CN115124425B

CN115124425B - 3, 5-dibromo-4-hydroxybenzoic acid dimer, synthesis method and application thereof

Info

Publication number: CN115124425B
Application number: CN202210736522.2A
Authority: CN
Inventors: 胡东云; 丁尊良; 樊天生; 邱小猛; 黎文辉; 叶山海
Original assignee: Zhejiang Chemsyn Pharm Co ltd
Current assignee: Zhejiang Chemsyn Pharm Co ltd
Priority date: 2022-06-27
Filing date: 2022-06-27
Publication date: 2023-10-17
Anticipated expiration: 2042-06-27
Also published as: CN115124425A

Abstract

The invention discloses a synthesis method of a 3, 5-dibromo-4-hydroxybenzoic acid dimer, which comprises the following specific steps: adding 3, 5-dibromo-4-hydroxybenzoic acid, a solvent and thionyl chloride into a four-necked flask, heating while stirring, cooling to room temperature after the reaction is finished, and filtering to obtain a 3, 5-dibromo-4-hydroxybenzoic acid dimer. The invention has the advantages of simple operation process, low energy consumption, low production cost and wide application range, and is suitable for large-scale preparation of 3, 5-dibromo-4-hydroxybenzoic acid dimer.

Description

3, 5-dibromo-4-hydroxybenzoic acid dimer, synthesis method and application thereof

Technical Field

The invention belongs to the technical field of medicine synthesis, and particularly relates to a 3, 5-dibromo-4-hydroxybenzoic acid dimer, a synthesis method and application thereof.

Background

With the rapid development of the plastic industry, wires and cables, printed wiring boards, automobiles, aerospace, textile clothing, decorative fabrics and the like, the need for flame retardants is more urgent. The traditional flame retardant is halogen flame retardant or synergistic flame retardant mixed by halogen and other compounds, wherein bromide is the most main flame retardant at present, for example tetrabromobisphenol A is a common bromine flame retardant at present, the product is widely applied to various electronic products such as televisions, mobile phones, notebook computers and the like, in a model of Pavilion250NL of Hewlett-packard company, the content of tetrabromobisphenol A (TBBA) serving as the brominated flame retardant is 20 percent of the weight of a plastic component of the product, and the weight of the brominated flame retardant accounts for a large amount.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims at a 3, 5-dibromo-4-hydroxybenzoic acid dimer, a synthesis method and application thereof, has the advantages of simple operation process, low production cost, good flame retardant property and wide application range, and is suitable for large-scale preparation.

In order to achieve the above object, the present invention adopts the following technical scheme:

a 3, 5-dibromo-4-hydroxybenzoic acid dimer having the following structural formula:

the synthesis method of the 3, 5-dibromo-4-hydroxybenzoic acid dimer comprises the following specific steps: adding 3, 5-dibromo-4-hydroxybenzoic acid, a solvent and thionyl chloride into a four-necked flask, heating while stirring, cooling to room temperature after the reaction is finished, and filtering to obtain a 3, 5-dibromo-4-hydroxybenzoic acid dimer, wherein the reaction equation is as follows:

preferably, the aforementioned solvent is one of ethyl acetate, propyl acetate, toluene and xylene.

Preferably, the weight ratio of the 3, 5-dibromo-4-hydroxybenzoic acid to the solvent is 1: (3-5).

Preferably, the molar ratio of the 3, 5-dibromo-4-hydroxybenzoic acid to the thionyl chloride is 1: (1-3).

Preferably, the temperature is raised to 60-80 ℃, and the mixture is stirred for 2-3 hours under heat preservation.

The application of 3, 5-dibromo-4-hydroxybenzoic acid dimer is used for preparing flame retardant.

