Butanol, also known as 1-butanol, n-butanol, n-butyl alcohol or normal butanol is a straight-chain primary alcohol with the chemical formula CH3(CH2)3OH or C4H9OH. Its isomers include isobutanol, sec-butanol, and tert-butanol.
The term butanol is generally accepted only for the n isomer.
Butanol is commonly used for the production of butyl esters, especially butyl acetate, used in the pharmaceutical and food industry.
Butanol is a colorless viscous liquid, with a fruity like odor. It is moderately soluble in water (73 g/L at 25°C), but miscible with organic solvents such as acetone, ethanol, ethyl acetate. It boils at 117.7 °C and melts at −89.8 °C. Butanol has a density of 0.81 g/cm3.
Butanol is available as car fuel, though it may contain other isomers depending on the product.
Butanol can also be found in some wood paint drying accelerators, usually for parquet. They tend to contain 7% HCl, that will require neutralization.
There are several ways to prepare butanol. One way is to hydrolyze or decarboxylate butyl esters, such as butyl acetate. Another involves the hydrolysis of halogenated butyl compounds.
It can also be produced via the ABE process, a biochemical route involving the use of anaerobic fermentation of sugars by any of several bacteria. This process takes place in aqueous solution and typically yields 3 parts acetone, 6 parts butanol and 1 part ethanol, albeit at a low concentration.
Industrially it is produced from propylene, that is hydroformylated and then hydrogenated to give butanol.
Due to the specialized nature and difficulties of the above routes, it is typically more economical to simply purchase the alcohol.
- Butyl acetate synthesis
- Butyric acid synthesis
- 1-chlorobutane synthesis
- Recrystallizing organic compounds
- THF synthesis
Butanol is readily absorbed through the intestinal tract and lungs, and also to some extent through the skin. It is extremely irritating to the eyes; repeated contact with the skin can also cause irritation. This is believed to be a generic effect of "defatting". The acute toxicity of butanol is relatively low, with oral LD50 values of 790–4360 mg/kg (for rat), while for ethanol are 7000–15000 mg/kg). No deaths were reported at an inhaled concentration of 8000 ppm (4-hour exposure, rats).
With a flash point of 35 °C, butanol presents a moderate fire hazard. It is slightly more flammable than diesel or kerosene fuel but less flammable than many other common organic solvents.
Butanol should be stored in closed bottles, away from any open flames or oxidizers.
Butanol can be safely burned, as it produces no hazardous products.