The key difference between chlorination and sulfonation is that chlorination is the addition of chlorine atoms to either organic compounds or water, whereas sulfonation is the addition of a sulfonic group to an organic compound directly.
Chlorination and sulfonation are different techniques with different applications. Chlorination is mainly used in disinfecting processes, while sulfonation is mainly important in organic synthesis processes.
What is Chlorination?
Chlorination is the process of adding chlorine or compounds containing chlorine to water for disinfection purposes. This method is useful in killing bacteria and other microorganisms in tap water since chlorine is highly toxic to them. Moreover, chlorination is very important in preventing water-borne diseases such as cholera and typhoid.
Chlorine is a highly efficient disinfectant. We can add it to public water supplies to kill disease-causing pathogens that commonly grow in water supply reservoirs. Chlorine is manufactured from salt via electrolysis. It usually occurs as a gas at room temperature, but we can liquefy it. Therefore, the liquefied form can be used in the disinfection process.
Chlorine is a strong oxidant. Thus, it kills bacteria via oxidation of organic molecules in microorganisms. Here, chlorine and hydrolysis product of chlorine, Hypochlorous acid, are charged chemical species which can easily penetrate into the negatively charged surface of pathogens. These compounds can disintegrate the cell wall lipid components and can react with intracellular enzymes. It makes the pathogen non-functional. Then the microorganisms die, or they lose their ability to undergo multiplication.
What is Sulfonation?
Sulfonation is an industrial process in which we can directly attach a sulfonic acid group, –SO3H, to carbon in an organic compound. The final product of this process is sulfonate. This process involves the reaction between an organic compound and a sulfur-containing acidic compound such as sulfur trioxide (SO3), sulfuric acid (H2SO4) or chlorosulfuric acid.
Sulfonation reactions form a C-S bond between one of the carbon atoms of the organic compound and the sulfur atom of the sulfur-containing compound. The final compound is an acidic compound and is categorized as a sulfonic acid. After the production, sulfonic acids can be isolated and stored due to their stability.
It is very difficult to use the sulfonation reaction on the industrial scale because it is a very rapid and extreme exothermic reaction. Most organic compounds form a black char when contacted with sulfur trioxide due to this rapid reaction and heat formation. The viscosity of organic compounds is also highly increased when it is converted into a sulfonic acid via sulfonation. When the viscosity is increased, it is difficult to remove heat from the reaction mixture. Therefore, a proper cooling operation is required. If not, unfavourable byproducts may form from side reactions. Due to these reasons, industrial-scale sulfonation reactions require special equipment.
On the other hand, the rapidity of the sulfonation reaction can be moderated by controlling the reactivity of sulfur trioxide. This can be done in two ways:
Complexing of sulfur trioxide can be done by following methods:
- Making sulfamic acid by reacting sulfur trioxide with ammonia
- Making chlorosulfuric acid by reacting sulfur trioxide with HCl
- Making Oleum by reacting sulfur trioxide with water
Therefore, the sulfation process can be carried out using one or some of these compounds. But when choosing the type of compound for sulfonation process in industrial productions, several factors should be considered. Some examples are given below:
- Desired final product and its quality
- Required production capacity
- Reagent cost
- Equipment cost
- Cost of waste disposal
What is the Difference Between Chlorination and Sulfonation?
The key difference between chlorination and sulfonation is that chlorination is the addition of chlorine atoms to either organic compounds or to water, whereas sulfonation is the process of addition of a sulfonic group to an organic compound directly. Moreover, chlorination is important in water disinfection, preventing water-borne diseases, the addition of chlorine atoms to organic compounds during organic synthesis reactions, etc. Meanwhile, sulfonation is important in the addition of sulfonic groups to organic compounds during organic synthesis reactions.
Below infographic summarizes the difference between chlorination and sulfonation.
Summary – Chlorination vs Sulfonation
Chlorination and sulfonation are addition reactions. The key difference between chlorination and sulfonation is that chlorination is the addition of chlorine atoms to either organic compounds or to water, whereas sulfonation is the process of addition of a sulfonic group to an organic compound directly.
1. “Nitration and Sulfonation of Benzene.” Chemistry LibreTexts, Libretexts, 5 June 2019, Available here.