Isopropyl Alcohol (IPA), also known as dimethylcarbinol and 2-propanol, is a clear, colorless liquid with a rubbing alcohol odor. It is an organic compound with the formula (CH3)2CH(OH) and is one of the isomers of n-propanol. It is soluble in water, alcohol, ether, benzene, chloroform and most organic solvents. The vapor of IPA can form an explosive mixture with air. The toxicity of its vapors is twice as high as ethanol.
Isopropyl alcohol can be manufactured by two processes:
1. Indirect Hydration Reaction: Propylene is first reacted with sulfuric acid to obtain isopropyl hydrogen sulfate, which produces isopropanol after hydrolysis.
CH3CH=CH2 + H2SO4 → (CH3)2CHOSO3H
(CH3)2CHOSO3H + H2O → (CH3)2CHOH + H2SO4
2. Direct Hydration: Propylene is directly hydrated in the presence of a catalyst, heat and high pressure to form isopropanol with a selectivity of 96%.
CH3CH=CH2 + H2O → (CH3)2CHOH
Compared with the indirect method, the direct hydration method avoids the issue of sulfuric acid corrosion and dilute acid concentration. Therefore, this method is dominant in industrial production.
It is used as a cleaning agent, and in the production of PCB holes for conductivity. It is also used for other electronic devices, including cleaning disc cartridge, floppy disk drives, magnetic tape, and the laser tip of the disc driver of CD or DVD player.
In the pharmaceutical and cosmetic industries, isopropanol can be used for the manufacturing of scouring liquid, hand and body lotions, antiseptics and the pharmaceutical redness agents. Isopropanol is also used to synthesize isopropyl ester, methyl isobutyl ketone, di-isopropylamine, di-isopropyl ether, isopropyl acetate, thymol and other various kinds of esters.
Isopropanol can be used as a solvent for flexographic printing, offset printing, gravure printing, and as equipment cleaner. It is also often supplied to the ink. It is also an important solvent for dilution and extraction in laboratory. In addition, isopropanol is also used as a gasoline additive and fuel pipeline deicers. In many industrial and consumer products, isopropanol is used as a low-cost solvent as well as a kind of extraction agents which can substitute the application of ethanol in many cases.
It can also be used as the reagent for determination of barium, calcium, magnesium, nickel, potassium, sodium and strontium. It can also be used as the reference material for chromatographic analysis. It is also used in paints, thinners, paint, cleaning and polishing, and surface sterilization, disinfection hospitals, food processing plants. Low-quality isopropanol can also be used in automotive fuels.