n-Butanol

Colourless, mobile solvent of medium volatility. Feedstock for syntheses.

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n-Butanol is a clear, mobile, neutral liquid with a characteristic odour. It is miscible with all common solvents, e. g. alcohols, ketones, aldehydes, ethers, glycols, and aromatic and aliphatic hydrocarbons. Its miscibility with water, however, is restricted. n-Butanol is used as a solvent and as a feedstock for syntheses. A survey of the various applications is presented below, but does not claim to be complete. About half of the production of pure n-Butanol and its derivates (primarily esters) is used as solvents in the coatings industry. The advantage here is that n-butanol prevents blushing of certain coatings when they dry under humid conditions. Thus it is widely used as a diluent in cellulose nitrate lacquers and serves to improve their flow, gloss and resistance to blushing (blushing only occurs in the presence of volatile solvents and at high humidities). For this purpose addition rates of 5-10 % are generally sufficient.

n-Butanol is an eminently suitable solvent for acid-curable lacquers and baking finishes derived from urea (Plastopal^®), melamine (Luwipal^®), or phenolic resins. In these applications, it is mostly used together with glycol ethers or ethanol. When added even in small proportions to alkyd resin paints, n-Butanol reduces their viscosity and thus improves their brushability and flow. Low concentrations of n-Butanol prevent cobwebbing in laquers formulated from sprit-soluble resins. Some butyl esters of dicarboxylic acids, phthalic anhydride and acrylic acid are established plasticizers for plastics, rubber mixes and dispersions. The most important are dibutyl phthalate (DBP), benzylbutyl phthalate (BBP) and butyl acrylate. Dibutyl sebacate (DBS) and dibutyl azelate (DBZ) are of lesser importance. The corresponding adipate is too volatile as a plasticizer and therefore of no practical significance in these applications.

Other applications for n-Butanol are as follows:

• Solvent for dyes, e. g. in printing inks.
• Extractant in the production of drugs and natural substances such as antibiotics, hormones, vitamines, alkaloids and camphor.
• Additive in polishes and cleaners, e. g. floor cleaners and stain removers.
• Solubilizer in the textile industry, e. g. additive in spinning baths or carrier for colouring plastics.
• Additive in de-icing fluids.
• Additive in gasoline for spark-ignition engines (prevents carburetter icing).
• Mobile phase in paper and thin-layer chromatography.
• Humectant for cellulose nitrate.
• Feddstock for the production of glycol ethers (in reaction with ethylene or propylene oxide).
• Starting material for various butyl monocarboxylates, e. g. butyl acetate and butyl butyrate, which are widely used as solvents.
• Feedstock for the production of flotation aids, e. g. butyl xanthate. M 2084 e March 2008 Page of 4 n-BUTANOL

The butyl esters of various dicarboxylic acids, e. g. sebacic, adipic and stearic acids, are used as synthetic and semisynthetic lubricants and hydraulic fluids.