Butanol

1-Butanol skeletal

2-butanol Line-Structure

Isobutanol

Tert-butyl-alcohol-2D-skeletal

Propen Hydroformylierung zu Butanol

Butanol is an alcohol with a 4-carbon structure and the molecular formula C4H10O. It is one of the group of "fusel alcohols" (or fusel oils), which are by-products of alcohol fermentation. Butanol is used in a variety of applications due to its solvent properties and is considered as a potential biofuel. There are four isomers of butanol: 1-butanol, 2-butanol, isobutanol, and tert-butanol, each differing in the position of the hydroxyl group (-OH) or the structure of the carbon chain.

Properties and Production

Butanol possesses a higher boiling point and a much less polar profile compared to lower alcohols like methanol and ethanol, making it more effective as a solvent for certain chemical reactions and industrial processes. Its production can be achieved through both biological and chemical means. The traditional method involves the fermentation of sugars by bacteria, which predominantly produces 1-butanol along with other types of alcohol. This biological process is known as ABE fermentation (Acetone-Butanol-Ethanol fermentation) and was once a major industrial route to butanol. Chemical synthesis of butanol, on the other hand, typically involves the hydroformylation of propene to form butyraldehyde, which is then hydrogenated to butanol.

Uses

Butanol is widely used in the manufacturing of plasticizers, brake fluids, extractants, and solvents for paints, coatings, and inks. Its low volatility and high solvency power make it valuable in these applications. Additionally, butanol is being researched as a potential biofuel. Due to its higher energy content compared to ethanol and its compatibility with existing gasoline engines and infrastructure, butanol presents an attractive alternative to other biofuels. However, challenges such as its production cost and competition with food supply for feedstock materials limit its current use as a fuel.

Health and Safety

Exposure to butanol can cause irritation to the eyes, nose, and throat, and prolonged exposure may result in central nervous system depression. It is less toxic than methanol and ethanol but requires careful handling to avoid health risks. Safety measures include using appropriate personal protective equipment (PPE) and ensuring good ventilation in areas where butanol is used or stored.

Environmental Impact

The environmental impact of butanol largely depends on its production method. Biobutanol, produced through fermentation, is considered more sustainable and environmentally friendly compared to butanol produced from fossil fuels. It can contribute to reduced greenhouse gas emissions when used as a biofuel, provided that the feedstock is sourced sustainably. However, the cultivation of crops for biofuel production can lead to land use changes and competition with food production, which are important considerations for the environmental assessment of biofuels like butanol.