PROCESS FOR PREPARING CYCLODODECANONE

Abstract

The invention relates to a method for producing cyclododecanone (CDON). During the production, contaminated cyclododecane (CDAN) is produced. This can be separated from CDON by distillation (CDAN-containing fraction). The separation of CDAN and impurities such as 13-oxabicyclo [7.3.1]tridacane occurs by crystallizing out CDAN from the CDAN-containing fraction.

Claims

1. A process for producing cyclododecanone (CDON) comprising the consecutive steps of: a) reaction of 1,5,9-cyclododecatriene (CDT) to afford a mixture of cyclododecanol (CDOL) and CDON, b) dehydrogenation of the CDOL to afford CDON, wherein a CDON-containing mixture which comprises cyclododecane (CDAN) is obtained, c) distillation of the CDON-containing mixture to obtain a fraction comprising CDAN (CDAN-containing fraction) and a CDON-containing fraction, and d) crystallizing-out CDAN from the CDAN-containing fraction.

2. The process according to claim 1, wherein the CDAN-containing fraction contains impurities which comprise 13-oxabicyclo[8.2.1]tridecane, 13-oxabicyclo[7.3.1]tridecane, 2-undecanone or mixtures thereof.

3. The process according to claim 2, wherein the impurity comprises 13-oxabicyclo[7.3.1]tridecane.

4. The process according to claim 1, wherein the mixture of CDOL and CDON is obtained by the consecutive steps of i) hydrogenation of CDT to afford CDAN and ii) oxidation of CDAN to afford the mixture of CDOL and CDON.

5. The process according to claim 1, wherein the mixture of CDOL and CDON is obtained by the consecutive steps of I) hydrogenation of CDT to afford cyclododecene (CDEN), II) epoxidation of CDEN to afford cyclododecane epoxide (CDAN epoxide) and III) rearrangement of CDAN epoxide to afford the mixture of CDOL and CDON.

6. The process according to claim 1, wherein the crystallized-out CDAN (step d) is oxidized to afford a mixture of CDOL and CDON.

7. The process according to claim 1, wherein the crystallized-out CDAN (step d) is converted into cyclododecanone oxime with nitrosyl chloride.

8. The process according to claim 1, wherein the CDON is removed from the CDON-containing fraction by distillation.

9. The process according to claim 1, wherein the CDAN-containing fraction is distilled to remove low boilers before the crystallizing-out.

10. The process according to claim 1, wherein the crystallizing-out is effected by melt crystallization or solution crystallization.

11. The process according to claim 10, wherein the melt crystallization is selected from static crystallization, falling film crystallization or suspension crystallization.

12. A process for purifying cyclododecane (CDAN), wherein the CDAN contains impurities, in particular 13-oxabicyclo[8.2.1]tridecane, 13-oxabicyclo[7.3.1]tridecane, 2-undecanone or mixtures thereof, wherein the CDAN is crystallized-out by crystallization, preferably melt crystallization or solution crystallization.

13. A process for the producing laurolactam comprising the consecutive steps of A) production of CDON according to claim 8, B) oximation of CDON to afford cyclododecanone oxime (CDON oxime) and C) rearrangement of CDON oxime to afford laurolactam.

Description

EXAMPLES

[0020] In the following examples CDAN fractions removed from a CDON-containing mixture by distillation were employed. The CDON-containing mixture was obtained by epoxidation of CDEN and subsequent rearrangement. THE CDAN fraction was worked up in different ways in the examples.

[0021] The impurities were determined by gas chromatography-mass spectrometry (GC-MS). GC instrument Agilent GC 6890/Agilent MSD 5973; separating column 60 m0.25 mm DB-Wax, film 0.25 m; injector: 250 C., split 50:1, 244 kPa Helium; oven temperature 150 C.-5 C./min-180 C. (10 min)-5 C./min-220 C. (40 min); injection 1 L sample; ionisation: electron impact ionization, 70 eV, and chemical ionization using ammonia as reactant gas.

Example A: Acid Catalyst (Noninventive)

[0022] A mixture according to table 1 was boiled over several hours at 230 C. over an acidic aluminosilicate powder. Final conversions of about 27% for the 2-undecanone and about 45% for the 1,5-C12-ether in each case based on the employed feed were obtained. The 1,4-C12-ether was decomposed to below the limit of detection.

TABLE-US-00001 TABLE 1 Conversion according to example A 2- 1,5-C12- 1,4-C12- wt % CDAN undecanone ether ether remainder feed 91.86% 3.73% 0.05% 0.23% 4.13% after 20 h 91.77% 2.74% 0.03% 5.47%

Example B: Hydrogenation (Noninventive)

[0023] A mixture consisting of CDAN and both C12-ethers was hydrogenated for 21 h at 200 C. under an H2 atmosphere (20 bar) over a Ru catalyst. The CDAN was partly cracked into cyclic C11 components. The 1,4-C12-ether was converted to an extent of 90%, but the 1,5-C12-ether only to an extent of 10%, in each case based on the employed feed.

TABLE-US-00002 TABLE 2 conversion according to example B 1.5-C12- 1.4-C12- wt % C11 CDAN ether ether remainder feed 98.90% 0.56% 0.50% 0.04% after 21 h 13.97% 85.48% 0.43% 0.05% 0.07%

Example C: Hydrogenation (Noninventive)

[0024] A mixture consisting of CDAN and 2-undecanone was hydrogenated for 68 h at 200 C. under an H2 atmosphere (20 bar) over a Ru catalyst. The 2-undecanone was converted to an extent of 97% based on the employed feed.

