The Concept of Autocatalytic Reaction

If one of the reaction products is also a catalyst for the same or a related process, the reaction is referred to as autocatalytic. This type of reaction is referred to as an autocatalytic reaction. A group of chemical reactions is considered to be “collectively autocatalytic” if a number of them provide catalysts for enough additional reactions as reaction products that the entire group of chemical reactions is self-sustaining given that a certain amount of input energy and food molecules.

Autocatalysis is a kinetic process in which a product of a reacting system acts as a catalyst, according to popular belief. As a result, adding the appropriate product to the unreacted mixture of reactants speeds up the reaction, offering a clear example of how a system can be identified as an autocatalysis either empirically or theoretically. Once approved, sigmoidal concentration–time profiles are common, though this is neither a necessary nor sufficient condition but since appropriate mechanistic and parametric conditions should be met for this kinetic feature to appear. Several mass action type kinetic models that produce sigmoidal concentration–time profiles are extensively investigated in order to determine their right categorization and characterisation

We have refined the definitions of autocatalysis and autocatalyst as a result of this procedure. Autocatalysis is a kinetic phenomena in which a product of a larger chemical event acts as a catalyst for at least one of its subsystems or the entire system. This definition clarifies that, in the instance of autocatalysis, the concentration of autocatalyst must grow over time in any true overall chemical or biological reaction..

Autocatalytic Reaction Rate

Catalysts are compounds that speed up a reaction while remaining unchanged themselves. The term catalyst was coined by Berzelius. An autocatalytic reaction is one in which one of the products is able to catalyse the process. The rate of reaction in these types reaction is initially very slow, but once the reaction progresses and products are being formed, the rate of reaction increases very rapidly. In this case, the product serves as a catalyst for self-production. A + B 2B is an autocatalytic process in which A interacts with B to create B while the original B, which acts as a catalyst, is kept. The graph of reactant to product conversion over time is sigmoidal. Due to the lack of a catalyst, conversion is slow at first, but subsequently accelerates at a steady pace as products are generated, which also act as a catalyst. With the depletion of reactants, the reaction rate slows down again.

Examples of Autocatalytic Reaction

The Briggs–Rauscher reaction, the Belousov–Zhabotinsky reaction (BZ reaction), the Bray–Liebhafsky reaction, and the iodine clock reaction are all instances of clock reactions. These are oscillatory reactions, and damped oscillations can be used to approximate product and reactant concentrations. A mixture of potassium bromate (KBrO3), malonic acid (CH2(COOH)2), manganese sulfate MnSO4 prepared in a heated solution with sulfuric acid H2SO4 as solvent. 

Glycolysis, an important metabolic cycle, is known to have a temporal order. Glycolysis is the breakdown of one molecule of glucose followed by the generation of two molecules of ATP. As a result, the process is critical to the energetics of live cells. Glucose, NAD, ADP, ATP, pyruvate and NADH are all involved in the global glycolysis reaction.

The process is fairly complicated, although phosphofructokinase autocatalyzes a piece of it (PFK). This section of the process is in charge of oscillations in the pathway, which cause the process to alternate between active and inactive states. As a result, the process can be modulated by the autocatalytic reaction.

Conclusion

Autocatalysis refers to reactions that accelerate in rate as time passes. An S-shaped conversion curve characterises these reactions. The most basic form of autocatalysis is when a product works as a catalyst for its own creation. Ester hydrolysis is an example of an autocatalytic reaction. Each ester group bond cleavage in the polymer backbone generates an organic acid, which catalyses hydrolytic bond cleavage. Autocatalysis occurs in many chemical and biological reactions. The acid-catalyzed hydrolysis of polyester is a frequent autocatalytic polymeric process. However, the rate equation is more difficult since both the molecular acid and the hydrogen ion produced by its dissociation can act as a catalyst. Step-growth polymerizations of thiol-epoxy and amine-epoxy are two further autocatalytic processes. Due to the continual creation of hydroxyl groups that promote the ring-opening of the epoxy groups, both are highly autocatalytic. We hope that you were able to grasp a clear concept of the topic autocatalysis, its reactions as well as examples of autocatalysis.