2-Mercaptothiazole

Product Name 2-Mercaptothiazole
Alias 2-MBT
Einecs 202-763-6
Mininmum Order 25G
Factory Site West Ujimqin Banner, Xilingol League, Inner Mongolia, China
Price Inquiry sales9@bouling-chem.com
Manufacturer Bouling Chemical Co., Limited
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In terms of specification, 2-Mercaptothiazole is supplied with purity ≥ 98% and melting point 144–148°C, making it suitable for corrosion inhibition in industrial cooling systems.

Specifications

HS Code	985000
Chemical Formula	C3H2NS2H
Molar Mass	115.19 g/mol
Appearance	white to light yellow crystals
Odor	characteristic mercaptan - like odor
Melting Point	178 - 182 °C
Solubility In Water	slightly soluble
Solubility In Organic Solvents	soluble in ethanol, ether, acetone
Pka	3.44
Stability	stable under normal conditions
Hazard Class	irritant (can cause skin, eye and respiratory irritation)

As an accredited 2-Mercaptothiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

Packing & Storage

Packing	2 - Mercaptothiazole packed in 5 - kg bags for secure storage and transport.
Shipping	2 - Mercaptothiazole is shipped in sealed, corrosion - resistant containers. Special care is taken to prevent exposure to moisture and heat during transit. Shipments follow strict chemical transportation regulations to ensure safety.
Storage	2 - Mercaptothiazole should be stored in a cool, dry, well - ventilated area. Keep it away from heat sources, flames, and oxidizing agents. Store in a tightly closed container to prevent moisture absorption and potential reaction with air components. Avoid storage near incompatible substances to ensure its stability and safety.

Application of 2-Mercaptothiazole

What Dictates the Brightener Consumption Rate in Via-Filling Electrolytes?

2‑Mercaptothiazole (2‑MT) functions as a grain‑refining brightener in acidic copper sulfate plating solutions, where its thiol group chemisorbs onto high‑current‑density sites on the cathode surface to suppress outward growth and promote lateral levelling. In practical printed circuit board (PCB) vertical continuous plating lines equipped with insoluble mixed‑metal oxide anodes and eductor‑based air sparging, the additive’s steady‑state concentration is maintained between 0.8 mg/L and 4.5 mg/L, while Hull Cell panels run at 2 A for 5 min are used to visually bracket the optimal range. Below 0.5 mg/L the deposit transitions from semi‑bright to matte, exhibiting a surface roughness increase from R_a 0.15 µm to R_a 0.65 µm as measured per ISO 4287. Above the upper threshold, copper becomes brittle due to excessive sulfur co‑deposition; cross‑sectional SEM imaging after 30 s of microetch reveals a columnar grain transition zone exceeding 4 µm, a failure mode that leads to via‑barrel cracks during IST‑288°C thermal stress testing conducted according to IPC‑TM‑650 2.6.8.Electrolyte make‑up follows IPC‑4552A threshold requirements for pure tin‑free final finishes but applies to the underlying copper layers. A typical virgin‑make‑up basestock contains 75–85 g/L Cu (as CuSO₄·5H₂O), 180–220 g/L H₂SO₄, 50–70 mg/L chloride ion, and a three‑component additive system: a polyalkylene glycol suppressor (200–800 mg/L), a bis‑(sulfopropyl)‑disulfide or equivalent carrier (4–12 mg/L), and 2‑MT as the primary brightener. The formulation’s consumable‑cost metric is dominated by the anodic oxidation and drag‑out loss of 2‑MT, which degrades irreversibly at anode surfaces exceeding 1.9 V vs. Ag/AgCl; this forces a replenishment schedule of 0.15–0.35 mL of a 1.0 wt% methanolic stock solution per ampere‑hour in patterns scaled to air‑agitated electroplating cells operating at 2.0–3.5 A/dm². A process control table validated on rotating‑cylinder‑electrode (RCE) rigs at 25°C and 400 rpm is provided below.

Process window data for 2‑MT brightener in high‑throw acid copper (RCE, **25°C**, **400 rpm**, **3.0 A/dm²**)
2‑MT (mg/L)	Deposit brightness (GU, 60°)	Elongation (%, ASTM E8 foil)	Via‑fill throwing power (%, IPC‑6012 Class 3)
0.5	210	8.2	72
2.0	780	6.5	94
4.5	910	2.1	98

The downstream manufacturing process is horizontal electroless‑copper‑seeded panel plating through L/D 12:1 blind microvias, followed by pattern‑plate resist definition with dry‑film photoresist and a subsequent copper electroplating step to 20–25 µm in the vias. Terminal articles are high‑density interconnect (HDI) rigid‑flex boards, interposer substrates for chip‑last fan‑out packaging, and automotive radar antenna boards requiring IPC‑6012D Class 3 acceptance.

