DE2350312C2 - Process for producing polyphenylene oxides - Google Patents

Description

OH

Production of polyphenylene oxides by oxidative coupling of phenols of the general formula

10 in rows and rows ^! are identical or different to one another and are optionally substituted by Cl or Br or a cyano group with 1 or 2 carbon atoms or for Cl or Br, in the presence of oxygen, at least one organic solvent and a copper complex, which is characterized in that as a copper complex a bis (l ^ -dicyanoäthylen-l, 2-dithioIato) -Cn- '·% omplex in an amount of 0.1 to 10 wt .-%, based on disubstituted phenol, used and the reaction at elevated or normal pressure in a temperature range of 20 to 60 ° C is carried out.
In the formula

NC S.

NC S.

Cu

S CN \

CN

35

essentially
will.

2,6-Dimethylphcr.ol uses the bis-Cl ^ -dicyanoäthylen-l ^ -dithiolatoJ-KompIexes K stands for a cation, preferably for Cu ⁺² .

The advantages of the process according to the invention are particularly evident when the phenols general formula

OH

It is known that from 2,6-dimethylphenol by oxidative coupling in the presence of copper (I) / pyridine complexes (cf. A.S. Hay, Adv. Polym. Schi 4,506 ff. [1967]) Can produce polyphenylene oxides.

The product obtained in this way shows an intrinsic viscosity after the usual work-up [77] from 3.7 to 0.8, has a relatively broad molecular weight distribution is weakly colored The process described in DE-AS 26 434 also leads to analogous results Products.

For the processes already known, however, it is essential that perfectly clean and pre-purified 2,6-dimethylphenol is available as the starting material, since otherwise products with a significantly reduced intrinsic viscosity [η] are created.

The object of the invention is to show a method that enables the production of high molecular weight Polyphenylene oxides with advantageous properties are also permitted from less fine starting material.

The invention relates to a process for which essentially 2,6-dimethylphenol is used. It is possible to produce products of polyphenylene oxide with the same high intrinsic viscosity bt ^:. To obtain technical starting 2,6-dimethylphenol when the catalysts used are Cu complexes of the bis (1,2-dicyanoethylene -1,2 dithiolato) - Cu complexes.

CN \ ² -

Cu

Cu

+2

The following is to be stated regarding the individual components and the process conditions:

As phenols of the general formula

OH

Example t

e.g. 2,6-dialkylphenols, such as 2-methyl-6- ι ο ethylphenol, 2,6-diethyIphenol, 2,6-di- (2-cyanoethyl) -phenol, the corresponding 2,6-dialkylphenols, whose alkyl groups are at least partially chlorine and / or are bromine-substituted, 2-chloro-6-alkylphenols, 2-bromo-6-alkylphenols, 2,6-dichloro- or dibromophenol; Of these, 2,6-dimethylphenol is particularly suitable.

As organic solvents in which the oxidative coupling of these phenols can be carried out, For example, toluene, chlorobenzene, dichlorobenzene and, preferably, pyridine, morpholine, acetone are suitable or nitrobenzene and mixtures of these solvents.

The solvents used should be anhydrous be.

Of the bis (dicyanoethylene-1,2-dithiolato) -Cu complexes to be used according to the invention the Cu-H complex is particularly suitable. The production this complex is expediently carried out according to the instructions of G. Manecke and D. Wöhrle, Makromolekulare Chemistry 116 (1 968), 36.

The inventive method can be in conventional reaction vessels, such as flasks, kettles or Mixing containers, stir well.

The following is to be carried out about the reaction conditions:

The Cu complex to be used according to the invention is in an amount of 0.1 to 10, preferably 0.5 to 5.0, percent by weight, based on the disubstituted Phenol, used

The oxygen to be used for the oxidative coupling is generally used in excess.

The reaction is carried out at elevated or normal pressure in a temperature range of from 20 to 60, preferably 40 to 50 ° C carried out

The concentration of the dialkylphenol in the solvent is generally between 5 and 30 percent by weight.

The work-up of the reaction product is expediently carried out in accordance with the known processes, z. B. by precipitation or reprecipitation in methanol, optionally in the presence of HCl.

The product obtained by the process according to the invention has intrinsic viscosities [η] between 0.8 and 1.1 and shows good performance properties.

The polyphenylene oxide produced according to the invention is suitable for applications in the electrical industry, especially for high temperature insulation.

The parts and percentages mentioned in the examples and comparative experiments are parts by weight and Weight percent.

To produce polyphenylene oxide (PPO), the solvents used were each passed through a molecular sieve 4 A dried

0.01 mol (4.05 parts) of bis (1,2-dicyanoethylene-1,2-dithioIato) -Cu-II complex were dissolved in 500 parts of pyridine, 240 g of MgSO ₄ (calcined) were added and O _{2 was passed} through the reaction solution slipped. Then 1 mol (122.2 parts) of 2,6-dimethylphenol (technically 98%), dissolved in 500 parts of acetone, was added and the mixture was stirred at 20 ° C. for 3 hours while _{constantly passing in O 2}

A further 0.5 part of the complex was then added and the mixture was stirred for a further 60 minutes

The deeply colored reaction solution was then precipitated with 6000 parts of methanol with the addition of 600 parts of 10% HCl, filtered off and washed acid-free with methanol. After the precipitate had dissolved in 10000 parts of CHCl ₃ and filtered, it was precipitated again in methanol

The product obtained was dried; the yield was 95.4 parts (78.0%) [η] dl / g 25 ° C CHCb 0.8Z

Example 2

The procedure was as stated in Example 1, except that O-dichlorobenzene was used as the solvent. The yield was 883 parts; [η] 0.73.

Example 3

If the procedure was as described above, but with acetone as the solvent, the yield was 43.5 Parts [η] 0.75.

Example 4

If the procedure described above was carried out, but at 40 ° C., the yield was 96.5 parts [η] 0.85.

Comparative examples

According to regulation
J.Polym.Sci.58,581 (196?)

O2 is passed into a solution of 135 parts of pyridine and 1 part of copper (I) chloride until it dissolves dark green then 5 parts of 2,6-dimethylphenol (100%) are added.

After 7 minutes the temperature rises from 28 to 46 ° C and the solution becomes viscous. Then in Methanol precipitated and washed out with HCl.

After drying, the resulting polymer has an intrinsic viscosity of 0.72 dl / g (CHG ₃ , 25 ° C.).

Will be a technical product as described above

a) 2,6-dimethylphenol 86%
or cleaned goods

b) 2,6-dimethylphenol 98%

is used and worked under otherwise identical conditions, it arises with

a) a polymer with an intrinsic viscosity of [η] 0.42 and with

b) a polymer with an intrinsic viscosity of [η] 0.5,

Claims (2)

Claims; 1. Process for the preparation of palyphenylene oxides by oxidative coupling of phenols of the general formula OH 15th in which R and Ri are identical or different to one another and represent alkyl groups with 1 or 2 carbon atoms, optionally substituted by Cl or Br or a cyano group, or Cl or Br, in the presence of oxygen, at least one organic solvent and a copper complex, marked thereby η η et that the copper complex used is a bis (l, 2-dicyanoethylene-l, 2-dithiolato) -Cu complex in an amount of 0.1 to 10% by weight, based on disubstituted phenol, and the reaction at elevated or normal pressure is performed at a temperature range of from 20 to 6O ⁰ C. 2. The method according to claim 1, characterized in that the phenols of the general formula