DE941373C - Process for the preparation of 6-acyl-2-oxy-naphthalenes - Google Patents

Description

Process for the preparation of 6-acyl-2-oxy-naphthalenes 6-acyl-2-oxy-naphthalenes are known not to be obtained by direct acylation of 2-oxynaphthalenes will. This is how 2-oxynaphthalenes are treated with acid chlorides in the presence of aluminum chloride predominantly I-acyl-2-oxynaphthalenes. Corresponding the alkyl ethers of 2-oxynaphthalene supply mainly I-acyl-2-alkoxy-naphthalenes in the acylation (Fries and Schimmelschmidt, reports of the Deutsche Chemischen Gesellscllaft, 58, P. 2835 [1925]).

Are 2-alkoxy-naphthalenes with succinic anhydride in the presence reacted by aluminum chloride, a mixture of 2-alkoxy-I-naphthoyl and 2-alkoxy-6-naphthoyl-propionic acid is formed, the decomposition of which is difficult. aside from that is another step after the separation, namely dealkylation of the mixture components, required to give free 2-oxy-6-succinyl-naphthalene come, so that this route is very arduous (Swain, Todd and Waring, J. Chem. Soc. [London], 1944, p. 548, and Sergeevskaya et al., Magazine. for general Chemie [russ.], 20, p. 2314, and 2I, p. 584). Acylation is the same the I-chloro-2-alkoxy-naphthalenes not a satisfactory process for the preparation of 6-acyl-2-oxy-naphthalenes, since the intermediate 6-acyl I-chloro-2-alkoxy-naphthalenes must be reduced and dealkylated with hydrogen yodide (Robinson and Tompson, J. Chem. Soc. [London] 1938, pp. 2co9).

It is also known that 2-oxynaphthalene-carboxylic acids and sulfonic acids acylated by the action of benzotrichloride and other aryl trichlorides can. However, this method is based on the introduction of very special aromatic Acyl groups restricted.

It has now been found that 6-acyl-2-oxy-naphthalenes are easier than so far by the action of acid chlorides or acid anhydrides in the presence of Aluminum chloride on 2-oxy-naphthalene-I-carboxylic acid or 2-oxy-naphthalene-I-sulfonic acid and splitting off the carboxyl or sulfonic acid group from the resulting Acylation products can be produced.

This finding was surprising insofar as the sulfonic acid group in 2-oxy-naphthalene-I-sulfonic acid in various reactions by others Substituents is displaced. ~ This is how z. B. in the bromination of this compound I-bromo-2-oxynaphthalene and 1,6-dibromo-2-oxynaphthalene, in the nitration 1,6-dinitro-2-oxynaphthalene and when exposed to phosphorus pentachloride, 2-chloro-naphthalene and a little 1,2-dichloro-naphthalene (Armstrong, Reports of the German Chemical Society, I5, p. 203 [I882]). The same is true of the adhesive strength of the carboxyl group in 2-oxynaphthalene-1-carboxylic acid as is well known, not very large. It was therefore to be expected that the as Starting material for the present process mentioned compounds in acylation their carboxyl resp.

Lose sulfonic acid group and enter the acyl group in the I-position would. In fact, however, it turned out that the acylation was almost exclusively leads to the formation of 6-acyl-2-oxy-naphthalene-I-carbonic acid or sulfonic acid.

From the acylation products formed as intermediates in the present process can the carboxyl or sulfonic acid group by known methods, for. B. by Heating in the presence of mineral acid, split off.

There is a preferred embodiment of the method according to the invention in that a crude sulfonation mixture is used as the starting material, the was obtained from 2-oxynaphthalene and chlorosulfonic acid in a solvent, that also for the following. Acylation is suitable. As such, e.g. B. nitrobenzene, Tetrachloroethane, dichloroethane and carbon disulfide should be mentioned.

The 6-acyl-2-oxyhaphthalenes obtainable by the process have Importance as intermediate products in the manufacture of dyes and drugs.

