CN1429799A - Synthesis method of 1-bromoane - Google Patents

Abstract

The present invention relates to a new synthesis method of 1-bromoalkane. It is a rapid completion of symmetric or asymmetric olefins and hydrogen bromide gas at -50-100°C under normal pressure or less than 2kg/ ^cm2 pressure in an initiator and solvent that can generate free radicals. After the reaction, after neutralization, washing, drying and distillation, 1-bromoalkane with high yield and high selectivity can be produced. The method has the advantages of convenient source of raw materials, low price, moderate reaction conditions, rapid reaction completion, no corrosion to equipment, batch or continuous synthesis, and is suitable for gaseous or liquid olefins. The invention is also a green synthetic method with safe operation and environmental friendliness.

Description

The synthetic method of 1-bromoalkane

Technical field The present invention relates to a kind of synthetic method of 1-bromoalkane organic compound.

Background Art Usually, 1-bromoalkane can be prepared by reacting primary alcohols, inorganic bromides (such as sodium bromide, potassium bromide, etc.) and inorganic acids (such as hydrochloric acid, sulfuric acid, etc.) together. This reaction is convenient in the laboratory to prepare 1-bromoalkane.

Under acid catalysis, the reaction of primary alcohol and hydrobromic acid to synthesize 1-bromoalkane is a commonly used method in industry.

In the 1930s, Kharasch M.S. discovered that in the presence of oxygen or peroxide, 3-bromopropene reacted with hydrogen bromide in a sealed tube for several days to obtain 1,3-dibromopropane. Then a series of α-alkenes were reacted with hydrogen bromide, and 1-bromoalkanes were obtained instead of Markovnikov addition products, which is called the peroxide effect of the reaction of alkenes with hydrogen bromide, also known as anti-Markovnikov addition. into a product. Kharasch has also published a series of papers and several patents.

In the existing method for synthesizing 1-bromoalkane, primary alcohol and hydrobromic acid react to synthesize primary bromoalkane, primary alcohol comes from the hydromethanolation reaction or hydration reaction of olefin, and hydrobromic acid is hydrogen bromide dissolved in water owned. Therefore, the cost of synthetic 1-bromoalkane is high. At the same time, hydrobromic acid is a highly corrosive acid, which seriously corrodes production equipment, and a large amount of acid water will be discharged in industrial production. The method for synthesizing 1-bromoalkane with primary alcohol, inorganic bromide and inorganic acid reaction is essentially the same as the method for preparing 1-bromoalkane with primary alcohol, hydrobromic acid reaction, has the same shortcoming, and its synthetic 1- The cost of bromoalkane is higher.

The Kharasch synthesis method has the advantage of low raw material cost, but its reaction time is long, and some gas olefins cannot be reacted under normal pressure, and must be reacted under pressure. Kharasch condenses olefins and hydrogen bromide into a glass tube at low temperature, then seals the tube, and then slowly rises to room temperature or reaction temperature. The selectivity of synthesizing 1-bromoalkane (i.e. the reverse Markovsky addition product) with the method of Kharasch is not very high, generally there are about 10% 2-bromoalkane (i.e. the Markovsky addition product) in the product, need to separate In order to obtain relatively pure 1-bromoalkane. In industrial production, various liquefied olefins can be obtained, but the compression of hydrogen bromide requires a special compressor, which brings great trouble to industrial production. So far, there is no report on the synthesis of 1-bromoalkane by the reaction of gaseous olefin and hydrogen bromide in a halogenated hydrocarbon solvent at a relatively low temperature in industrial production.

SUMMARY OF THE INVENTION In the present invention, gaseous or liquid symmetric or asymmetric olefin CH ₂ =CR ¹ R ² and hydrogen bromide gas are fed into the In a reactor containing a non-aqueous halogenated hydrocarbon RX solvent and a free radical initiator, under normal pressure or less than 2kg/ ^cm2 pressure, a rapid reaction is carried out at a temperature of -50-100 ° C, and the obtained product is neutralized , washed with water, dried and distilled to produce 1-bromoalkane with high yield and high selectivity.

