Preparation of 1,2-dibromobenzene_Kain Industrial Additive

Background and overview^[1]

1,2-Dibromobenzene is also called o-dibromobenzene. O-dibromobenzene is a colorless or light yellow liquid, soluble in ethanol, easily soluble in ether, acetone, benzene and carbon tetrachloride, insoluble in water, and can be used in organic synthesis or dye intermediates.

Preparation^[1]

The traditional production method of o-dibromobenzene is through a two-step method of diazotization and decomposition reaction. The dropping reaction temperature of 1-10°C cannot produce a high-purity diazonium salt solution and contains impurities. It will affect the purity of the final product of o-dibromobenzene, resulting in low yield and low purity, and the raw materials are rarely recycled and the cost is high. Patented a production process for the synthesis of o-dibromobenzene (application number is 201410261598. is 0 ℃, weigh sodium nitrite and water to form a solution, continue to stir the mixture in the reaction kettle and add the prepared solution, the temperature is below 10 ℃, obtain the heavy ammonium salt solution, take it out for later use, weigh the copper bromide and Make a solution of 50% hydrobromic acid and heat it until it boils. Add heavy ammonium salt solution, pass in water vapor for distillation, separate the lower oil layer, wash until the pH of the solution is 7, dry, distill, and collect at 223-225°C. The resulting mixture, which is o-dibromobenzene, is packaged and stored in storage. The preparation of this invention is convenient and simple, and the raw materials are easily available, but the purity of the reaction is low, the waste of raw materials is large, and the cost is high.

CN201710084081.1 provides a preparation method of o-dibromobenzene, including the following preparation steps:

S1: Add water to the reaction kettle, and then add sodium nitrite while stirring. After complete dissolution, obtain the sodium nitrite solution and put it into a bucket for later use;

S2: Add 18 parts of hydrobromic acid with a mass fraction of 48% to the reaction kettle, and add 6 parts of o-bromoaniline while stirring. After the two are completely dissolved, start freezing and cooling to below 10°C, and then start from Add ice cubes to the manhole to cool down, add 8 parts of the sodium nitrite solution prepared in step S1 dropwise at a temperature of 0-5°C, stir and cool for 1 hour after the dropwise addition is completed;

S3: Perform suction filtration to remove impurities within a temperature range of 0-5°C to obtain a diazonium salt solution;

S4: Add 7 parts of hydrobromic acid with a mass fraction of 48% to the reaction kettle equipped with a steam distillation device, add 3.5 parts of cuprous bromide under stirring, and dissolve completely to obtain a mixed solution;

S5: Heat the mixed solution in step S4 to boiling, add dropwise the diazonium salt solution prepared in step S3, and steam out o-dibromobenzene at the same time. After the dropwise addition, continue to heat and perform steam distillation until No more oily liquid is produced;

S6: Collect the products obtained in step S5, wash the qualified products, neutralize them to a pH of 7, and finally dehydrate them, and perform distillation or water distillation on the unqualified products;

S7: Add 18 times the amount of water to the residual liquid after distillation in step S5, stir and cool for 0.4 hours, and then centrifuge and dry to obtain cuprous bromide, which can be recycled.

The beneficial effects of the present invention are:

(1) In step S2 of the present invention, sodium nitrite solution is added dropwise within the temperature range of 0-5°C. Compared with the traditional reaction temperature of 0-10°C, the temperature range is more precise and is conducive to the full progress of the reaction. , which is beneficial to improving product purity and yield; after this reaction, suction filtration is performed to remove impurities, which can ensure the cleanliness of the diazonium salt solution.

(2) In the present invention, the residual liquid after distillation is processed to obtain recyclable cuprous bromide, thereby reducing costs.

(3) The material of the present invention is easy to obtain and has low cost.

Apply ^[2-3]

1. Used in the preparation of optoelectronic material intermediate 9-(4′-chlorobiphenyl-2-yl)carbazole

In organic electroluminescent devices (OLEDs), the main chemical structures of currently commonly used hole transport materials almost all contain carbazole groups. Because the derivatives of the carbazole group have a high glass transition temperature, are easily evaporated into films by heat, and also have hole transport characteristics, they have become the main structure of currently commonly used hole transport materials, especially for carbazole. The research on the 9-position substituent is more concerned. The 9-position modification of carbazole can not only meet the above advantages, but also effectively change the wavelength absorption of the main structure. Some substituents also include Cl and Br, which can increase the substituent structure. Therefore, optoelectronic material intermediates have become the key to improving the quality of optoelectronic materials.

CN201710003192.5 provides a new synthesis method of 9-(4′-chlorobiphenyl-2-yl)carbazole with high yield, low cost and few by-products, which is used for the preparation of optoelectronic materials. In order to achieve the purpose of the present invention, the technical solution is as follows: the 9-(4′-chlorobiphenyl-2-yl)carbazole is realized by the following method:

(1) Place carbazole, o-dibromobenzene and potassium carbonate in the reactor, stir, replace with nitrogen, add copper iodide and L-lysine, heat to 150-170°C for reaction, TLC Detect that there is no raw material, add water to terminate the reaction, stir to precipitate the solid, filter and dry it to obtain 9-(2-bromophenyl)carbazole.

(2) Place a mixed solvent of 9-(2-bromophenyl)carbazole, p-chlorophenylboronic acid, potassium carbonate, toluene, ethanol and distilled water in the reactor, stir, replace with nitrogen, and add Pd2( dba)3, The organic layer is adsorbed on silica gel to filter out the catalyst, and the solvent is evaporated under reduced pressure, cooled, and evacuated.�, vacuum drying to obtain 9-(4′-chlorobiphenyl-2-yl)carbazole.

2. Raw materials for the synthesis of iron-catalyzed phenothiazine compounds

Phenothiazines are also called sulfur-containing (hetero)anthracenes and thiodiphenylamines. They have important application value in the synthesis of drugs, dyes, organic light-emitting materials and other fields. As an excellent polymerization inhibitor for alkenyl monomers, it is widely used in the production of acrylic acid, acrylate, methacrylate, and vinyl acetate. It can also be used in the fields of antioxidants, rubber antioxidants, livestock anthelmintics, and fruit tree insecticides. Phenothiazine derivatives have been successfully used in the treatment of many diseases such as mental illness, heart disease, antitussive, analgesic and itching. CN201410513543.3 Develop a new method for the synthesis of biometal (iron)-catalyzed drug precursor phenothiazine compounds. The invention uses N-(2-mercaptophenyl)acetamide and o-dibromobenzene under the catalysis of iron salt to directly obtain phenothiene through C-S coupling, C-N coupling and deacylation at one temperature in a reaction kettle. Methods for oxazines. The method has simple operation, mild conditions, wide application range, generally high yield, short reaction time, and good industrial prospects. The technical solution of the present invention is: the molar ratio of N-(2-mercapphenyl)acetamide, o-dibromobenzene, iron salt catalyst, ligand and base is 1:1-5:0.1-1:0.1 -1:2-8 is added to the reactor, using DMF as the solvent, reacting under inert gas protection, reacting at a temperature of 100°C-150°C for 10-30h, then cooling to room temperature, extracting with ether, drying and purifying to obtain the target product phenol Thiazides.

Main reference materials

[1] CN201710084081.1 Preparation method of o-dibromobenzene

[2] CN201710003192.5 A synthesis method of optoelectronic material intermediate 9?(4′?Chlorobiphenyl?2?yl)carbazole

[3] CN201410513543.3 Synthesis method of iron-catalyzed phenothiazine compounds