DE4000163A1 - Alpha-omega alkane di:carboxylic acids prepn. - by reaction of cycloalkene(s) with ozone, redn. of peroxide(s) and oxidn. in safe process - Google Patents

Abstract

Prepn. of alpha-omega-alkane dicarboxylic acids of formula HOOC-A-COOH (I) comprises: (a) reaction of a cycloalkane of formula (II) with ozone in an inert solvent; (b) catalytic peroxide soln. to give a dialdehyde; and (c) oxidn. of the dialdehyde in an inert aprotic solvent. A = (CH2)n; n = 4-14. USE/ADVANTAGE - (I) are important intermediates and starting materials in the prodn. of, e.g. pharmaceuticals, cosmetics, and ointments. The process is safer than previous methods as peroxide intermediates are destroyed before addn. of a further oxidising agent. The process gives (I) in good yield (65-45%) and high purity (at least 95%).

Description

The invention relates to a method for producing alpha- omega-alkanedicarboxylic acids based on cycloalkenes.

Alpha-omega-alkanedicarboxylic acids are valuable starting products in the chemical industry and can be found, for example, at Manufacture of pharmaceuticals, cosmetics, lubricants and. the like Use.

There are already processes for the production of alpha-omega-alkanedicarboxylic acids known.

For example, in Chemical Abstracts Vol 96, (1982) 199107 a the production of alpha-omega-alkanedicarboxylic acids by oxidative ring cleavage of the corresponding cycloalkenes Help of ozone in the presence of methanol and sulfuric acid, Oxidation of the peroxide solution with H₂O₂ and subsequent saponification of the resulting dimethyl ester, whereupon the The resulting dicarboxylic acid is purified by recrystallization must become.

Furthermore, from Chemical Abstracts Vol 97 (1982) 216903 × Ozonization of cyclooctene in propionic acid to acyloxy hydroperoxide, which rearranges to omega-formyl carboxylic acid and subsequent Oxidation of this solution with H₂O₂ in the presence of a organic acid known to dicarboxylic acid, which also must be recrystallized.

There is a serious disadvantage with these two methods in that a peroxide-containing solution with an oxidizing agent must be relocated. A reaction mixture consisting of a peroxide and another oxidizing agent Combination that decompose very easily explosively can. The application of such a method on a larger scale is therefore questionable for safety reasons.

It could now be a safe process for making Alpha-omega-alkanedicarboxylic acids can be found starting from  obtained from cycloalkenes alkane dicarboxylic acids in high purity will. The ones that serve as the starting compounds Cycloalkenes treated with ozone during ozonization The resulting peroxide-containing ozonide solution is catalytically hydrogenated and the dialdehyde formed is then oxidized to diacid. The dangerous peroxides in the reduction of the peroxide-containing Solution are destroyed, the oxidation takes place in peroxide-free Solution instead, which eliminates the risk of explosion consists.

The invention therefore relates to a method for the production of alpha-omega-alkanedicarboxylic acids of the general formula I,

in which A is an alkylene radical with 4-14 C atoms, that is characterized in that a cycloalkene of the general Formula II,

in which A has the meaning given above, with ozone in the presence a solvent, the resulting peroxide solution catalytically hydrogenated, whereupon the dialdehyde formed in the presence an inert aprotic solvent for diacid Formula I is oxidized.

In the formulas I and II, A is an alkyl radical with 4 to 14 carbon atoms, for example a butylene, pentylene, hexylene, Heptylene, octylene, nonylene, decylene, undecylene, Dodecylene, tridecylene or tetradecylene radical. Preferably A represents a pentylene, a hexylene or decylene radical.  

The ozonization and subsequent hydrogenation can be carried out in the usual way Way. To do this, the output connections dissolved in a suitable organic solvent and with Treated ozone. The solution of the ozonolysis products is then Catalytically hydrogenated using hydrogen. As Catalysts are usually used for hydrogenations Precious metal catalysts in the form of powder contacts can be used with carrier materials or without carrier material can, for example Pd, Pt, Ru, Rh, Ni catalysts. Activated carbon, for example, is suitable as a carrier material optionally with an alkaline earth metal carbonate, Aluminum oxides, silica gel and diatomaceous earth. Preferably Pt or Pd / C with CaCO₃ used as a catalyst.

Ozonization and subsequent hydrogenation are preferred carried out by the method described in EP-A-01 47 593. It is used to carry out the reaction of the cycloalkene in an organic solvent in which it is readily soluble, for example in a lower aliphatic alcohol, preferably dissolved in methanol and with the equivalent amount Treated ozone. Ozonation occurs at temperatures of around -30 to 0 ° C, preferably about -20 to 0 ° C.

The catalytic hydrogenation following ozonization the ozonolysis products are carried out in dilute solution, preferably a controlled one during the hydrogenation Peroxide content of at most 0.1 mol / l is observed. To becomes a suspension of the catalyst in the solvent and hydrogen submitted and the ozonolysis solution fed continuously. By keeping this measure low Peroxide content of the reaction medium becomes poisoning and an Loss of activity of the catalyst prevented.

The hydrogenation takes place under practically depressurized conditions, these are pressures of 1 to 3 bar that are usually applied to prevent air from entering the hydrogenation reactor prevent.  