When HCl Pickling Baths Exceed 60°C in Continuous Strip Lines

In carbon‑steel hot‑strip pickling using 15–18 wt% HCl at line speeds of 120–180 m/min, the primary corrosion challenge shifts from uniform loss to hydrogen‑blistering and under‑deposit pitting when bath temperature surpasses 65°C. 2‑Mercaptothiazole introduced as a high‑temperature acid inhibitor at 0.08–0.25 wt% relative to the acid bath volume forms a chemisorbed monolayer on the steel surface via the exocyclic sulfur atom, while the ring nitrogen undergoes protonation in the acidic medium, creating a cationic barrier that repels hydronium ions from micro‑cathodic sites. Weight‑loss coupons tested per NACE TM0169‑2020 in stirred 15% HCl at 85°C for 6 h yield an inhibition efficiency of 94–97% at the upper concentration limit, dropping to 78% when the inhibitor concentration dips below 0.05 wt% due to desorption kinetics accelerating above 70°C.Production‑scale implementation in a push‑pickling tunnel with 5‑zone cascading acid circulation imposes strict compatibility with lignosulfonate‑based or non‑ionic ethoxylated alcohol wetting agents already present in the bath at 0.5–1.5 g/L. A documented incompatibility exists with amine‑based inhibitors: the combination of 2‑MT and fatty‑amine ethoxylates triggers precipitation of an oily‑waxy film on acid‑recovery‑unit (ARU) roasters, leading to burner nozzle coking after 48 h of continuous operation. The downstream process therefore prescribes a pre‑diluted inhibitor injection skid programmed to dose 2‑MT into the turbulent‑flow section of the return acid loop after a 10 µm cartridge filter, with injection synchronized to the bath‑level controller to avoid accumulation of free‑acid‑insoluble degradation products.Compliance with the General Steel Sheet Surface Condition requirements of EN 10025‑1 and the pickled‑strip tolerances of ISO 5952 is verified by residual chloride ion spot‑testing with potassium ferricyanide‑nitric acid solution. Terminal substrate formats include cold‑reduced uncoated coils destined for automotive exposed body panels via hot‑dip galvanizing, and Si‑alloyed grades for electrical steel laminations where residual inhibitor‑derived sulfur must be kept below 0.003 wt% to prevent magnetic aging.The application of 2‑mercaptothiazole in oxidative permanent hair colorants exploits the nucleophilicity of the thiol toward electrophilic quinonediimine intermediates generated in situ from primary dye precursors. Under alkaline (pH 9.8–10.5) conditions created by ammonium hydroxide or monoethanolamine buffers, the thiolate anion of 2‑MT rapidly adds to the para‑position of p‑phenylenediamine’s oxidized form, forming a stable indo‑aniline–type chromophore that shifts the final shade away from the pure primary‑precursor color space. The formulation incorporate 2‑MT as a coupler‑component base paste containing 0.4–1.2 wt% of the active in a fatty‑alcohol + nonoxynol‑ethoxylate cream base, mixed 1:1 with a 6–9% hydrogen peroxide developer immediately before application to keratin fiber.Product registrations referencing this coupler are contingent upon safety assessments aligned with EU Cosmetics Regulation (EC) No 1223/2009, Annex III, and with the Scientific Committee on Consumer Safety (SCCS) opinion framework. A negative sensitization result in the local lymph node assay (LLNA) at concentrations up to 2.0% is routinely required, and the residual free‑thiol content must be quantified by HPLC with post‑column derivatization to maintain batch conformity. During production, the emulsion concentrate is cold‑processed at 35–40°C under nitrogen blanket to prevent premature oxidation, then filled into aluminum‑barrier laminate tubes that exclude oxygen ingress. The terminal cosmetic articles are permanent hair color creams, tinting shampoos for grey coverage, and professional salon‑tray mixing systems packaged with developer bottles and applicator brushes.

