DE500160C - Process for the preparation of anthraquinone and its offshoots - Google Patents

Description

Process for the preparation of antbrachinone and its derivatives In the 496,393 patent is a method of preparing anthraquinone and its Descendants described, which consists in the fact that one condensation products i mol. of an a-naphthoquinone and i mol. of an i # 3-butadiene in the presence of hydrogen absorbent agents treated with alkaline agents. It is shown in patent 498,360 that this reaction probably proceeds in the way that the starting materials. a rearrangement in i # ¢ -Dihydroanfhrahydrochix.: one suffer from which by dehydration depending on the conditions, i # q.-dihydroanthraquinones or A, nthraquinones are formed.

It has now been found that the same products are obtained if the condensation products obtained from i # 3-butadienes are mixed with α-naphthoquinones which are negative in the 2-position or in the 2- and 3-positions, e.g. B. by halogen, are substituted, intramolecular hydrogen halide, etc. split off. This gives i # q: -dihydroanthraquinones or anthraquinones according to the following reaction equations: °,? Ie @ e @ hir £ ramolecular cleavage ahn effected in the most varied of ways xd`ep, Z. ß. erch heating the said Koltdensati # h $ p # ukt eucts individually or in units presence of thinners,. by the action of acids, bases or suitable salts, etc. By suitable choice of working conditions, e.g. B. Working at a higher temperature or in a suitable diluent such as alcohol, the preparation of the starting materials can be carried out under certain circumstances with the aforementioned intramolecular cleavage in one operation.

The primarily resulting reaction products of equations i and 2 can undergo secondary changes in the course of the reaction, e.g. B. when hydrogen-absorbing or hydrogen-supplying substances are present during their production. For example, by heating 2-chloro-i # 4-naphthoquinone with 2 # 3-dimethyl-i # 3-butadiene in alcohol, which according to equation i leads to 2 # 3 - dimethyl - i # 4 - dihydraanthraquinone, under certain circumstances 2 # 3-dimethylanthraquinone can also be obtained by dehydrating dimethyldihydroanthraquinone that is primarily formed by unreacted chloronaphthoquinone. On the other hand, in the presence of hydrogen-yielding agents, such as sodium hydrosulfite, hydro compounds of the reaction products expected according to equations i and 2 can be obtained, e.g. B. according to equation 3: Example i The condensation product obtainable by heating equal amounts of z-chloro-i = 4-naphthoquinone and 2 # 3 -dimethyl-i # 3-butadiene to 70 ° is heated to boiling for a short time with 20 parts of 5% sodium hydroxide solution with the addition of a little sodium hydrosulfite. The resulting yellow solution contains the 2 # 3-dimethyl-i # 4-dihydroanthrahydroquinone described in Example 6 of Patent 498 36o. Passing air through the liquid, which has been cooled to 0 °, precipitates colorless flakes which essentially consist of the 2 # 3-dimethyl-i # 4-dihydroanthraquinone also described in the example mentioned.

EXAMPLES 1 part of the condensation product is boiled from 1 mol. 2 # 3-dichloronaphthoquinone and 1 mole. 2 # 3 - dimethyl - i - 3 - butadiene, which Crystallized from alcohol in colorless flakes, with 15 parts of 5% alcohol Potash lye for 2 hours, the 2 # 3-dimethylanefhraquinone formed precipitates with water and recrystallizes it from benzene.

Example 3 That from 8-nitro-2 # 3. @ Dichlor-i # 4-naphthoquinone and 2 # 3-Dimethyl-i # 3-butadiene obtainable condensation product (obtained from a mixture from ligroin and benzene crystallized in colorless needles) becomes with the aofachen Amount of 5 percent aqueous potassium hydroxide solution heated to boiling for 2 hours. By Adding hydrosulfite to the reaction mixture, the resulting yellow-red vat is filtered and blown out with air, whereupon the separated red precipitate is suctioned off and unicrystallized from aqueous pyrudine. The product obtained in this way is identical with that of example 3 of patent 496 393, thus probably 6 # 7-dimethyli-aminoanthraquinone. example Equal parts of 2-chloro-i # q.-naphthoquinone and isoprene are under pressure for 5 hours heated to i2o ° for a long time. The viscous mass is stirred with alcohol, whereupon After some time, the reaction product separates out in solid form. It can go through Recrystallization, e.g. B. from benzene, cleaned and then consists of pure 2-methylanthraquinone.

Example s A solution of 5 parts of 2-chlorine - i # q is heated. - Naphthoquinone and 5 parts of 2 # 3-dimethyl-i # 3-butadiene in 20 parts of alcohol for 5 hours in a closed vessel at 100 to 10 5 °. After cooling, the resulting crystal pulp is sucked off and the residue, e.g. B. from benzene, recrystallized. Colorless needles of pure 2 # 3-dimethylanthraquinone are obtained.

Claims (1)

PATENT CLAIM: Further development of the process of patent 496 393, characterized in that condensation products of i # 3-butadienes and those naphthoquinones which contain negative substituents in the 2-position or in the 2- and 3-positions, such as halogen, etc., splitting off intramolecular hydrogen halide, etc., it being possible, if appropriate, to work in the presence of hydrogen-absorbing or hydrogen-supplying agents.