TABLE-US-00003 TABLE 3 hydrogenation according to example C 2- wt % C11 CDAN undecanone remainder feed 95.89% 4.03% 0.08% 68 h 1.07% 95.41% 0.12% 3.40%

Example 1 (Inventive)

[0025] 1439 g of an industrial CDAN-containing fraction containing not only CDAN but also cyclic and non-cyclic C11-hydrocarbons, oxidized C11- and C12-constitutents such as 1,4-C12-ether, 1,5-C12-ether and 2-undecanone according to table 4 was melted at 70 C. in a glass container. Upon reaching a temperature at which the complete mixture was in the form of a melt, the temperature was reduced via a separately temperature-controllable cooling finger submerged in the middle of the container. This was effected such that the surface temperature of the cooling finger was reduced at a constant cooling gradient of 0.5 K/minute until an appreciable amount of solid had formed at the cooling finger surface. At the end of the experiment the remaining mother liquor from the crystallization was separated from the crystals adhering to the cooling finger by discharging the mother liquor and then analysed. Subsequently, by slowly increasing the cooling finger temperature, a sweat fraction of 1.44 g was melted off, withdrawn and analyzed by gas chromatography. Subsequently the crystals were melted off the cooling finger, withdrawn separately and analyzed by gas chromatography. Table 4 summarizes the amount and the gas chromatography analytical results for the various fractions.

TABLE-US-00004 TABLE 4 Purification of a CDAN-containing fraction mother sweat crystal fraction feed liquor fraction fraction fraction amount g 1439.0 1206.6 11.4 221.0 CDAN area % 97.5 97.2 97.4 99.0 C11-components area % 1.6 1.8 1.7 0.6 2-undecanone area %-% 0.3 0.3 0.3 0.1 1,4-C12-ether area % 0.1 0.1 0.1 0.0 1,5-C12-ether area % 0.1 0.1 0.1 0.0 remainder area % 0.4 0.4 0.4 0.3 The crystallizing-out according to the invention increased the purity of CDAN from 97.5% to 99.0%. The proportion of byproducts in the CDAN was reduced from 2.5% to 1.0%; in particular the difficult-to-separate substances 2-undecanone and the two C12-ethers were reduced/no longer detectable.

Example 2 (Inventive)

[0026] 182 g of the crystal fraction from example 1 were melted in a smaller experimental apparatus and subsequently subjected to static crystallization. Via the separately temperature-controllable cooling finger submerged in the middle the surface of the cooling finger was in turn cooled at a temperature gradient of 0.5 K/minute and a crystal layer generated at the surface of the cooling finger.

[0027] At the end of the experiment the remaining mother liquor from the crystallization was separated from the crystals by discharging the mother liquor and then analysed. Subsequently, by slowly increasing the cooling finger temperature a sweat fraction of 0.8 g was melted off, withdrawn and analyzed by gas chromatography. Subsequently the crystals were melted off the cooling finger, withdrawn separately and analyzed by gas chromatography. Table 5 summarizes the amount and the gas chromatography analytical results for the various fractions.

TABLE-US-00005 TABLE 5 Purification of the crystal fraction from example 1 mother sweat crystal fraction feed liquor fraction fraction fraction amount g 182 142.98 0.8 38.22 CDAN area % 99.0 98.8 99.3 99.6 C11-components area % 0.6 0.7 0.4 0.2 2-undecanone area % 0.1 0.1 0.0 0.0 remainder area % 0.3 0.3 0.3 0.2 Static crystallizing-out of CDAN having an initial purity of 99.0% increased the purity of CDAN to 99.6%. The proportion of byproducts in the CDAN was reduced by more than half. 2-Undecanone was no longer detectable.

Example 3 (Inventive)

[0028] 1367 g of an industrial CDAN-containing fraction containing not only CDAN but also an elevated concentration of cyclic and non-cyclic C11-hydrocarbons, oxidized C11- and C12-constitutents such as 1,4-C12-ether, 1,5-C12-ether and 2-undecanone according to table 6 was melted at 70 C. in a glass container. Upon reaching a temperature at which the complete mixture was in the form of a melt, the temperature was reduced via a separately temperature-controllable cooling finger submerged in the middle of the container. This was effected such that the surface temperature of the cooling finger was reduced at a constant cooling gradient of 0.5 K/minute until an appreciable amount of solid had formed at the cooling finger surface. At the end of the experiment the remaining mother liquor from the crystallization was separated by discharging the mother liquor and then analysed. Subsequently, by slowly increasing the temperature a sweat fraction of 12.4 g was melted off, withdrawn and analyzed by gas chromatography. Subsequently the crystals were melted off the cooling finger, withdrawn separately and analyzed by gas chromatography. Table 6 summarizes the amount and the gas chromatography analytical results for the various fractions.

TABLE-US-00006 TABLE 6 Purification of a CDAN-containing fraction mother sweat crystal fraction feed liquor fraction fraction fraction amount g 1367.0 1164.2 5.3 197.5 CDAN area % 93.1 92.3 97.5 97.6 C11-components area % 5.8 6.4 2.2 2.2 2-undecanone area % 0.5 0.6 0.1 0.0 1,4-C12-ether area % 0.1 0.1 0.0 0.0 1,5-C12-ether area % 0.2 0.2 0.0 0.0 remainder area % 0.3 0.3 0.2 0.2 The crystallizing-out according to the invention increased the purity of CDAN from 93.1% to 97.6%. The proportion of byproducts in the CDAN was reduced from 6.9% to 2.4%. 2-Undecanone and the C12-ethers were no longer detectable after crystallization.