Surface Passivation Chemistry for Copper Alloy Interconnects

Aqueous immersion processes deploying 2‑MT at 0.8–2.5 g/L in deionized water adjusted to pH 4.5–5.8 with acetic acid‑sodium acetate buffer create a nanometer‑scale organometallic film on brass, phosphor bronze, and beryllium‑copper surfaces that withstands mixed‑fluxing‑gas corrosion per IEC 60068‑2‑60 Method 4 for 15 days without visible tarnish. The film thickness, measured by spectroscopic ellipsometry on Cu‑30Zn coupons, stabilizes at 18–32 nm after 90 s of immersion at 55°C; the treatment replaces benzotriazole‑type inhibitors in applications where residual nitrogen‑containing films interfere with subsequent Au‑Ni spot plating or wire‑bonding pull‑strength tested at 5 gf minimum on 25 µm gold wire. Process control charts from connector stamping lines show that the 2‑MT passivation bath can operate 5–7 shifts before drag‑out‑corrected replenishment is required, provided the dissolved copper concentration remains below 120 mg/L to avoid precipitation of a copper‑thiolate sludge.The downstream manufacturing sequence integrates the passivation dip after a citric‑acid‑based degreasing and sulfuric‑acid‑peroxide microetch stage, and before a forced hot‑air drying tunnel set to 90–110°C. Terminal connector bodies, lead‑frames for quad‑flat‑no‑leads (QFN) packages, and EMI shielding finger‑strips are the primary articles of commerce. Satisfying the solderability shelf‑life requirement of J‑STD‑002 Category 3 after 12 months of warehouse storage in humid (30°C / 85% RH) conditions is a mandatory gate‑release criterion that the 2‑MT film meets provided the post‑treatment rinse conductivity remains below 15 µS/cm.Catalytic synthesis of certain 7‑amino‑cephalosporanic acid (7‑ACA) derivatives utilizes 2‑mercaptothiazole as the sulfur‑bearing heterocyclic precursor for the aminothiazole‑acetyl side‑chain introduction. The optimized manufacturing process entails an alkylation step in which 2‑MT is reacted with ethyl bromoacetate in the presence of anhydrous potassium carbonate in dimethylformamide at 0–5°C for 4 h, forming ethyl 2‑(thiazol‑2‑ylthio)acetate, which is subsequently coupled to the cephem nucleus after saponification and activation via a mixed anhydride. The intermediate stream must be filtered through a 0.45 µm in‑line capsule and crystallized from isopropanol‑water (70:30 v/v) to meet residual heavy‑metal limits below 10 ppm as specified in ICH Q3D for parenteral drug substances. The active pharmaceutical ingredient (API) derived from this route typically registers under a Type II Drug Master File, with the process validation batches manufactured in ISO 8 cleanrooms following ICH Q7 Good Manufacturing Practice guidance. Finished dosage forms are lyophilized powder for injection containing 0.5–1.0 g of cephalosporin, administered as an intravenous infusion.

Regulatory and standard cross‑reference by industrial scenario
Application segment	Primary compliance framework	Key test method or clause
Acid copper plating	IPC‑6012D Class 3	IST thermal stress per IPC‑TM‑650 2.6.8
HCl strip‑line inhibition	NACE TM0169‑2020	Mass loss coupon, 15% HCl, 85°C, 6 h
Permanent hair dye	EC 1223/2009, Annex III	LLNA skin sensitisation (OECD TG 442B)
Copper alloy passivation	IEC 60068‑2‑60	MFG corrosion, Method 4
API side‑chain intermediate	ICH Q7, Q3D	Residual Pd and As below 10 ppm

The preparation of cationic azo‑methine dyes for wet‑spun polyacrylonitrile tow relies on the condensation of 2‑mercaptothiazole with reactive quaternized heterocyclic aldehydes under reflux in ethanol‑acetic acid mixtures for 6 h. A 1.0:1.02 molar ratio of aldehyde to 2‑MT is maintained to prevent residual thiol that would otherwise redox‑decolourise the final dye liquor. Upon solvent‑stripping and drowning into 5°C water, the crude dye cake is reslurried in n‑butanol and drum‑dried to a moisture below 2.0 wt%. The synthetic route is audited against ZDHC MRSL v3.1 conformance for textile chemicals, with a required limit of detection below the 5 mg/kg reporting threshold for aniline‑cleavable aryl amines. The isolated dye powder is standardised with sodium sulfate diluent to a strength of 200–400% relative to a type‑standard batch, then packed into water‑soluble PVA sachets for pre‑metered dyebath addition. The principal end‑use is the production of solid‑shade acrylic sweater yarns, upholstery velours, and carbon‑fibre precursor oxidization‑resistant marker threads where the specific orange‑red to violet‑red hue space achievable with 2‑MT‑derived methine chromophores cannot be matched by conventional anthraquinone colorants without exceeding the 0.3% “phosphate‑free” wet‑fastness drift limit.

