Chemical Properties
Isopropyl alcohol is a clear, colorless, mobile, volatile, flammable liquid with a characteristic, spirituous odor resembling that of a mixture of ethanol and acetone; it has a slightly bitter taste.It is miscible with water, ethyl ether, and ethyl alcohol. Isopropyl alcohol is incompatible with strong oxidizers, acetaldehyde, chlorine, ethylene oxide, acids, and isocyanates.
Occurrence
Reported found in apple and cognac aromas (esterified). Also found in apple, banana, grapefruit and lime
juice, melon, papaya, pear, onion, peas, rutabaga, tomato, wheat bread, cheeses, milk, boiled egg, cooked beef, pork and mutton, hop
oil beer, rum, cocoa, coffee, scotch whiskey, grape wines, peanut, pecan, soybean, honey, beans, plum brandy, walnut, crab, clam,
prickly pear and clary sage.
Application
Isopropyl Alcohol is used in a variety of applications including as a solvent for industrial processes and coating; as a component in cleaning, car care and deicing products; as a wetting agent for printing inks and as a feedstock in the manufacture of ester and Mogas/Luboil additives.
isopropyl alcohol is a carrier, anti-bacterial, and solvent for skin care lotions. Isopropyl alcohol is made from propylene, a petroleum derivative.
When compared to ethanol, 50% less is required for nucleic acid precipitation, thus minimizing the total volume to be centrifuged for DNA or RNA recovery.
Isopropyl alcohol 70% is used as an ingredient in alcohol swabs and alcohol wipes for wound cleaning, it is found in hand sanitizers, and in ear drops to prevent swimmer's ear.
Definition
ChEBI: Isopropyl Alcohol is a secondary alcohol that is propane in which one of the hydrogens attached to the central carbon is substituted by a hydroxy group. It is an isomer of propyl alcohol with antibacterial properties.
Preparation
Isopropyl alcohol may be prepared from propylene; by the catalytic reduction of acetone, or by fermentation of certain carbohydrates.
Aroma threshold values
Detection: 40 to 601 ppm
General Description
Volatile, colorless liquid with a sharp musty odor like rubbing alcohol. Flash point of 53°F. Vapors are heavier than air and mildly irritating to the eyes, nose, and throat. Density approximately 6.5 lb / gal. Used in making cosmetics, skin and hair preparations, pharmaceuticals, perfumes, lacquer formulations, dye solutions, antifreezes, soaps, window cleaners. Sold in 70% aqueous solution as rubbing alcohol.
Air & Water Reactions
Highly flammable. Water soluble.
Reactivity Profile
Isopropyl alcohol(67-63-0) can react with AIR and OXYGEN over time to form unstable peroxides that can explode. Contact with 2-butanone increases the rate of peroxide formation. An explosive reaction occurs when Isopropanol is heated with (aluminum isopropoxide + crotonaldehyde). Forms explosive mixtures with trinitromethane and hydrogen peroxide. Reacts with barium perchlorate to form a highly explosive compound. Ignites on contact with dioxygenyl tetrafluoroborate, chromium trioxide and potassium-tert-butoxide. Vigorous reactions occur with (hydrogen + palladium), nitroform, oleum, COCl2, aluminum triisopropoxide and oxidizing agents. Reacts explosively with phosgene in the presence of iron salts. Incompatible with acids, acid anhydrides, halogens and aluminum . Isopropanol can react with PCl3, forming toxic HCl gas. (Logsdon, John E., Richard A. Loke., sopropyl Alcohol. Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. 1996.).
Health Hazard
Exposures to isopropyl alcohol cause irritation to the eyes and mucous membranes. Exposures to isopropyl alcohol for 3–5 min (400 ppm) caused mild irritation of the eyes, nose, and throat, and at 800 ppm these symptoms became severe. Ingestion or an oral dose of 25 mL in 100 mL of water produced hypotension, facial flushing, bradycardia, and dizziness. Ingestion in large quantities caused extensive hemorrhagic tracheobronchitis, bronchopneumonia, and hemorrhagic pulmonary edema. Prolonged skin contact with isopropyl alcohol caused eczema and sensitivity. Delayed dermal absorption is attributed to a number of pediatric poisonings that have occurred following repeated or prolonged sponge bathing with isopropyl alcohol to reduce fever. In several cases, symptoms included respiratory distress, stupor, and coma. Laboratory animals exposed to isopropyl alcohol develop poisoning with symptoms of hind leg paralysis, unsteadiness, lack of muscular coordination, respiratory depression, and stupor. Isopropyl alcohol is a potent CNS depressant, and in large doses causes cardiovascular depression.
Fire Hazard
Isopropyl Alcohol(IPA) is highly flammable in its liquid and vapor forms and flammable atmospheres can be created at temperatures as low as 540°F /120℃ . This means that any environment where IPA is being used needs to be well ventilated. It should be kept away from heat and open flame. As the vapour is heavier than air, it may spread along the ground, so care needs to be taken that the vapour is not ignited by a distant source.
Pharmaceutical Applications
Isopropyl alcohol (propan-2-ol) is used in cosmetics and pharmaceutical
formulations, primarily as a solvent in topical formulations.( It is not recommended for oral use owing to its toxicity.
Although it is used in lotions, the marked degreasing properties
of isopropyl alcohol may limit its usefulness in preparations used
repeatedly. Isopropyl alcohol is also used as a solvent both for tablet
film-coating and for tablet granulation, where the isopropyl
alcohol is subsequently removed by evaporation. It has also been
shown to significantly increase the skin permeability of nimesulide
from carbomer 934.
