Production
Isopropyl alcohol is produced by combining water and
propene.
[2] There are two processes for achieving this: indirect
hydration via the sulfuric acid process and direct hydration. The former process, which can use low-quality propylene, predominates in the USA while the latter process, which requires high-purity propylene, is more commonly used in Europe. These processes give predominantly isopropyl alcohol rather than 1-propanol because the addition of water or
sulfuric acid to propylene follows
Markovnikov's rule.
The indirect process reacts propylene with sulfuric acid to form a mixture of sulfate esters. Subsequent
hydrolysis of these esters produces isopropyl alcohol. Direct hydration reacts propylene and water, either in gas or liquid phases, at high pressures in the presence of solid or supported acidic
catalysts. Both processes require that the isopropyl alcohol be separated from water and other by-products by
distillation. Isopropyl alcohol and water form an
azeotrope and simple distillation gives a material which is 87.9% by weight isopropyl alcohol and 12.1% by weight water.
[3] Pure (anhydrous) isopropyl alcohol is made by
azeotropic distillation of the "wet" isopropyl alcohol using either
diisopropyl ether or
cyclohexane as azeotroping agents.
[edit] Uses
Toxicology
Isopropyl alcohol is oxidized by the liver into
acetone by
alcohol dehydrogenase.
Symptoms of isopropyl alcohol poisoning include
flushing,
headache,
dizziness,
CNS depression,
nausea,
vomiting,
anesthesia, and
coma. Use in well-ventilated areas and use protective gloves while using. Poisoning can occur from ingestion, inhalation, or absorption.
Isopropyl alcohol is about twice as toxic as
ethanol, and acts as a
central nervous system (CNS) depressant. Its metabolite,
acetone, is a CNS depressant in its own right. Around 15 g of isopropanol can have a toxic effect on a 70 kg human if left untreated. However, it is not nearly as toxic as methanol or
ethylene glycol.
[8] Isopropyl alcohol does not cause an
anion gap acidosis (in which as lowered blood serum pH causes depletion of
bicarbonate anion) as do
ethanol and
methanol. Isopropyl alcohol does, however, produce an
osmolal gap between the calculated and measured osmolalities of serum, as do the other alcohols. Overdoses may cause a fruity odor on the breath as a result of its metabolism to
acetone, which is not further metabolized.
[9]