The dye industry is an industry with a relatively long history in the fine chemical industry, which is related to many fields of the national economy, such as textiles, inks, rubber, plastics, leather, stationery, food and cosmetics, as well as some high-tech fields and so on. It can be said that the dye industry has enriched people's material and cultural life. Behind this, the branch of intermediates occupies an important position.

Intermediate

Intermediate intermediate, also known as organic intermediate, intermediate refers to semi-finished product, which is an intermediate product in the production of certain products. For example, to produce a product, it can be produced from the intermediate to save costs. called dye intermediates.

Where do dye intermediates come from

Dye intermediates generally refer to various aromatic hydrocarbon derivatives used in the production of dyes and organic pigments, mainly using aromatic hydrocarbons such as benzene, toluene, naphthalene and anthracene from coal chemical industry and petrochemical industry as basic raw materials, through a series of organic synthesis unit processes. and made.

The chemical reactions most commonly used to process raw materials into dye industry intermediates are as follows:

(1) Sulfonation reaction

(2) Nitrification reaction

(3) Halogenation reaction

(4) Reduction reaction to prepare amino group

(5) Diazotization reaction (often accompanied by coupling reaction)

(6) Substitute sulfonic acid group into hydroxyl group by alkali fusion reaction

(7) Acylation reaction

(8) Oxidation reaction

(9) Condensation and carbonation reaction

(10) Aromatization reaction (mainly amino)

(11) Mutual displacement reaction of hydroxyl and amino

(12) Hydrocarbonylation of hydroxyl or amino groups

According to the main aromatic ring structure of fine chemical intermediates, intermediates can be divided into aliphatic, benzene, naphthalene, anthraquinone, heterocyclic and fused ring systems. my country can produce more than 400 varieties of dyes and pigment intermediates such as benzene series, naphthalene series, anthraquinone series, heterocyclic series, etc., which can basically meet the development needs of dyeing and pigment industry.

Where do dye intermediates go

Dye intermediates are almost ubiquitous, red orange, yellow, green, blue, purple, and colors bring different splendor to the world. The application of dye intermediates is inseparable from the inconspicuous corners of our daily life.

o-Chlorobenzoic acid

o-Chlorobenzoic acid is an important intermediate in the pesticide, pharmaceutical and dye industries with a wide range of uses. It is used in the manufacture of chlorpromazine, anti-inflammatory spirits and other drugs, as a preservative for adhesives and coatings, and as a raw material for organic synthesis. Can be used for dyes and color films. Can also be used as a fungicide.

H acid

H acid is a chemical substance mainly used in the production of acid, direct and reactive dyes, such as acid magenta 6B, acid scarlet G, acid black 10B, direct black, reactive brilliant red K-2BP, reactive violet K-3R, reactive More than 90 kinds of soluble blue K-R, these dyes are used for dyeing wool and cotton fabrics. It can also be used to produce medicines.

2-Naphthol

It is an organic synthesis raw material and dye intermediate, which is used in the manufacture of torus acid, butyric acid, β-naphthol-3-carboxylic acid and azo dyes. It is also a raw material for rubber antioxidants, mineral dressing agents, fungicides, mildew inhibitors, preservatives, parasite control and anthelmintic drugs. It is also used in spices, leather tanning agents, textile printing and dyeing auxiliaries, etc.

9,10-Anthraquinone

Also known as anthraquinone, English name Anthraquinone, yellow needle-like crystals, used as dye intermediates, papermaking cooking agents and hydrogen peroxide raw materials.

Development and use of intermediates

But on the other hand, the development of the use of intermediates is multi-faceted. A certain intermediate used in dyes is called dye intermediates, while those used in pesticides and medicines are also called pesticides and pharmaceutical intermediates. Rigid division into dye intermediates, pesticide intermediates, and pharmaceutical intermediates by industry is too restrictive, which will reduce the scope of use of some intermediates and affect their development. Intermediates should be considered as a whole branch of the fine chemical industry.

 The research on fine chemical intermediates is characterized by a wide variety. Except for a few varieties whose production scale is particularly large, most varieties are not very large in tonnage, but the preparation process is often complicated, involving many unit reactions and separation processes. A considerable amount of "three wastes" need to be properly disposed of. Therefore, the process research of serialized products should be carried out, and the production of intermediates should be rationally organized in order to obtain good scale benefits.