CN1305980A

CN1305980A - Process for preparing bromo-n-dodecane

Info

Publication number: CN1305980A
Application number: CN 01106416
Authority: CN
Inventors: 汤俊明; 王新阳; 王正; 高琦; 鲜栋
Original assignee: 汤俊明
Current assignee: Henan Normal University
Priority date: 2001-01-04
Filing date: 2001-01-04
Publication date: 2001-08-01
Anticipated expiration: 2021-01-04
Also published as: CN1190398C

Abstract

A process for preparing bromo-n-dodecane includes the reaction of hydrobromic acid on n-dodecanol at 90-150 deg.C for 3-4 hrs, reflux, neutralizing with alkali, water washing, drying, and vacuum distillation to purify the product. Its advantages include simple process, short reaction time, high output rate and purity of product, and cyclic use of catalyst.

Description

Process for preparing bromo-n-dodecane

The invention belongs to the technical field of preparation of acyclic saturated compounds containing bromine atoms, and particularly relatesto a novel preparation process of bromo-n-dodecane.

The synthesis method of bromo-n-dodecane is probably as follows:

(1) the concentrated sulfuric acid catalytic method has the reaction formula: 。

the specific process is as follows: firstly, a certain amount of concentrated H is added₂SO₄With lauryl alcoholStirring and mixing at low temperature, adding a certain amount of HBr (48%), heating to 90 ℃, keeping the temperature for a certain time, heating to 100-120 ℃, reacting for 8-9 hours, standing overnight, and removing an acid layer. With NHCO₃Washing the product with water solution, 40% concentration alcohol water solution and water successively, drying and vacuum distilling to obtain the final product. The method has complex process and low conversion rate (up to 90-92%); and the product is often H₂SO₄Presence, blackening in color; the post-treatment is easy to emulsify and the layering time is long; consumes a large amount of acid and alkali, and has serious pollution and large loss.

(2) Using benzalkonium bromide (benzyl dimethyl n-dodecyl ammonium bromide) as catalyst to make phase transfer catalytic synthesis: namely, HBr is reacted with n-dodecanol (lauryl alcohol) in a certain proportion in the presence of sodium bromide and potassium bromide. The specific process is as follows: firstly, mixing lauryl alcohol, benzyl dimethyl n-dodecyl ammonium bromide and NBr according to a certain proportion, then treating the mixture with 48 percent HBr aqueous solution for general time at 80-100 ℃, stirring and heating the mixture to 120 ℃ for reaction for 3 hours, simultaneously carrying out water separation and oil-water separation, washing an oil layer with alkaline water and water, and obtaining the bromo-n-dodecyl with the conversion rate of 97-99.4 percent and the yield of 96 percent. The product obtained by the method has lighter color, unreacted hydrobromic acid can be repeatedly used, and the post-treatment process is simple and convenient. However, the reaction must be carried out in the presence of NaBr or KBr, the catalyst is used once, and high-proportion hydrobromic acid is adopted, so that the product obtained by the process is expensive, and the whole process is complex.

(3) The method adopts expensive and difficultly obtained tri-n-butyl-n-hexadecyl quaternary phosphonium salt (phosphonium bromide) and has little significance in production.

(4) The synthesis is carried out by phase transfer catalysis with bromo-stearyl alcohol pyridinium salt as catalyst: the method allows lauryl alcohol and 48 percent HBr aqueous solution to react for 24 hours under the temperature of 100-105 ℃ with stirring. The yield is only 90%, and the catalyst has the defects of long reaction time, low yield and large defect.

(5) The halogen exchange synthesis method makes iodocarbon and Br react in bromohydrocarbon solution under the catalysis of tetrabutylammonium bromide to prepare bromo-n-dodecane with purity of over 98 percent, the raw materials used in the method are expensive iodocarbon and bromine, the solvent is expensive bromohydrocarbon, and the preparation cost is obviously higher.

(6) Concentrated H₂SO₄-tetra-n-butylammonium bromide catalytic synthesis: in the concentration of H₂SO₄And under the action of tetra-n-butylammonium bromide, 48% hydrobromic acid and n-dodecanol are heated and refluxed for 3 hours, and then reacted with H₂SO₄、40％CH₃Washing OH aqueous solution and water, drying, and vacuum distilling to obtain product, wherein the product is prepared byusing tetra-n-butylammonium bromide and concentrated H₂SO₄The reaction product turns black in color and the working-up uses concentrated H₂SO₄And 40% CH₃Aqueous OH solutions emulsify badly.

The invention aims to provide a novel preparation process of bromo-n-dodecane, which is simple in process, high in conversion rate and capable of repeatedly using a catalyst.

In order to achieve the purpose, the invention adopts the following technical scheme: the new preparation process of bromo-n-dodecane includes the reaction reflux of hydrobromic acid and n-dodecanol and the separation and purification of product, and the catalyst used in the reaction is tetra-n-butylammonium bromide.

The concentration of the hydrobromic acid in percentage by weight is 10-50%, the mol ratio of the hydrobromic acid to the n-dodecanol is 1: 5, the reaction temperature is 90-150 ℃, and the reaction time is 3-4 hours.

The product separation and purification process comprises the steps of alkali neutralization, water washing, drying and reduced pressure distillation, wherein the alkali liquor used in the step of alkali neutralization is 1-30% Na₂CO₃Or NaHCO₃An aqueous solution.

The method adopts tetra-n-butylammonium bromide as a catalyst, has simple process and short reaction time, has less side reaction due to no existence of concentrated sulfuric acid, and has simple product post-treatment and high conversion rate (more than or equal to 99.6 percent); the product purity is high (more than or equal to 98 percent), the yield is high (more than or equal to 97 percent), and the color is good; the tetra-n-butyl ammonium bromide has low price relative to the tri-n-butyl-n-hexadecyl quaternary ammonium salt and is easy to obtain, sothe product cost is low; tetra-n-butylammonium bromide does not participate in the reaction between hydrobromic acid and n-dodecanol, and can be recycled and reused after reaction, and unreacted hydrobromic acid can be recycled, thereby further reducing the product cost to a certain extent. The process is also suitable for synthesizing long-chain brominated alkanes such as bromo-n-octane, bromo-n-octadecyl and the like.

The invention is further illustrated by the following examples.

Example 5kg of n-dodecanol and 6kg of 48% hydrobromic acid were mixed in a reactor, stirred, dissolved by adding 500g of 98% tetra-n-butylammonium bromide, and then the mixture was heated slowly to 90 ℃ with stirring, and the reaction was terminated by refluxing with water-splitting for 3 hours. Cooling and layering, transferring supernatant into refining bottle, adding equal volume of clear water and 100ml of 5% NaHCO₃Adjusting pH =7-8, stirring and washing, and standing and layering. Washing the lower oil layer with water for 2 times, and adding anhydrous Na₂SO₄Drying, vacuum distilling, collecting 160-.

Claims

1. The new preparation process of bromo-n-dodecane includes the reaction reflux of hydrobromic acid and n-dodecanol and the separation and purification of product.

2. The process of claim 1, wherein the concentration of hydrobromic acid is 10-50% by weight, the molar ratio of hydrobromic acid to n-dodecanol is 1: 5, the reaction temperature is 90-150 ℃, and the reaction time is 3-4 hours.

3. The process according to claim 1 or 2, wherein the product separation and purification step comprises the steps of alkali neutralization, water washing, drying and reduced pressure distillation, and the alkali solution used in the alkali neutralization step is 1-30% Na₂CO₃Or NaHCO₃An aqueous solution.