What is Schotten Baumann Reaction Mechanism and Applications
Schotten – Baumann reaction is used for commercial production of amides. It is the method of synthesis of amides by using acid chloride. It is named after German Chemists Carl Schotten and Eugen Baumann, as the reaction was first described by these two chemists in 1883.
Schotten – Baumann reaction is a condensation reaction of organic chemistry. In this reaction, acid chloride (acyl halide) or anhydride reacts with amine (primary or secondary) and base to produce amide. The general reaction is given below.
(Image Will be Updated Soon)
Sometimes this reaction also indicates the reaction between acid chloride (acyl halide) or anhydride with alcohol and base to produce an ester. The general reaction is given below.
Examples of Schotten – Baumann Reaction
Schotten – Baumann reaction also refers to the benzoylation reaction of active hydrogen-containing compounds. Some examples of the Schotten – Baumann reaction are given below.
Benzoylation of phenol
(Image Will be Updated Soon)
The reaction of benzylamine with acetyl chloride
The reaction of the acid chloride with primary amine
Benzoylation of aniline - reaction of the acid chloride with primary amine (aromatic)
Mechanism of Schotten -Baumann Reaction
The Schotten – Baumann reaction mechanism is given for the reaction of an amine with acid chloride and base. It can be explained by the following two steps:
Step 1. Attack by Nitrogen Atom of Amine on Carbonyl Carbon of Acyl Halide
The nitrogen atom of the secondary amine has a lone pair of electrons. So, it attacks the carbonyl carbon atom of acyl halide. Thus, the reaction begins. It leads to rearrangement of acyl halide and removal of halide. Thus, nitrogen gets attached with carbonyl carbon of acyl halide. The reaction is given below-
(Image Will be Updated Soon)
Step 2. Deprotonation: Now the compound formed in step 1 reacts with the base. Hydrogen atoms attached with nitrogen combine with hydroxyl ions of base and form water molecules. Thus deprotonation takes place and nitrogen being more electronegative than hydrogen gets the electrons towards itself and forms amide. The reaction is given below-
(Image Will be Updated Soon)
Applications of Schotten – Baumann Reaction
This reaction is widely used in synthesis in organic chemistry. Few applications of this reaction are given below.
It is used in the synthesis of N-vanillyl nonanamide or capsaicin.
It is used in the synthesis of benzamide from benzoyl chloride and phenethylamine.
It is used in the acylation of benzylamine.
It is used in Fischer's synthesis of peptides.
Products of this reaction such as ester and amides are very useful in many industries such as food, medicine etc.
It was all about the Schotten – Baumann reaction and its mechanism. If you are looking for more methods of preparation of amides and esters or other name reactions, then explore through our website.
Important Points About the Schotten-Baumann Reaction
The most important point about Schotten-Baumann's reaction that every student should remember are:
The Schotten-Baumann reaction of benzoylation of phenols is a very important reaction method in the field of organic chemistry.
The Schotten-Baumann reaction is named after two German scientists who discovered the reaction.
The reaction is mainly used in the field of organic chemistry for the benzoylation of phenols with benzoyl chloride.
The base catalysts that are used in the Schotten-Bauman reaction, to keep the medium of the reaction basic, are sodium hydroxide and pyridine because the reactants involved in the reaction are always acidic.
The phenol and the base involved in the reaction condition react to give phenoxide ion. Afterward, the benzoyl chloride is attacked by a phenoxide ion.
The negative charge prevalent in the reaction shifts to the oxygen molecule present in benzoyl chloride. The negative charge is then utilized to form a double bond between the oxygen atom and the carbon atom.
Since the carbon atom has the capability of forming only four bonds, the bond present between the carbon atom and the chlorine atom has to break. This bond breaks easily because of the electronegativity difference between the two atoms and the polar nature of the bond. This finally results in the formation of the final product, that is, phenyl benzoate.
The conditions of the Schotten-Baumann reaction make it easy to perform benzoylation of phenols.
The same condition of Schotten-Baumann can also be used for carrying out benzoylation of aromatic amines, synthesizing amides from acid chlorides and amines wherein acyl chlorides are reacted with amines to produce amides.
