Pivalic acid is one of the most widely used alkyl carboxylic acids, also known as 2,2-methylpropionic acid or trimethylacetic acid. It is an important chemical raw material and chemical reagent. Trimethylacetic acid is connected to a tertiary carbon atom due to its carbonyl functional group to form a stable molecular structure. It exhibits special and useful physical and chemical properties. It is used as an organic intermediate. Fine chemical synthesis has a wide range of applications.
1. Synthetic technique The carbonyl function of trimethylacetate is attached to the tertiary carbon atom, so the preparation method is different from the common fatty acid. There are more than a dozen kinds of literature synthesis processes, but industrialization or industrialization prospects are mainly: methyl imidi tert-butyl ketone haloform reaction; tert-butyl magnesium chloride and carbon dioxide reaction; isobutanol or tert-butanol and formic acid Reaction; Reppe reaction; Koch reaction. Among them, the first three methods have complex technological processes, high production costs, and low yields, and are not suitable for large-scale industrial production. They are only suitable for small-scale or laboratory production. The Reppe reaction is a conventional carboxylic acid preparation method. The Reppe reaction is reacted with an olefin, carbon monoxide, and water to obtain a normal or isomer mixture of carboxylic acids, but the ratio of trimethylacetic acid obtained by this method is relatively low, accounting for only 5 of the total production. About 10% of the production is only by producing other carboxylic acids and by-producing trimethylacetic acid. The Koch reaction is a high-pressure method for the reaction of olefins, carbon monoxide, and water to synthesize carboxylic acids by the acid-catalyzed reaction of DuPont, which uses isobutylene, carbon monoxide, and water as raw materials to prepare trimethylacetic acid with a yield of 70-80%. The purity of the product can reach 98%, so the Koch reaction has become the main method for the industrialization of trimethylacetic acid. The key to this process technology lies in the development of catalysts. Commonly used catalysts include sulfuric acid, phosphoric acid, hydrofluoric acid, BF3 catalysts, and solid acid catalysts. Among them, the foreign industrialized plants mainly use phosphoric acid and BF3 catalysts. Because the catalytic process of solid acid catalysts is easy to control, the corrosiveness is small, and the separation of products and catalysts is easy, it has become a hot spot in recent years and has considerable potential for development.
2. Trimethylacetic acid is mainly used for synthesizing polymer initiators, pesticide intermediates, pharmaceutical intermediates, plasticizers, food additives, coatings, lubricants, glycidol, dispersants, and perfumes, etc., also in the synthesis of fine chemical products. Wide range of applications.
The pivaloyl peroxide initiator prepared by the reaction of trimethylacetic acid chloride with tert-butyl peroxide is also known as the PV initiator. It is a high-efficiency initiator for high-pressure polyethylene, and it is also a polymerization of vinyl chloride, acrylate, vinyl acetate, etc. The high-efficient initiators are very stable compared with other initiators, and can be used in aqueous solutions of various pH values ​​and at low temperatures. As initiators, the polymers produced have good thermal stability, good electrical insulation properties, and no Poison, in the structure of the product has a large molecular weight and good linearity, has been widely used in foreign countries. In recent years, the new peroxide initiator synthesized by trimethylacetic acid in Japan has been used to hydrolyze tert-pivalyl peroxide (HPP). It can significantly shorten the polymerization reaction time, increase the production efficiency, and release the heat of polymerization reaction in PVC suspension production. The product appearance is good, the range of relative molecular mass is narrow, and the product quality is greatly improved. Every year, there are a large number of patent studies on trimethylglyoxal synthesizers in foreign countries. The development of new products emerges in an endless stream. Its use and market demand increase rapidly, and it has great potential for development.
Trimethylacetic acid is used in the pharmaceutical industry to produce ampicillin, amoxycillin, and cefazolin. The ampicillin is a new type of high-efficiency antibacterial agent. Its performance is superior to that of penicillin. It has bright prospects for development in China. Currently, there are nearly ten companies in China. Production, with a total production capacity of approximately 300 t/a, requires all raw materials of trimethylacetic acid to be imported. In addition, prednisone prepared by hydrogenation of trimethylacetic acid has good solubility, high curative effect and little side effects and can be used for treating rheumatoid arthritis. Benzoyl trimethyl acetic acid increases blood vessel stability and is used to treat active ingredients in psoriasis ointment. Trimethylacetic acid can also produce furazolidone, bis-pentaephrine and the like.
