Preparation and use of 2-bromo-3-methylpyridine_Industrial additives

Background and overview of the preparation and use of 2-bromo-3-methylpyridine

2-Bromo-3-methylpyridine is a halomethylpyridine compound. Halogenated methylpyridines are important fine chemical intermediates and are widely used in the fields of medicine and pesticides. Halopyridines containing bromine and iodine are widely used in pesticides, medicines, functional materials and other fields.

Physical and chemical properties of 2-bromo-3-methylpyridine

Bright brown liquid, boiling point: 218-219℃.

Preparation and uses of 2-bromo-3-methylpyridine

Preparation and use of 2-bromo-3-methylpyridine 1. 2-bromo-3-iodopyridine is produced by halogenation reaction from 2-bromopyridine as raw material

Dissolve 2,2,6,6-tetramethylpiperidine (10.9g, 69mmol, 1.1eq) in tetrahydrofuran (40mL). After the system is replaced with nitrogen three times, it is cooled to below -20°C and added to the system. Add n-butyllithium (32mL, 69mmol, 1.1eq) dropwise. During the dripping process, a large amount of methoxypyridine will exotherm and outgas. The temperature should not exceed -20°C. After the dropwise addition, the temperature should be controlled below -70°C. React for 1 hour, add 2-bromopyridine (10.0g, 63mmol, 1.0eq) dropwise, complete the addition, control the temperature at -70~-60°C and react for 2h, then add 1M anhydrous zinc chloride in tetrahydrofuran solution (69mL, 69mmol, 1.1eq), continue the reaction for 1 hour after the addition is completed. Add dropwise a mixed solution of iodine (24.0g, 95mmol, 1.5eq) and tetrahydrofuran (50mL), and continue the reaction for 0.5h. Monitoring shows that there is less raw material remaining, stop the reaction, naturally rise to room temperature, add 100 mL of saturated aqueous ammonium chloride solution, extract the product twice with 200 ml of ethyl acetate, combine the organic phases, add anhydrous sodium sulfate to dry, filter, and spin the filtrate to obtain 17.5g thick solid. The solid was added to 40 mL of cyclohexane and the temperature was raised to 70°C and stirred for 1 h. After the system was naturally cooled to room temperature, it was further cooled to 5-10°C for crystallization for 1 hour. Filter, wash the filter cake with cyclohexane (2×10 mL), and then dry the filter cake to a constant weight at 40°C in a blast drying oven. After weighing, 9.8g of light yellow solid was obtained, with a yield of 55% and a purity of 94.8%.

Preparation and use of 2-bromo-3-methylpyridine 2. Reaction of 2-bromo-3-iodopyridine as raw material to generate 2-bromo-3-methylpyridine

Dissolve 2-bromo-3-iodopyridine (10g, 35mmol, 1.0eq) in THF (100mL, 10vol), stir until completely dissolved, warm to -70°C, and add n-BuLi in n-hexane dropwise Solution (14mL, 35mmol, 1.0eq), after the dropwise addition, stir for 10min, then add methyl iodide (15g, 105mmol, 3.0eq) dropwise, continue stirring for 30min, TLC shows that there is no remaining raw material, raise the temperature to 0°C, slowly add 50mL dropwise The reaction was quenched with saturated sodium bisulfite aqueous solution, and the reaction system was naturally raised to room temperature. Ethyl acetate (100 mL × 2) was added for extraction. The organic phases were combined, washed with 25% sodium chloride aqueous solution (100 mL), and allowed to stand for separation. liquid, the organic phase was concentrated under reduced pressure until no liquid came out, and weighed to obtain 1.8g of liquid, namely 2-bromo-3-methylpyridine, with a yield of 30%.

Preparation and uses of 2-bromo-3-methylpyridine

Preparation and uses of 2-bromo-3-methylpyridine Application 1.

CN201710234455.3 reports a preparation method of 2-cyano-5-hydroxypyridine. This method uses 2-bromo-5-nitropyridine, NaCN, CuCN, dimethylformamide and KH2PO4 as starting materials to first generate 2-cyano-5-nitropyridine; then add ethyl acetate and An appropriate amount of reduced Fe powder and a sufficient amount of acetic acid are added; finally, an appropriate amount of H2SO4 solution and NaNO2 are added, filtered and dried to finally obtain an orange solid 2-cyano-5-hydroxypyridine. This method has easy-to-obtain raw materials, mild reaction conditions, low cost, and is suitable for large-scale factory production.

Preparation and uses of 2-bromo-3-methylpyridine 2.

CN201711461109.5 discloses a glass plate immobilizing ammonia-oxidizing bacteria. After cleaning the glass plate, it is modified with a mixture prepared by potassium hydrogen tartrate, potassium tert-butoxide, agarose, and potassium hydrogen phthalate to obtain substance A; substance A is treated with 2-chloro-3 neodymium carbonate dihydrate-cyano group The mixture prepared by pyrazine, 2-bromo-5-nitropyridine and 4-bromotetrahydropyran was modified to obtain substance B; substance B was prepared by tetrahydrothiopyran-4-one and 1-aminoanthraquinone. After modification of the mixed solution, substance C is obtained; after immobilizing ammonia-oxidizing bacteria on substance C, the substance obtained is a glass plate with immobilized ammonia-oxidizing bacteria. The beneficial effect of the present invention is that the prepared glass plate immobilized with ammonia-oxidizing bacteria has the function of high bacterial activity and efficient degradation of ammonia nitrogen in wastewater.

References

[1] [Chinese invention] CN202011084475.5 A synthesis process of 2-bromo-4-iodo-3-methylpyridine

[2] Preparation method of CN201710234455.32-cyano-5-hydroxypyridine

[3] CN201711461109.5 Glass plate for immobilizing ammonia-oxidizing bacteria and preparation method thereof