most important industrial alcohols: methanol, mainly for the production of formaldehyde and as a fuel additive ethanol, mainly for alcoholic beverages, fuel additive, solvent 1-propanol, 1-butanol, and isobutyl alcohol for use as a solvent and precursor to solvents C6–C11 alcohols used for plasticizers, e.g. in polyvinylchloride fatty alcohol (C12–C18), precursors to detergents Methanol is the most common industrial alcohol, with about 12 million tons/y produced in 1980. The combined capacity of the other alcohols is about the same, distributed roughly equally. Toxicity With respect to acute toxicity, simple alcohols have low acute toxicities. Doses of several milliliters are tolerated. For pentanols, hexanols, octanols and longer alcohols, LD50 range from 2–5 g/kg (rats, oral). Ethanol is less acutely toxic. All alcohols are mild skin irritants. The metabolism of methanol (and ethylene glycol) is affected by the presence of ethanol, which has a higher affinity for liver alcohol dehydrogenase. In this way methanol will be excreted intact in urine. Physical properties In general, the hydroxyl group makes alcohols polar. Those groups can form hydrogen bonds to one another and to most other compounds. Owing to the presence of the polar OH alcohols are more water-soluble than simple hydrocarbons. Methanol, ethanol, and propanol are miscible in water. Butanol, with a four-carbon chain, is moderately soluble. Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers. The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon hexane, and 34.6 °C for diethyl ether. Occurrence in nature Simple alcohols are found widely in nature. Ethanol is the most prominent because it is the product of fermentation, a major energy-producing pathway. Other simple alcohols, chiefly fusel alcohols, are formed in only trace amounts. More complex alcohols however are pervasive, as manifested in sugars, some amino acids, and fatty acids. Production Hydroxylation Many alcohols are produced by hydroxylation, i.e., the installation of a hydroxy group using oxygen or related oxidant. Hydroxylation is the means by which the body processes many poisons, converting lipophilic compounds into hydrophilic derivatives that are more readily excreted. Enzymes called hydroxylases and oxidases facilitate these conversions. Many industrial alcohols, such as cyclohexanol for the production of nylon, are produced by hydroxylation. Ziegler and oxo processes In the Ziegler process, linear alcohols are produced from ethylene and triethylaluminium followed by oxidation and hydrolysis. An idealized synthesis of 1-octanol is shown: Al(C2H5)3