Alcohols, Phenols and Ethers

Isopropyl Alcohol

Isopropyl alcohol is the common name given to the compound propan-2-ol. The other common names generally used for this compound are isopropanol, isopropyl, and 2-propanol. Isopropyl alcohol is a colourless compound. This chemical compound is flammable in nature and possesses a strong odour. The Hydroxyl group is connected to an isopropyl group. Secondary alcohol is an alcohol that contains the alcohol bearing carbon atom attached to two other carbon atoms.

Thus, isopropyl alcohol is the simplest and smallest example of a secondary alcohol. Alcohols and ethers are functional isomers. Thus, ethyl methyl ether is a functional isomer of isopropyl alcohol. On the other hand, 1-propanol is the structural isomer of isopropyl alcohol. Isopropyl alcohol has a wide variety of uses in the manufacture of industrial and household chemicals. This organic compound is also a major ingredient in the production of major chemicals like detergents, disinfectants, and antiseptics.

Isopropyl alcohol

                                                                                              Isopropyl alcohol

Production of Isopropyl Alcohol

The primary method of production of isopropyl alcohol is by combining water and propene in a reaction called hydration. It can also be produced by the hydrogenation of acetone. In both the processes of the production of isopropyl alcohol, separation is required. The product isopropyl alcohol is required to be separated from by-products like water. This is done by the process of distillation.

In the case of simple distillation, isopropyl alcohol forms a solution that is 87.9% by weight isopropyl alcohol and the rest is water. This is an azeotropic solution and has a common boiling point of the mixture. Thus, to obtain pure isopropyl alcohol, we need to carry out azeotropic distillation. This process is done by using azeotroping agents like cyclohexane and di-isopropyl ether. The body also produces small amounts of isopropyl alcohol in the process of diabetic ketoacidosis.

Indirect Hydration

Reaction of propene with sulfuric acid results in the formation of sulfate esters. Low-quality propene can be used in this type of indirect hydration. Adding sulfuric acid to propene follows Markovnikov’s rule. The hydrolysis of these esters with the help of steam produces isopropyl alcohols. A major by-product of this reaction is diisopropyl ether. This compound is recycled back and again hydrolyzed to give the wanted product.

Direct Hydration

The reaction of propene and water in the liquid or gas phase, at relatively high pressures, resulting in direct hydration. This process takes place in the presence of solid acidic catalysts. The requirement of highly pure propane is present here.

Hydrogenation of Acetone

The hydrogenation of acetone is also used for the preparation of isopropyl alcohol. But this approach involves an additional step related to the above methods. This is because acetone is prepared by the cumene process on propene. This process seems efficient, economical and easy.

Properties of Isopropyl Alcohol

1.Physical Properties

  1. This organic compound is miscible in liquids like ether, ethanol, water and chloroform.
  2. It serves as a solvent for chemicals like polyvinyl butyral, ethylcellulose, many oils, gums, alkaloids, and naturally existing resins.
  3.  On the other hand, isopropyl alcohol, unlike methanol and ethanol, is not miscible with salt solutions.
  4. This compound can be separated from aqueous solutions by the addition of salts like sodium chloride. This process of separating out the isopropyl alcohol is salting out. This makes the isopropyl alcohol to form a different layer in the solution which can be separated out.
  5. With water, isopropyl alcohol forms an azeotropic mixture. This azeotropic mixture has a boiling point of 80.370 C. This mixture holds a composition of 87.7 % by weight of isopropyl alcohol that is 91% by volume of isopropyl alcohol. This mixture of water and isopropyl alcohol possess depressed melting points. The mixture has a bitter taste and is unsafe for drinking.
  6. Isopropyl alcohol shows a rapid increase in its viscosity with the decrease in temperature. The freezing point of the compound is -890 C.
  7. The absorbance of isopropyl alcohol can attain a maximum value of 205nm in an ultraviolet-visible spectrum.

2.Chemical Properties

  1. Isopropyl alcohol undergoes oxidation to form the corresponding ketone that is acetone. This oxidation takes place with the use of oxidizing agents like chromic acid. Oxidation can also be done over a heated copper catalyst by undergoing dehydrogenation.
  2. Phosphorous tribromide is used to convert isopropyl alcohol into 2-bromopropane. When isopropyl alcohol is heated in the presence of sulfuric acid, it gets dehydrated. Dehydration of isopropyl alcohol results in the formation of propene.
  3. Isopropyl alcohol also reacts with active metals like sodium and potassium. This reaction results in the formation of isopropoxides. These isopropoxides are reacted with aluminium to form aluminium isopropoxide. This compound acts as a catalyst.

Uses of Isopropyl Alcohol

  1. Isopropyl alcohol is widely in use in developed nations. The common use of isopropyl alcohol is as a solvent for coverings or for various industrial processes.
  2. Isopropyl alcohol also has its applications in personal care articles and household purposes. It is also majorly in use as an ingredient in the pharmaceutical industries. This is because isopropyl alcohol has low toxicity.
  3. Many non-polar compounds are soluble in isopropyl alcohol.
  4. In comparison with the other solvents, isopropyl alcohol is relatively non-toxic.
  5. The evaporation of isopropyl alcohol is quick, and it does not leave any oil traces behind. These properties make it suitable for use as a cleaning fluid and a solvent. This cleaning fluid is useful to clean electrical contacts, audiotapes, optical disc lenses and eyeglasses.
  6. The esterification of isopropyl alcohol provides us with another solvent isopropyl acetate. This compound reacts with sodium hydroxide and carbon disulfide to produce a herbicide, sodium isopropyl xanthate. This compound also acts as an ore floatation reagent.
  7. Isopropyl alcohol is an integral part of the solutions of hand sanitisers, rubbing alcohol and disinfecting pads. A solution of isopropyl alcohol with water that is 70% volume by volume is useful as a hand sanitiser.
  8. Isopropyl alcohol is also useful for water-drying purposes. This method reduces the chances of otitis externa commonly called swimmer’s ear.

FAQs about Isopropyl Alcohol

Q.1. What is IPA (Isopropyl alcohol) poisoning?

Answer. Isopropanol that is isopropyl alcohol is a common ingredient of rubbing alcohol, cleaning products and hand sanitisers. When our liver is not capable of allowing more amount of IPA in our body, it is IPA poisoning. It causes confusion, dizziness, stomach pain and a reduction in breathing rate.

Q.2. What is the role of isopropyl alcohol in the automotive industry?

Answer. Gas dryer fuel additives contain isopropyl alcohol as an important ingredient. When fuel tanks contain significant amounts of water, it could be a problem. This is because, at low temperatures, it can freeze the supply lines. When isopropyl alcohol is added to the mixture, it does not remove water from the tank. It instead solubilizes water in the gasoline of the tank.

Q.3. What hazards can cause by using isopropyl alcohol?

Answer. Isopropyl alcohol is flammable in nature. Its vapour is denser than the air and thus it could catch fire and quickly. The flammability range in the air is between 2 and 12.7%. Thus, isopropyl alcohol should be kept away from open flame and heat for safety purposes. When isopropyl alcohol is distilled over magnesium, the formation of peroxide takes place. These peroxides could cause an explosion upon concentration. Isopropyl alcohol is a potential allergen and can cause irritation to the eyes.

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