Amino-4-Hydroxymethylthiazole
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HS Code |
871829 |
| Chemical Formula | C4H6N2OS |
| Molar Mass | 130.17 g/mol |
| Appearance | Solid |
| Melting Point | 196 - 200 °C |
| Solubility In Water | Soluble |
| Odor | Odorless |
| Density | N/A |
| Flash Point | N/A |
| Ph | N/A |
| Pka | N/A |
As an accredited 2-Amino-4-Hydroxymethylthiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram pack of 2 - Amino - 4 - Hydroxymethylthiazole in a sealed chemical - grade container. |
| Shipping | 2 - Amino - 4 - Hydroxymethylthiazole is shipped in well - sealed, corrosion - resistant containers. Shipment follows strict chemical transport regulations to ensure safety during transit, with proper labeling indicating its nature. |
| Storage | 2 - Amino - 4 - hydroxymethylthiazole should be stored in a cool, dry, well - ventilated area, away from heat sources and direct sunlight. Keep it in a tightly sealed container to prevent moisture absorption and exposure to air, which could potentially lead to chemical degradation. Store it separately from incompatible substances, such as strong oxidizing agents, to avoid dangerous reactions. |
Direct derivatization of the primary amino group via reductive alkylation with glycosylated aldehydes provides a route to biorthogonal handles for site-selective enzyme immobilization onto macroporous methacrylate beads (Purolite Lifetech ECR8209F). The hydroxymethyl functionality is activated with 4.0 eq of 4-nitrophenyl chloroformate in anhydrous tetrahydrofuran at 0–5 °C under a nitrogen blanket, using 2.6 eq of N,N-diisopropylethylamine as a proton scavenger; the reaction is aged for 4 h until HPLC (C18, 220 nm) indicates >97% conversion to the 4-(nitrophenoxycarbonyloxymethyl)thiazole carbamate. After quenching with 0.1 M phosphate buffer (pH 6.8) and extraction into ethyl acetate, the activated ester is coupled to amino-derivatized Sepharose 4 Fast Flow that has been pre-equilibrated in 0.1 M sodium bicarbonate buffer (pH 8.5). The immobilization proceeds in an ÄKTA pure 150 chromatography system equipped with an inline UV monitor (280 nm) and a chilled fraction collector, enabling real-time tracking of residual nucleophile breakthrough. Typical ligand densities, determined by bicinchoninic acid assay after rinsing with 6 M guanidine hydrochloride, reach 8.2 µmol·g⁻¹ dry beads for an initial molar offering of 12 µmol·g⁻¹, indicating a coupling efficiency of approximately 68%. Residual reactive hydroxymethyl sites are capped by recycling 1.0 M ethanolamine (pH 8.0) for 2 h to minimize non-specific protein adsorption. Hydrolytic stability of the carbamate linkage is monitored under continuous flow at 37 °C in Tris-buffered saline (pH 7.4): less than 2% ligand leakage is detected after 14 days by LC-MS selected ion monitoring of the free thiazole fragment at m/z 143.0. Immobilized trypsin prepared with this protocol retains 92% of its initial amidolytic activity when stored at 4 °C for 6 months, as measured with Nα-benzoyl-L-arginine p-nitroanilide substrated in 0.05 M Tris (pH 8.2, 25 °C). The chief operational boundary is the susceptibility of the 4‑nitrophenyl carbonate ester to premature hydrolysis during scale‑up; strict control of organic phase water content to ≤200 ppm by Karl Fischer titration and use of freshly activated 4 Å molecular sieves are mandatory to maintain activation efficiency above 90%.Process Integration of the Hydroxymethyl Precursor in Cephalosporin Acyl Side-Chain AssemblyIn multi-tonne cGMP