An Overview On Aldehydes And Ketones

Aldehydes and ketones are characterised by the general formula CnH2nO and the presence of the C = O carbonyl group in their molecules. Hence, aldehydes (with general formula R-CHO) and ketones (with general formula R-CO-R) are usually known as carbonyl compounds. 

What are aldehydes?

In aldehydes, a carbon atom shares a single bond with a hydrogen atom, a double bond with an atom of oxygen and a single bond with another atom or group of atoms. They are used to create fragrances for the products like soaps, detergents, and perfume. 

What are ketones? 

Ketones are a class of organic compounds that are characterised by the presence of the carbonyl group, wherein the carbon atom forms a double bond with the oxygen atom. They do not share their bond with the hydrogen atoms in the carbonyl group. Ketones are widely used as solvents for textiles and paints and are commonly used as chemical intermediaries. 

Occurrence of ketones and aldehydes

When combined with other functional groups, ketones and aldehyde are widespread in nature. Citra (lemongrass), camphor (camphor trees), cinnamaldehyde (cinnamon bark), helminthosporium (a fungal toxin), and carvone (spearmint and caraway) are all compounds that are found chiefly in plants. However, hormones such as progesterone (female sex organ), testosterone (male sex organ), cortisone (adrenal hormone), and muscone (musk deer) have both animal and human origins.

Uses of aldehydes and ketones 

Aldehydes and ketones are used widely in sectors such as food, cosmetics, fragrance, and pharmaceutical due to their chemical properties. They are an inevitable part of various industrial processes. Let us know about their uses in detail.

Uses of aldehydes 

Aldehydes are natural products that occur in vanilla beans and cinnamon bark and can also be manufactured in laboratories. Aldehyde compounds like acetaldehyde and formaldehyde are crucial to forming other chemicals used in dyes and organic acids.

• Formalin, a chemical used to preserve biological specimens, is formed with the help of formaldehyde with 40% solution in water. Usually, formaldehyde is found in gaseous form.  
• The phenol-formaldehyde resin commonly known as bakelite is used in plastics, adhesives, and coatings and has many other uses. 
• Aldehydes serve as a precursor in various industrial processes such as tanning and polymeric goods. 
• Aldehydes are used by the cosmetic, dye, and perfume industries for their product formation. 
• The manufacturing of acetic acid and its other derivatives, such as pyridine, also rely on aldehydes.
• Formaldehyde is used for embalming, photography, and testing drugs and is widely employed in manufacturing industries on a large scale. 
• Aldehydes like glutaraldehyde act as antiseptics, germicides, fungicides and insecticides. It works by affecting the cell membrane and cell walls of the bacteria, thereby preventing them from working. 
• Cinnamaldehyde is used for adding the flavour of cinnamon to recipes. 
• Benzaldehyde (an aromatic aldehyde) is used as a flavouring agent and is added to different products to lend an almond taste. 
• Coriander, a commonly used herb in cooking, is formed with 40 different chemicals, with approximately 82% of them being aldehydes, which are responsible for the aroma.
• A significant role is played by aldehydes in the formation of caramelised sugar. While sugar is being cooked, the aldehyde group present in sugar gets converted into unsaturated aldehyde with the help of amino acids, which helps sugar get the brown colour of the caramel.

Uses of ketones 

Ketones play a crucial role in the products used by us every day. They are widely used for formulating ink applications, wood coatings and adhesives.

• The most commonly used type of ketone is acetic acid. It is used in the formation of nail paint removers and paint thinners. 
• Acting as a great solvent for some types of synthetic fibres and plastics, ketones are of great utility. 
• Acetophenone, an aromatic ketone, is used in scents such as cherry, strawberry, honeysuckle, and jasmine. 
• Cyclohexanone, a cyclic ketone, is an important component in the production of nylon. 
• Some essential functions of humans and other organisms are also performed by ketones. Hormones such as progesterone, testosterone, cortisone and aldosterone are all ketones. 
• Butanone, also known as methyl ethyl ketone, is a common solvent used in manufacturing plastics, paint thinners, varnishes, textiles, etc. 
• Ketones are widely used in the cosmetic industry and for the treatment of acne.
• Ketones are necessary for the production of many organic compounds. 

Conclusion 

The basic differentiating factor between aldehydes and ketones is that in an aldehyde, a carbon atom shares a single bond with a hydrogen atom, a double bond with an atom of oxygen and a single bond with another atom, whereas in ketones, the carbon atom forms a double bond with the oxygen atom.

Aldehyde compounds like acetaldehyde and formaldehyde are crucial to forming other chemicals used in dyes and organic acids. Aldehydes and ketones are widely used in various industries such as food, pharmaceuticals, perfumes and cosmetics.