Preparation and application of 3-pyridine sulfonic acid_Industrial additives

Background and overview of the preparation and application of 3-pyridinesulfonic acid

3-Pyridinesulfonic acid can be used as an intermediate in organic synthesis, such as the preparation of 3-hydroxypyridine. 3-Pyridine sulfonic acid is an irritating substance that can irritate the eyes, respiratory system and skin. 3-hydroxypyridine is widely used in organic synthesis, medicine and dye preparation, and can be used as Pharmaceutical intermediates. 3-Pyridinesulfonic acid is a highly desirable compound in electroplating because of its ability to improve the precipitation properties of electrodeposition baths. 3-Pyridine sulfonic acid is also used as an intermediate product in the production of sulfonamides and other pharmaceutical preparations, and as a water-soluble reactive dye.

Preparation and application of 3-pyridine sulfonic acid

3-Pyridinesulfonic acid is prepared as follows:

1) Add 75g hydrogen peroxide (70% by weight) dropwise to 113.5g chloropyridine and 250ml acetic acid at 80°C within 3 hours, and stir at 80°C for 5 hours. After removal of the oxidant by adding sodium sulfite solution, the acetic acid/water was distilled in a water jet vacuum until the liquidus temperature rose to 80°C methoxypyridine. Add 334g sodium hydroxide (50% by weight) at 50°C. The product phase separation was taken up in 167 ml of toluene. (If three phases form, additional sodium hydroxide must be added). After phase separation, the basic phase is stirred with 167 ml of toluene and the combined organic phases are distilled in a manner known per se to remove the toluene, thereby obtaining 98-99% of 3-chloropyridine-N-oxide. . Analysis: Assay (Product): 98% to 99%. SO4: 0.2 to 0.5%. DC: 4 to 5 components.

2) Stir 3-chloropyridine-N-oxide, 252g of sodium sulfite and 700ml of distilled water at 145°C for 17 hours. After the reaction, distill off a large amount of water and then distill it. The mixture was acidified at 70°C with 500 ml of concentrated hydrochloric acid. The suspension is stirred for half an hour and pyridine-3-sulfonic acid-N-oxide is recovered in a manner known per se by crystallization and drying, yielding pyridine-3-sulfonic acid-N-oxide in a yield of 76-80 .% of the rational melting point of synthetic mica at 247°C.

3) Dissolve 51g (0.29mol) pyridine-3-sulfonic acid-N-oxide in 200ml H2O, make the solution alkaline with 25g sodium hydroxide (50wt%), and mix with 5g Raney nickel. The reaction solution was heated to 95° C. in an autoclave and hydrogenated at 7 bar. After 3 hours, the hydrogenation was completed, the catalyst was removed, and the mother liquor was concentrated to dryness. Dissolve the residue in 140 ml of isopropyl alcohol and 150 ml of concentrated hydrochloric acid, and add 4 g of sodium chloride and 4 g of activated carbon. After stirring for 1 hour, the suspension was withdrawn and mixed with 240 ml of isopropyl alcohol. Pyridine-3-pyridine sulfonic acid precipitated in the form of white crystalline flakes with a chloride content of 0.06%.

Preparation and application of 3-pyridine sulfonic acid

3-pyridine sulfonic acid can be used to prepare 3-hydroxypyridine: the mixture of 3-pyridine sulfonic acid and alkaline substances is heated to a molten state. The heating temperature is 160°C, and then the temperature is raised for 2.5 hours. The heating temperature is The temperature is 250°C, and the pH value is adjusted to 9 with saturated sodium carbonate solution after cooling, and 3-hydroxypyridine is obtained after post-processing.