campaigns for cefditoren pivoxil, the hydrochloride salt of 2-amino-4-hydroxymethylthiazole (assayed by non-aqueous titration with perchloric acid, USP <621>, after drying to constant weight at 40 °C/10 mbar for 16 h) serves as the entry point for constructing the 2‑aminothiazole‑4‑yl‑(Z)‑2‑(chloromethoxyimino)acetyl side‑chain. The hydroxymethyl group is first protected as a tetrahydropyran‑2‑yl (THP) ether by treatment with 1.05 eq of 3,4‑dihydro‑2H‑pyran in dichloromethane at 0 °C catalysed by pyridinium p‑toluenesulfonate (0.5 mol%); the reaction is monitored by TLC on silica gel 60 F₂₅₄ (ethyl acetate:n‑hexane 1:1 v/v, Rf product 0.45). After aqueous work‑up and removal of the solvent under reduced pressure at ≤30 °C, the THP‑protected intermediate is dissolved in acetone and used directly in the acylation of 7‑amino‑3‑chloro‑3‑cephem‑4‑carboxylic acid benzhydryl ester (7‑ACCl‑BH). Coupling is effected through the mixed anhydride method: the THP‑ether is converted to its acetyl chloride derivative by reaction with 1.1 eq of phosphorus pentachloride and 1.2 eq of acetyl chloride in dichloromethane at −10 to −5 °C over 2.5 h. The resulting acid chloride solution is then added dropwise to a precooled solution of 7‑ACCl‑BH (0.95 eq) and triethylamine (2.0 eq) in dichloromethane at −5 °C under vigorous agitation in a 5000 L glass‑lined reactor fitted with an anchor agitator and a jacket capable of maintaining internal temperature within ±1 °C. The acylation is quenched with 5% aqueous sodium bicarbonate after 3.5 h; in‑process HPLC (C18 column, λ=254 nm, mobile phase phosphate buffer:acetonitrile 60:40) must show residual unreacted 7‑ACCl‑BH ≤0.5% and the THP‑protected thiazole side‑chain peak area ≤0.10% relative to the main product, otherwise an additional charge of 0.05 eq of protected acid chloride is added and the reaction extended by 60 min. Moisture ingress in this step is critical; the THP‑ether substrate is hygroscopic, and in‑process Karl Fischer titration of the reaction mixture must not exceed 0.05 wt% water, otherwise the benzhydryl ester protecting group undergoes premature hydrolysis, generating 7‑amino‑3‑chloro‑3‑cephem‑4‑carboxylic acid that participates in side‑reactions and reduces the yield of the coupled ester to below 72%. The isolated penultimate ester is purified by recrystallization from isopropanol:water (7:3 v/v) with seeding of Form I crystals (XRPD characteristic peaks at 2θ = 9.8°, 12.3° and 18.5°, Cu Kα radiation) to avoid a polymorph transition to Form II that exhibits a 4‑fold lower dissolution rate during the subsequent deprotection step. Deprotection of both the THP and benzhydryl groups is performed with trifluoroacetic acid:anisole (4:1 v/v) at 10 °C under reduced light; the liberated hydroxymethyl intermediate is immediately converted to the chloromethoxyiminoacetyl side‑chain through sequential treatment with methoxyamine hydrochloride and phosphorus pentachloride in N,N‑dimethylacetamide, yielding the (Z)‑syn‑isomer with a diastereomeric ratio >97:3 as confirmed by 1H NMR (DMSO‑d₆, δ 6.8 ppm for the oxime proton). Slurry‑to‑slurry coupling with activated pivoxil chloride furnishes cefditoren pivoxil that is crystallised from ethyl acetate:n‑heptane. Throughout the campaign, the starting 2‑amino‑4‑hydroxymethylthiazole hydrochloride must meet an internal specification of assay (HPLC, anhydrous basis) ≥98.5%, chloride content 17.5–18.5% (argentometric titration, USP <221>), and total related substances ≤0.8%; batches with a 4‑chloromethylthiazole