Properties of Alcohol

Alcohol is an organic compound that possesses at least one hydroxyl group that is attached to the saturated carbon atom present in the alcohol molecule. The alcohol that is generally used to denote the primary alcohol (i.e. attached to one carbon atom) is ethanol. Ethanol is present in the drugs and is the main component of alcoholic drinks. Alcohol denotes an entire class of alcohol of which methanol and ethanol are the primary members and the higher alcohols including the primary ones are expressed generally with the formula CₙH₂ₙ₊₁OH.   

The suffix (-ol) appears where the -OH group, that is the hydroxyl group, is present as one of the main functional groups and is the highest priority functional group present according to the IUPAC chemical naming. When another highest priority group is present in the compound, then the -OH group is referred to as hydroxy. The subject of this article includes the primary, secondary and tertiary alcohols along with their properties. 

Properties of Alcohols

Physical Properties of Alcohols 

The physical properties of alcohol can be explained by the following points –

• Alcohols are colourless. 

• They generally give a sweet smell except for glycerol and a few lower alcohols. 

• They are flammable and produce a blue flame. 

• They don’t produce any smoke while burning. 

• They are generally liquid at room temperature. Although glycerol is a viscous liquid. 

• Boiling Point of Alcohol - They generally have higher boiling points if we compare them with other hydrocarbons. For example, ethanol shows a boiling point of 78.29℃ while hexane shows a boiling point of 69℃. This is because of the presence of intermolecular hydrogen bonding between hydroxyl groups of alcohols. The boiling point of alcohol increases with an increasing number of carbon atoms in organic alcoholic compounds. 

• Alcohols work as suitable solvents for many organic compounds as organic compounds are insoluble in water. 

• Alcohols are acidic in nature. They react with metals such as sodium, potassium etc. It is due to the polarity of the bond between a hydrogen atom and the oxygen atom of the hydroxyl group. Primary alcohols are more acidic than secondary and tertiary alcohols. 

• Due to the polar -OH bond in alcohols, they are more soluble in water than other simple hydrocarbons. For example, methanol and ethanol are miscible in water.

Chemical Properties of Alcohols

The chemical properties of alcohol can be explained by the following points –

• Oxidation Reaction of Alcohol – Alcohols produce aldehydes and ketones on oxidation. The reaction is given below –

C₂H₅OH + 2O 🡪  CH₃COOH + H₂O

            Ethanol                   Methanoic acid

• Combustion of Alcohol – On heating ethanol gives carbon dioxide and water and burns with a blue flame. The reaction is given below –

            C₂H₅OH + 3O₂ 🡪 2CO₂ + 3H₂O

• Dehydration of Alcohol – Alcohol can be dehydrated in an acidic medium. The removal of water molecules from a compound is called dehydration. Upon dehydration of alcohol alkenes are produced. The reaction is given below –

C2H5OH (conc. H₂SO₄,▵)→C₂H₄ + H₂O

• The reaction of Alcohol With Metal – Due to its acidic nature alcohol reacts with metal and forms alkoxide. For example, when ethanol reacts with sodium forms sodium ethoxide and hydrogen gas. The reaction is given below –  

            
2C₂H₅OH + 2Na →2C₂H₅ONa + H₂

• Formation of Halides From Alcohols – Alcohol reacts with HCl and forms alkyl halides by removal of hydroxyl groups. The reaction is given below

ROH + HCl (Zn) 🡪 R-Cl + H₂

• Esterification – Alcohol reacts with a carboxylic acid in presence of a catalyst and forms ester. It is called Fischer esterification. The reaction is given below –

C₂H₅OH + C₂H₃COOH →C₄H₈O₂ + H₂O

Application of Alcohol

There is a long history of alcohol for myriad uses. For instance, mono-alcohols are the most important alcohols that are used in industries. Some of the applications of alcohol are as follows:-

1. For formaldehyde and fuel additive production, methanol is mainly used. 

2. For alcoholic beverages, fuel additives, solvent production, ethanol is mainly used. 

3. 1-propanol, 1-butanol, and isobutyl alcohol are used as a solvent and precursors to solvents.

4. C6–C11 alcohols are used for plasticizers in polyvinylchloride and many more. 

5. fatty alcohol (C12–C18) are utilized as precursors to detergents.