Example 1 Regarding the molecular compound of AlCl3 and acetyl chloride, by entering 60 parts by weight of AlCl3 and then 32 parts by weight Acetyl chloride is represented in 50 parts by volume of nitrobenzene, is left at 30 to 40 ° a sulfonation run in, which by slow addition of 25 parts by weight Chlorosulfonic acid to a mixture of 80 parts by volume of nitrobenzene and 29 parts by weight 2-oxynaphthalene was obtained at 0 to 5 ° and stirring for one hour, and predominantly consists of 2-oxy-naphthalene-I-sulfonic acid. Strong hydrochloric acid development. Afterward is heated to 70 "for 8 hours, after which the evolution of hydrochloric acid has ended Carrying out on ice results in a thick slurry of crystals.

After suction filtration and dissolving with 400 ccm of hot water, it is mixed with 80 parts by weight of pure sulfuric acid and boiled for 1 hour while distilling off remaining nitrobenzene is removed. The reaction product separates out oily, but solidifies already below 1000. After suction filtering and washing with water is for the purpose of cleaning and separating recovered 2-oxynaphthalene with diluted Sodium hydroxide solution dissolved around the sodium salt from the solution by adding table salt of the 6-acetyl-2-oxy-naphthahns deposited. The sodium salt is after suction filtering dissolved in hot water.

The solution is clarified with animal charcoal and acidified with hydrochloric acid. The separated 6-acetyl-2-oy naphthalene is sucked hot, washed and dried; F. 1710. The yield is 800%, based on the 2-oxynaphthalene used.

Example 2 In a mixture of 700 parts by volume of dichloroethane, 94 parts by weight 2-oxy-naphthalene-1-carboxylic acid and 60 parts by weight of succinic anhydride 250 parts by weight of aluminum chloride entered. The temperature rises below brisk H Cl evolves by itself to 40 "and is increased by heating at 70 to 5 hours 80 ". About 800 parts by weight of water are left in at this temperature Add dropwise distilling off the dichloroethane. Then it is sucked and with warm Water washed. The reaction product is dissolved with zooo parts by volume of a 10% Sulfuric acid treated at the boil for 2 hours.

It initially melts while foaming. According to I bis For 1/2 hour it becomes increasingly crystalline. After cooling to 50 ° it is sucked and washed with water. The product is now dissolved with dilute soda solution, leaving a greasy residue. After clarifying with charcoal it will be at 40 bis 50 ° acidified with hydrochloric acid; the deposited crystals are sucked up and washed with water. After drying, 73.5 parts by weight (= 6 ° / o of theory) p- (2-Oxynaphthoyl-6 -) - propionic acid was obtained. The raw melting point is 2160. After cleaning with the sparingly soluble sodium salt, the melting point is included 229 to 2300.

Example 3 In a mixture of 300 parts by volume of dichloroethane, 60 Parts by weight of succinic anhydride and 250 parts by weight of aluminum chloride leaves a sulfonation mixture, which by the action of 62 parts by weight of chlorosulfonic acid to a mixture of 400 parts by volume of dichloroethane and 72 parts by weight of 2-oxy-nåphthalin was obtained at 0 to 5 ° and consists mainly of 2-oxy-naphthalene-I-sulfonic acid, to run. Then it is heated to 600 for 3 to 4 hours, until the development of hydrochloric acid is finished. 1200 parts by volume of water are left in while the solvent is distilled off dropwise to obtain a solution. 180 parts by weight are added to the solution concentrated sulfuric acid added. After one hour of boiling, the separated B- (2-oxy-naphthoyl-6) propionic acid sucked hot and washed.

Raw melting point 226 up to 7 ".

Claims (2)

PATENT CLAIMS: I. Process for the preparation of 6-acyl-2-oxynaphthalenes, characterized in that one uses 2-oxynaphthalene-I-carboxylic acid or 2-oxynaphthalene-I-sulfonic acid Allow acid anhydrides or acid chlorides to act in the presence of aluminum chloride and the carboxyl or sulfonic acid group from the acylation products formed in this way splits off in a manner known per se. 2. The method according to claim I, characterized in that one to Instead of pure 2-oxynaphthalene-I-sulfonic acid, a crude sulfonation mixture is used, that of 2-oxynaphthalene and chlorosulfonic acid in one, also for the following Acylation suitable solvent - has been obtained. Attached publications: German patent specifications No. 378 908, 378 gog and 4I8 034.