The reaction temperature in the hydrogenation is about 20-40 ° C. The pH is in a range during the hydrogenation held by 2-7. Since small amounts of acidic by-products can arise, the pH value optionally by adding a base, preferably dilute Sodium hydroxide solution or potassium hydroxide solution can be kept in the desired range.

The catalyst is then filtered off and the solvent away. The backlog is left in for the subsequent one Oxidation step suitable inert solvent dissolved and oxidized using an oxidizing agent.

Inert come as solvents under reaction conditions aprotic, organic solvents, for example aromatic Hydrocarbons such as benzene, toluene, chlorobenzene, dichlorobenzene and the like. As an oxidizing agent oxygen or air, preferably oxygen, is used. The oxidation is preferably carried out under pressure, with Pressures of 3-10 bar are preferred. The reaction is at Temperatures of 50-100 ° C, preferably carried out at 70-90 ° C.

After the reaction has ended, the reaction solution is cooled to a certain volume is concentrated or the solvent removed, the dicarboxylic acid being obtained in crystalline form.

According to the method of the invention, alpha-omega-dicarboxylic acids in high purity and with excellent yields receive. As a rule, yields of 65-85%, reached 75-95% after working up the mother liquor. The Dicarboxylic acids are obtained with a purity of at least 95%, whereby usually a further cleaning of the end product is not necessary.

Example 1 Dodecanedioic acid Dodecandial

130.1 g (1 mol) cyclododecene (purity 95%) were in 1500 ml Dissolved methanol, cooled to -20 ° C and an O₂ / O₃ mixture, the 4 wt .-% Ozone contains up to 2 moles of ozone introduced into the solution have been introduced.

Then in a hydrogenation reactor in which 5 g of Pd / C were presented with CaCO₃ (Lindlar catalyst) and with Hydrogen was filled, the ozonization solution obtained fed continuously via a metering vessel that the Peroxide content does not exceed 0.02 mol / l. With vigorous stirring and hydrogen addition was made up to negative peroxide sample hydrated.

The hydrogenation solution obtained contained 72.96% dodecanedial (GC).

Dodecanedioic acid

The solvent was evaporated from the hydrogenation solution and the residue dissolved in 1000 ml of chlorobenzene. The solution was in an autoclave with oxygen at a pressure of 5 bar added with stirring and heated to 80 ° C. After finished The autoclave was depressurized, the solution opened Cooled to room temperature and the solutions to about 300 ml constricted.

The crystalline precipitate which formed was filtered off and washed with water. There were 151 g (0.655 mol) of dodecanedioic acid (65% based on cyclododecene) with a purity of 96% received.

Example 2 Octandial

110.2 g (1 mol) of cyclooctene (purity 95%) were in 1500 ml Methanol dissolved cooled to -20 ° C and an O₂ / O₃ mixture containing 4 wt .-% Contains ozone, introduced until 2 mol of ozone in the solution have been introduced.

Then in a hydrogenation reactor in which 5.0 g Lindlar catalyst (Pd / C with CaCO₃) were submitted, and the  was filled with hydrogen, the ozonization solution obtained fed continuously via a metering device that the Peroxide content does not exceed 0.02 mol / l. With vigorous stirring and hydrogen was added until the negative peroxide sample hydrated. The pH dropped from 7 to 5.4. The hydrogenation solution obtained contained 78.75% octandial.

Octanedioic acid

The solvent was removed from the hydrogenation solution and the Residue dissolved in 1000 ml chlorobenzene. This solution was in an autoclave with oxygen at a pressure of 5 bar Stirring was added and the temperature was kept at about 80.degree. To When the reaction was complete, the autoclave was depressurized and the solution opened Cooled to room temperature and the solvent to about 300 ml away. The one that forms when cooled to about 7 ° C Precipitate was filtered off and washed with water.

116.2 g (0.702 mol) of octanedioic acid (70.2%) were obtained 95% cyclooctene used with a purity of 98.5% receive.

Claims (9)

1. Process for the preparation of alpha-omega-alkanedicarboxylic acids of the general formula I, in which A is an alkylene radical having 4-14 C atoms, characterized in that a cycloalkene of the general formula II in which A has the meaning given above, is reacted with ozone in the presence of an inert solvent, the peroxide solution formed is catalytically hydrogenated, whereupon the dialdehyde formed is oxidized to the diacid of the formula I in the presence of an inert aprotic solvent. 2. The method according to claim 1, characterized in that as Starting product cycloheptene, cyclooctene or cyclododecene is used. 3. The method according to any one of claims 1 or 12, characterized in that the reaction with ozone in the presence of a low aliphatic alcohol is carried out. 4. The method according to claim 3, characterized in that the Reaction carried out with the equivalent amount of ozone becomes.   5. The method according to any one of claims 1 or 2, characterized in that during the hydrogenation of the ozonolysis products a peroxide content of at most 0.1 mol / l is maintained. 6. The method according to claim 5, characterized in that the pH during the catalytic hydrogenation in the range of 2-7 is held. 7. The method according to any one of claims 5 or 6, characterized in that that as catalyst Pd on activated carbon with CaCO₃, or Pt is used. 8. The method according to any one of claims 1 or 2, characterized in that that in the oxidation step following the hydrogenation Oxygen or air is used as an oxidizing agent becomes. 9. The method according to claim 8, characterized in that the Oxidation at a pressure of 3-10 bar and at a temperature from 70 to 90 ° C is carried out.