The invention has the advantages that:

(1) The invention has the advantages of simple operation process, low energy consumption, low production cost and wide application range, and is suitable for large-scale preparation of 3, 5-dibromo-4-hydroxybenzoic acid dimer;

(2) The 3, 5-dibromo-4-hydroxybenzoic acid dimer is formed by condensing and dehydrating two molecules of 3, 5-dibromo-4-hydroxybenzoic acid, wherein the molecular weight contains 4 bromine atoms and 4 oxygen atoms, the flame retardant property is higher than that of tetrabromobisphenol A through test, the 3, 5-dibromo-4-hydroxybenzoic acid dimer has a difunctional structure, polyester fiber or polyurethane resin with flame retardant property can be prepared through decolorization and esterification, and the application range of the structure of hydroxyl functional groups and carboxylic acid functional groups in polymer synthesis is greatly expanded;

(3) The bromine content in the 3, 5-dibromo-4-hydroxybenzoic acid dimer prepared by the invention is up to 56%, the flame retardant effect is good, and the compound is easy to be decomposed into micromolecular substances again when meeting high temperature in the flame retardant process, so the flame retardant has the advantage of no pollution to the environment.

Drawings

FIG. 1 is a reaction equation of the present invention;

FIG. 2 is a nuclear magnetic resonance spectrum of the product of example 1 of the present invention;

FIG. 3 is a graph showing the flame retardant property test of the product of example 1 of the present invention.

Detailed Description

The invention is described in detail below with reference to the drawings and the specific embodiments.

Example 1

The synthesis method of the 3, 5-dibromo-4-hydroxybenzoic acid dimer comprises the following specific steps:

100g (0.338 mol) of 3, 5-dibromo-4-hydroxybenzoic acid, 200g of ethyl acetate and 60g (0.507 mol,1.5 eq) of thionyl chloride are added into a four-necked flask, the temperature is raised to 70 ℃ under stirring, the mixture is kept at the temperature for 2 hours under stirring, after the reaction is finished, the temperature is reduced to room temperature, and the mixture is filtered to obtain a 3, 5-dibromo-4-hydroxybenzoic acid dimer, wherein the reaction equation is as follows:

example 2

120g (0.405 mol) of 3, 5-dibromo-4-hydroxybenzoic acid, 220g of toluene and 106g (0.891 mol,2.2 eq) of thionyl chloride are added into a four-necked flask, the temperature is raised to 78 ℃ under stirring, the mixture is kept at the temperature for 3 hours under stirring, after the reaction is finished, the temperature is reduced to room temperature, and the mixture is filtered to obtain the 3, 5-dibromo-4-hydroxybenzoic acid dimer.

Example 3

the four-necked flask was charged with 95g (0.321 mol) of 3, 5-dibromo-4-hydroxybenzoic acid, 180g of xylene and 50g (0.417 mol,1.3 eq) of thionyl chloride, and the mixture was heated to 65℃with stirring, stirred for 2.5 hours with heat preservation, cooled to room temperature after the reaction was completed, and filtered to obtain a 3, 5-dibromo-4-hydroxybenzoic acid dimer.

Example 4

150g (0.507 mol) of 3, 5-dibromo-4-hydroxybenzoic acid, 350g of propyl acetate and 157g (1.318 mol,2.6 eq) of thionyl chloride are added into a four-necked flask, the temperature is raised to 78 ℃ under stirring, the mixture is kept at the temperature for 2 hours under stirring, after the reaction is finished, the temperature is reduced to room temperature, and the mixture is filtered to obtain the 3, 5-dibromo-4-hydroxybenzoic acid dimer.

Comparative example

100g (0.338 mol) of 3, 5-dibromo-4-hydroxybenzoic acid, 300g of octyl acetate and 20g of 98% sulfuric acid are added into a four-necked flask, the temperature is raised to 180 ℃ under stirring, the temperature is kept for 4 hours under stirring, the temperature is reduced to room temperature after the reaction is finished, and the 3, 5-dibromo-4-hydroxybenzoic acid dimer is obtained through filtering.

