Tert-butyl alcohol behaves unlike most alcohols, and formulators often ask whether it can really serve as a solvent. It can, and its structure gives it a combination of water miscibility and organic compatibility that few other liquids match. This guide explains the properties behind that behaviour, the applications that depend on it, the storage and handling requirements for CAS 75-65-0, and the quality points to specify when ordering.
What Is Tert-Butyl Alcohol?
Tert-butyl alcohol, abbreviated TBA, is the simplest tertiary alcohol, with the molecular formula C4H10O and CAS number 75-65-0. It is also known as tert-butanol or 2-methyl-2-propanol. Three methyl groups are attached to the same central carbon atom that carries the hydroxyl group, and that compact, branched shape controls both its physical behaviour and its solvent power. Pure TBA is a colourless solid with a camphor-like odour at room temperature, melting at about 25.7 °C, which means the commercial product is supplied and stored as a liquid, often kept above its melting point or handled as a water-containing mixture to depress the freezing point.
| CAS number | 75-65-0 |
| Molecular formula | C4H10O |
| Molar mass | 74.12 g/mol |
| Appearance | Colourless liquid or crystalline solid near room temperature |
| Melting point | about 25.7 °C |
| Boiling point | 82.4 °C |
| Flash point | about 11 °C closed cup |
| Density at 25 °C | 0.775 g/cm3 |
| Water solubility | Fully miscible in all proportions |
| UN number | 1120, flammable liquid |
Is Tert-Butyl Alcohol a Solvent?
Yes. TBA is a genuine, versatile solvent rather than a marginal one. Its defining feature is complete miscibility with water and with most organic solvents, including other alcohols, ethers, ketones, esters, and aromatic hydrocarbons. That dual solubility makes it an effective coupling agent: a single formulation can contain both an aqueous phase and an organic phase, with TBA bridging them so that the system remains homogeneous instead of separating.
The branched tertiary structure also makes the molecule resistant to oxidation and esterification under normal storage conditions, so formulations built around it remain stable over time. That combination of compatibility and stability is what separates TBA from straight-chain alcohols such as ethanol or propanol, which are less effective at coupling water-rich and oil-rich phases.
What Makes TBA Effective in Formulations?
No phase separation: High miscibility with water and organics removes the cloud point and separation problems typical of mixed solvent systems.
Moderate evaporation rate: Coatings and inks have time to level and flow after application before the film dries, reducing brush and spray marks.
Chemical stability: Resistance to oxidation and esterification keeps the solvent and the formulation consistent through storage.
Solvency for polar and nonpolar resins: Dissolves cellulose derivatives, many synthetic resins, and dyes, and can therefore replace more than one solvent in a blend.
Low viscosity contribution: Unlike high-viscosity coupling solvents, TBA does not push formulation viscosity up, so solids content can be kept high.
Main Industrial Uses of TBA
In pharmaceutical manufacturing, TBA is used as a reaction medium and as a crystallisation solvent because it dissolves a wide range of intermediates and active ingredients and gives well-formed crystals with controlled morphology. The resin, polymer, and coatings industries use it to dissolve cellulose derivatives, synthetic resins, and dyes, and to improve flow and wetting in coatings and inks. Cleaning formulations incorporate TBA as a coupling agent that allows water-based cleaners to carry oily soils into solution, and paint strippers use it to penetrate and swell cured films so that the finish lifts cleanly from the substrate.
TBA is also an important chemical intermediate. It is dehydrated to isobutylene, which is the feedstock for methyl tert-butyl ether and for butyl rubber, and it is used to produce methacrylic acid and esters. Smaller volumes are used as a denaturant, as a laboratory reagent, and as an additive in fuel and lubricant formulations. Because the molecule is miscible with water, its use as an intermediate is normally carried out in closed systems to keep water out of the reaction.
Safety, Storage and Handling
TBA is classified as a flammable liquid. Its flash point near 11 °C means it can release ignitable vapour at ambient temperature, and the vapour is heavier than air, so it can travel along the floor towards a remote ignition source. It is also irritating to the eyes and respiratory tract, and repeated skin contact causes dryness and irritation. Storage areas must be cool, well ventilated, and free of ignition sources, with containers kept closed and bonded to earth during transfer.
| GHS hazard classes | Flammable liquid category 2, eye irritation category 2, specific target organ toxicity single exposure category 3 for respiratory irritation |
| Flash point | about 11 °C closed cup |
| Explosive limits in air | approximately 2.3 to 8.0 percent by volume |
| Personal protection | Chemical-resistant gloves, splash goggles, and antistatic clothing for transfer operations |
| Spill response | Contain with inert absorbent, remove ignition sources, ventilate, and dispose as hazardous waste |
Two handling points deserve emphasis because they are specific to this product. First, because TBA is fully water-miscible, spills cannot be contained on water and should never be flushed to drains; absorb and remove the material, and collect contaminated water for treatment. Second, because the melting point is close to ordinary room temperature, liquid lines and tanks in cold weather require trace heating or a water blend to prevent the product from solidifying and blocking the system.
Quality Points When Ordering TBA
Assay and water content: Specify the required minimum purity and a water limit, and note whether a dry or a blended grade is needed for the process.
Colour and odour: Confirm colour limits and odour specification, which matter in pharmaceutical and coating applications.
Impurity profile: Define limits for isobutylene-related and other organic impurities, and request chromatographic data per batch.
Packaging and logistics: Drums, ISO tanks, or road tankers in correct UN 1120 packing, with heat management for cold-season transport.
Documentation: Certificate of analysis, safety data sheet, and dangerous goods documentation for every consignment.
Frequently Asked Questions
Q: Is tert-butyl alcohol a solvent?
Yes. TBA is a versatile solvent that is fully miscible with water and with most organic solvents, which makes it valuable as a coupling agent in coatings, cleaners, and paint strippers.
Q: Is TBA the same as rubbing alcohol?
No. TBA is a tertiary alcohol with CAS number 75-65-0, while rubbing alcohol is normally isopropyl alcohol, a different compound with different properties.
Q: Can TBA dissolve both water-based and oil-based materials?
It can. TBA is miscible with water and with most organic solvents, so it acts as a bridge between aqueous and organic phases in a single formulation.
Q: What is the flash point of tert-butyl alcohol?
The flash point is approximately 11 °C closed cup, which classifies TBA as a flammable liquid and requires storage away from ignition sources.
Q: Why is TBA used in paint strippers?
TBA penetrates cured coating films and helps the other active ingredients swell and lift the finish from the substrate, which speeds removal.
Q: Is TBA used in pharmaceutical manufacturing?
Yes. It serves as a reaction medium and as a crystallisation solvent for pharmaceutical intermediates and active ingredients.
Q: How should TBA containers be stored?
Store them tightly sealed and grounded in a cool, well-ventilated area away from heat, sparks, and flames, and keep the product above its melting point in cold conditions.