Preparation[1]
The existing synthesis technology of bromobutane mainly includes n-butanol and sodium bromide sulfuric acid method, n-butanol and hydrobromic acid sulfuric acid method, n-butanol and hydrobromic acid solid acid catalysis method, n-butanol and bromine sulfurization method. and so on.
According to reports in the literature, most domestic manufacturers use the sodium bromide sulfuric acid process route. However, this method is intermittent production, the amount of catalyst concentrated sulfuric acid is large, and a large amount of dilute sulfuric acid is produced as a by-product, which is very serious to environmental pollution. The production cost of the product is high, the product content is low, the equipment is seriously corroded, and the utilization rate is low. Environmental protection treatment or raw material recovery The utilization is relatively complicated, and the processing cost is high, which increases the production cost.
Hydrobromic acid and n-butanol react in the presence of a catalyst to produce 1-bromobutane. Since hydrobromic acid is a by-product of mass production of aryl bromide flame retardants, it is economically reasonable and has been a research hotspot in recent years. Sulfuric acid as a catalyst will produce a large amount of dilute sulfuric acid in the production process, and the post-treatment is relatively troublesome; the solid acid catalysis method is easily affected by the failure of the catalyst, resulting in unstable product yield, and the complex synthesis and regeneration process of the catalyst affects the promotion of this process. . Chinese invention patent CN102826954 discloses a “preparation method of bromoalkane”, which is mixed according to the molar ratio of n-butanol and hydrobromic acid of 1:5, heated to a reflux state, and continuously and uniformly added dropwise and the gas outlet speed is adjusted to make the liquid The amount of dripping and the amount of steaming out are corresponding to keep the kettle liquid stable. However, this method has a long reaction time, needs 6-12 hours, and has a large amount of hydrobromic acid and a low utilization rate.
Chinese invention patent CN102766013A discloses a “environmentally friendly method for preparing bromoalkane”. First, a certain amount of hydrobromic acid solution is preheated in a reactor until steam is generated, and the molar ratio of n-butanol and hydrobromic acid is 1 : 1 was mixed and added to the reactor, while raising the reaction temperature. However, the reaction time of this method is still long, and it is a batch production, which cannot be continuously produced.
Chinese invention patent CN102875323B discloses a method for preparing bromo-tert-butane by brominating tert-butanol in a microchannel reactor. Using concentrated sulfuric acid as a catalyst, tert-butanol and hydrobromic acid are reacted in a micro-channel reactor to prepare tertiary bromide. Butanol. However, this method still uses concentrated sulfuric acid, so it is necessary to deal with the problem of equipment corrosion caused by concentrated sulfuric acid and the problem of environmental pollution caused by waste acid.
Therefore, there is still a need to develop new processes for producing 1-bromobutane with high efficiency, high yield, high selectivity, low cost, low by-products, and no pollution. CN201810594072.1 provides a continuous process for preparing bromobutane in a microchannel reactor. Compared with the existing process, the process has the advantages of precise control of reaction conditions, no catalyst, short reaction time, good selectivity, high yield, few by-products, high product purity, flexible, safe and efficient operation. An example is as follows:
Using a plunger pump, 48wt% hydrobromic acid and 99wt% n-butanol were continuously passed to the microchannel reactor, the feeding rate of the measured n-butanol was 5g/min, and the feeding rate of hydrobromic acid was 13.6g/min, That is, the molar ratio of n-butanol and hydrobromic acid is 1:1.2. After feeding, adjust the temperature and pressure of the reactor, use the refrigeration heating temperature control system to adjust the system temperature to 140 °C, and use the pressure valve to adjust the front pressure of the system to 1.5MPa, no bubbles appear in the reaction section, and the residence time is 260s. The reaction was quenched by running tap water in the last module of the reactor. After the material feed amount, reaction temperature and reaction pressure were stabilized, sampling was performed after waiting for 3 residence times. The sample was left to stand for stratification, and the separated oil phase was washed with saturated sodium carbonate solution to pH=7, then washed with water, and dried with anhydrous magnesium sulfate in the laboratory to obtain 1-bromobutane with a purity of 95%. The conversion of butanol was 94%.