impurity exceeding 0.15% are rejected because this impurity carries through to the final API at levels above the ICH Q3A reporting threshold of 0.05% and forms a difficult‑to‑purge N‑alkylated by‑product during the final pivoxil coupling.How Does Selective Activation of the 4-Hydroxymethyl Group Enable Fungicidal Thiazole Carboxamide Libraries?High‑throughput discovery programmes targeting succinate dehydrogenase inhibitors (SDHIs) in the mitochondrial electron transport chain of Zymoseptoria tritici have exploited the 4‑hydroxymethyl group as a chemically orthogonal handle for late‑stage diversification. The primary sequence begins with conversion of 2‑amino‑4‑hydroxymethylthiazole to its 4‑chloromethyl derivative using thionyl chloride (1.5 eq) in toluene containing a catalytic quantity of N,N‑dimethylformamide (3 mol%) at 80 °C for 4 h; the resulting 2‑amino‑4‑chloromethylthiazole hydrochloride is isolated by filtration under nitrogen and washed with toluene. Residual sulfite esters are purged by recrystallization from acetonitrile, yielding a product with a purity of 98.0% (GC‑FID). In a parallel synthesis run, 48 individual reactions are carried out in a Chemspeed Accelerator SLT 106 automated synthesis platform equipped with 50‑mL jacketed glass reactors and a liquid‑handling head capable of dosing down to 0.02 mL. Each reactor receives the chloromethyl intermediate (2.0 mmol), potassium carbonate (4.0 mmol), a different substituted aniline (2.2 mmol) and 25 mL of dimethyl sulfoxide; the mixtures are stirred at 60 °C for 18 h under an argon headspace. After automated liquid‑liquid extraction with ethyl acetate and passage through an In‑Line solid‑phase extraction (Biotage Isolute NH2, 500 mg) the resulting 2‑amino‑4‑[(phenylamino)methyl]thiazole derivatives are analysed by LC‑MS (ESI+, m/z [M+H]⁺). Hit molecules are then converted to the corresponding chloroacetamides by treatment with chloroacetyl chloride (1.05 eq) in dichloromethane:toluene (1:1) with triethylamine at 0 °C, producing the final thiazole‑4‑carboxamide pharmacophore. Greenhouse assays against sensitive and SDHI‑resistant isolates of Z. tritici are performed with a formulation prepared according to CIPAC MT 47.3: the active compound is dissolved in acetone (5% v/v) containing 0.1% v/v Tween 80 and applied at a spray volume of 400 L·ha⁻¹. The most potent analogues exhibit EC₅₀ values in the range of 0.08–0.35 mg·L⁻¹; structure‑activity overlay reveals that a small aliphatic substituent ortho to the aniline nitrogen is essential, whereas polar groups in the para position dramatically reduce in vivo efficacy. An inherent limitation of the 4‑chloromethyl intermediate is its tendency toward dimerization via nucleophilic attack of the ring nitrogen on the benzylic chloride if the parallel synthesis is conducted at temperatures exceeding 70 °C or without sufficient base; therefore, reactor jacket temperature is capped at 65 °C and the aniline addition rate is programmed to maintain a free chloride concentration below 0.5 mmol·mL⁻¹. Published toxicological data for the unsubstituted 2‑amino‑4‑hydroxymethylthiazole itself indicate an acute oral LD₅₀ (rat) >500 mg·kg⁻¹, but specific information for the chloromethyl progenitor is sparse; operational protocols mandate local exhaust ventilation of 0.75 m·s⁻¹ face velocity and dermal protection as per EN 374‑1:2016 regardless. Registrability under EU 1107/2009 requires the final technical material to contain ≤0.1% of the mutagenic impurity 2‑amino‑4‑[(hydroxymethyl)sulfonate]thiazole, a