In the pesticide industry, quinalone, synthesized from trimethylacetate and acetone, is a very tight pesticide intermediate in China. Pinazone can synthesize many new types of fungicides, plant growth regulators, and insecticides. Such as triadimenol, benzyl trinidazole, triadimefon, paclobutrazol, bixaconazole, niconazole, ketrazolone, tebuconazole, thiazole, condensation azole, oxazolone, etc., these products have high efficiency , low toxicity, internal absorption, low-spectrum consumption, long residual period and other characteristics.
In the perfumery industry, trimethylacetates have anti-hydrolysis and certain aromatic odors and can be used as fragrance additives such as soaps, shampoos, and hair gels. Different esters have different aromas, and have the characteristics of pure fragrance, long fragrance, and not easy to decompose.
In the coating industry, polyacrylate coatings obtained using trimethylacetic acid as an initiator have anti-aging, gloss retention, and high gloss retention in harsh environments compared to coatings obtained using conventional initiators. Powder coating is favored because it does not use solvent. Glycidyl ester made of trimethylacetic acid is used as the treatment agent of epoxy resin powder coating. It can make powder coating have excellent color and luster, and it is durable and not easy to decompose.
In addition, trimethylacetic acid can be used to prepare aqueous polymer dispersants; trimethylacetic acid polyethylene glycol monoester can be used as a vehicle brake oil, and its lithium salt is used as an engine fuel additive to increase the octane number; The acetic acid and dicarbonic acid diester reactants are used as food and food preservatives, maintaining good stability to both hydrolysis and heat; trimethylacetic acid can also be used as metal extractants, wood preservatives, and the like.
3. It is suggested that China began to research and develop trimethylacetic acid since the 1970s. However, there is no industrialized production device yet, which limits the development and application of its downstream products. Currently, China imports a large amount of PV initiators and trimethyl Acetic acid is used for pharmaceutical production. With the development of China's petrochemical industry, the demand for trimethylacetic acid has increased rapidly, and there is a bright prospect for the development and production of trimethylacetic acid in China. Therefore, China's qualified petrochemical enterprises should establish a C5-C11 carboxylic acid production plant with a scale of 5000t/a to 10000t/a, and arrange production of trimethylacetic acid, isophthalic acid and other fine chemicals as required by market demand plans. acid. The Koch reaction is the preferred process and the development of solid acid catalysts that meet environmental requirements.
1. Synthetic technique The carbonyl function of trimethylacetate is attached to the tertiary carbon atom, so the preparation method is different from the common fatty acid. There are more than a dozen kinds of literature synthesis processes, but industrialization or industrialization prospects are mainly: methyl imidi tert-butyl ketone haloform reaction; tert-butyl magnesium chloride and carbon dioxide reaction; isobutanol or tert-butanol and formic acid Reaction; Reppe reaction; Koch reaction. Among them, the first three methods have complex technological processes, high production costs, and low yields, and are not suitable for large-scale industrial production. They are only suitable for small-scale or laboratory production. The Reppe reaction is a conventional carboxylic acid preparation method. The Reppe reaction is reacted with an olefin, carbon monoxide, and water to obtain a normal or isomer mixture of carboxylic acids, but the ratio of trimethylacetic acid obtained by this method is relatively low, accounting for only 5 of the total production. About 10% of the production is only by producing other carboxylic acids and by-producing trimethylacetic acid. The Koch reaction is a high-pressure method for the reaction of olefins, carbon monoxide, and water to synthesize carboxylic acids by the acid-catalyzed reaction of DuPont, which uses isobutylene, carbon monoxide, and water as raw materials to prepare trimethylacetic acid with a yield of 70-80%. The purity of the product can reach 98%, so the Koch reaction has become the main method for the industrialization of trimethylacetic acid. The key to this process technology lies in the development of catalysts. Commonly used catalysts include sulfuric acid, phosphoric acid, hydrofluoric acid, BF3 catalysts, and solid acid catalysts. Among them, the foreign industrialized plants mainly use phosphoric acid and BF3 catalysts. Because the catalytic process of solid acid catalysts is easy to control, the corrosiveness is small, and the separation of products and catalysts is easy, it has become a hot spot in recent years and has considerable potential for development.
2. Trimethylacetic acid is mainly used for synthesizing polymer initiators, pesticide intermediates, pharmaceutical intermediates, plasticizers, food additives, coatings, lubricants, glycidol, dispersants, and perfumes, etc., also in the synthesis of fine chemical products. Wide range of applications.
