CN104402812A - Synthetic method for pyridinecarboxylic acid - Google Patents

Abstract

The invention discloses a method for synthesizing picolinic acid. The treatment method comprises: heating an alkylpyridine to 300-450 DEG C on a fixed bed, and turning all of it into steam after 3 hours of continuous heating. Fully react the pyridine steam with ammonia, water vapor and oxygen, and let it stand in the container for half an hour. Add titanium tetrachloride to the gas for catalysis, and wait for 2 hours to obtain pyridinecarbonitrile. Add 1.2 g of deionized water to the obtained pyridinecarbonitrile and start stirring, heat up to 40-70°C, add NaOH, stir, heat up to 80-95°C, and keep warm for 4-12 hours. After finishing the reaction, lower the temperature to 30-60° C., filter, wash with deionized water, and dry to obtain 10 g of solid powder. Yield: 83.3%. The problem of environmental pollution in the traditional method is avoided, the yield is greatly improved, and the reaction can be performed at normal temperature and pressure or under low pressure.

Description

A kind of method for synthesizing picolinic acid

technical field

The invention belongs to the field of organic chemical synthesis and relates to a synthesis method of picolinic acid. the

Background technique

The molecular formula of picolinic acid is: C ₅ H ₅ NO ₂ . It has both Lewis acid and Lewis basic functional groups in structure, and is a typical heterocyclic amphoteric compound. Picolinic acid series are widely used in medicine, chemical industry, food and life, and have irreplaceable functions and values. Therefore, scholars and experts at home and abroad have carried out a lot of research on the synthesis of picolinic acid. Picolinic acid includes a, B, and 7 three isomers: picolinic acid, nicotinic acid and isonicotinic acid. The traditional method for synthesizing picolinic acid is: gas-phase catalytic oxidation. It is based on the vaporization of alkylpyridine at high temperature, mixing with air and water vapor, and directly oxidizing into picolinic acid through a catalyst bed. The catalyst in this method has high requirements on the purity of raw materials, and it is easy to produce tar and poisonous gas, causing environmental pollution.

Contents of the invention

In order to solve the problem of easy generation of environmental pollution existing in the prior art, the invention provides a method for synthesizing picolinic acid, using the method to synthesize picolinic acid, avoiding the problem of environmental pollution in the traditional method, greatly improving the yield, And it can react at normal temperature and pressure or under low pressure. the

Reach above-mentioned object, the synthetic route of picolinic acid of the present invention is:

The synthetic process of picolinic acid involved in the present invention comprises the following steps:

(1) 12g of alkylpyridine is heated to 300-450°C on a fixed bed, and all become steam after 3 hours of continuous heating;

(2) fully react the pyridine steam with ammonia, water vapor and oxygen, and let it stand in the container for half an hour;

(3) add 5mol titanium tetrachloride again in gas and carry out catalysis, obtain the pyridinecarbonitrile of 0.85g after waiting for 2 hours;

(4) Add 1.2g of deionized water to the obtained pyridinecarbonitrile and start stirring, heat up to 40-70°C, add 0.08g of NaOH at one time, stir, heat up to 80-95°C, and keep warm for 4-12 hours . Finish the reaction, lower the temperature to 30-60° C., filter, wash with 0.4 g of deionized water, and dry to obtain 10 g of solid powder. Yield: 83.3%. the

Specific implementation plan:

Heat 12g of alkylpyridine on a fixed bed to 300-450°C, and after 3 hours of continuous heating, it will all become steam. Fully react the methylpyridine vapor with ammonia, water vapor, and oxygen, and let it stand in the container for half an hour. Add 5 mol of titanium tetrachloride to the gas for catalysis, and wait for 2 hours to obtain 0.85 g of pyridinecarbonitrile. Add 1.2 g of deionized water to the obtained pyridinecarbonitrile and start stirring, and heat up to 40-70°C. Add 0.08g of NaOH at one time, stir, raise the temperature to 80-95°C, and keep it warm for 4-12 hours. After finishing the reaction, lower the temperature to 30-60° C., filter, and wash with 0.4 g of deionized water to obtain 10 g of solid powder. Yield: 83.3%;

Example 1

Heat 12g of alkylpyridine on a fixed bed to 300°C, and after 3 hours of continuous heating, all of it turns into steam. Fully react the methylpyridine steam with ammonia, water vapor, and oxygen, let it stand in the container for half an hour, and then Add 5 mol of titanium tetrachloride to the gas for catalysis, and wait for 2 hours to obtain 0.85 g of pyridinecarbonitrile. Add 1.2 g of deionized water to the obtained pyridinecarbonitrile and start stirring, raise the temperature to 40 °C, and add 0.08 g of pyridinecarbonitrile at one time. g NaOH, stirred, heated up to 80°C, and kept for 4 hours. After the reaction was completed, the temperature was lowered to 30° C., filtered, and washed with 0.4 g of deionized water to obtain 9.5 g of solid powder. Yield: 79.1%. the

Example 2

Heat 12g of alkylpyridine to 350°C on a fixed bed, and after 3 hours of continuous heating, all of it turns into steam. Fully react the methylpyridine steam with ammonia, water vapor, and oxygen, let it stand in the container for half an hour, and then Add 5mol of titanium tetrachloride to the gas for catalysis, and wait for 2 hours to obtain 0.85g of pyridinecarbonitrile. Add 1.2g of deionized water to the obtained pyridinecarbonitrile and start stirring, raise the temperature to 70°C, and add 0.08 g of pyridinecarbonitrile at one time. g of NaOH, stirred, and the temperature was raised to 85° C., and the temperature was kept for 6 hours. After the reaction was completed, the temperature was lowered to 30° C., filtered, and washed with 0.4 g of deionized water to obtain 9.8 g of solid powder. Yield: 81.7%. the

Example 3

Heat 12g of alkylpyridine to 450°C on a fixed bed, and after 3 hours of continuous heating, all of it turns into steam. Fully react the methylpyridine steam with ammonia, water vapor, and oxygen, let it stand in the container for half an hour, and then Add 5 mol of titanium tetrachloride to the gas for catalysis, and wait for 2 hours to obtain 0.85 g of pyridinecarbonitrile. Add 1.2 g of deionized water to the obtained pyridinecarbonitrile and start stirring, raise the temperature to 40 °C, and add 0.08 g of pyridinecarbonitrile at one time. g of NaOH, stirred, heated up to 80°C, and kept for 12 hours. After the reaction was completed, the temperature was lowered to 60° C., filtered, and washed with 0.4 g of deionized water to obtain 9.9 g of solid powder. Yield: 82.5%. the

Claims (1)

1. a method for pyridine synthesis formic acid, is characterized in that:

(1) alkyl pyridine of 12g is heated to 300-450 DEG C on a fixed bed, the continuous heating through 3 hours all becomes steam;

(2) methane pyridine vapor and ammonia, water vapour, oxygen fully reacts, and leaves standstill half an hour in a reservoir;

(3) titanium tetrachloride adding 5mol again in gas carries out catalysis, waits for the pyridine carbonitrile obtaining 0.85g after 2 hours;

(4) add in the pyridine carbonitrile obtained 1.2g deionized water then start stir, be warmed up to 40-70 DEG C, disposable add 0.08g hydroxide that, stir, be warmed up to 80-95 DEG C, insulation 4-12 hour.Terminate reaction, be cooled to 30-60 DEG C, filter, wash with the deionized water of 0.4g, dry to obtain the pressed powder of 10g.