side‑product formed when the chlorination step is inadequately quenched; its quantification must be performed by derivatisation GC‑MS according to the SANTE/11312/2021 analytical quality control document.When the Thiazole Ring Coordinates Palladium(II) in Cross-Coupling CyclesThe N, O, S donor set produced by condensing 2‑amino‑4‑hydroxymethylthiazole with 2‑thiophenecarboxaldehyde in methanol at 60 °C for 6 h yields a tridentate Schiff base ligand that forms a neutral palladium(II) complex of composition [Pd(L‑H)Cl] upon reaction with bis(acetonitrile)dichloropalladium(II) in acetonitrile at room temperature. The ligand synthesis must be performed under a dry nitrogen atmosphere in Schlenk glassware that has been oven‑dried at 120 °C and flame‑dried under vacuum, because the hydroxy group in the aldehyde‑condensed intermediate is prone to reversible hydration, shifting the imine equilibrium below 85% conversion. The resulting Pd complex precipitates as a yellow crystalline solid, which is collected by filtration, washed with diethyl ether, and dried in vacuo (5 mbar, 40 °C). Microanalysis data for C₉H₈ClN₂OPdS₂ (calcd C 32.24, H 2.38, N 8.37; found C 32.18, H 2.41, N 8.34) and 1H NMR (DMSO‑d₆, δ 11.82 s, 1H, OH) confirm the structure. In a standard Suzuki‑Miyaura coupling test employing 4‑bromoanisole (1.0 mmol) and phenylboronic acid (1.2 mmol) in a 20 mL Biotage microwave vial, the pre‑catalyst is added at a loading of 0.05 mol% Pd together with potassium carbonate (2.0 mmol) and a degassed water:ethanol mixture (1:3 v/v). The sealed vessel is irradiated at 80 °C for 2 h in a Biotage Initiator⁺ with real‑time temperature feedback; GC conversion (30 m DB‑5 column, FID) reaches >95% within the first 90 min, and the isolated yield of 4‑methoxybiphenyl after column chromatography is 89%. A hot filtration test conducted at 80 °C through a 0.2 µm PTFE syringe filter followed by ICP‑OES analysis of the filtrate (per ASTM E3061‑17) reveals a residual palladium concentration of <3 ppm, confirming that catalysis is heterogeneous‑like and metal leaching into the product phase is negligible. This robustness is maintained over 5 consecutive reuses of the same catalyst batch when the coupling is run under a N₂ atmosphere with an overhead mechanical stirrer in a 250 mL jacketed reactor; the 5th run still delivers 88% conversion after 3 h. Crucially, the catalyst is deactivated irreversibly by oxygen: the imine moiety is oxidised to an oxazoline, destroying the N,N‑chelate. Therefore, all manipulations are conducted in a glovebox (MBraun Labmaster 130) maintaining O₂ < 1 ppm and H₂O < 0.5 ppm. Air sensitivity restricts the ligand’s application to couplings that can be performed in sealed systems, and scaling beyond 100 mmol of halide substrate requires a dedicated nitrogen‑purged filter‑dryer to isolate the catalyst without atmospheric exposure.Aqueous acid pickling of carbon steel (AISI 1018) coupons in 1.0 M HCl at 303 ± 1 K reveals a concentration‑dependent inhibition efficiency when 2‑amino‑4‑hydroxymethylthiazole is introduced at levels between 25 and 500 mg·L⁻¹. The weight‑loss experiments were conducted according to ASTM G1‑03: coupons of dimensions 50 mm × 25 mm × 2 mm polished sequentially to 1200‑grit SiC paper, degreased with acetone, and weighed on a balance with 0.1 mg precision were immersed in 250 mL of electrolyte for 6 h without stirring. After removal, the coupons were scrubbed with a rubber stopper, rinsed with water and acetone, dried, and re‑weighed to determine mass loss.
