DE1186053B - Process for the preparation of adducts from 5, 5-dialkoxy-1, 2, 3, 4-tetrachlorocyclopentadienes - Google Patents

Description

Process for the preparation of adducts from 5,5-dialkoxy-1,2,3,4-tetrachlorocyclopentadienes The present invention relates to the preparation of valuable adducts from 5,5-dialkoxy-1,2,3,4-tetrachlorocyclopentadienes of the general formula where R is a preferably lower alkyl radical and the benzene nucleus A can still be substituted.

One arrives at these connections. if you have equimolecular amounts of 1,4-naphthoquinone and a 5,5-dialkoxy-1,2,3,4-tetrachlorocyclopentadiene of the general formula where R has the above meaning, heated to temperatures above IOOGC by processes known per se.

The dialkoxytetrachlorocyclopentadiene of the above general Formula can be made by treating hexachlorocyclopentadiene. which a technical Large product represents, with alcoholic, for example methyl or ethyl alcoholic Potash can easily be obtained.

The addition reaction is exothermic and gives when started dissipates a considerable amount of heat. It can therefore apply to larger approaches Prove to be appropriate. the reaction in an inert diluent, for example a high-boiling organic solvent. such as nitrobenzene, di- or trichlorobenzene or water.

The reaction product becomes practically quantitative in the crystalline state Yield and obtained in high purity. It is a valuable connection which can be used, for example, for pest control, or above all as Starting material for the production of anthraquinone compounds of great interest is. For example, it can be converted into tetrachlorodihydroanthraquinone by treatment with sulfuric acid transfer, the latter by treating with an oxidizing agent. z. B. atmospheric oxygen or hydrogen peroxide, passes into tetrachloroanthraquinone.

According to US Pat. No. 2,584,139, it is known that the reaction of 1,4-naphthoquinone with hexachlorocyclopentadiene only very slowly and poorly Yield. namely only to 53 to 540in. Furthermore, from the literature (s. M c B e e, J. Am. Chem. Soc., Brd. 77. 1955.

Pp. 285 to 287) known. that the reaction of 5.5-dimethoxy-1.2. 3,4-tetrachlorocyclopentadiene runs very slowly and incompletely with benzoquinone; for a yield of 820in is z. B. 48 hours of heating required.

Due to this state of the art could not with such a smooth reaction between the components to be used according to the invention will; the success of the process according to the invention is therefore surprising. aside from that the claimed method represents a valuable addition to the technology, since there are new technically viable routes for the synthesis of anthraquinone compounds in good yield opened.

In the examples below, the parts unless they mean nothing otherwise indicated, parts by weight. the percentages percentages by weight. and temperatures are given in degrees Celsius.

Example 1 A mixture of 158 parts of 1,4-naphthoquinone is heated and 264 parts of 5,5-dimethoxy-1,2,3,4-tetrachlorocyclopentadiene at 115 to 1200C.

A strongly exothermic reaction sets in at this temperature, whereby complete solution occurs.

Within a few minutes the temperature rises to 170 ° C. Then crystallizes the adduct is completely exhausted while the temperature rises again to about 210 °. That light gray reaction product is obtained in practically quantitative yield and is analytically pure after single recrystallization from glacial acetic acid or ethyl acetate; white needles, F. 225 to 226 ° (uncorrected).

If the product obtained above is treated with 100% sulfuric acid treated, a decomposition reaction takes place with foaming. with one stabbing smelling substance occurs. If you treat the degradation product with air or a little Hydrogen peroxide, 1,2,3,4-tetrachloranthraquinone is obtained in yellow needles (F. 189 to 1900, uncorrected.

Chlorine content 40.9010).

Example 2 63.2 parts of 1,4-naphthoquinone (= 0.4 mol) and 105.6 parts 5,5-Dimethoxy-1,2,3,4-tetrachlorocyclopentadiene (= 0.4 mol) are added with stirring heated to 115 °. At this temperature a strongly exothermic reaction sets in, complete dissolution occurs. The temperature is increased by adding 170 parts by volume Trichlorobenzene held between 150 and 1600. Then the mixture is warmed up briefly to 175 °. let it cool to room temperature and stir it until complete Crystallization.

The adduct is filtered off, washed with alcohol and dried. Yield 147.4 parts or 87.30 / o of theory. White crystals from the melting point 225 (uncorrected), chlorine content 33.60 / 0 (calculated 33.600 / 0).

Example 3 A mixture of 7.9 parts of 1,4-naphthoquinone and 16 Share 5.5-di-n-propoxy-l .2,3,4-tetrachloro- Cyclopentadiene is heated to 1200. At this temperature the batch is completely dissolved and an exothermic reaction begins Reaction causing the temperature to rise to around 1600C. After short After a while, the temperature falls again and the crude, beige-colored adduct crystallizes in practically quantitative yield. It is used for cleaning from ethyl alcohol recrystallized: white crystals with a melting point of 174 to 175 ° (uncorrected), Chlorine content 29.60wo (calculated 29.660 / 0).

Claims (1)

Claim: Process for the preparation of adducts from 5,5-dialkoxy-1,2,3,4-tetrachlorocyclopentadienes of the general formula wherein R is a preferably lower alkyl radical and the benzene nucleus A can optionally also be substituted, characterized in that an equimolecular mixture of a 5,5-dialkoxy-1,2,3,4-tetrachlorocyclopentadiene and 1,4-naphthoquinone, optionally in the presence of an inert solvent, heated to temperatures above 100 "by methods known per se. Documents considered: German Auslegeschrift No. 1,035,651; German Patent No. 968 171; U.S. Patent No. 1,890,040, 2,584,139; Ber. German chem. Ges., Vol. 62 B, 1929, pp. 2337 to 2377; Chem. Ber., Vol. 88, 1955, 5. 2003 to 2011; J. Am. Chem. Soc., Vol. 77, 1955, pp. 385-387.