The pivaloyl peroxide initiator prepared by the reaction of trimethylacetic acid chloride with tert-butyl peroxide is also known as the PV initiator. It is a high-efficiency initiator for high-pressure polyethylene, and it is also a polymerization of vinyl chloride, acrylate, vinyl acetate, etc. The high-efficient initiators are very stable compared with other initiators, and can be used in aqueous solutions of various pH values ​​and at low temperatures. As initiators, the polymers produced have good thermal stability, good electrical insulation properties, and no Poison, in the structure of the product has a large molecular weight and good linearity, has been widely used in foreign countries. In recent years, the new peroxide initiator synthesized by trimethylacetic acid in Japan has been used to hydrolyze tert-pivalyl peroxide (HPP). It can significantly shorten the polymerization reaction time, increase the production efficiency, and release the heat of polymerization reaction in PVC suspension production. The product appearance is good, the range of relative molecular mass is narrow, and the product quality is greatly improved. Every year, there are a large number of patent studies on trimethylglyoxal synthesizers in foreign countries. The development of new products emerges in an endless stream. Its use and market demand increase rapidly, and it has great potential for development.
Trimethylacetic acid is used in the pharmaceutical industry to produce ampicillin, amoxycillin, and cefazolin. The ampicillin is a new type of high-efficiency antibacterial agent. Its performance is superior to that of penicillin. It has bright prospects for development in China. Currently, there are nearly ten companies in China. Production, with a total production capacity of approximately 300 t/a, requires all raw materials of trimethylacetic acid to be imported. In addition, prednisone prepared by hydrogenation of trimethylacetic acid has good solubility, high curative effect and little side effects and can be used for treating rheumatoid arthritis. Benzoyl trimethyl acetic acid increases blood vessel stability and is used to treat active ingredients in psoriasis ointment. Trimethylacetic acid can also produce furazolidone, bis-pentaephrine and the like.
In the pesticide industry, quinalone, synthesized from trimethylacetate and acetone, is a very tight pesticide intermediate in China. Pinazone can synthesize many new types of fungicides, plant growth regulators, and insecticides. Such as triadimenol, benzyl trinidazole, triadimefon, paclobutrazol, bixaconazole, niconazole, ketrazolone, tebuconazole, thiazole, condensation azole, oxazolone, etc., these products have high efficiency , low toxicity, internal absorption, low-spectrum consumption, long residual period and other characteristics.
In the perfumery industry, trimethylacetates have anti-hydrolysis and certain aromatic odors and can be used as fragrance additives such as soaps, shampoos, and hair gels. Different esters have different aromas, and have the characteristics of pure fragrance, long fragrance, and not easy to decompose.
In the coating industry, polyacrylate coatings obtained using trimethylacetic acid as an initiator have anti-aging, gloss retention, and high gloss retention in harsh environments compared to coatings obtained using conventional initiators. Powder coating is favored because it does not use solvent. Glycidyl ester made of trimethylacetic acid is used as the treatment agent of epoxy resin powder coating. It can make powder coating have excellent color and luster, and it is durable and not easy to decompose.
In addition, trimethylacetic acid can be used to prepare aqueous polymer dispersants; trimethylacetic acid polyethylene glycol monoester can be used as a vehicle brake oil, and its lithium salt is used as an engine fuel additive to increase the octane number; The acetic acid and dicarbonic acid diester reactants are used as food and food preservatives, maintaining good stability to both hydrolysis and heat; trimethylacetic acid can also be used as metal extractants, wood preservatives, and the like.
3. It is suggested that China began to research and develop trimethylacetic acid since the 1970s. However, there is no industrialized production device yet, which limits the development and application of its downstream products. Currently, China imports a large amount of PV initiators and trimethyl Acetic acid is used for pharmaceutical production. With the development of China's petrochemical industry, the demand for trimethylacetic acid has increased rapidly, and there is a bright prospect for the development and production of trimethylacetic acid in China. Therefore, China's qualified petrochemical enterprises should establish a C5-C11 carboxylic acid production plant with a scale of 5000t/a to 10000t/a, and arrange production of trimethylacetic acid, isophthalic acid and other fine chemicals as required by market demand plans. acid. The Koch reaction is the preferred process and the development of solid acid catalysts that meet environmental requirements.
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