Safety of Isopropanol

Isopropanol  is a common name for a chemical compound with the molecular formula C3H8O or C3H7OH. It is a colorless, flammable chemical compound with a strong odor. It is the simplest example of a secondary alcohol, where the alcohol carbon atom is attached to two other carbon atoms sometimes shown as (CH3)2CHOH. It is a structural isomer of propanol. Isopropanol is denatured for certain uses, in which case the NFPA 704 rating is changed to 2,3,1.

1. Properties

Isopropanol(CAS.NO:67-63-0) is miscible in water, alcohol, ether and chloroform. It will dissolve ethyl cellulose, polyvinyl butyral, many oils, alkaloids, gums and natural resins. It is insoluble in salt solutions. Unlike ethanol or methanol, Isopropanol can be separated from aqueous solutions by adding a salt such as sodium chloride, sodium sulfate, or any of several other inorganic salts, since the alcohol is much less soluble in saline solutions than in salt-free water. The process is colloquially called salting out, and causes concentrated Isopropanol to separate into a distinct layer.

Isopropanol forms an azeotrope with water, which gives a boiling point of 80.37 oC and a composition of 87.7 wt% (91 vol%) Isopropanol. Water-Isopropanol mixtures have depressed melting points. It has a slightly bitter taste, and is not safe to drink.

Isopropanol becomes increasingly viscous with decreasing temperature. At temperatures below −70 °C Isopropanol resembles maple syrup in viscosity. Isopropanol has a maximum absorbance at 204 nm in an ultraviolet-visible spectrum.

2. Effects of Human Exposures 

Currently, there are no adequate chronic exposure data for isopropanol in humans. While isopropanol is not considered a dermal irritant, it is a defatting agent and can cause dermatitis with prolonged exposure to skin . A subacute study of daily oral intake of isopropanol (2.6 or 6.4 mg/kg body weight) by groups of 8 men for 6 weeks had no effect on blood cells, serum or urine and produced no subjective symptoms . A 

pharmacokinetic study of men occupationally exposed to Isopropanol revealed that uptake occurs readily via the inhalation route; acetone is the major metabolite . Acetone was eliminated mainly by the lung but was also eliminated in the urine.

3. Safety

Isopropanol vapor is denser than air and is flammable with a combustible range between 2 and 12.7% in air. It should be kept away from heat and open flame.Isopropanol has also been reported to form peroxides, which may explode upon concentration. Isopropanol is a skin irritant.

4. Toxicology

Isopropanol and its metabolite, acetone, act as central nervous system (CNS) depressants. Symptoms of Isopropanol poisoning include flushing, headache, dizziness, CNS depression, nausea, vomiting, anesthesia, and coma. Poisoning can occur from ingestion, inhalation, or absorption; therefore, well-ventilated areas and protective gloves are recommended. 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. Isopropanol does not cause an anion gap acidosis (in which a lowered blood serum pH causes depletion of bicarbonate anion) unlike ethanol and methanol. Isopropanol 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 further metabolized to produce the nutrients acetate and glucose. Isopropanol is oxidized to form acetone by alcohol dehydrogenase in the liver.