Colourless, mobile solvent of medium volatility. Feedstock for syntheses.
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:
The butyl esters of various dicarboxylic acids, e. g. sebacic, adipic and stearic acids, are used as synthetic and semisynthetic lubricants and hydraulic fluids.