Uses of propanol: Propanol Formula, Types and their structures, Preparation, Physical and Chemical Properties, Uses, Practice Problems and FAQs

You might have been advised from childhood to wash your hands thoroughly, may be with soap before eating. But during the coronavirus pandemic, every now and then and on physical touching of anything, It become a condition for everybody to wash or sanitise their hands.

What is this sanitizer and what is the constituent in it, that make it effective against the microorganisms?
A sanitizer is a material that kills the microorganisms and viruses that cause infectious diseases in humans and animals.

Did you know, however, that these sanitisers contain 99.5 percent alcohol?
Ethyl alcohol and iso-propanol are used in laboratories and commercial applications respectively for protection against microorganism and viruses..

Let us know more about propanol in particular her that we all use in these pandemic days..

Table of contents:

• Propanols
• Formula and Structure of propanols
• Preparation of propanols
• Physical properties of propanols
• Uses of propanol
• Practice problems

Propanol:

Propanol is a hydroxy hydrocarbon, with one hydrogen in propane being replaced by a hydroxyl group. The formula of propanol is C₃H₇OH. It is third out of the first four aliphatic alcohols homologues. It is also called propyl alcohol.

Types and structure of Propanol

Propanol is of two types- propan-1-ol and propan-2-ol depending upon the position of attachment of the hydroxyl group to either the terminal or middle carbon. The two alcohols are positional isomers. Propanol is also referred to as 1-propanol, primary propyl alcohol and n-propanol. Propan-2-ol is referred to as 2-propanol or secondary propanol isopropyl alcohol.
Propanols have a linear structure.

Preparation of propan-1-ol:

Propionaldehyde (CH₃CH₂ CH=O) is hydrogenated in the presence of a catalyst to produce propan-1-ol. But to make this normal propanol, propionaldehyde has to be synthesised from ethylene.

The oxo process produces propionaldehyde in the above reaction (the hydroformylation of ethylene with hydrogen and carbon monoxide in the presence of a catalyst such as cobalt octa-carbonyl or a rhodium complex).

After the preceding process, propionaldehyde will be hydrogenated. Hydrogenation is the process of saturating unsaturated substances by adding pairs of hydrogen atoms.

Preparation of propan-2-ol:

Isopropyl alcohol is manufactured by three processes-

1. Direct hydration of propene with strong sulphuric acid

2. Indirect hydration wih pure propene with water in the presence of acidic catalysts
3. Hydrogenation of acetone

Physical properties of propanol:

Propanols are a colourless liquid that is completely miscible with water and highly miscible with all common solvents, including glycols, ketones, alcohols, aldehydes, ethers, and aliphatic hydrocarbons.

The smaller alcohols, such as methanol, ethanol, and propanol, dissolve quickly in water. This is because water can establish hydrogen bonds with the hydroxyl group in these molecules, and the overall energy of these water-alcohol hydrogen bonds is more than enough to compensate for the energy lost when the alcohol-alcohol hydrogen bonds are broken. However, when you try butanol, you will observe that as you add more and more to the water, it begins to develop its own layer on top of the water.

Propanol has a more pleasant odour than higher alcohols and absorbs less water than lower alcohols.

Some general properties of propan-1-ol are given below.

Propanol liquid and vapour are highly flammable and must be maintained away from intense heat and all sources of fire. It should be stored below 40 ^o C in dry conditions, away from aldehydes, halides, halogenated organics, halogens, strong acids, and strong oxidizers.

Uses of propanols:

Because of its miscibility, strong flammability, and effects on the human body, propanol has a wide range of applications.

Some of the more common applications are as follows:

1) As a solvent: 

Propanols are used mostly as a solvent as well as an intermediate product. Propanol is mostly used as a solvent in printing inks, particularly flexographic ink. It is added to floor polishes and metal degreasing agents in the cleaning agent industry. Propanol is used as an extra solvent in the production of adhesives.

Propanol is used as a semi-volatile alcohol in the coating industry to improve drying properties, such as in the production of alkyd resin paints, baking finishes, and electrodeposition paints.

Propanol is also used in deicing fluids, extracting agents, and entrainer in azeotropic distillations. Propanol readily produces esters and ethers, the majority of which have high commercial value.

Propanol is often used as a solvent or in the production of other solvents such as antifreezes, lacquer formulations, soaps, dye solutions, window cleaning agents, and other products. Propanol is used as a chemical intermediate in the synthesis of halides, propyl amines, propyl acetate, and many other compounds. It's also used to make degreasing fluids, adhesives, and window cleaners.

2) Medical use:

Propanol is also used in a variety of pharmaceuticals. Propan-2-ol is the main component of rubbing alcohol bottles. It also serves as an antiseptic. Propan-2-ol can be found in hand sanitizers in the form of solutions or wipes. Furthermore, propanol is frequently utilised in inhalant products in place of ethanol, particularly in nebulizers.

Because n-propyl alcohol can cause modest central nervous system depression, it is utilised as a pain reliever.

