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History
The compound was discovered by Gustave Chancel in 1853 by fractional distillation of fusel oil. He measured its boiling point at 96°C, correctly identified its empirical formula, studied some of its chemical properties and gave it two names: propionic alcohol and hydrate of trityl.
After several unsuccessful attempts, it was synthesized independently and by two different routes by Eduard Linnemann and Carl Schorlemmer in 1868.
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Occurrence
Fusel alcohols like 1-Propanol are grain fermentation byproducts, and therefore trace amounts of 1-Propanol are present in many alcoholic beverages.
Chemical properties
1-Propanol shows the normal reactions of a primary alcohol. Thus it can be converted to alkyl halides; for example red phosphorus and iodine produce n-propyl iodide in 80% yield, while PCl3 with catalytic ZnCl2 gives n-propyl chloride. Reaction with acetic acid in the presence of an H2SO4 catalyst under Fischer esterification conditions gives propyl acetate, while refluxing propanol overnight with formic acid alone can produce propyl formate in 65% yield.
Oxidation of 1-propanol with Na2Cr2O7 and H2SO4 gives a 36% yield of propionaldehyde, and therefore for this type of reaction higher yielding methods using PCC or the Swern oxidation are recommended. Oxidation with chromic acid yields propionic acid.
Preparation
1-Propanol is manufactured by catalytic hydrogenation of propionaldehyde. Propionaldehyde is produced via the oxo process by hydroformylation of ethylene using carbon monoxide and hydrogen in the presence of a catalyst such as cobalt octacarbonyl or a rhodium complex.
H2C=CH2 + CO + H2 → CH3CH2CH=O CH3CH2CH=O + H2 → CH3CH2CH2OH
Other proposed industrial processes include the two-step isomerization and hydrogenation of propylene oxide.
A traditional laboratory preparation of 1-propanol involves treating n-propyl iodide with moist Ag2O.
1-Propanol can also be prepared via the hydrogenation of acrolein with metal catalysts.
Safety
1-Propanol is thought to be similar to ethanol in its effects on the human body, but 2 to 4 times more potent according to a study conducted on rabbits. Many toxicology studies find oral acute LD50 ranging from 1.9 g/kg to 6.5 g/kg (compared to 7.06 g/kg for ethanol). It is metabolized into propionic acid. Effects include alcoholic intoxication and high anion gap metabolic acidosis. As of 2011, one case of lethal poisoning was reported following oral ingestion of 500mL of 1-propanol. Due to a lack of long term data, the carcinogenicity of 1-propanol in humans is unknown.
1-Propanol as fuel
1-Propanol has a high octane number and is suitable for use as engine fuel. However, propanol is too expensive to use as a motor fuel. The research octane number (RON) of propanol is 118, and the anti-knock index (AKI) is 108.