Performance test

1. The products of example 1 were each subjected to a magnetonuclear analysis and, as can be seen from FIG. 1, the synthesized end product was 3, 5-dibromo-4-hydroxybenzoic acid dimer.

2. The mass of the 3, 5-dibromo-4-hydroxybenzoic acid dimer, which was the product prepared in examples 1 to 4 and comparative example, was weighed, and the total yield of the product was calculated, with the calculation results shown in the following table:

comparing examples 1 to 4 with comparative examples, in which concentrated sulfuric acid was added, dehydration polymerization was performed at high temperature, coking was easy, and tar-like impurities were formed, resulting in low reaction yield and poor product quality, whereas in examples 1 to 4, thionyl chloride was used as a dehydrating agent, high temperature reaction was avoided, production was easy, and no tar-like impurities were generated, and reaction yield and product quality were remarkably improved.

3. The 3, 5-dibromo-4-hydroxybenzoic acid dimer and commercial PE powder were mixed as flame retardant property test article, and the 3, 5-dibromo-4-hydroxybenzoic acid dimer was added in an amount of 5%, 7% and 10% to the commercial PE powder, and the results of the firing test were shown in FIG. 2.

As can be seen from FIG. 2, at the beginning, the curve change is small, the decomposition and combustion of the polymer are not obvious, the ignition weight loss is obvious when the temperature is 280-420 ℃, and the difference of different curves is obvious, so that the flame retardant mainly has the flame retarding effect at 280-420 ℃. The pure PE powder starts to decompose and burn at 300 ℃, the pure 3, 5-dibromo-4-hydroxybenzoic acid dimer starts to decompose and carbonize at 260-280 ℃, after the 3, 5-dibromo-4-hydroxybenzoic acid dimer is added into the PE powder, hydrogen bromide and water are released by decomposition and carbonize after 260 ℃, the contact of a burner and air is isolated, bromine free radicals generated by decomposition of the hydrogen bromide in flame can capture hydrogen free radicals, and the chained combustion reaction of gas phase free radicals can be interrupted, so that the continuous combustion of the burner is prevented. It can be seen in fig. 2 that the flame retardant has shown a good flame retardant effect on PE when the amount added is 5 to l 0%.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be appreciated by persons skilled in the art that the above embodiments are not intended to limit the invention in any way, and that all technical solutions obtained by means of equivalent substitutions or equivalent transformations fall within the scope of the invention.

Claims

1. A 3, 5-dibromo-4-hydroxybenzoic acid dimer having the formula:

。

2. the method for synthesizing 3, 5-dibromo-4-hydroxybenzoic acid dimer according to claim 1, comprising the following specific steps: adding 3, 5-dibromo-4-hydroxybenzoic acid, a solvent and thionyl chloride into a four-necked flask, heating while stirring, cooling to room temperature after the reaction is finished, and filtering to obtain a 3, 5-dibromo-4-hydroxybenzoic acid dimer, wherein the reaction equation is as follows:。

3. the method for synthesizing a 3, 5-dibromo-4-hydroxybenzoic acid dimer according to claim 2, wherein the solvent is one of ethyl acetate, propyl acetate, toluene and xylene.

4. The method for synthesizing 3, 5-dibromo-4-hydroxybenzoic acid dimer according to claim 2, wherein the weight ratio of 3, 5-dibromo-4-hydroxybenzoic acid to solvent is 1: (3-5).

5. The method for synthesizing 3, 5-dibromo-4-hydroxybenzoic acid dimer according to claim 2, wherein the molar ratio of 3, 5-dibromo-4-hydroxybenzoic acid to thionyl chloride is 1: (1-3).

6. The method for synthesizing 3, 5-dibromo-4-hydroxybenzoic acid dimer according to claim 2, wherein the temperature is raised to 60-80 ℃, and the mixture is stirred for 2-3 hours under heat preservation.

7. Use of a 3, 5-dibromo-4-hydroxybenzoic acid dimer as defined in claim 1 for the preparation of flame retardants.