This article provides a brief introduction to the Maillard reaction and the Fenton reaction, which are two very important named reactions in organic chemistry that you should know about! The Maillard reaction is a named reaction that occurs between reducing sugars and amino acids in food items. Furthermore, the Maillard reaction is responsible for the characteristic ‘browning’ of food items when they are heated. On the other hand, the Fenton reaction plays a crucial role in the treatment of wastewater. In this reaction, hydrogen peroxide (catalyzed by iron) is used to treat a wide spectrum of water pollutants including formaldehyde and phenols. More details on these named reactions and their applications in the field of organic chemistry have been provided in the subsequent subsections.
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The Maillard Reaction
The Maillard reaction is an organic reaction between amino acids and reducing sugars. This reaction is named after the French physician and chemist Louis Camille Maillard. The reaction was first described in the year 1912. Maillard first encountered reaction when he attempted to artificially induce protein synthesis. The Maillard reaction can be classified as a non-enzymatic browning reaction. This reaction is known to proceed rapidly in a temperature range of 140 degrees Celsius to 165 degrees Celsius. It is important to note that the Maillard reaction is replaced by caramelization at very high temperatures. The latter involves the browning and subsequent pyrolysis of sugars. It can also be noted that this process is highly accelerated when the reaction environment is somewhat alkaline. One important application of the Maillard reaction is in the production of artificial flavoring agents. The Maillard reaction can be observed in many cooking processes. Some common examples of the Maillard reaction are listed below.
- The darkening of the crust of baked items such as bread and cakes.
- The golden-brown colour acquired by potatoes when they are fried (such as in french fries).
- The browning of marshmallows when they are toasted.
- The darkening of peanuts when they are roasted.
- The darkening of meat-based food when they are heated past a certain temperature point.
The Fenton Reaction
The Fenton reaction is a named reaction in organic chemistry that is widely used to treat wastewater by oxidizing the contaminants present in it. It generally involves the treatment of the wastewater with Fenton’s reagent. The Fenton reaction was discovered by (and is named after) the British chemist Henry John Horstman Fenton. It can also be noted that Fenton’s reagent was developed by this chemist in the early 1890s as an analytical reagent. Fenton’s reagent can be defined as a solution of hydrogen peroxide and a compound containing the ferrous ion. Common examples of ferrous ion sources include FeSO4 and FeO. In this reaction, the ferrous ion is oxidized to the ferric ion by the action of hydrogen peroxide (a chemical compound with the formula H2O2). This results in the formation of a hydroxyl free radical along with a hydroxide ion. This hydroxyl radical is highly reactive in nature.