The olefin CH ₂ =CR ¹ R ² used in the present invention is a single gas or liquid, or a mixture of olefins with less than 4 carbon atoms and a mixture of olefins and alkanes; wherein R ¹ and R ² are hydrogen atoms or contain 1 - Straight-chain alkyl, branched-chain alkyl, cycloalkyl, aryl, alkaryl, aralkyl with 16 carbon atoms; or one or more of the same or different F, C1, Br, I halogen atom, acyl group, nitro group, amino group, amido group, hydroxyl group, cyano group, ester group; liquid olefins are gasified before use or added to the reactor together with a solvent for reaction.

The solvent halogenated hydrocarbon RX used in the present invention, R is straight-chain alkyl, branched-chain alkyl, cycloalkyl, aryl, alkaryl, aralkyl containing 1-16 carbon atoms; These groups are one Valence group, subunit or secondary group; X is one or more identical or different F, Cl, Br, I halogen atoms. After the solvent is recovered, it can be recycled.

The used initiator of the present invention is the organic peroxide that can produce free radical, as: benzoyl peroxide, dicumyl peroxide, cumene peroxide, tert-butyl alcohol peroxide, hydrogen peroxide, peroxygen Acids, etc., and azo compounds as initiators, such as: azobisisobutyronitrile, azobisisoheptanonitrile, azobisisobutyronitrile, etc. The initiator can be dissolved or suspended in the solvent at a concentration of 0.05-10%.

The synthetic hydrogen bromide used in the present invention is a gas without water, and can also be a by-product produced by the bromination reaction of organic matter, and the hydrogen bromide gas without water can be obtained through recovery treatment.

The reaction temperature of the present invention is usually at -50-100°C for fast reaction; fast reaction refers to the reaction as soon as the raw material gas and the initiator come into contact.

The reaction of the present invention is carried out under normal pressure or less than 2kg/cm ² pressure.

When the present invention adopts the batch reaction mode, the solvent and the initiator are added together in the reactor, and then pass into gas olefin and hydrogen bromide gas; After flowing out of the reactor, gas olefin or liquid olefin and hydrogen bromide are still continuously added, and the initiator is intermittently or continuously added to the reactor to keep the concentration of the initiator in the reactor constant.

The present invention has convenient sources of raw materials, low price, mild reaction conditions, most of the reactions are completed under normal pressure, no corrosion to equipment, batch or continuous synthesis can be adopted, and it is suitable for rapid reaction of gas or liquid symmetrical and asymmetrical olefins, and it is also a one-step operation A safe and environmentally friendly green synthesis method.

Detailed ways

Example 1

In the reaction tube, add 100 g of bromopropane and 1 g of benzoyl peroxide, place the reaction tube in a water bath at 6-8° C., and continuously feed two gases of ethylene and hydrogen bromide into the reaction tube respectively. Adjust the feed rate of the gas through a liquid seal to prevent the gas from escaping. After 70 minutes, stop feeding ethylene and hydrogen bromide, then wash the reaction mixture with water to about pH=7, dry it with magnesium sulfate, and collect 78.8 by fractional distillation. The fraction of gram 37-39 ℃ was analyzed by gas chromatography, and the content of bromoethane product was 98.8%.

Example 2

Add 70.4 grams of bromopropane and 0.3 grams of azobisisobutyronitrile into the reaction tube, place the reaction tube in a water bath at 10°C, feed propylene and hydrogen bromide gas into the reaction tube, react for 95 minutes and pass through the example 1 process treatment, to obtain 107.5 grams of 70-72 ℃ bromopropane distillate. Analysis by gas chromatography showed that the content of 1-bromopropane was 99.1%.

Example 3-13

Reaction equipment and process are the same as embodiment 1, adopt different olefins, different solvents, obtain the result of different products as in table 1:

Table 1 Example Olefin solvent Initiator Reaction temperature (°C) 1-bromoalkane selectivity (%) 3 Propylene bromopropane Benzoyl peroxide 50 97.0 4 Propylene chlorobenzene Benzoyl peroxide 10 97.0 5 Propylene bromopropane dicumyl peroxide 6-8 97.2 6 Propylene bromopropane tert-butanol peroxide 6-8 97.0 7 Propylene bromopropane Azobisisobutyramide 6-8 97.0 8 Propylene bromopropane Azobisisobutyronitrile -20 97.6 9 1-butene bromobutane Benzoyl peroxide 6-8 91.0 10 1-Hexene bromopropane Benzoyl peroxide 6-8 83.8 11 1-octane bromopropane Benzoyl peroxide 6 88.2 12 Styrene Hexyl bromide Azobisisobutyronitrile 90 >99.5 13 Styrene Bromoethylbenzene Benzoyl peroxide 90 >99.5

