In the next 5-10 years, the scale process of China’s chemical industry will end and the process of refinement will accelerate. At present, many domestic research institutions, especially those under the leading enterprises, are increasing their investment in the research and development of fine chemicals.
For the development direction of fine chemicals in China, one is to use low carbon hydrocarbons as raw materials for deep processing direction research, downstream mostly concentrated in pharmaceutical intermediates, pesticide intermediates and other fields. The second is for the deep processing and utilization of multi-carbon hydrocarbons, and the downstream is in the fields of high-end fine chemical materials and auxiliaries; the third is for the separation and purification of high-carbon hydrocarbon raw materials and deep processing and utilization, and the downstream is in the fields of surfactants and plasticizers.
In terms of cost latitude, the extension of fine chemicals for low carbon raw materials is the lowest cost way for production and research at present. At present, several research institutions in China are actively extending the fine chemical research for low carbon hydrocarbons. The representative products are the fine chemical extension of isobutylene industry chain and the fine chemical industry chain extension of aniline industry chain.
There are more than 50 kinds of fine chemical industry chain extensions downstream of high-purity isobutylene, and the industry chain refinement rate of downstream products is high. There are more than 60 kinds of fine chemical industry chain extensions downstream of aniline, and there are many downstream application directions.
Aniline is currently mainly produced by nitrobenzene catalytic hydrogenation, which is the hydrogenation production of nitric acid, hydrogen and pure benzene as raw materials, with downstream applications in MDI, rubber additives, dyestuff and pharmaceutical intermediates, gasoline additives, etc. Pure benzene in refining and chemical production enterprises cannot be used for oil blending, prompting the extension and utilization of the downstream industry chain of pure benzene to become a key direction of concern for the chemical R&D industry at present.
According to the different industries in which p-aniline downstream products are applied, they can be roughly divided into the following industries: First, they are applied in the field of rubber accelerators and antioxidants, and can be roughly divided into five products, which are p-aminodiphenylamine, p-hydroquinone, diphenylamine, cyclohexylamine and dicyclohexylamine. Most of these aniline products are used in the field of rubber antioxidants, such as para-aminodiphenylamine can produce antioxidants 4050, 688, 8PPD, 3100D, etc.
Consumption in the field of rubber accelerator and antioxidant is an important consumption direction of aniline downstream in the field of rubber, accounting for about 11% or more of the total consumption of aniline downstream, with the main representative products being p-aminodiphenylamine and hydroquinone.
Among the diazo compounds, using products such as aniline and nitrate, products such as p-aminoazobenzene hydrochloride, p-hydroxyaniline, p-hydroxyazobenzene, phenylhydrazine, and fluorobenzene can be produced. These products, are widely used in the fields of intermediates of dyestuffs, pharmaceuticals and pesticides, etc. Representative products include: p-aminoazobenzene hydrochloride, which is used to synthesize azo dyes, umphaline dyes, disperse dyes, and also used in the manufacture of paints and pigments and as indicators. P-hydroxyaniline is used in the production of blue sulfide FBG, weak acid yellow 5G and other dyes, paracetamol, Antoine and other drugs, also used in the production of contrast agents, antioxidants, etc.
At present, the aniline compounds used in China’s dye industry are mostly p-aminoazobenzene hydrochloride and p-hydroxyaniline, which account for about 1% of the downstream consumption of aniline, an important application direction in the nitrogen compounds in the downstream of aniline, and an important direction for the current industry technology research.
Another important downstream application of aniline is the halogenation of aniline, such as the production of p-iodoaniline, o-chloroaniline, 2.4.6-trichloroaniline, N-acetoacetanilide, N-formylaniline, phenylurea, diphenylurea, phenylthiourea, and other products.Due to the numerous reaction products of aniline halogenation, it is initially estimated that there are nearly 20 kinds, which has become an important direction for the extension of the downstream fine chemical industry chain of aniline.
Using the downstream products of aniline halogenation, such as o-chloroaniline, is used to produce dyes such as blue sulfide FBG, weak acid tender yellow 5G, and manufacture drugs such as paracetamol and Antomin, and also used to make contrast agents, antioxidants, etc. Diphenylthiourea is used to produce vulcanization accelerator, vulcanization capsule, water tire, wire and cable, as well as pharmaceutical and dye intermediates. n-Acetoacetanilide is used to produce sulfa drugs, painkillers, antipyretic ice and antiseptic, as well as rubber vulcanization accelerator, etc.
The number of downstream aniline fine chemicals of aniline halogenation accounts for about 40% of the number of downstream chemicals of aniline, but the products are mostly applied in high-end fields and the overall scale is not large. With the booming development of pharmaceutical field, the technology research of aniline halogenation has become an important development direction of technology R&D in China.
Another important reaction of aniline is the reduction reaction, such as aniline and hydrogen to produce cyclohexylamine, aniline and concentrated sulfuric acid and soda ash to produce dicyclohexane, and aniline and sulfuric acid and sulfur trioxide to produce p-aminobenzenesulfonic acid. Such reactions, which require numerous auxiliary materials and a small number of downstream products, are roughly estimated to have about five products.
Among them, such as p-aminobenzenesulfonic acid, the manufacture of azo dyes, etc., used as benchmark reagents, experimental reagents and chromatographic analysis reagents, can also be used as a pesticide to prevent and control wheat rust. Dicyclohexylamine, is the preparation of dye intermediates, as well as pesticides textile wheat rust, and the preparation of spices, etc.
The reduction reaction conditions of aniline are relatively harsh, and it is currently concentrated in the laboratory and small-scale production stage in China, with a very small consumption share, which is not the main direction for the extension of the downstream fine chemical industry chain of aniline.
The fine chemical industry chain using aniline as raw material extends to aromatization reactions, alkylation reactions, oxidation and nitration reactions, cyclization reactions, aldehyde condensation reactions and complex chemistry reactions. There are many chemical reactions in which aniline can be involved, and many downstream applications.
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