JPH0482848A - Production of bromoethylpolybromobenzene - Google Patents

Abstract

PURPOSE:To obtain the objective compound having faint color and low impurity content in high yield by brominating alpha-and/or beta-bromoethylbenzene in the presence of iron powder at a specific temperature. CONSTITUTION:The objective alpha-and/or beta-bromoethylpolybromobenzene of formula (n is integer of 1-5) having faint color, low impurity content and excellent quality and useful as an intermediate for a nucleus-brominated styrene, especially mono-to tribromostyrene useful as a monomer for reactive flame retardant for polymeric material or for optical material can be produced in high yield by brominating alpha-and/or beta-bromoethylbenzene in the presence of usually about 0.001-0.5mol of iron powder (based on 1mol of the compound) at -30 to +30 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing α- and/or β-bromoethylpolybromobenzene (hereinafter abbreviated as BEBB). More specifically, α- and/or β-bromoethylbenzene (
The present invention relates to a method for brominating BEB (hereinafter abbreviated as BEB).

The structure of BEBB is shown in formula [I].

(In the formula, n represents a number from 1 to 5.) In the method for producing α and/or β-bromoethylpolybromobenzene represented by 30 to 30℃
A method for producing α/β-bromoethylpolybromobenzene, characterized in that bromination is carried out at a temperature range of (in the formula, n represents a number from 1 to 5). It is. Cyclobrominated styrenes, specifically mono-, di-, and tribromostyrenes and mixtures thereof, are useful compounds as reactive flame retardants for polymeric materials or as monomers for optical materials.

[Prior art] As a method for brominating BEB, polymer
r), IQ, pp. 479-487 (1969), β
- A method is disclosed for producing β-bromoethyl dibromobenzene by adding bromine dropwise to bromoethylbenzene in the presence of a ferric chloride catalyst.

However, with this method, the coloring of the obtained β-bromoethyldibromobenzene is large, and the final product dipromostyrene is strongly yellow-colored, and the Friedel-Krauf alkylation reaction is not performed during the bromination reaction. concurrently,
It had drawbacks such as the generation of many impurities.

When such colored ring-brominated styrene is blended into various resins as a homopolymer, various copolymers, or graft polymers, the blended resin will also be colored, causing a major problem in terms of appearance. Moreover, the above-mentioned impurities are undesirably contained in the ring brominated styrene and adversely affect the polymerizability and physical properties of the blended resin composition.

[Problems to be Solved by the Invention] The present inventors have conducted intensive studies to establish a method for producing BEBB that overcomes these drawbacks, and have found that by combining a specific catalyst and reaction temperature, coloring is small and coloring is small. They also discovered that BEBB with less impurity formation can be obtained and completed the present invention. That is, in the present invention, when BEB is brominated, in the presence of iron powder, -30 to 30
This is a method for producing BEBB, characterized in that bromination is carried out in a temperature range of .degree.

The present invention will be explained in more detail below.

[Function] In the method of the present invention, BEB dissolved in an organic solvent is brominated by dropping a brominating agent in the temperature range of -30 to 30°C in the presence of iron powder.

BEB used in the present invention refers to α and/or β-bromoethylbenzene, and may be a mixture thereof. Among these, the β-form is preferably used because it causes fewer side reactions during bromination.

This BEB can be produced by a hydrogen bromide addition reaction of styrene or a bromination reaction of ethylbenzene.

The brominating agent used in the present invention specifically refers to bromine, bromine chloride, etc., and the amount used is 1 to 1 to 1 mole of BEBI.
The amount is about 5 moles, preferably about 1.5 to 4 moles.

The iron powder referred to in the present invention is a compound in which the surface of zero-valent iron particles is covered with iron oxide such as iron oxide or triiron tetroxide and is stabilized even in the air.

The amount of iron powder used is usually 0.0 per mole of BE'81.
About 0.01 to 0.05 mol is used.

If the amount of iron powder is less than 0.001 mol, the bromination reaction is extremely slow, and if it exceeds 0.05 mol, it is not economical.

The bromination is carried out in the equipment commonly used for this purpose.
It is carried out at a temperature range of ~30°C.

Preferably, the temperature range is 0 to 30°C.

If the reaction temperature is below -30°C, the bromination reaction will be extremely slow;
If the temperature exceeds 30°C, a large amount of by-products will be produced and the distribution of the degree of bromination of the product will tend to be widened, which is not preferable.

In order to prevent side reactions, the reaction is preferably carried out in the dark.