Apart from the stated above, the reaction can also be used in the synthesis of various compounds and chemicals in the laboratory.
FAQs on Schotten Baumann Reaction in Organic Chemistry
1. What is the Schotten–Baumann reaction?
The Schotten–Baumann reaction is a method for preparing amides or esters by reacting an acid chloride with an amine or alcohol in the presence of a base. It is typically carried out in a biphasic system (aqueous base + organic solvent). For example:
C6H5COCl + C6H5NH2 + NaOH → C6H5CONHC6H5 + NaCl + H2O
This reaction is widely used for benzoylation of amines and alcohols in organic chemistry.
2. What is the purpose of the base in the Schotten–Baumann reaction?
The base in the Schotten–Baumann reaction neutralizes the HCl formed during acylation and drives the reaction forward. When an acid chloride reacts with an amine or alcohol, hydrogen chloride is produced as a by-product.
- The base (commonly NaOH or KOH) reacts with HCl to form salt and water.
- It prevents protonation of the amine, keeping it nucleophilic.
- It shifts equilibrium toward amide or ester formation.
3. How does the Schotten–Baumann reaction work?
The Schotten–Baumann reaction works through a nucleophilic acyl substitution mechanism. The reaction proceeds in the following steps:
- The amine or alcohol acts as a nucleophile and attacks the carbonyl carbon of the acid chloride.
- A tetrahedral intermediate is formed.
- Chloride ion (Cl−) leaves, forming the amide or ester.
- The base neutralizes the HCl produced.
4. What are the reactants used in the Schotten–Baumann reaction?
The main reactants in the Schotten–Baumann reaction are an acid chloride, an amine or alcohol, and an aqueous base. Specifically:
- Acid chloride (e.g., benzoyl chloride, C6H5COCl)
- Primary or secondary amine (for amide formation)
- Alcohol (for ester formation)
- Base such as NaOH or KOH
5. Can you give an example of the Schotten–Baumann reaction?
A classic example of the Schotten–Baumann reaction is the formation of benzanilide from benzoyl chloride and aniline. The balanced reaction is:
C6H5COCl + C6H5NH2 + NaOH → C6H5CONHC6H5 + NaCl + H2O
Here, benzoyl chloride reacts with aniline in the presence of sodium hydroxide to form the amide benzanilide.
6. What type of reaction is the Schotten–Baumann reaction?
The Schotten–Baumann reaction is a nucleophilic acyl substitution reaction involving an acid chloride. It belongs to the broader category of:
- Acylation reactions
- Condensation reactions (when forming amides or esters)
- Substitution reactions at the carbonyl carbon
7. What is the difference between the Schotten–Baumann reaction and simple acylation?
The key difference is that the Schotten–Baumann reaction is performed in the presence of an aqueous base to neutralize HCl, while simple acylation may occur without a biphasic basic medium. In detail:
- Schotten–Baumann uses acid chloride + amine/alcohol + aqueous base.
- It is typically carried out in a two-phase system.
- The base prevents protonation of the nucleophile.
8. Why is the Schotten–Baumann reaction carried out in a biphasic system?
The Schotten–Baumann reaction is carried out in a biphasic (aqueous–organic) system to improve reaction efficiency and neutralize HCl simultaneously. Typically:
- The acid chloride is dissolved in an organic solvent (like ether).
- The base (NaOH or KOH) is in the aqueous layer.
- The interface allows reaction while HCl is immediately neutralized.
9. What products are formed in the Schotten–Baumann reaction?
The main products of the Schotten–Baumann reaction are amides (from amines) or esters (from alcohols), along with salt and water. Generally:
- Acid chloride + amine → amide + HCl (neutralized to salt)
- Acid chloride + alcohol → ester + HCl (neutralized to salt)
10. What are the applications of the Schotten–Baumann reaction?
The Schotten–Baumann reaction is widely used for synthesizing amides and esters in laboratory and industrial organic chemistry. Its main applications include:
- Preparation of benzoyl derivatives for identification of amines and alcohols.
- Synthesis of pharmaceuticals and intermediates.
- Protection of amine functional groups via acylation.
- Production of fine chemicals and specialty materials.
