N-Methyl-1,3-Benzothiazol-2-Amine in Acidic Corrosion Inhibitors
pH-Dependent Solubility Breakpoints of N-Methyl-1,3-Benzothiazol-2-Amine in Hydrofluoric and Phosphoric Acid Blends
In formulating acidic corrosion inhibitors for oilfield acidizing and industrial cleaning, the solubility of N-methylbenzothiazol-2-amine (CAS 16954-69-1) is a critical parameter. This heterocyclic amine, also referred to as 2-Methylaminobenzothiazole, exhibits pH-dependent solubility that directly impacts its efficacy in hydrofluoric (HF) and phosphoric acid (H3PO4) blends. At ambient temperatures, the compound remains fully soluble in 15% HCl, but in HF-containing systems, solubility drops sharply below pH 2.5 due to protonation equilibrium shifts. Field experience shows that in 12% HCl/3% HF mud acid, a solubility threshold of 0.8% w/w is typical before micro-crystallization occurs. For phosphoric acid-based rust removers, the solubility window narrows further: at 25°C, maximum solubility in 20% H3PO4 is approximately 0.5% w/w, but this can be extended to 1.2% w/w by pre-dissolving in a polar co-solvent such as diethylene glycol monobutyl ether. A non-standard parameter often overlooked is the compound's tendency to form a metastable supersaturated solution when rapidly cooled from 40°C to 5°C, leading to delayed crystallization that can clog injection quills. This behavior is particularly pronounced in winterized formulations where viscosity modifiers are absent. For precise solubility data, please refer to the batch-specific COA.
Surfactant Compatibility and Micelle Disruption: Phase Separation Risks at High Inhibitor Loadings
N-Methyl-1,3-Benzothiazol-2-Amine, also known as N-(2-Benzothiazolyl)methylamine, is often combined with surfactant packages to enhance wetting and dispersion in acidizing fluids. However, at inhibitor loadings above 1.5% w/w, this compound can disrupt micellar structures of common nonionic surfactants like ethoxylated alcohols (e.g., C12-14 + 7EO). The amine's planar benzothiazole ring intercalates into the palisade layer of micelles, reducing the critical micelle concentration (CMC) and causing phase separation. In a typical 15% HCl gelled acid system, adding 2% w/w of our N-methyl-2-aminobenzo[d]thiazole to a formulation containing 0.5% w/w of a quaternary ammonium surfactant resulted in a hazy solution with visible oiling-out after 24 hours at 60°C. To mitigate this, formulators should maintain a surfactant-to-inhibitor ratio of at least 1:1.5 and consider using amphoteric surfactants like cocamidopropyl betaine, which exhibit better tolerance. For those sourcing high-purity material, our trace metal tolerance guidelines provide additional insights into impurity-driven incompatibilities.
Optimal Dosing Windows for Metal Passivation Without Viscosity or Foam Penalties
Effective corrosion inhibition with N-methyl-2-aminobenzo[d]thiazole requires balancing passivation performance against fluid rheology. In continuous injection treatments for N80 and L80 steel, the optimal dosing window lies between 0.3% and 0.8% v/v in 15% HCl. Below 0.3%, the inhibitor film is discontinuous, leading to pitting corrosion; above 0.8%, the excess amine can react with acid to form viscous polyamine salts, increasing fluid viscosity by up to 30% and causing foam stabilization. In one field trial, a 1.2% dose in a 20% HCl blend at 80°C resulted in a 40% increase in apparent viscosity, necessitating additional defoamer. The compound's performance as a drop-in replacement for propargyl alcohol-based inhibitors is well-documented, offering comparable protection at lower cost and without the handling hazards. For formulators working with benzothiazole amine intermediates, our article on tire accelerator formulations highlights the versatility of this chemical family.
Industrial-Grade Specifications, COA Parameters, and Bulk Packaging for N-Methyl-1,3-Benzothiazol-2-Amine
NINGBO INNO PHARMCHEM CO.,LTD. supplies N-Methyl-1,3-Benzothiazol-2-Amine as a white to off-white crystalline powder with a typical purity of 99.0% (HPLC). The industrial-grade product is available in 25 kg fiber drums or 500 kg supersacks, with moisture content controlled below 0.5% to prevent caking. Key COA parameters include melting point (42-46°C), loss on drying, and residue on ignition. For bulk shipments, we offer 210L drums and IBC totes upon request. The table below compares our standard grades:
| Parameter | Technical Grade | High-Purity Grade |
|---|---|---|
| Purity (HPLC) | ≥98.5% | ≥99.5% |
| Melting Point | 42-46°C | 43-45°C |
| Water Content | ≤0.5% | ≤0.2% |
| Appearance | White to pale yellow powder | White crystalline powder |
| Packaging | 25 kg drum | 25 kg drum or 500 kg supersack |
This compound, also referred to as 2-methylamino-benzthiazole, is manufactured via a controlled synthesis route ensuring minimal isomer contamination. For detailed specifications, consult our product page: N-Methyl-1,3-Benzothiazol-2-Amine technical data.
Frequently Asked Questions
How does benzotriazole prevent corrosion?
Benzotriazole forms a protective chemisorbed film on metal surfaces, particularly copper, by donating electrons from its triazole ring to the metal's d-orbitals. This film blocks corrosive species from reaching the surface. In contrast, N-Methyl-1,3-Benzothiazol-2-Amine operates via a similar mechanism but offers better thermal stability in acidic environments.
What is the effect of some aliphatic amines as corrosion inhibitors for AZ91 alloy?
Aliphatic amines like hexamethylenetetramine can inhibit corrosion of magnesium alloys by raising the local pH and forming insoluble hydroxide layers. However, they often lack the film persistency of heterocyclic amines like N-methylbenzothiazol-2-amine, which provide longer-lasting protection in dynamic acid flow conditions.
Is corrosion inhibitor a surfactant?
Not all corrosion inhibitors are surfactants, but many exhibit surface-active properties. N-Methyl-1,3-Benzothiazol-2-Amine is not a classical surfactant; it adsorbs onto metal surfaces without significantly lowering surface tension. However, it can interact with surfactant micelles, as discussed in the compatibility section.
What is imidazoline based corrosion inhibitors?
Imidazoline-based inhibitors are widely used in oilfield applications due to their excellent film-forming properties. They are typically synthesized from fatty acids and polyamines. N-Methyl-1,3-Benzothiazol-2-Amine offers a complementary mechanism, often used in blends to enhance high-temperature performance and resistance to acid gases.
Sourcing and Technical Support
For formulators seeking a reliable supply of N-Methyl-1,3-Benzothiazol-2-Amine with consistent quality and competitive pricing, NINGBO INNO PHARMCHEM CO.,LTD. offers comprehensive technical support, including solubility testing and compatibility assessments. Our logistics team ensures secure packaging in 210L drums or IBCs for global delivery. Ready to optimize your supply chain? Reach out to our logistics team today for comprehensive specifications and tonnage availability.