1. Basic Chemical Building Blocks (Intermediates) ...

1. Basic Chemical Building Blocks (Intermediates)
These are organic compounds that form the base structure of dyes.

Chemical Type Examples Purpose
Aromatic Amines Aniline, o-Toluidine, p-Toluidine For azo dye formation
Aromatic Hydrocarbons Benzene, Toluene, Naphthalene Starting point for sulfonation/nitration
Phenols Phenol, Resorcinol, α-Naphthol Used in acid and disperse dyes
Naphthols 1-Naphthol, 2-Naphthol For azo coupling reactions
Nitro Compounds Nitrobenzene, dinitrotoluene For reduction to amines

⚗️ 2. Functional Reagents
These help introduce specific dye properties.

Reagent Type Examples Purpose
Sulfonating Agents Oleum, Sulfuric acid Water solubility (acid dyes)
Diazotizing Agents Sodium nitrite + HCl Diazotization of aromatic amines
Coupling Agents β-Naphthol, Phenol derivatives Azo dye coupling
Alkalis Sodium carbonate, Caustic soda Neutralization or pH control
Oxidizing Agents Sodium dichromate, potassium permanganate Used in vat and sulfur dyes
Reducing Agents Sodium hydrosulfite, glucose Vat dyes and sulfur dye solubilization

🧪 3. Solvents & Carriers
Used to dissolve or transport intermediates during reactions.

Water – Primary solvent

Alcohols – Methanol, Ethanol (for solubilization)

Acetic Acid – As buffer in dye baths

Benzene / Toluene – Organic reactions (now limited due to toxicity)

🌿 4. Natural Raw Materials (used in eco-friendly dyes)
Indigo – From Indigofera plant (now also synthetic)

Henna (Lawsone) – Natural dye for skin/hair

Turmeric (Curcumin) – Yellow dye

Madder Root – Alizarin red

Logwood, Walnut husks – Tannins and dark shades

🌈 5. Dye-Specific Raw Materials
Dye Class Raw Materials Needed
Azo Dyes Aromatic amines + coupling components (like phenols)
Vat Dyes Indigo, Anthraquinone + reducing agents
Reactive Dyes Cyanuric chloride, Vinyl sulfone
Sulfur Dyes Aromatic amines + sulfur + sodium sulfide
Disperse Dyes Mono/di amino benzene derivatives + esters or ketones
Acid Dyes Aromatic amines + sulfonated intermediates

📦 Additives and Finishers
Leveling agents – Ensure even dyeing

Fixing agents – Improve fastness

Softening agents – Improve feel of fabric