The reaction is carried out, for example, by dissolving BEB in a halogenated hydrocarbon solvent inert to the bromination reaction, or in the absence of a solvent. That is, iron powder is then added to the reaction substrate solution, and a predetermined amount of bromine is slowly added dropwise while stirring and cooling. The reaction mixture may be allowed to stir for some time to complete the reaction.

After the reaction, the reaction mixture is worked up in a conventional manner. Excess bromine is removed by treatment with a reducing agent, such as an aqueous solution of sodium bisulfite, and washing with water.

The reaction solution can be distilled under reduced pressure to separate and purify BEBB, or can be subjected to the dehydrobromination reaction of BEBB to produce the next ring-brominated styrene without distillation.

[Effect of the invention] As is clear from the above explanation, according to the method of the present invention,
It has become possible to obtain high-quality BEBB with little coloring and little impurity formation in a high yield, which has been difficult with conventional methods.

[Examples] The method of the present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

The degree of coloring is determined by the absorbance (AB
S) was compared.

・Measurement cell: 1 cm square quartz cell ・Tl constant wavelength: 460 nm Example 1 Capacity: 500 m1 with thermometer, stirrer, and reflux condenser tube
β-BEB in the four mouthpieces.

92.50 g (0,500 mol) and methylene chloride.

Add 215.70 g of iron powder and 0.85 g (0,015 mol) of bromine while stirring at 20°C.
168.00 g (1,050 mol) was added dropwise over 3 hours to react. Thereafter, in order to complete the reaction, the mixture was stirred and aged at the same temperature for 1 hour. Unreacted bromine and dissolved hydrogen bromide in the aged reaction solution were removed by reduction with an aqueous sodium bisulfite solution and washing with water. Methylene chloride in the resulting reaction solution was removed by distillation. In this way, β-BEBB
.

1.72.21 g was obtained. By gas chromatography and liquid chromatography, the conversion rate of β-BEB, β
-The yield, product composition, and amount of impurities of BEBB were determined.

The reaction results and degree of coloration obtained are shown in Table-1.

Example 2 Example 1 except that methylene chloride was not added and no solvent was used.
β-B
EBB: 172.69g was obtained.

The reaction results and degree of coloring are shown in Table 1.

Example 3 The same charging amount, reaction conditions, and post-treatment method as in Example 1 were used except that the reaction temperature was set to 0°C, and β-BEBB; 170
．． 04g was obtained. The reaction results and degree of coloring are shown in Table-1.

Example 4 Except that the iron powder was 0.28g (0,005 mol),
The same charging amount, reaction conditions, and post-treatment method as in Example 1 were used to obtain 170.13 g of β-BEBB. The reaction results and degree of coloring are shown in Table-1.

Example 5 Bromine at 88%. The same charge amount, reaction conditions, and post-treatment method as in Example 1 were used, except that the amount was changed to 0.0g (0,550 mol), and 8.131.21 g of β-BEB was obtained. The reaction results and degree of coloring are shown in Table-1.

Example 6 Bromine at 248. The same charge amount, reaction conditions, and post-treatment method as in Example 1 were used except that the amount of β-BEBB was changed to 1,550 mol, and 199.45 g of β-BEBB was obtained. The reaction results and degree of coloring are shown in Table-1.

Comparative Example 1 Iron powder; 0.85 g (0,015 mol); anhydrous ferric chloride; 2.43 g (0,015 mol);
The same charge amount, reaction conditions, and post-treatment method as in Example 1 were used to obtain 171.26 g of β-BEBB. The reaction results and degree of coloring are shown in Table-1.

Comparative Example 2 Iron powder: 0.85 g (0,015 mol) and anhydrous ferric chloride: 0.81 g (0,005 mol) were used.
The same amount of charge, reaction conditions, and post-treatment method as in Example 1 were used to obtain 169.54 g of β-BEBB. The reaction results and degree of coloring are shown in Table-1.

Comparative Example 3 The same charging amount, reaction conditions, and post-treatment method as in Example 1 were used except that the reaction temperature was 40°C, and β-BEBB; 17
2.70g was obtained. The reaction results and degree of coloring are shown in Table-1.

*1: *2: *3: *4: Total value of mono-, di-, and tri-isomers (β-BEB standard) Refers to β-bromoethyl monobromobenzene.

Refers to β-bromoethyldibromobenzene.

Refers to β-bromoethyltribromobenzene.

Claims (1)

[Claims] α and/or β-bromoethylbenzene is brominated, and the general formula [I] ▲There are numerical formulas, chemical formulas, tables, etc.▼ [I] (In the formula, n represents a number from 1 to 5.) In the method for producing α and/or β-bromoethylpolybromobenzene shown in
A method for producing α/β-bromoethylpolybromobenzene, characterized by carrying out bromination in a temperature range of