Coupling reaction occur when two fragments are joined together in the presence of a matel.
What is coupling reaction?
In organic chemistry, a coupling reaction is a one type of chemical reaction in which when 2 fragments are joined together in the presence of a matel.
The best examples of coupling reaction is wurty reaction.
When both alkyl and halides are different.
Benzene diazonium (cation) is a weak electrofile. they react with highly reactive aromatic compound. such as,
Highly reactive aromatic compound – phenol or Amines
Benzene diazonium cation are react with highly reactive aromatic compound, (phenol) then as a result p – hydroxyazobenzene are formed.
Coupling reaction examples
1. Di – Azo coupling reaction
Here, we are going to discuss about chemical reaction of di-azo coupling reaction. And we are also discuss about dye formations.
There are main three important dye formation are learn and also discuss about dye mechanism.
- Phenol orange dye
- Aniline yellow dye
- Napthole red dye
Now, first discuss about reaction and then discuss about mechanism.
a. Phenol orange dye
Preparation of phenol orange dye, when aniline react with in the presence of NaNo2/HCl at the temperature 0-5°C. As a result azo component is formed. Or orange azo dye is formed. this azo dye is know as phenol orange dye. reaction of phenol orange dye is given below.
In this reaction, it gives benzene diazonium chloride. and after this, reaction is carried out with phenol. and after this coloring compound is formed. this mean, azo coloring compound is formed and it gives orange azo dye. it is also known as phenol orange dye.
b. Aniline yellow dye
When aniline solution is react with benzene diazonium chloride then result is yellow azo components or dye are formed. You can understand properly with the help of chemical reaction. the chemical reaction of aniline yellow dye is given below.
Azo – N reaction with aniline:
In this process, Aniline is directly react with benzene diazonium chloride, as a result azo component or yellow azo dye is formed. but it required to maintain ph >7.
c. Napthole red dye
When nepthole is react with benzene diazonium chloride then as a result red azo component or dye is formed. this azo dye is known as napthole red dye.
2. Suzuki Coupling reaction
Commonly refered to as the suzuki cross – coupling.
Palladium catalyzed cross – coupling between organobron compound and organic halides leading to the formation of carbon – carbon bonds.
3. Heck coupling reaction
The heck reaction is the chemical reaction of an saturated halide (R’ – X) with an alkene in the presence of catalyst palladium catalysts (pd) as a result substituted alkene is formed.
In this chemical reaction, Heck chemical reaction produce substituted alkane. When saturated halide with alkane in the presence of catalysts (pd) then substituted alkane is formed as a final product.
4. Stille coupling reaction
The stille coupling reaction is also know as C-C bond forming reaction between stannanes Or halids. In this reaction, palladium catalysts is use as a catalysts. it can be used 18 or 16 electrons as a source of catalysts. but some limitations on R groups.