Isobutyl alcohol, registered under CAS number 78-83-1, is a branched-chain primary alcohol with the molecular formula C4H10O. Its systematic IUPAC name is 2-methyl-1-propanol, and in commercial paperwork the material usually appears as isobutanol or under the abbreviation IBA. Four different butanols share the same molecular formula, so formulators and buyers confirm identity through the CAS registry number rather than the trade name.
What Is Another Name for Isobutyl Alcohol?
The most widely used alternative name is isobutanol. Chemists also refer to the same substance as 2-methyl-1-propanol, 2-methylpropan-1-ol, isopropyl carbinol, and IBA. Technical data sheets, safety data sheets, and customs declarations may use any of these terms, so it helps to recognise them as one and the same compound.
Isobutanol - the dominant commercial synonym
2-methyl-1-propanol - positional naming used in older literature
2-methylpropan-1-ol - preferred IUPAC name
Isobutyl alcohol / iso-butanol - form used in solvent specifications
IBA - abbreviation found on tank labels and certificates of analysis
Similar-sounding names such as n-butanol, sec-butanol, and tert-butanol describe different isomers with different physical behaviour, so they can never be substituted for one another in a formulation.
Identity and the Four Butanol Isomers
All four butanols share the formula C4H10O, but their carbon skeletons differ, and that changes boiling point, density, and solvent strength. Separating them at the procurement stage prevents blending errors later.
| Compound | CAS number | Structure | Boiling point |
|---|---|---|---|
| 1-Butanol | 71-36-3 | Straight chain, primary | about 118 °C |
| 2-Butanol | 78-92-2 | Straight chain, secondary | about 100 °C |
| Isobutyl alcohol | 78-83-1 | Branched, primary | about 108 °C |
| tert-Butyl alcohol | 75-65-0 | Branched, tertiary | about 82 °C |
Key Physical Properties
| Property | Typical value |
|---|---|
| Molecular formula | C4H10O |
| Molar mass | 74.12 g/mol |
| Appearance | Colourless liquid with a mild, slightly sweet odour |
| Boiling point | about 108 °C at atmospheric pressure |
| Flash point | about 28 °C (closed cup) |
| Density | about 0.80 g/cm³ at 20 °C |
| Water solubility | about 8.5 g per 100 mL at 20 °C |
| Miscibility | Fully miscible with most common organic solvents |
A closed-cup flash point near 28 °C places the material in the flammable liquid range of the GHS classification system, and shipments normally carry UN 1212 in packaging group III. The moderate evaporation rate gives coatings and inks a workable open time without the slow drying associated with heavier alcohols.
Industrial Solvent and Intermediate Applications
Surface coatings absorb the largest share of global isobutyl alcohol demand. In automotive and general industrial paints it acts as a flow and levelling promoter, reducing orange peel and helping pigment dispersions wet out evenly. Printing inks, adhesives, and cleaning formulations use the same properties, particularly where a solvent with partial water tolerance is required.
Isobutyl acetate - the main derivative, a low-odour ester solvent used in nitrocellulose lacquers and printing inks
Plasticizers - esterification products that soften PVC and cellulose-based films
Amino resins - crosslinking and etherification reactions in baking enamels
Process solvent - crystallisation and reaction medium for pharmaceuticals, agrochemicals, and flavour and fragrance ingredients
Extraction and cleaning - degreasing agents and specialty cleaning blends
Its moderate polarity and low water uptake make it suitable for water-sensitive intermediates, where a fully water-miscible alcohol would hydrolyse the batch or introduce moisture into the finished product.
Storage, Handling and Quality Control
Store isobutyl alcohol in tightly closed containers in a cool, well-ventilated area away from ignition sources, strong oxidising agents, and direct sunlight. Bond and ground drums, totes, and transfer lines to prevent static discharge, and keep spill containment in place around storage tanks. Personnel should wear chemical-resistant gloves, splash goggles, and appropriate respiratory protection where local exhaust ventilation cannot hold vapour concentrations low.
For incoming inspection, buyers typically confirm assay by gas chromatography, water content by Karl Fischer titration, colour on the platinum-cobalt scale, and distillation range. Non-volatile residue and acidity checks round out a standard specification. Every shipment should arrive with a certificate of analysis and an up-to-date safety data sheet stating the CAS number 78-83-1 and the synonyms in use, which avoids confusion when material is repacked or re-labelled downstream.
Frequently Asked Questions
Q: What is another name for isobutyl alcohol?
It is most often called isobutanol. Other accepted names are 2-methyl-1-propanol, 2-methylpropan-1-ol, and the abbreviation IBA.
Q: What is the CAS number of isobutyl alcohol?
The CAS registry number is 78-83-1, and the molecular formula is C4H10O.
Q: Is isobutyl alcohol the same as n-butanol?
No. Both have the formula C4H10O, but they are different isomers with different structures, boiling points, and solvent behaviour.
Q: What is isobutyl alcohol used for?
It is a solvent in coatings, inks, adhesives, and cleaning products, and a raw material for isobutyl acetate, plasticizers, and amino resins.
Q: Is isobutanol flammable?
Yes. With a closed-cup flash point near 28 °C it is classified as a flammable liquid and must be stored away from ignition sources with proper grounding.
Q: Does isobutyl alcohol dissolve in water?
Only partly. Solubility is roughly 8.5 g per 100 mL at 20 °C, while it mixes freely with most organic solvents.