Tetrabutylammonium hydrogen sulfate, commonly abbreviated as TBAHS (CAS 32503-27-8), is one of the most frequently requested quaternary ammonium salts in fine chemical procurement. Buyers sourcing this reagent are usually supporting one of two workflows: phase transfer catalysis in organic synthesis, or ion-pair chromatography in analytical laboratories. Because the same compound serves both markets at very different quality expectations and volumes, purchasing TBAHS well requires understanding what the material is, how grade requirements differ by application, and which specification points actually matter on a certificate of analysis. This guide walks through those questions from a buyer’s perspective.
What TBAHS Is and Why the Counterion Matters
TBAHS is a quaternary ammonium salt built on the tetrabutylammonium cation, the same lipophilic cation found in tetrabutylammonium bromide (TBAB). The difference is the anion: instead of bromide, TBAHS carries a hydrogen sulfate (bisulfate) counterion. That single change has practical consequences.
First, the hydrogen sulfate anion is weakly acidic, so aqueous solutions of TBAHS are acidic rather than neutral. In two-phase reactions run under strongly basic conditions, the bisulfate is simply neutralized and the tetrabutylammonium cation does the catalytic work, so TBAHS can often be considered interchangeable with TBAB in hydroxide-mediated chemistry. Second, the sulfate-based anion is far less nucleophilic than bromide. In reactions where bromide could compete with the intended nucleophile or generate unwanted alkyl bromide side products, TBAHS may be evaluated as a cleaner alternative. Third, the absence of halide makes TBAHS attractive in processes where halide contamination of the product or of downstream waste streams is a concern.
Physically, TBAHS is a white crystalline solid with good water solubility. It is typically offered at 98 percent minimum assay for synthesis use, with tighter, low-UV-absorbance grades positioned for chromatography.
Main Applications Buyers Are Sourcing For
In organic synthesis, TBAHS is commonly explored as a phase transfer catalyst for alkylations, etherifications (including Williamson-type ether synthesis), N-alkylations, esterifications and certain oxidation and condensation reactions carried out in two-phase liquid-liquid or solid-liquid systems. The tetrabutylammonium cation shuttles the reactive anion from the aqueous or solid phase into the organic phase, which can allow milder conditions, cheaper inorganic bases and simpler solvent choices. Where a process chemist wants phase transfer activity without introducing halide, TBAHS is often the first candidate considered. A broader overview of related catalysts is available on our phase transfer catalysts category page.
In analytical chemistry, TBAHS is a standard ion-pairing reagent for reversed-phase HPLC. Added to the mobile phase, the tetrabutylammonium cation pairs with anionic analytes and improves their retention on hydrophobic columns. For this use, low UV absorbance and consistent trace impurity profiles matter far more than they do in preparative synthesis, which is why chromatography-grade TBAHS commands a premium and should not be substituted casually with technical material.
TBAHS also appears in electrochemistry as a supporting electrolyte component and in various extraction and separation protocols where an acidic, halide-free quaternary ammonium salt is useful.
Specification Points That Matter on the COA
When comparing offers, buyers can focus on a short list of parameters:
Assay. 98 percent minimum by titration is the common baseline for synthesis grade. Confirm the analytical method stated, since argentometric methods used for halide quats do not apply here.
Melting range. A sharp melting range close to the literature value is a quick indicator of purity and dryness. Broad or depressed melting ranges can suggest residual solvent or moisture.
Water content. TBAHS is hygroscopic enough that storage and packaging matter. Karl Fischer moisture data should be requested if your process is water-sensitive.
Residual solvents and related substances. For chromatography or electronic applications, ask about residual tributylamine and other synthesis-related impurities, since amine residues can affect both UV background and reaction selectivity.
Appearance and solubility check. A clear, colorless aqueous solution at working concentration is a reasonable incoming inspection test; color bodies may indicate oxidation or thermal history issues.
These are the same categories of checks we recommend across our quaternary ammonium salts range, adjusted for the anion chemistry of each product.
Practical Sourcing, Packaging and Handling Notes
TBAHS is normally packed in fiber drums or cartons with double inner liners, commonly 25 kg net, with smaller packs available for laboratory demand. It should be stored sealed, cool and dry, away from strong oxidizers and strong bases. Because the solid is acidic and can be irritating to skin, eyes and the respiratory tract, standard chemical handling precautions and appropriate personal protective equipment apply; always follow the current safety data sheet supplied with each batch.
For buyers planning a switch between TBAB and TBAHS in an existing process, it is worth remembering that catalyst loading is usually quoted in mole percent, and the two salts have different molecular weights. Small-scale trials with the actual supplier lot are the reliable way to confirm equivalence, since trace impurity profiles differ between manufacturers and can influence sensitive reactions. Sample evaluation before commercial commitment is a service any serious supplier should support without friction.
Why AXIA CHEM
AXIA CHEM supplies tetrabutylammonium hydrogen sulfate (TBAHS) alongside a full line of tetrabutylammonium salts and other phase transfer catalysts, giving buyers a single point of contact for comparative sampling and consolidated shipments. We work with audited manufacturing partners, review batch documentation before release, and provide COA, SDS and packing documentation with every order. Our team responds quickly to technical questions, supports pre-shipment samples, and has practical experience shipping quaternary ammonium products to the Middle East and other export markets. If you are qualifying TBAHS for synthesis or chromatography use, contact us for current availability, specifications and a quotation.
Regulatory disclaimer: These products are supplied for research, formulation development, industrial and non-regulated applications. Final suitability for pharmaceutical, oral care, cosmetic, food-contact or biocidal applications shall be verified by the buyer according to local regulations. AXIA CHEM does not claim that any product is FDA approved, USP/EP certified, GMP grade or approved for any specific regulated end use unless otherwise confirmed in writing with supporting documentation.