Process for purifying a crude composition including a monoterpene compound, such as a monocyclic monoterpene alcohol, by layer melt crystallization

Patent metadata

Field	Value
Publication number	US-10745332-B2
Application number	US-201816604642-A
Country	US
Kind code	B2
Filing date	Apr 13, 2018
Priority date	Apr 13, 2017
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

A process for purifying a crude composition includes a monoterpene compound selected from the group consisting of monocyclic monoterpene alcohols, monocyclic monoterpene ketones, bicyclic epoxy monoterpenes and mixtures of two or more of the aforementioned compounds, such as preferably a monocyclic monoterpene alcohol. The process comprises performing a layer crystallization with a melt of the crude composition, and the melt of the crude composition subjected to the layer crystallization includes oxygen-containing solvent in a concentration of 20 ppm to 2% by weight. The oxygen-containing solvent is selected from the group consisting of water, C1-6-alcohols, C1-6-carboxylic acids, C1-6-ketones, C1-6-aldehydes, C1-12-ethers, C1-12-esters and mixtures of two or more of the aforementioned solvents.

First claim

The invention claimed is:

1. A process for purifying a crude composition including a monoterpene compound selected from the group consisting of monocyclic monoterpene alcohols, monocyclic monoterpene ketones, bicyclic epoxy monoterpenes and mixtures of two or more of the aforementioned compounds, the process comprising performing a layer crystallization with a melt of the crude composition,
the melt of the crude composition, which is subjected to the layer crystallization, including oxygen-containing solvent in a concentration of 20 ppm to 2% by weight, the oxygen-containing solvent selected from the group consisting of water, C1-6-alcohols, C1-6-carboxylic acids, C1-6-ketones, C1-6-aldehydes, C1-12-ethers, C1-12-esters and mixtures of two or more of the aforementioned solvents.

2. The process in accordance with claim 1 , wherein the crude composition contains a compound selected from the group consisting of isopulegol, menthol, alpha-terpineol, thymol, carvacrol, piperitenol, perillyl alcohol, 1,4 cineol, 1,8-cineol, carvone and mixtures of two or more of the aforementioned compounds.

3. The process in accordance with claim 1 , wherein the crude composition contains a mixture of L-(−)-n-isopulegol and D-(−)-n-isopulegol, wherein the content of the L-(−)-n-isopulegol in the mixture is more than 70% by weight.

4. The process in accordance with claim 1 , wherein the solvent is selected from the group consisting of water, methanol, ethanol, iso-propanol, n propanol, 1-butanol, 2-butanol and mixtures of two or more of the aforementioned solvents.

5. The process in accordance with claim 1 , wherein the melt of the crude composition, which is subjected to the layer crystallization, includes 50 ppm to 1.5% by weight of the oxygen-containing solvent.

6. The process in accordance with claim 1 , wherein the process additionally comprises a priming comprising wetting of plates of the crystallizer with a monoterpene compound, which corresponds to that to be purified, having a purity of at least 70% by weight.

7. The process in accordance with claim 1 , wherein the layer crystallization comprises a first crystallization stage through a tenth crystallization stage.

8. The process in accordance with claim 7 , wherein after the first crystallization stage, oxygen-containing solvent is added to at least one fraction to be crystallized in one or more of the further crystallization stages.

9. The process in accordance with claim 8 , wherein oxygen-containing solvent is added to the at least one fraction to be crystallized in one or more of the further crystallization stages between before any of the second to before the final crystallization stage.

10. The process in accordance with claim 1 , wherein the crude composition contains isopulegol as monoterpene compound and wherein with the process a first and a second product stream are produced, wherein the first product stream is an enriched L-(−)-n-isopulegol fraction with a purity of L-(−)-n-isopulegol of at least 98% by weight.