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Certification & Compliance

2-Mercaptothiazole 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

A heterocyclic thiol supplied under CAS 96‑53‑7 (2‑thiazoline‑2‑thione tautomer) as a white to pale yellow crystalline solid, 2‑Mercaptothiazole exhibits a melting range of 47–49 °C and a boiling point of 117 °C at 2.0 kPa. Commercial technical‑grade material typically carries an assay of ≥98.0% (GC, area normalization) with a water content not exceeding 0.5% w/w determined by coulometric Karl Fischer titration in accordance with ISO 760. Bulk density ranges from 0.55 g/cm³ to 0.70 g/cm³ and the flash point exceeds 100 °C (closed cup). The molecule serves simultaneously as a mercapto‑type vulcanization modifier, a corrosion inhibitor for copper‑based alloys, and a synthetic intermediate. When 2‑Mercaptothiazole Replaces MBT in Sulphur Vulcanization In accelerated sulphur cure systems for natural rubber, styrene‑butadiene rubber, and ethylene‑propylene‑diene terpolymer compounds, 2‑Mercaptothiazole functions as a secondary accelerator that shifts the onset of crosslinking to longer processing times without sacrificing the rate of cure once the reaction is triggered. Comparative moving‑die rheometer data (ASTM D5289, 160 °C, 0.5° arc) for a model tread compound based on SMR‑20 (100 phr) and N‑330 carbon black (50 phr) are presented in Table 1. Substitution of 1.0 phr 2‑Mercaptobenzothiazole (MBT) with an equal molar mass of 2‑Mercaptothiazole (0.69 phr) increases the scorch safety margin t_s2 by 2.1 min while the torque maximum M_H remains within 5% of the reference. A binary system composed of 0.5 phr 2‑Mercaptothiazole and 0.7 phr dibenzothiazyl disulphide (MBTS) delivers a t₉₀ of 8.4 min with a Mooney scorch time (MS‑t₅, 127 °C, ASTM D1646) of 28.1 min—approximately 7 min longer than an equivalent MBT/MBTS pair. The delay arises from the absence of the fused benzene ring, which lowers the acidity of the thiol proton (pK_a ≈ 7.6 in water at 25 °C versus 6.9 for MBT) and moderates the rate of active sulphurating agent formation. Industrial‑scale mixing on a 1.6 L intermeshing internal mixer (Banbury type, rotor speed capped at 40 rpm) requires that the dump temperature never exceed 115 °C when 2‑Mercaptothiazole is added in the second stage; exceeding this threshold by as little as 4 °C causes a measurable fall in compound Mooney viscosity from the accumulation of scorched binder domains. Where a twin‑screw compounding extruder (co‑rotating, L/D 44, barrel zones set to 90–110 °C) is used for masterbatch preparation, the mercaptothiazole is metered downstream of the carbon‑black feed to keep residence time below 25 s.

**Table 1** — Cure characteristics at **160 °C** for an NR‑based tread formulation (**ASTM D5289**, MDR 2000 rheometer).
Accelerator System (phr)	t₁₀ (min)	t₉₀ (min)	ΔTorque (dNm)
1.0 MBT + 1.0 MBTS	2.8	9.3	14.2
1.0 2‑Mercaptothiazole + 1.0 MBTS	4.9	10.1	13.8
0.5 2‑Mercaptothiazole + 0.7 MBTS	3.4	8.4	14.5

Another operational advantage over MBT is reduced surface bloom after extended storage. Visual assessment of compression‑moulded sheets conditioned at 25 °C and 50% relative humidity for 168 h (evaluation protocol adapted from ISO 11345) shows no crystalline efflorescence for the 2‑Mercaptothiazole‑cured specimens, whereas the MBT‑containing controls develop a dull film within 72 h. The lower molecular weight (115.18 g/mol) and higher polarity of the simple thiazole ring increase compatibility with the hydrocarbon matrix and reduce the driving force for migration. Corrosion Inhibition of Copper Alloys in Aqueous Systems: A Chemisorption Model 2‑Mercaptothiazole adsorbs onto copper and brass surfaces through the sulphur atom and the ring nitrogen, forming a polymerised Cu(I)‑thiolate film that blocks both anodic dissolution and cathodic oxygen reduction. Weight‑loss coupon tests performed according to ASTM G1 (24 h immersion in aerated 3% NaCl at 30 °C, copper UNS C11000, surface finish 600 grit) yield a corrosion rate of 0.026 mm/year in the presence of 10 mg/L 2‑Mercaptothiazole, compared with 0.41 mm/year for the uninhibited blank. Electrochemical linear polarisation resistance measurements (ASTM G59, scan rate 0.167 mV/s) give a polarisation resistance R_p of 18.4 kΩ·cm² at 15 mg/L inhibitor, a 14‑fold increase over the 1.3 kΩ·cm² recorded in blank electrolyte. Table 2 summarises the concentration‑dependent inhibition efficiency calculated from Tafel extrapolation of potentiodynamic curves (ASTM G5, potential range ±250 mV vs. OCP).