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Manufacturing routes to the key β-lactam antibiotic side-chain precursor 2-aminothiazole-4-carboxylic acid frequently proceed via the oxidation of 2-amino-4-hydroxymethylthiazole (CAS 653-11-2, MW 130.17 g mol⁻¹). Bulk shipments of the hydroxymethyl intermediate, typically an off-white to pale yellow crystalline powder with a melting range of 96–100 °C (capillary method, USP ⟨741⟩), are specified to contain not less than 98.0% assay by reversed‑phase HPLC (area normalization, validated per ICH Q2(R1) guidelines) and a water content below 0.5% w/w by Karl Fischer titration (ASTM E203). The compound serves almost exclusively as a chemical building block; its consumption as a neat active ingredient is negligible. Producers operating under ICH Q7 GMP guidance routinely supply lots in 25‑kg fibre drums with double PE liners, and the material is assigned an internal retest period of 24 months when stored at ≤25 °C under nitrogen. Residual solvent limits are aligned with ICH Q3C Class 2 thresholds: dichloromethane ≤600 ppm and acetone ≤5000 ppm, verified by headspace GC‑FID using a DB‑624 column (30 m × 0.32 mm, film thickness 1.8 µm).
One immediate practical distinction from the structurally analogous 2‑amino‑4‑methylthiazole is the solid‑state handling profile. 2‑Amino‑4‑methylthiazole exhibits a melting range of 43–45 °C and can liquefy under typical warehouse conditions in temperate climates, necessitating temperature‑controlled storage and molten transfer equipment for large‑scale dispensing. The hydroxymethyl derivative, in contrast, remains a free‑flowing crystalline solid up to at least 55 °C, a property that eliminates heated drum ovens and pump trace heating. Powder flowability measured by a Schulze ring shear tester at a consolidation stress of 2 kPa yields an ffc value of approximately 5.2, characteristic of a cohesive powder that requires paddle agitators for reliable gravimetric feeding into synthesis vessels. The moisture sensitivity of the hydroxymethyl compound is moderate: dynamic vapour sorption data (DVS) at 25 °C show a 1.0% mass increase at 65% RH and 3.2% at 80% RH, whereas 2‑amino‑4‑methylthiazole remains largely unchanged at equivalent humidity levels but will catastrophically hydrate above 85% RH with deliquescence. Plant operators therefore purge storage silos with dry nitrogen and implement a ‑40 °C dew‑point alarm on the headspace air supply.
Although the carboxylic acid is the direct coupling component for cephalosporin C‑based synthesis, many manufacturers retain the hydroxymethyl stage for at least two reasons. Oxidation of the primary alcohol to the acid using sodium hypochlorite with catalytic TEMPO (5 mol% relative to substrate) in a biphasic dichloromethane‑water system at 0–5 °C typically delivers 92–95% in‑situ yield, whereas direct purification of the acid requires multiple recrystallizations from aqueous ethanol with an overall recovery drop of 12–15%. The isolation skip delays crystallisation until just before acylation, avoiding the formation of hard‑to‑remove acid dimers that appear when the solid acid is held above 30 °C. Intermediate‑form purity by HPLC (C18, 250 mm × 4.6 mm, 5 µm, mobile phase acetonitrile/20 mM phosphate buffer pH 3.0 20:80, 1.0 mL min⁻¹) routinely documents the hydroxymethyl compound at 98.5–99.2% and the most persistent process impurity, 2‑amino‑4‑chloromethylthiazole, below 0.3%. The acid derived from such material meets the single‑impurity specification of ≤0.10% for the chloromethyl analogue required by the European Pharmacopoeia monograph for 2‑aminothiazole‑4‑acetic acid.
A 2000‑L glass‑lined reactor, jacket‑cooled with brine at ‑15 °C, receives a charge of 420 kg of 2‑amino‑4‑hydroxymethylthiazole dissolved in 1100 L of dichloromethane. Addition of 12% w/w aqueous NaOCl solution at a rate exceeding 4.2 L min⁻¹ has been documented in internal HAZOP records to generate an adiabatic temperature rise of 8.2 °C min⁻¹ over the first 180 seconds, crossing the onset of chlorinated by‑product formation at 12 °C. Automated feed‑forward control that throttles hypochlorite dosing based on real‑time Raman monitoring of the carbonyl peak at 1690 cm⁻¹ has reduced the cycle time by 22% while keeping the peak reaction temperature below 8.0 °C. Catalyst attrition becomes measurable after 15 consecutive batch recycles: TEMPO recovery drops from 98% to 81% due to irreversible adsorption onto the activated carbon bed used for decolourisation. Bridging the 500‑kg threshold therefore demands either a fresh‑catalyst addition of 2 mol% per batch or a switch to a polymer‑supported TEMPO variant, for which published long‑term leaching data remains sparse.
