Preparation of Yellow Aniline

Our Objective 

Preparation of aniline yellow 


The Theory 

What is Organic Chemistry? 

Organic chemistry is a discipline of chemistry that studies the structure, characteristics, reactions, and synthesis of organic molecules. Because carbon and hydrogen are key components of all organic substances, they are referred to as hydrocarbons. Organic compounds contain components other than carbon and hydrogen, such as oxygen, sulphur, nitrogen, and halogens. These are classified as hydrocarbon derivatives. 

Organic Synthesis 

Organic synthesis is a branch of chemical synthesis that deals with the deliberate creation of organic molecules. Because organic molecules are frequently more complicated than inorganic ones, their synthesis has evolved into one of the most significant disciplines of organic chemistry. Within the broad field of organic synthesis, there are three major study areas: total synthesis, semi synthesis, and methodology. 

Aniline Yellow is an aromatic amine and a yellow azo dye. It is an azobenzene derivative. It appears to be an orange powder. The first azo dye was aniline yellow. C. Mene created it for the first time in 1861. Bismarck Brown was the second azo dye introduced in 1863. Aniline Yellow became the first commercial azo dye in 1864, a year after Aniline Black. It is derived from aniline. 

Aniline yellow is a volatile chemical that serves as a catalyst in the creation of other colours. It is formed through the reaction of benzene diazonium chloride with phenylamine, which is also known as aniline. In the first stage, aniline acts as a nucleophile, interacting with benzene diazonium chloride to form a C-N bond. The azo dye is formed when the product loses its H+ and forms an aromatic ring. The reaction of benzene diazonium chloride with aniline produces aniline yellow (para-amino azobenzene) in an acidic media. Because it is an acid-sensitive dye, it has little industrial significance. 

Step 1: Ar-NH2 + NaNO2 + HCl → Ar-N2 + -Cl-  

Step 2: Ar-N2 + - Cl- + Ar-NH2 → Ar-N=N-NH-Ar 

Step 3: Ar-N=N-NH-Ar → Ar-N=N-Ar-NH2 (Aniline yellow) 

Uses of yellow aniline 

Aniline Yellow is used for vital staining in microscopy, in pyrotechnics for yellow-coloured smokes, and in yellow pigments and inks, especially inks for inkjet printers. Insecticides, lacquers, varnishes, waxes, oil stains, and styrene resins are also made from it. It is also used as an intermediary in the production of other dyes such as chrysoidine, indulines, Solid Yellow, and Acid Yellow. 

Synthesis Design 

Elias James Corey was awarded the Nobel Prize in Chemistry in 1990 for developing a more formal method to synthesis design based on retrosynthetic analysis. The synthesis is planned backwards from the product utilising established guidelines in this technique. The procedures for "breaking down" the parent structure into manageable component pieces are depicted graphically using retrosynthetic. 


Learning Outcomes 

  • Students understand the concepts of organic compounds, classification of organic compounds, functional groups, substitution, addition, elimination and rearrangement reactions. 
  • They will be able to understand the diazotisation mechanism. 
  • Students understand the chemicals required for the preparation of the above compounds. 
  • Students understand important safety precautions before using hazardous chemicals.