Intermediates: Dye (pigment) intermediates are an extremely important branch of the fine chemical industry. The rapid development of the dye (pigment) industry depends on the development of supporting intermediates. The production of dye and pigment intermediates in my country has made great progress since the 1950s. As market competition becomes increasingly fierce, dye and pigment intermediates have made innovations in production technology; in developing new varieties and improving production Breakthroughs have been made in several aspects such as technology, research on new methods, new uses of old varieties, and environmental protection. Clean processes are used for intermediate production of dyes and pigments.
1 Development of use of intermediates
In fact, the use of intermediates is developed in many aspects. A certain kind of intermediate used in dyes is called dye intermediates, and used in pesticides and medicines is also called pesticides and pharmaceutical intermediates. Intermediates should be considered as a whole branch of the fine chemical industry and should not be rigidly divided into dye intermediates, pesticide intermediates, and pharmaceutical intermediates by industry. This will reduce the scope of use of some intermediates and affect their development.
The research on fine chemical intermediates is characterized by a wide variety of varieties. Except for a few varieties with extremely large production scales, 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” are also generated during production and need to be properly dealt with. Therefore, we should conduct process research on serialized products and rationally organize the production of intermediates to achieve good economies of scale.
Judging from the situation abroad, the research and production of intermediates tend to be appropriately centralized to achieve serial production. A set of production equipment can produce several to more than a dozen varieties of intermediates. Such research and production will be easier to implement through overall development and new technologies, and will achieve twice the result with half the effort. The situation in Japan can be used as a reference. The original production of intermediates in Japan was also very scattered. It has been adjusted and centralized seven times since the 1960s.
Through transformation and development, my country’s dye and pigment intermediates industry has reached a higher level in terms of production scale, technology, equipment level, etc., which can not only meet the needs of domestic dye and pigment intermediates meet the needs of industry development and can provide more high-quality intermediate products to foreign countries.
The raw materials required for the synthesis of intermediates are mainly obtained from the products of the petroleum and coking chemical industries. Most of them are benzene, naphthalene, and anthraquinone compounds, and some Some heterocyclic compounds, organic pigments prepared from heterocyclic compound intermediates have been on the rise in recent years. In addition, when complex raw materials such as phenanthrene, pyridine, oxofluorene, quinoline, indole, carbazole, and biphenyl series compounds are used in dye manufacturing, the use of synthetic raw materials will become more extensive and common.
2 The most commonly used chemical reactions of intermediates
The most commonly used chemical reactions for processing raw materials into intermediates in the dye (pigment) industry are as follows:
(1) Sulfonation reaction
(2) Nitration reaction
(3) Halogenation reaction
(4) Reduction Reaction to prepare amino groups
(5) Diazotization reaction (often accompanied by coupling reaction)
(6) Alkali fusion The reaction replaces the sulfonic acid group with a hydroxyl group
(7) Acylation reaction
(8) Oxidation reaction
(9) Condensation and carbonation reaction
(10) Aromatization reaction (mainly amino group)
(11) Mutual replacement reaction of hydroxyl group and amino group
(12) Alkylation reaction of hydroxyl group or amino group
According to The main aromatic ring structure of fine chemical intermediates can be divided into aliphatic, benzene, naphthalene, anthraquinone, heterocyclic and fused ring systems. Our country can produce more than 400 varieties of dye and pigment intermediates such as benzene series, naphthalene series, anthraquinone series and heterocyclic series, which can basically meet the development needs of the dye and pigment industry.
3 Main varieties of benzene series
2,4-dinitrochlorobenzene, o-nitrochlorobenzene, p-nitrochlorobenzene, p-nitrophenol, N, N-dimethylaniline, p-aminoanisole, p-nitroaniline, o-methyl Aniline, 2-bromo-6-chloro-p-nitroaniline, N-ethylaniline, m-hydroxydiethylaniline, 2,4-dinitro-6-bromoaniline, o-m, p-phenylenediamine, 3,3 -Dichlorobenzidine, dianisidine, p-aminobenzene sulfonic acid, o-, p-aminoanisole, DSD acid, p-aminoanisole, CTL acid, o-cyano-p-nitroaniline, acetoacetyl-o-methoxy Aniline, hydroquinone, m-phenylenediamine, N-methyl m-toluidine, N-ethyl m-toluidine, N, N-dimethyl m-toluidine, N, N-diethyl m-toluidine, N-methylhydroxyethyl m-toluidine, N-ethylhydroxyethyl m-toluidine, N-methylcyanoethyl m-toluidine, N-ethylcyanoethyl m-toluidine, N-methylphenyl m-toluidine, p-methyl, ethoxyaniline, 2-4-dimethylaniline, 4-chloro-3-aminobenzamide, 4-methyl-3-aminobenzamide, 4-methoxy- 3-Aminobenzoylanilide, 4-methoxy-3-amino-N,N-diethylbenzenesulfonamide, 2,4,5-trichloroaniline, m- and p-esters, etc.
4 Main varieties of naphthalene series intermediates
2-Naphthol, H-acid, K-acid, 2,3-acid, 2,6-acid, Tobaic acid, 6-nitro-1,2,4 acid oxyform, J-acid, Peripheral acid, γ-acid, G-salt, R-salt, amino K-acid, 2-naphthylamine-1,5-disulfonic acid, 1-naphthol-5-sulfonic acid, 1,5-dihydroxy Naphthalene, 2,6-naphthalenedicarboxylic acid, 2R-acid, etc. �The main varieties of quinone series intermediates are: anthraquinone, 1-aminoanthraquinone, 1,4-diaminanthraquinone, bromoacid 1,5-dimethylanthraquinone, 1,5-diaminanthraquinone, 1 -Amino-5-benzoylanthraquinone, 1,5-dihydroxyanthraquinone, 1,8-hydroxyanthraquinone, 1,8-dihydroxy-4,5diaminoanthraquinone, etc.
5 Main varieties of heterocyclic and condensed ring systems
Cyanogen chloride, barbituric acid, 2-amino-6-nitrobenzothiazole, 2-amino-5,6-dichlorobenzothiazole, 2-aminothiazole, dehydrogenated sulfide Substituted p-toluidine disulfonic acid, 3-cyano-4-methyl-6-hydroxy-N-ethylpyridone, 3-formamido-4-methyl-6-hydroxy-N-ethylpyridone , 4-chloro-1,8-naphthalene anhydride, naphthalenetetracarboxylic anhydride, !tetracarboxylic anhydride, etc. </p