**Table 2** — Inhibition efficiency for copper C11000 in 3% NaCl at **25 °C** (**ASTM G5**).
Concentration (mg/L)	E_corr (mV vs. SCE)	i_corr (µA/cm²)	Inhibition Efficiency (%)
blank	−228	10.2	—
2	−217	4.1	59.8
5	−204	1.9	81.4
10	−192	0.82	92.0
25	−179	0.34	96.7

Film persistence is maintained in cooling‑water matrices adjusted to pH 8.0–9.2 with sodium carbonate/bicarbonate buffers, satisfying the requirements of recirculating systems operated under ASTM D1384 test conditions. The inhibitor does not induce pitting on copper‑nickel 90/10 alloy when the chloride concentration stays below 500 mg/L and the free‑chlorine residual is held under 0.5 mg/L. A recurring failure in field installations has been traced to inadvertent combination with amine‑based filming inhibitors; the amines displace the thiolate layer and the mixed film shows an R_p drop of more than 80% within 8 h. Therefore, 2‑Mercaptothiazole should not be co‑dosed with cyclohexylamine or morpholine corrosion inhibitors. What Distinguishes the Simple Thiazole Accelerator from Benzo‑Fused Thiazoles in Coagent Activity? Beyond vulcanisation, the reactivity profile of 2‑Mercaptothiazole differs from its benzothiazole analogues in several polymer‑modification pathways. In the free‑radical emulsion polymerisation of chloroprene, 2‑Mercaptothiazole acts as a chain‑transfer agent that regulates molecular weight without generating the strong mercaptan odour associated with dodecyl mercaptan. The chain‑transfer constant C_s measured at 50 °C in a 2‑chloro‑1,3‑butadiene system is approximately 0.35, substantially lower than the 1.0‑1.5 range of primary alkyl thiols, which permits finer control of Mooney viscosity in the dried crumb. Trials on a 30‑L pilot reactor with a 0.15 phr charge of 2‑Mercaptothiazole consistently yield a chloroprene rubber with ML 1+4 at 100 °C between 45 and 52 MU, meeting the specification of a medium‑viscosity mercaptan‑modified grade. As a copper‑corrosion inhibitor for industrial cleaners formulated with phosphoric acid, 2‑Mercaptothiazole outperforms 2‑Mercaptobenzimidazole at pH values below 3.0. While the benzimidazole‑derived film degrades through protonation of the imidazole nitrogen, the thiazole ring retains its adsorptive integrity down to pH 1.5, documented by electrochemical impedance spectra that show a stable charge‑transfer resistance above 10 kΩ·cm² for 48 h in 5% H₃PO₄ at 60 °C. This characteristic supports its selection for acid descaling operations in petrochemical heat‑exchanger networks. With a melting point 20 °C lower than MBT and a vapour pressure of 0.12 Pa at 25 °C, 2‑Mercaptothiazole begins to sublime noticeably above 60 °C. In open‑mill compounding, this necessitates the use of a stock blender or an enclosed mixer when mill‑roll temperatures exceed 70 °C to avoid weight‑loss discrepancies of 2–4% across the batch. Conversely, its higher water solubility (1.2 g/100 mL at 20 °C) facilitates aqueous alkaline extraction in recycling processes, allowing quantitation by HPLC according to ISO 21461 methodology without the need for prolonged Soxhlet digestion. Stability and Regulatory Boundaries Under the European Union REACH regulation, 2‑Mercaptothiazole is registered with EC number 202‑504‑3 and is not included in the Annex XIV Authorisation list or the Annex XVII restriction entries at the date of publication. The substance is enumerated on the US EPA Toxic Substances Control Act inventory and is permitted as a component of rubber articles intended for repeated food contact under FDA 21 CFR 177.2600, provided that total extractives do not exceed the simulant‑specific limits. Aqueous ecotoxicity data indicate a 96‑h LC₅₀ of 7.2 mg/L for rainbow trout, placing the product in acute category 2 (H401). Transport classification follows UN 3077 (Environmentally hazardous substance, solid, n.o.s.) in packing group III. Storage must exclude contact with primary amines, strong oxidisers, and open ignition sources; the recommended shelf life in original sealed packaging at ≤25 °C and ≤60% relative humidity is 24 months. Extended exposure to ambient moisture raises the free‑sulphur content and leads to a shift in melting point of up to 2.5 °C, detectable by differential scanning calorimetry at a heating rate of 10 °C/min.