Hydrogenation of catmint oil
View Patent ↗Disclosed are methods for treating catmint oil. The process allows the separation of sulfur-containing compounds from the 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) distilling a beginning amount of crude catmint oil that has at least about 150 ppm of sulfur-containing compounds to produce (i) a distillate fraction that comprises at least about 8 wt % of the amount of sulfur-containing compounds in the beginning amount of crude catmint oil, and (ii) a pot fraction;
(b) contacting the pot fraction produced in step (a) with hydrogen and a hydrogenation catalyst to produce hydrogenated catmint oil; and
(c) optionally, recovering the hydrogenated catmint oil of step (b).
2. The process of claim 1 wherein the step of distilling (a) comprises a step of (i) vacuum distilling, (ii) steam distilling, (iii) solvent distilling, or (iv) steam distilling followed by solvent distilling.
3. The process of claim 2 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.
4. The process of claim 3 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.
5. The process of claim 2 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.
6. The process of claim 2 wherein steam distilling, solvent distilling, or steam distilling followed by solvent distilling, is performed under vacuum.