Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/10—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction with carbon monoxide

Definitions

• the present invention is in the technical field of intermediates which can be used, for example, for the synthesis of azo dyes and polyester base materials.
• 2-Hydroxy-naphthalene-6-carboxylic acid is not only a valuable synthetic building block for pharmaceuticals, textile auxiliaries and dyes (see, for example, European Patent Application Publication No. 0 292 955A), but in particular also an important monomer for the production of liquid-crystalline high-performance plastics and fibers with superior properties (see U.S. Patent 4,393,191).
• Schmitt reaction ie by reacting the potassium salt of ⁇ -naphthol with carbon dioxide under pressure at 200-300 ° C (see, for example, US Pat. Nos. 1,593,816, 4,329,494 and 4,287,357).
• the procedures described in these publications have some technical disadvantages; this gives rise to considerable proportions of decomposition products, such as tars and resins, which, like the 2-hydroxy-naphthalene-3-carboxylic acid and 2-hydroxy-naphthalene-3,6-dicarboxylic acid formed in side reactions, are difficult to separate off.
• the formate serving as solvent (diluent) is used in at least the same molar amount as the potassium ⁇ -naphtholate starting product; the amount of potassium formate used is not critical and can vary within wide limits. However, it is advantageous to use potassium formate in a larger amount as a solvent (diluent), for example in 2.5 to 18 times, preferably in 6 to 15 times, the amount by weight of the potassium ⁇ -naphtholate used, by one the best possible mixing of the reactants dissolved in potassium formate potassium- ⁇ -naphtholate and potassium carbonate and the gaseous
• the potassium formate used as a solvent (diluent) not only brings about a high selectivity of the reaction with the formation of the potassium salt of 2-hydroxy-naphthalene-6-carboxylic acid, but it also has the advantage that it is not a foreign product in the reaction mixture, but is identical to the by-product of the implementation.
• the potassium formate can therefore be completely replaced in later Reactions are used, or else carbon monoxide is obtained from the excess of this product by heating with concentrated sulfuric acid, which can be recycled into a later reaction.
• the potassium carbonate likewise used in the process according to the invention is used in the reaction in at least the same molar amount as the potassium ⁇ -naphtholate.
• the molar ratio of potassium ⁇ -naphtholate to potassium carbonate is between 1: 1 and 1: 1.5.
• the batch can be worked up in various ways and the 2-naphthol-6-carboxylic acid formed is isolated.
• One way is that
• the fine cleaning is carried out analogously to known procedures, for example by pressure redissolving in water or by cleaning with 1,4-dioxane (see, for example, German Offenlegungsschrift 38 00 989).
• the reaction mixture is then cooled, the autoclave is depressurized, the reaction product is dissolved in water, the pH is adjusted to 7 with concentrated sulfuric acid, and the precipitated, unreacted ⁇ -naphthol is filtered off, and the filtrate is adjusted to a pH of 1 using sulfuric acid and the now precipitated 2-hydroxy-naphthalene-6-carboxylic acid is isolated.
• the 2-naphthol-6-carboxylic acid can be separated from the by-products from the crude product in a conventional manner and thus be obtained in pure form. Yield: 34% of theory, based on the ⁇ -naphthol as
• Example 1 The procedure of Example 1 is followed, with the difference that the reaction is carried out at 300 ° C. and with 125 parts of potassium formate. You get that
• EXAMPLE 3 The procedure described in the examples above is carried out at a carbon monoxide pressure of 100 bar and a temperature of 320 ° C. for about 5 hours Use of 10 parts of potassium ⁇ -naphtholate, 7, 6 parts of potassium carbonate and 75 parts of potassium formate. After working up the reaction mixture, 2-hydroxy-naphthalene-6-carboxylic acid is obtained in a yield of 37.5% of theory. Th. in addition to 5.7% 2-naphthol-3-carboxylic acid.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6399256

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (1)

Citations (3)

Family Cites Families (5)

• 1990
  • 1990-02-02 DE DE4003043A patent/DE4003043A1/de not_active Withdrawn
• 1991
  • 1991-01-22 IN IN61/CAL/91A patent/IN170980B/en unknown
  • 1991-01-24 WO PCT/EP1991/000132 patent/WO1991011422A1/de active IP Right Grant
  • 1991-01-24 DE DE59103290T patent/DE59103290D1/de not_active Expired - Fee Related
  • 1991-01-24 CA CA002075197A patent/CA2075197A1/en not_active Abandoned
  • 1991-01-24 EP EP91902673A patent/EP0513053B1/de not_active Expired - Lifetime
  • 1991-01-24 US US07/917,049 patent/US5312976A/en not_active Expired - Fee Related
  • 1991-01-24 JP JP3502541A patent/JPH05504346A/ja active Pending

Patent Citations (3)

Also Published As

Similar Documents

Legal Events