What CAS 108-10-1 Is
108-10-1 is the CAS number of 4-methyl-2-pentanone, better known as methyl isobutyl ketone (MIBK). It is a colourless, mobile, medium-boiling ketone with a characteristic ketone odour, an EINECS number of 203-550-1, the molecular formula C6H12O and a molecular weight of 100.16. Its density at 25 °C is about 0.801 g/mL. MIBK is miscible with ethanol, ether, acetone, benzene and most other organic solvents, and its water solubility is limited but appreciable, which makes it a useful bridge between aqueous and organic phases.
Chemically MIBK is a saturated aliphatic ketone. The carbonyl group gives it strong solvency for resins, and the branched isobutyl group keeps its evaporation rate moderate, so it stays in a film long enough to level and then leaves without a heavy residual odour. That combination of medium evaporation rate and strong solvency explains why it became a workhorse solvent in coatings, adhesives, inks and extraction processes.
Identity and Physical Data
| Property | Value |
|---|---|
| Chemical name | 4-Methyl-2-pentanone |
| Common name | Methyl isobutyl ketone (MIBK) |
| CAS number | 108-10-1 |
| EINECS number | 203-550-1 |
| Molecular formula | C6H12O |
| Molecular weight | 100.16 |
| Density at 25 °C | 0.801 g/mL |
| Appearance | Clear colourless liquid |
| Solubility | Miscible with ethanol, ether, acetone, benzene; partly soluble in water |
Industrial Applications
Extraction: an excellent extractant for isolating and separating target compounds from complex mixtures in chemical production and in laboratories, and a common choice for dearomatisation and for recovering organics from aqueous streams.
Adhesives: it adjusts viscosity and drying speed, improves adhesion to wood, leather, rubber and metal, and dissolves the elastomers and resins used in contact and laminating adhesives.
Printing inks: it dissolves pigments and resins so that the ink wets the substrate well, dries quickly and prints sharply.
Electronics: it cleans circuit boards and components, removing oils, flux residues and particulate contamination without attacking the parts being cleaned.
Coatings and thinners: a medium-evaporating solvent for nitrocellulose, acrylic, epoxy and vinyl systems, used to balance flow, blush resistance and dry time.
Chemical intermediate: a starting point for downstream synthesis, including the manufacture of antioxidants and other fine chemicals.
Comparison with Related Solvent Ketones
Selecting a ketone is a question of balancing solvency, evaporation rate and flash point. The table compares MIBK with the ketones most often considered alongside it.
| Solvent | CAS number | Typical position |
|---|---|---|
| Acetone | 67-64-1 | Fastest evaporating, lowest solvency for resins |
| Methyl ethyl ketone | 78-93-3 | Fast, strong general-purpose solvent |
| Methyl isobutyl ketone | 108-10-1 | Medium evaporation, strong resin solvency |
| Diisobutyl ketone | 108-83-8 | Slow evaporating, high-boiling coupling solvent |
| Cyclohexanone | 108-94-1 | Very strong solvency, high boiling |
Health, Safety and Storage
MIBK is harmful if inhaled or swallowed, is irritating to the eyes and respiratory tract, and is flammable, so it must be handled under proper ventilation with appropriate personal protective equipment such as gloves, safety goggles and a respirator where vapour concentrations require it. Work areas should be grounded and free of ignition sources. For storage, keep the material in a cool, dry, well-ventilated warehouse away from fire and heat, out of direct sunlight, with containers kept sealed and stored separately from oxidising agents. Prolonged skin contact should be avoided, and local exhaust ventilation at the point of use is the most effective control for open processes.
Quality Control and Supply
Commercial MIBK is normally specified by purity, water content, colour, acidity and non-volatile residue, with gas chromatography used to confirm the isomer distribution and trace impurities. Moisture matters because it affects both solvent performance and downstream reaction yields, and colour is a useful indicator of storage history and of ketone ageing under exposure to air and light.
Packaging is available from small drums through intermediate bulk containers to bulk road tanker, and reductions of batch size allow trial quantities to be evaluated before full-scale production is committed. Batch documentation typically includes a certificate of analysis covering the parameters named above together with safety data.
Frequently Asked Questions
Q: What is CAS number 108-10-1?
It is the CAS registry number of 4-methyl-2-pentanone, also called methyl isobutyl ketone or MIBK, an organic solvent with the formula C6H12O.
Q: What is MIBK mainly used for?
Its largest uses are as a solvent for coatings, adhesives and printing inks, as an extractant in chemical production, and as a cleaning agent for electronic assemblies.
Q: Is MIBK miscible with water?
Only partly, but its solubility in water is appreciable and it is fully miscible with ethanol, ether, acetone and benzene, which is what makes it useful as a coupling solvent.
Q: How does MIBK differ from MEK?
MIBK has a higher boiling point, a slower evaporation rate and a higher flash point than MEK, so it gives better flow and levelling but needs more drying time or forced drying.
Q: How should MIBK be stored?
Keep containers sealed in a cool, ventilated warehouse away from fire, heat, sunlight and oxidising agents, and use local exhaust ventilation when the material is handled in the open.
Q: What purity grades are available?
Standard industrial grades are typically above 99 percent purity with controlled water and colour, and purity is confirmed by gas chromatography.