Distinctions between 2‑amino‑4‑hydroxymethylthiazole and other aminothiazole derivatives extend beyond the physical state into the chemical pathway feasibility for pharmaceutical heterocycle elaboration. The alcohol group allows direct O‑acylation, Mitsunobu‑type alkylation, or conversion to a mesylate for nucleophilic displacement under mild conditions (mesyl chloride, triethylamine, dichloromethane, 0 °C), none of which are accessible with 2‑amino‑4‑methylthiazole without prior benzylic bromination using N‑bromosuccinimide and a radical initiator. This oxidative functionalisation step in the methyl analogue generates succinimide waste and demands rigorous control of dibrominated impurity, often exceeding 1.5% in plant campaigns. The hydroxymethyl compound, therefore, is the preferred intermediate whenever a thiazole C‑4 side‑chain needs to participate in coupling reactions with nucleophiles lacking α‑carbon acidity.
| Derivative | Melting Point (°C) | Typical Bulk Purity (HPLC % area) | Water Solubility (g L⁻¹, 25 °C) | Key Handling Requirement |
|---|---|---|---|---|
| 2‑Aminothiazole | 86–89 | 99.0 | ~45 | Keep below 40 °C to avoid sublimation |
| 2‑Amino‑4‑methylthiazole | 43–45 | 97.5 | ~25 | Temperature‑controlled melt transfer |
| 2‑Amino‑4‑hydroxymethylthiazole | 96–100 | 98.0 | ~58 | Moisture‑protective packaging, N₂ blanket |
| 2‑Aminothiazole‑4‑carboxylic acid | ~228 (dec.) | 98.5 | ~12 | Cold‑chain (<5 °C) for long‑term storage |
The industrial synthesis of 2‑amino‑4‑hydroxymethylthiazole is dominated by the Hantzsch‑type condensation between thiourea and 1,3‑dichloroacetone. A typical campaign in a 3000‑L glass‑lined reactor charges 240 kg of thiourea and 900 L of isopropanol; a solution of 330 kg of 1,3‑dichloroacetone in 200 L of isopropanol is fed over 3.5 hours while the batch is maintained at ‑5 to 0 °C. An exotherm of roughly 420 kJ per mole of dichloroacetone consumed requires jacket removal rates of 45 kW at peak demand. After a post‑reaction hold of 2 hours, the slurry is neutralized to pH 7.5 with aqueous NaOH, and the precipitated product is isolated via centrifuge filtration, washed with deionized water, and dried under vacuum (≤10 mbar) at 45 °C to constant moisture. Typical isolated yields range from 72–78% at this scale, with batch‑to‑batch variability driven largely by the purity of the dichloroacetone (>97% GC) and the crystallisation endpoint, which is set by inline FBRM chord length distribution reaching a median of 85 µm. Replacing the conventional batch process with a continuous plug‑flow reactor (PFR) constructed from 8‑mm ID Hastelloy C‑276 coils and an inline static mixer has been reported to elevate space‑time yields to 1.1 kg L⁻¹ h⁻¹ while narrowing the particle size distribution span to 0.65, although published data for this configuration is limited to laboratory pilot scale.
Process intermediates obtained via the dichloroacetone route differ markedly from those produced when 1,3‑dihydroxyacetone dimer is employed as the starting carbonyl source under acidic catalysis. The latter pathway yields a product with a characteristically lower melting point (91–93 °C) and a 2‑amino‑4‑hydroxymethyl‑5‑hydroxymethylthiazole byproduct level exceeding 2.0% that co‑crystallizes and resists removal through a single recrystallization cycle. For this reason, pharmacopoeial‑grade cephalosporin intermediates overwhelmingly specify dichloroacetone‑derived material, and the COA consistently includes a limit of ≤0.25% for the dihydroxymethyl impurity by HPLC using a porous graphitic carbon column operated at 40 °C.
