What Is Isobutyl Alcohol?
Isobutyl alcohol is a branched-chain primary alcohol with the molecular formula C4H10O and CAS number 78-83-1. Its systematic name is 2-methyl-1-propanol. At room temperature it is a colorless, flammable liquid with a characteristic, slightly sweet odor. It is partly miscible with water and fully miscible with most organic solvents, which makes it useful across many formulation systems.
Alternative Names and How Chemicals Are Identified
Different industries use different names for the same substance. Isobutyl alcohol is commonly known as isobutanol, 2-methyl-1-propanol, and IBA. To remove ambiguity, chemists rely on the CAS registry number, a unique numeric identifier assigned by the Chemical Abstracts Service. For isobutyl alcohol the number is 78-83-1, and buyers should always confirm this number when sourcing material, since similar-sounding names such as n-butanol refer to different compounds.
Related Isomers
Four butanol isomers share the formula C4H10O: 1-butanol, 2-butanol, isobutyl alcohol, and tert-butyl alcohol. Each has a different structure and distinct physical properties, so they are not interchangeable in a formulation.
Key Physical Properties
Isobutyl alcohol has a molar mass of 74.12 g/mol, a boiling point of about 108 °C, and a flash point of about 28 °C, placing it in the flammable liquid category. Its evaporation rate is moderate, giving coatings and inks a workable open time. Its density is about 0.80 g/cm³, slightly lower than water, and its solubility in water is limited to roughly 8.5 g per 100 mL at 20 °C.
Industrial Applications
The largest use of isobutyl alcohol is as a solvent in surface coatings, including automotive and industrial paints, where it helps control flow and leveling. It is also used in adhesives, printing inks, and cleaning formulations. In the chemical industry it is converted into isobutyl acetate, a low-odor solvent for nitrocellulose lacquers, and into plasticizers, amino resins, and other derivatives used in manufacturing.
Pharmaceutical and Pesticide Processing
Isobutanol serves as a process solvent in the manufacture of pharmaceuticals, agrochemicals, and flavor and fragrance compounds. Its moderate polarity and low water uptake make it suitable for reactions and crystallizations involving water-sensitive intermediates.
Storage and Safety Basics
Because isobutyl alcohol is flammable, storage areas should be cool, well ventilated, and away from ignition sources. Containers should be kept tightly closed and grounded during transfer. Skin and eye contact should be avoided, and vapor exposure should be kept low with local exhaust ventilation. Material safety data sheets and certificates of analysis should be requested from the supplier before use.
Frequently Asked Questions
What is another name for isobutyl alcohol? It is also called isobutanol, 2-methyl-1-propanol, and IBA.
What is the CAS number of isobutyl alcohol? The CAS number is 78-83-1.
Is isobutyl alcohol the same as n-butanol? No. They are isomers with the same molecular formula but different structures and properties.
What is isobutyl alcohol used for? It is used as a solvent in coatings, adhesives, inks, and cleaning products, and as a raw material for isobutyl acetate and other derivatives.
Does isobutyl alcohol have a smell? Yes, it has a characteristic sweet, slightly pungent odor typical of higher alcohols.
Is isobutanol flammable? Yes, with a flash point near 28 °C, it is classified as a flammable liquid and must be kept away from ignition sources.