CS256776B1 - Process for producing tetrahloro- (2,2) paracyclophane - Google Patents

Abstract

The present invention relates to the production of tetrachloro-/2,2/paracyclophane, which consists in thermal decomposition at 30 to 140 °C, preferably at 30 to 90 °C of an aqueous solution of /diochloro-4-methylbenzyl/trimethylammonium hydroxide prepared in situ from /diochloro-4-methylbenzyl/trimethylammonium bromide in a solution of a strong base, dimethyl sulfoxide and a hydrocarbon solvent. Tetrachloro-/2,2/paracyclophane is a starting material for the preparation of a polymer of dichloro-poly-xylylene.

Description

The invention relates to a process for the preparation of tetrachloro- (2,2) paracyclophan. Tetrachloro- (2,2) paracyclophan is a known compound of formula IV, which is used to prepare a polydichloro-p-xylene polymer having excellent dielectric properties, chemical, mechanical and thermal stability, very low permeability to aggressive gases such as HgS, SOg, Olg and humidity. These properties are used in microelectronics, optics and medicine for long-term protection of components against corrosion and contamination of their surfaces.

Processes for the preparation of tetrachloro- (2,2) paracyclophane based on chlorination (2,2) paracyclophane / U.S.Pat. No. 3221068, 3342754].

A disadvantage of these processes for the preparation of tetrachloro- (2,2) paracyclophan is that they require (2,2) paracyclophan as a starting compound, a compound that is difficult to access and expensive. A further disadvantage of the described processes for the preparation of tetrachloro- (2,2) paracyclophane is that the reaction product resulting from the chlorination of (2,2) paracyclophane contains unreacted starting material, monochloro derivative, dichloro derivative, trichloro derivative, pentachloro derivative and tetrachloride - a derivative having three chlorine atoms attached to one aromatic ring and one chlorine atom attached to the other aromatic ring. Due to their further use, the production of a well-defined polymer, these additives are undesirable and must be removed, for example, by rectification under reduced pressure.

Said drawbacks of the preparation of tetrachloro- (2,2) paracyclophan are solved by the process according to the invention, characterized in that ee to quaternary ammonium salts of the general formula II, wherein R is the same or different alkyl of 1 to 12 carbon atoms and X is chlorine, bro256776

- 2 mu or iodine acts as a strong base in a system consisting of an inert hydrocarbon solvent and dimethyl sulfoxide, and the resulting quaternary ammonium base of formula I, wherein R is as defined above, decomposes without further isolation in this environment at an elevated temperature of 50 to 140 ° C; preferably at 50 to 90 ° C. The inert hydrocarbon solvent according to the invention may be, for example, aromatic hydrocarbons benzene, toluene and xylene. The alkyl radical R is preferably methyl or ethyl. The strong base is preferably an aqueous solution of sodium or potassium hydroxide.

The quaternary ammonium salt of the formula II can be prepared in a manner known per se from the corresponding halogenated derivative III, where X is as defined above, by reaction with trimethylamine to form a quaternary ammonium salt II, which is converted to the ammonium base I as described above.

procedure

It is an advantage of the invention that the quaternary ammonium base is not isolated, that the purification of the intermediates is eliminated and that the yields are between 70 and 75% by weight. A major advantage of the invention is that the tetrachloro-2,2-paracyclophane formed has a precisely defined structure, characterized by the presence of two chlorine atoms on each benzene nucleus. , which so far no known procedure allowed.

The process according to the invention is best illustrated in the following example.

Example

To a mixture containing 4 L of toluene, a solution of 120 g of NaOH in 180 ml of water and 750 ml of dimethylsulfoxide was added with stirring a suspension of 512.0 g of (dichloro-4-methylbenzyl) trimethyl ammonium bromide in 500 ml of water over 1 hour. Upon completion of the addition, the temperature was raised to 40 ° C and the mixture was stirred for 2 hours. After this, the temperature was raised to 60 ° C over 4 hours with stirring, and after 4 hours the temperature was raised to a final 90 ° C. . The mixture was stirred at this temperature for 8 hours.

After cooling the reaction mixture, the phases are separated, the organic phase is washed with water, filtered and evaporated to dryness.

Yield 129.0 g of tetrachloro- (2,2) paracyclophan, i.e. 75 wt.

Claims (3)

SUBJECT OF THE INVENTION A process for the preparation of tetrachloro [1,2] paracyclophan, characterized in that the quaternary ammonium salt of the general formula (II), wherein R is the same or different alkyl of 1 to 12 carbon atoms and X is a chlorine, bromine or iodine atom, A mixture of an inert hydrocarbon solvent and a dimethyl sulfoxide with a strong base and the resulting quaternary ammonium base of formula I, wherein R is as defined above, and then decomposes at elevated temperatures of 30 to 140 ° C, preferably at 30 to 90 ° without isolation. C. 2. A process according to claim 1, wherein the strong base is an aqueous solution of sodium or potassium hydroxide. 3 · method according to claim 1 to 2 _F, wherein the inert hydrocarbon solvent are aromatic hydrocarbons such as benzene, toluene or xylene.