Isopropyl alcohol has some antimicrobial activity and a 70% v/v aqueous solution is used as a topical disinfectant.
Therapeutically, isopropyl alcohol has been investigated for the
treatment of postoperative nausea or vomiting.
Safety
Isopropyl alcohol is about twice as toxic as ethanol and should therefore not be administered orally; isopropyl alcohol also has an unpleasant taste. Symptoms of isopropyl alcohol toxicity are similar to those for ethanol except that isopropyl alcohol has no initial euphoric action, and gastritis and vomiting are more prominent; see Alcohol. Delta osmolality may be useful as rapid screen test to identify patients at risk of complications from ingestion of isopropyl alcohol. The lethal oral dose is estimated to be about 120–250mL although toxic symptoms may be produced by 20 mL.
Adverse effects following parenteral administration of up to 20mL of isopropyl alcohol diluted with water have included only a sensation of heat and a slight lowering of blood pressure. However, isopropyl alcohol is not commonly used in parenteral products.
Although inhalation can cause irritation and coma, the inhalation of isopropyl alcohol has been investigated in therapeutic applications.
Isopropyl alcohol is most frequently used in topical pharmaceutical formulations where it may act as a local irritant. When applied to the eye it can cause corneal burns and eye damage.
LD50 (dog, oral): 4.80 g/kg
LD50 (mouse, oral): 3.6 g/kg
LD50 (mouse, IP): 4.48 g/kg
LD50 (mouse, IV): 1.51 g/kg
LD50 (rabbit, oral): 6.41 g/kg
LD50 (rabbit, skin): 12.8 g/kg
LD50 (rat, IP): 2.74 g/kg
LD50 (rat, IV): 1.09 g/kg
LD50 (rat, oral): 5.05 g/kg
Synthesis
Synthetically prepared from acetylene or propylene.
Carcinogenicity
CD-1 mice were exposed by inhalation
to 0, 500, 2500, or 5000 ppm of isopropanol vapor for
6 h/day, 5 days/week for 18 months. An additional group of
mice (all exposure levels) were assigned to a recovery group
that were exposed to isopropanol for 12 months and then
retained until study termination at 18 months. There was
no increased frequency of neoplastic lesions in any of the
isopropanol-exposed animals. Nonneoplastic lesions were
limited to the testes (males) and the kidney. In the testes,
enlargement of the seminal vesicles occurred in the absence
of associated inflammatory or degenerative changes. The
kidney effects included tubular proteinosis and/or tubular
dilatation. The incidence of testicular and kidney effects
was not increased in the isopropanol-exposed recovery
animals.
Environmental Fate
The vast majority of isopropanol in the environment originates
from manufacturing processes. Small amounts are
produced by certain microbes, fungi, and yeast. The high
volatility of isopropanol ensures that when it is released
into the environment in any state, it eventually ends up in
the atmosphere. There, it can be degraded by hydroxyl radicals
or it can return to soil or water through precipitation. Its
half-life in the environment is approximately 3.2 days and is
highly biodegradable; bioaccumulation in plants and animals
does not occur.
Purification Methods
Isopropyl alcohol is prepared commercially by dissolution of propene in H2SO4, followed by hydrolysis of the sulfate ester. Major impurities are water, lower alcohols and oxidation products such as aldehydes and ketones. Purification of isopropanol follows substantially the same procedure as for n-propyl alcohol. Isopropanol forms a constant-boiling mixture, b 80.3o, with water. Most of the water can be removed from this 91% isopropanol by refluxing with CaO (200g/L) for several hours, then distilling. The distillate can be dried further with CaH2, magnesium ribbon, BaO, CaSO4, calcium, anhydrous CuSO4 or Linde type 5A molecular sieves. Distillation from sulfanilic acid removes ammonia and other basic impurities. Peroxides [indicated by liberation of iodine from weakly acid (HCl) solutions of 2% KI] can be removed by refluxing with solid stannous chloride or with NaBH4 then the alcohol is fractionally distilled. To obtain isopropanol containing only 0.002M of water, sodium (8g/L) is dissolved in material dried by distillation from CaSO4. Isopropyl benzoate (35mL) is then added and, after refluxing for 3hours, the alcohol is distilled through a 50-cm Vigreux column (p 11). [Hine & Tanabe J Am Chem Soc 80 3002 1958.] Other purification steps for isopropanol include refluxing with solid aluminium isopropoxide, refluxing with NaBH4 for 24hours, and removing acetone by treatment with, and distillation from, 2,4-dinitrophenylhydrazine. Peroxides re-form in isopropanol if it is kept for several days in contact with air. [Beilstein 1 IV 1461.]
Toxicity evaluation
Isopropanol is similar to other alcohols in its ability to induce
central nervous system (CNS) depression by enhancing
inhibitory neuronal activity and antagonizing excitatory
neuronal activity. It also can cause localized irritation upon
contact with skin and mucous membranes after dermal exposure
and ingestion, respectively.
Incompatibilities
Incompatible with oxidizing agents such as hydrogen peroxide and
nitric acid, which cause decomposition. Isopropyl alcohol may be
salted out from aqueous mixtures by the addition of sodium
chloride, sodium sulfate, and other salts, or by the addition of
sodium hydroxide.
Regulatory Status
Included in the FDA Inactive Ingredients Database (oral capsules,
tablets, and topical preparations). Included in nonparenteral
medicines licensed in the UK. Included in the Canadian List of
Acceptable Non-medicinal Ingredients.
