Sec-Butanol Also known as 2-butanol, Sec-Butanol is a by-product of the methanol synthesis from CO and H2. It can also be made by the hydrolysis of butylene (cracked gas) with sulfuric acid. The flash point is 70°F (21.1°C) and the LEL is 1.66% in air. Like all four butyl alcohols, it is a VOC. It has an asymmetric carbon atom and is optically active. However, it is almost always sold as the racemic mixture. Surprisingly, mice have repeatedly tolerated a 1,650ppm level in air for seven hours without incident. The suggested eight-hour maximum exposure concentration is 100ppm in air. In aerosols, it is mainly a thinner for lacquers. Iso-Butanol The earliest known butanol, it is made from fusel oil by careful fractional distillation. It is also a byproduct of methanol syntheses from CO and H2. The flash point is 82°F (26.6°C) and the LEL is 1.68% in air. It is a mild skin irritant. The eighthour maximum exposure concentration is 100ppm in air. It is utilized as a thinner for white nitrocellulose lacquers at up to about 5%. Tert-Butanol Often called TBA, this camphor-smelling butanol is produced mainly by the hydrolysis of iso-butylene with sulfuric acid. It is the simplest solid alcohol, melting at 25.6°C (78.9°F). It has a flash point of 52°F (11.1°C) and an LEL of 1.33% in air. It is used in aerosols only to the extent that one pint (473mL) is added to every 100 U.S. gallons of SDA-40 (95%) ethanol as a denaturant. The eight-hour maximum is 100ppm in air, but this is of no consequence, since only very dilute ethanol solutions are encountered. Pentyl Alcohols The eight known isomers are almost always referred to as amyl alcohols in commerce. N.amyl alcohol (or n.pentanol) is prepared by several routes: from fusel oil, from norlucine and so forth. Other isomers can be distilled from fusel oil. N.amyl alcohol has a flash point of 91°F (32.7°C) and an LEL of 1.20% in air. It is a VOC. It has sometimes been used as a spot remover and an ingredient of paints and coatings. The other C5 isomers have similar properties and uses. “OXO-Process” Alcohols About 1952, the Enjay Chemical Co. commercialized three new, highly branched C8, C13 and C16 alcohols made by the “OXO-process,” which involves the reaction of olefins, CO and H2 under heat and pressure and catalyzed by tetracarbonylhydrogencobalt, HCo(CO)4. The initial aldehydes rearrange and are then reduced to the desired alcohols. The three “OXO-alcohols” are colorless clear liquids. C8H17-OH has a very slight odor; the other two are odorless. The C8 mixture, sometimes erroneously called “iso-octanol,” is used as a foam breaker and solvent. The C16 mixture, “iso-hexadecanol” has been sprayed into swimming pools, where it spreads prodigiously, forming a top film said to be both continuous and monomolecular in places. The non-volatile lipophilic “R” groups orient to face the air. Swimming pools so treated have water evaporation rates up to 65–80% less than untreated pools. The films are undetectable, but must be reapplied every 3–5 days. March 2017 Spray 41
Spray March 2017
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