Propanol increases the activity of partly purified human erythrocyte acid phosphatase (eapase) thrice, according to a study published in Chem Pharm Bull in Tokyo in 1980. The amount of n-propanol activation of human prostatic acid phosphatase (papase) was less than that of eapase.

Propanol Tablet is used to treat, control, prevent, and improve supraventricular arrhythmias, ventricular tachycardias, digitalis-induced tachyarrhythmias, resistant tachyarrhythmias caused by excessive catecholamine activity during anaesthesia, and other conditions.

Propanol is found in trace amounts as a volatile flavour in a number of foods and non-alcoholic beverages.

Propanol is also used to produce herbicides and pesticides.

3) Cosmetics:

Propanol is a common ingredient in a wide range of cosmetics. Because of its moderate corrosive qualities, acetate is used as a remover for acrylic nails and fingernail polish. It can be found in soaps and hair care products. It's also found in perfumes, hand sanitizers, and moisturisers.

4) Fuel:

Propanol has a fire hazard rating of 2 and is a highly flammable liquid. Propanol has a high octane number and is ideal for use as a fuel in internal combustion engines. However, the manufacture of propanol is too expensive to make it a popular fuel, hence it is not often utilised for this purpose. When propane is used as a fuel, the anti-knock index (AKI) is 108 and the research octane number (RON) is 118.

While the primary application of propanol is as a solvent, other applications and uses of propanol are expanding significantly in various parts of the world. Furthermore, propanol is a less hazardous chemical to employ than other synthetic alcohol solutions.

Practice problems:

Q1.Isopropyl alcohol and n-propyl alcohol are

(A) Chain isomers
(B) Positional isomers
(C) Functional isomers
(D) Tautomers

Answer: (B)

Solution: Position isomers are constitutional isomers with the same carbon backbone and functional groups but different functional group locations. The -OH group is found on the first C atom in n-propyl alcohol. The -OH group is found on the second C atom in isopropyl alcohol.

Q2.n-Propanol is 

(A) Primary alcohol 
(B) Secondary alcohol
(C) Tertiary alcohol
(D) Quaternary alcohol

Answer: (A)

Solution: Primary alcohols are those in which the hydroxyl group (-OH) carbon atoms are bonded to only one single alkyl group. Propan-1-ol is a primary alcohol because the hydroxyl group is linked to a terminal carbon atom, i.e. a carbon atom at the end of the carbon chain.

Q3. Which of the following alcohols is the most water soluble?

(A) Propanol
(B) Hexanol
(C) Pentanol
(D) Butanol

Answer: (A) 

Solution: Propanol is the most soluble in water of the listed alcohols, as the solubility of alcohols in water decreases as molecular mass increases.

Q4. What is the correct acidic strength order?

(A) CH₃OH
(B) CH₃CH₂OH
(C) CH₃CH₂CH₂OH
(D) CH₃CH₂CH₂CH₂OH

Answer: (A)

Solution: Though alcohols are not considered acid, among the given alcohol, methanol is more acidic. This is due to the fact that higher alkyl groups are connected to the -OH , increasing the electron density on oxygen atom via the +I effect and thereby strengthening the O-H bond. The stronger the O-H bond, the weaker the acid.

Frequently asked questions:

Question 1. Is Rubbing Alcohol the same as Isopropyl Alcohol?
Answer: Rubbing alcohol is an antiseptic that comprises at least 68 percent and up to 72percent isopropyl alcohol. The remaining volume is water, with or without suitable stabilisers, scent oils, and colour additives approved for use in medications by the FDA. Rubbing alcohol differs from more pure versions of isopropyl alcohol in that it contains denaturants, which make the solution unpleasant for human consumption. Technically, all grades of rubbing alcohol having 68-72 percent isopropyl alcohol is classified as "rubbing alcohol" for home use. Because isopropyl alcohol concentrations greater than 91 % by volume have limited bactericidal efficiency and are less effective for antiseptic usage, its classification as "rubbing alcohol" is not warranted and may cause confusion.

Question 2. Which of the following has a higher boiling point: 1-propanol or 2-propanol?
Answer: When pressure and temperature are constant, 1-propanol molecules are more closely (densely) packed than 2-propanol molecules. As a result, only a few molecules are capable of vaporisation. Because it takes more energy to break the larger electric dipole between 1-propanol molecules than 2-propanol molecules, it has a higher boiling point.

Question 3. Why does propanol have a greater boiling point than the hydrocarbon butane?
Answer: The boiling point of a compound is directly proportional to the intermolecular forces present. Intermolecular hydrogen bonding and Van der Waals forces exist in propanol.

In butane, the only forces between the molecules are weak van der Waals forces of attraction. As a result, propanol has a higher boiling point (391 K) than butane (309 K).

Question 4. What is the difference between isopropyl alcohol and propanol?
Answer: The safety of isopropyl alcohol and denatured alcohol for your skin is a key difference. When applied to the skin, isopropyl alcohol is considered non-toxic. It may induce dryness, although it has no specific poison. Denatured alcohol, on the other hand, includes the deadly methanol. If exposed, this can be absorbed via the skin, therefore use caution when handling denatured alcohol.

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