Devise a synthesis of "Diamine Green B" based on nitrobenzene, aniline, phenol, and H-acid.

To begin the synthesis, first convert nitrobenzene into m-phenylenediamine. This can be done through a reduction reaction followed by an ammonolysis reaction. 1. Reduction of nitrobenzene to aniline: Reduce nitrobenzene (\(C_6 H_5 NO_2\)) to aniline (\(C_6 H_5 NH_2\)) by using a reducing agent like tin (Sn) and hydrochloric acid (HCl). This process usually involves boiling the reaction mixture for several hours. The reaction is: \[ C_6 H_5 NO_2 + 3Sn/HCl ⟶ C_6 H_5 NH_2 + 3SnCl_2 + H_2 O\] 2. Ammonolysis of aniline to form m-Phenylenediamine: In a subsequent step, react the aniline with ammonia (\(NH_3\)) under pressure in the presence of a catalyst like copper chromite (CuCrO_4). Then, separate m-phenylenediamine by fractional crystallization. The overall reaction is: \[ 2 C_6 H_5 NH_2 + NH_3 ⟶ NH_2 - C_6 H_4 - NH_2 \] Now we have m-phenylenediamine as an intermediate product.

Next, we need to synthesize H-acid, which is 8-amino-1-naphthol-3,6-disulfonic acid. To do this, we'll need to convert aniline and phenol into intermediate products and then react them together. 1. Sulfonate aniline to form p-anilinesulfonic acid: React aniline (\(C_6 H_5 NH_2\)) with concentrated sulfuric acid (H2SO4) to introduce a sulfonate group (\(-SO_3 H\)) on the para-position. The reaction is: \[ C_6 H_5 NH_2 + H_2 SO_4 ⟶ C_6 H_4 (NH_2)(SO_3 H) + H_2 O\] 2. Oxidize phenol to form 1,4-naphthoquinone: React phenol (\(C_6 H_5 OH\)) with an oxidizing agent like chromium trioxide (CrO3) to transform it into 1,4-naphthoquinone. The reaction is: \[C_6 H_5 OH + 2CrO_3 ⟶ C_{10}H_6 O_2 + 2CrO_2\] 3. React p-anilinesulfonic acid with 1,4-naphthoquinone to form H-acid: In a suitable solvent like concentrated hydrochloric acid (HCl), mix p-anilinesulfonic acid and 1,4-naphthoquinone in a 1:1 stoichiometric ratio and react them over a few hours. This forms H-acid, 8-amino-1-naphthol-3,6-disulfonic acid: \[ C_6 H_4 (NH_2)(SO_3 H) + C_{10}H_6 O_2 ⟶ H-Acid\] Now we have H-acid as an intermediate product.

In this step, couple m-phenylenediamine with H-acid to form Diamine Green B. React them in a weak alkaline solution, such as sodium carbonate (Na2CO3), at room temperature under stirring: \[NH_2 - C_6 H_4 - NH_2 + H-Acid ⟶ Diamine Green B\] After this coupling reaction, a green precipitate is formed. Separate this product by filtration and dry it to obtain the Diamine Green B dye as the final product. Now we have successfully synthesized Diamine Green B using the given starting materials nitrobenzene, aniline, phenol, and H-acid in three synthesis steps.