Example 14

Add the mixture of 182.4g 1-bromopropane and 2-bromopropane in the reaction tube, 1.8g benzoyl peroxide, water bath temperature 6 ℃, continuously add propylene and hydrogen bromide, supplement benzoyl peroxide continuously simultaneously; Make reaction The concentration of benzoyl peroxide in the mixture remains constant, and the reaction mixture overflows continuously. After 220 minutes of reaction, 280.7 g of the reaction solution is obtained. The selectivity of 1-bromopropane is 97% through chromatographic analysis, and the selectivity of 2-bromomethane is 97%. 3% and no other products.

Claims (7)

1, a kind of preparation method with alkene and the synthetic 1-bromoalkane of hydrogen bromide is characterized in that present method is with symmetry or asymmetric rare hydrocarbon CH ₂=CR ¹R ²And bromize hydrogen gas, with mol ratio 1-10: 10-1, adopt intermittently or the successive mode, be passed in the reactor that water-free halohydrocarbon RX solvent and radical initiator be housed, at normal pressure or less than 2kg/cm ²Under the pressure, carry out rapid reaction in-50-100 ℃, the product that obtains makes the 1-bromoalkane of high yield, highly selective through neutralization, washing, dry, distillation.

2,, it is characterized in that the alkene CH that present method is used according to the preparation method of the described 1-bromoalkane of claim 1 ₂=CHR ¹R ²Be the single thing of gas or liquid, or less than the mixture of 4 carbon atom alkene and the mixture in alkene and alkane footpath thereof; R wherein ¹R ²For hydrogen atom or contain straight chained alkyl, branched-chain alkyl, cycloalkyl, aryl, alkaryl, the aralkyl of 1-16 carbon atom; Or have one, a plurality of identical or different F, Cl, Br, I halogen atom, acyl group, nitro, amino, amido, hydroxyl, cyano group, ester group on the above-mentioned group; Liquefied olefines gasification earlier again with or be added in the reactor with solvent and react.

3, according to the preparation method of the described 1-bromoalkane of claim 1, it is characterized in that the used solvent halohydrocarbon RX of present method is single thing, mixture or reaction product of the present invention, R is straight chained alkyl, branched-chain alkyl, cycloalkyl, aryl, alkaryl, the aralkyl that contains 1-16 carbon atom; These groups are monad radical, subunit or inferior base; X is one or more identical or different F, Cl, Br, I halogen atom.

4, according to the preparation method of the described 1-bromoalkane of claim 1, it is characterized in that the used initiator of present method is benzoyl peroxide, dicumyl peroxide, dicumyl peroxide, tertbutanol peroxide, hydrogen peroxide, peroxy acid organo-peroxide and Diisopropyl azodicarboxylate, 2,2'-Azobis(2,4-dimethylvaleronitrile), azo two NSC 18620 azo-compounds, initiator concentration is 0.05-10%, and initiator is dissolved in or is suspended in the solvent.

5,, it is characterized in that rapid reaction is meant that unstripped gas contacts i.e. reaction with initiator one according to the preparation method of the described 1-bromoalkane of claim 1.

6,, it is characterized in that solvent joins in the reactor with initiator, feeds gas alkene and bromize hydrogen gas then when adopting the rhythmic reaction mode according to the preparation method of the described 1-bromoalkane of claim 1; When adopting the successive reaction mode, begin identically, behind the reaction solution outflow reactor, still add gas alkene or liquid olefin and bromination gas continuously with the intermittent reaction process, initiator then is interrupted or joins continuously in the reactor, and is constant with initiator concentration in the maintenance reactor.

7,, it is characterized in that the used synthesizing hydrogen bromide of the present invention is water-free gas, or, obtain water-free bromize hydrogen gas after treatment with the by-product of organism bromination reaction according to the preparation method of the described 1-bromoalkane of claim 1.