11. The process in accordance with claim 1 , wherein the crude composition contains a mixture of L-(−)-n-isopulegol and D-(−)-n-isopulegol as monoterpene compound and wherein the process comprises the following steps:
a) melting the crude composition;
b) adding water and/or methanol as oxygen-containing solvent to the crude composition so that the concentration of the oxygen-containing solvent in the melt is 20 ppm to 2% by weight;
c) subjecting the melt obtained in step b) to a first static layer melt crystallization stage in a static crystallizer;
d) after the crystallization, removing the remaining melt as a first residue fraction from the static crystallizer used in step c), melting the crystal layer deposited during the first crystallization stage in the static crystallizer to obtain a first crystallized fraction and subjecting the first crystallized fraction to a second static layer melt crystallization stage in a static crystallizer;
e) after the crystallization of step d), removing the remaining melt as a second residue fraction from the static crystallizer, melting the crystal layer deposited during the second crystallization stage in the static crystallizer used in step d) to obtain as a second crystallized fraction a first product stream of enriched L-(−)-n-isopulegol having a purity of at least 98% by weight;
f) subjecting the remaining melt discharged as the first residue fraction from the static crystallizer used in step c) to a third static layer melt crystallization stage in a static crystallizer;
g) after the crystallization of step f), removing the remaining melt as a third residue fraction from the static crystallizer, melting the crystal layer deposited during the third crystallization stage in the static crystallizer used in step f) to obtain a third crystallized fraction and subjecting the remaining melt discharged from the static crystallizer as the third residue fraction to a fourth static layer melt crystallization stage in a static crystallizer; and
h) after the crystallization of step g), removing the remaining melt as a fourth residue fraction from the static crystallizer to obtain a second product stream of a racemic mixture of L-(−)-n-isopulegol and D-(−)-n-isopulegol, and melting the crystal layer deposited during the fourth crystallization stage in the static crystallizer to obtain a fourth crystallized fraction.

12. The process in accordance with claim 11 , wherein the process further comprises one or more of the following steps:
feeding the remaining melt discharged as the second residue fraction from the static crystallizer used in step d) to the static crystallizer of the first static layer melt crystallization stage;
feeding the third crystallized fraction to the static crystallizer of the first static layer melt crystallization stage; and
feeding the fourth crystallized fraction to the static crystallizer of the third static layer melt crystallization stage.

13. The process in accordance with claim 11 , wherein the process further comprises one or more of the following steps:
before melting in step d) the crystal layer deposited during the first crystallization stage, carrying out a sweating of the crystal layer and feeding a first portion of the sweating fraction obtained thereby to the first residue fraction and feeding a second portion of the sweating fraction obtained thereby to the static crystallizer of the first static layer melt crystallization stage;
before melting in step e) the crystal layer deposited during the second crystallization stage, carrying out a sweating of the crystal layer and feeding a first portion of the sweating fraction obtained thereby to the second residue fraction and feeding a second portion of the sweating fraction obtained thereby to the static crystallizer of the second static layer melt crystallization stage;
before melting in step g) the crystal layer deposited during the third crystallization stage, carrying out a sweating of the crystal layer and preferably feeding a first portion of the sweating fraction obtained thereby to the third residue fraction and feeding a second portion of the sweating fraction obtained thereby to the static crystallizer of the third static layer melt crystallization stage; and
before melting in step h) the crystal layer deposited during the fourth stage, carrying out a sweating of the crystal layer and feeding a first portion of the sweating fraction obtained thereby to the second product stream obtained as fourth residue fraction and feeding a second portion of the sweating fraction obtained thereby to the static crystallizer of the fourth static layer melt crystallization stage.

Assignees

• Sulzer Management Ag

Inventors

• Stepanski Manfred
• Lippuner Florian
• Brack Hans-Peter

Classifications

• C07D493/08

  Bridged systems · CPC title

• C07C2601/16

  the ring being unsaturated · CPC title

• C07C2601/14

  The ring being saturated · CPC title

• C07C49/647

  having unsaturation outside the ring · CPC title

• C07C45/81

  by change in the physical state, e.g. crystallisation · CPC title