Hydrogenation of catmint oil
View Patent ↗Disclosed are methods for treating catmint oil. The treated catmint oil can be used for the production of hydrogenated catmint oil, which is enriched in the insect repellent, dihydronepetalactone.
1. A process for preparing hydrogenated catmint oil comprising:
(a) contacting crude catmint oil with an oxidizing agent comprising hydrogen peroxide to produce a first treated catmint oil;
(b) separating the first treated catmint oil from the oxidizing agent to produce a second treated catmint oil;
(c) contacting the second treated catmint oil with hydrogen and a hydrogenation catalyst to produce hydrogenated catmint oil; and
(d) optionally recovering the hydrogenated catmint oil.
2. The process of claim 1 further comprising:
(a-1) distilling a beginning amount of the second treated catmint oil to produce (i) a distillate fraction comprising volatile components driven off from the second treated catmint oil, wherein the weight of the distillate fraction comprises about 2% to about 20% of the weight of the beginning amount of the second treated catmint oil, and (ii) a pot fraction;
(b-1) contacting the pot fraction produced in step (a-1) with hydrogen and a hydrogenation catalyst to produce hydrogenated catmint oil; and
(c-1) optionally, recovering the hydrogenated catmint oil of step (b-1).
3. The process of claim 1 wherein the weight of the distillate fraction comprises about 5% to about 10% of the weight of the beginning amount of the second treated catmint oil.
4. The process of claim 1 wherein the step of distilling (a-1) comprises a step of (i) vacuum distilling, (ii) steam distilling, (iii) solvent distilling, or (iv) steam distilling followed by solvent distilling.
5. The process of claim 4 which comprises a step of solvent distilling, or of steam distilling followed by solvent distilling, and wherein, at the beginning of solvent distilling, the weight of the solvent comprises about 5% to about 60% of the combined weight of catmint oil plus solvent.
6. The process of claim 5 wherein, at the beginning of solvent distilling, the weight of the solvent comprises about 10% to about 25% of the combined weight of catmint oil plus solvent.
7. The process of claim 4 which comprises a step of solvent distilling, or of steam distilling followed by solvent distilling, and wherein a solvent comprises a C 1 to C 5 straight-chain or branched alcohol.
8. The process of claim 7 wherein the alcohol is selected from the group consisting of methanol, ethanol, isopropanol and n-propanol.
9. The process of claim 4 wherein steam distilling, solvent distilling, or steam distilling followed by solvent distilling, is performed under vacuum.
10. The process of claim 1 wherein the pot fraction is contacted with hydrogen and a hydrogenation catalyst at a temperature of about −10° C. to about 200° C.
11. The process of claim 1 wherein the second treated catmint oil is contacted with hydrogen and a hydrogenation catalyst at a temperature of about −10° C. to about 200° C.
12. The process of claim 1 wherein distillation is conducted at a temperature of lower than about 200° C.
13. The process of claim 1 wherein distillation is conducted at a pressure of less than about 68.9 kPa.
14. The process of claim 12 wherein distillation is conducted at a pressure of less than about 68.9 kPa.