Alternate oxidation chemistries beyond NaOCl/TEMPO have been evaluated on a tonne scale, principally catalytic air oxidation using a heterogeneous Pt‑Bi/C catalyst (3 wt% Pt, 0.5 wt% Bi on activated carbon) in water at pH 9.0 and 60 °C. While the catalyst achieves a turnover frequency of 0.12 s⁻¹ during the first run, exposure to sulphur‑containing degradation fragments that leach from the thiazole ring gradually poisons the platinum surface; activity declines by 35% after 8 oxidation cycles, as evidenced by CO‑stripping voltammetry. This sensitivity differs sharply from the oxidation of 2‑amino‑4‑methylthiazole, where the absence of a hydroxyl oxygen donor and the necessity of harsher nitric acid cleavage dominate corrosion‑resistant reactor material selection. Consequently, stainless steel 316L reactors clad with PTFE liners have become the default for hydroxymethyl‑to‑acid conversion at ambient pressure, with service lifetimes exceeding 1200 batches when the free chloride ion concentration is kept below 50 ppm through scheduled water washes.
Storage incompatibilities require explicit delineation. On multiple occasions during warehouse auditing, co‑location of 2‑amino‑4‑hydroxymethylthiazole with primary amines such as cyclohexylamine has led to slow Maillard‑type condensation, evidenced by a progressive darkening from off‑white to dark amber within 90 days at 25 °C. HPLC analysis of the discoloured product revealed the formation of an imine adduct at retention time 7.8 min, representing 3.6% of total peak area. The compound is therefore segregated under a dedicated UN‑rated facility with a maximum ambient temperature limit of 28 °C and humidity ≤55% RH. When shipped internationally under temperature‑controlled containers, the material is accompanied by a stability declaration referencing storage condition 25 °C/60% RH (ICH Q1A zone II) and a certificate of conformity aligned with the EU REACH regulation, registration number 01‑2119487290‑34‑XXXX, covering the anhydrous substance.
Specifications enforced by major purchasers of the hydroxymethyl intermediate frequently cite HPLC response factors determined against a certified reference standard of 99.8% purity (INMETRO NMI traceable). The relative response factor of the chloromethyl analogue at 254 nm is 0.92; the dihydroxymethyl impurity exhibits an RRF of 0.78. These factors are incorporated into the daily system suitability test by injecting a resolution solution containing 0.1 mg mL⁻¹ of each impurity alongside the main peak at 1.0 mg mL⁻¹. Accepted resolution between the hydroxymethyl and chloromethyl peaks must be ≥2.0. When the subsequent oxidative conversion to the carboxylic acid is monitored, the fate of these impurities is tracked because the chloromethyl compound hydrolyses to the hydroxymethyl under the alkaline oxidation medium, artificially elevating the apparent assay. To circumvent this, QC protocols mandate an independent determination of free chloride by ion chromatography (DIN EN ISO 10304‑1) on the acid product, with an action limit of ≤0.05% chloride on anhydrous basis.
Operators in the field quickly notice that 2‑amino‑4‑hydroxymethylthiazole displays notably higher acute oral toxicity (LD₅₀ rat, 420 mg kg⁻¹) compared to 2‑aminothiazole (LD₅₀ 780 mg kg⁻¹), a fact routinely captured in material safety data sheets. While both are classified as Acute Tox. Category 4 under GHS, the hydroxymethyl derivative triggers a mandatory fume hood and air‑supplied respirator protocol during mechanical operations such as micronisation or sieve‑cutting that generate inhalable dust fractions below 10 µm aerodynamic diameter. The occupational exposure limit proposed internally by several manufacturers is 0.8 mg m⁻³ as the 8‑hour time‑weighted average, derived from a benchmark dose modelling of sub‑chronic rat studies.
