Process for producing prenol and prenal from isoprenol

Patent metadata

Field	Value
Publication number	US-10414707-B2
Application number	US-201716084285-A
Country	US
Kind code	B2
Filing date	Mar 14, 2017
Priority date	Mar 15, 2016
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

The present invention relates to a process for preparing 3-methyl-2-butenol (prenol) and 3-methyl-2-butenal (prenal) from 3-methyl-3-butenol (isoprenol), in which 3-methyl-3-butenol is subjected to a catalytic isomerization over a carbon-supported Pd catalyst in the presence of a gas mixture comprising 1% to 15% by volume of oxygen to obtain a first product mixture, and the first product mixture is subjected to an oxidative dehydrogenation over a Pd catalyst comprising SiO 2 and/or Al 2 O 3 as support material, or over a carbon-supported Pd/Au catalyst in the presence of a gas mixture comprising 5% to 25% by volume of oxygen.

First claim

The invention claimed is:

1. A process for preparing a composition comprising 3-methyl-2-butenol and 3-methyl-2-butenal, comprising
i) subjecting 3-methyl-3-butenol to a catalytic isomerization over a carbon-supported Pd catalyst in the presence of a gas mixture comprising 1% to 15% by volume of oxygen to obtain a first product mixture comprising at least 40% by weight of 3-methyl-2-butenol, at least 5% by weight of 3-methyl-3-butenol and 0% to 15% by weight of 3-methyl-2-butenal, based on the total weight of the first product mixture,
ii) subjecting the first product mixture obtained in step i) to an oxidative dehydrogenation over a Pd catalyst comprising SiO 2 and/or Al 2 O 3 as support material, or over a carbon-supported Pd/Au catalyst in the presence of a gas mixture comprising 5% to 25% by volume of oxygen, to obtain a second product mixture which is enriched in 3-methyl-2-butenal and depleted in 3-methyl-2-butenol compared to the first product mixture, where the molar ratio of 3-methyl-2-butenol to 3-methyl-2-butenal in the second product mixture is in the range from 75:25 to 35:65,
wherein the oxidative dehydrogenation in step i) is conducted in the presence of a base.

2. The process according to claim 1 , wherein the catalyst used in step ii) is a Pd catalyst comprising SiO 2 and/or Al 2 O 3 as support material.

3. The process according to claim 1 , wherein the gas mixture used in step i) comprises 3% to 10% by volume of oxygen.

4. The process according to claim 1 , wherein the gas mixture used in step ii) comprises 8% to 15% by volume of oxygen.

5. The process according to claim 1 , wherein the oxygen content of the gas mixture used in step i) is 2% to 10% by volume below the oxygen content of the gas mixture used in step ii).

6. The process according to claim 1 , wherein the first product mixture obtained in step i) consists of
i.1 40% to 80% by weight of 3-methyl-2-butenol,
i.2 0% to 15% by weight of 3-methyl-2-butenal,
i.3 5% to 59% by weight of 3-methyl-3-butenol and
i.4 0% to 10% by weight of compounds other than i.1, i.2 and i.3.

7. The process according to claim 1 , wherein the first product mixture obtained in step i) consists of
i.1 45% to 70% by weight of 3-methyl-2-butenol,
i.2 5% to 10% by weight of 3-methyl-2-butenal,
i.3 20% to 50% by weight of 3-methyl-3-butenol and
i.4 0% to 5% by weight of compounds other than i.1, i.2and i.3.

8. The process according to claim 1 , wherein the total proportion of 3-methyl-2-butenol, 3-methyl-2-butenal and 3-methyl-3-butenol in the first product mixture obtained in step i) is at least 80% by weight, based on the total weight of the first product mixture.

9. The process according to claim 1 , wherein step i) is conducted without supply of an external solvent.

10. The process according to claim 1 , wherein the catalytic isomerization of 3-methyl-3-butenol in the presence of oxygen is run up to a conversion of 30% to 80%, based on the 3-methyl-3-butenol used.

11. The process according to claim 1 , wherein the output from the catalytic isomerization, optionally after removal of the catalyst, is used without further purification in the oxidative dehydrogenation in step ii).

12. The process according to claim 1 , wherein the proportion of the base in the reaction mixture is 0.01% to 2% by weight, based on the total weight of the first product mixture used in step ii).

13. The process according to claim 1 , wherein step ii) is conducted without supply of an external solvent.

14. The process according to claim 1 , wherein, in steps i) and ii), an oxygen-enriched gas mixture is supplied continuously to the respective reaction zones and an oxygen-depleted gas mixture is removed continuously, wherein the supply of the oxygen-enriched gas mixture is below the liquid surface of the respective reaction mixtures.

15. The process according to claim 1 , wherein the process is performed continuously.

16. The process according to claim 1 , wherein the second product mixture obtained in step ii) is subjected to a distillative separation into a product fraction enriched in 3-methyl-2-butenol and 3-methyl-2-butenal and a reactant fraction enriched in 3-methyl 3-butenol.

17. The process according to claim 16 , wherein the reactant fraction enriched in 3-methyl-3-butenol, optionally with addition of fresh 3-methyl-3-butenol, is used in step i).

Assignees

• Basf Se

Inventors

• Dehn Martine
• Brunner Bernhard
• Ebel Klaus
• Huber Sabine

Classifications

• C07C47/21

  with only carbon-to-carbon double bonds as unsaturation · CPC title

• B01J21/04

  Alumina · CPC title

• C07C29/56 Primary

  by isomerisation · CPC title

• B01J23/44

  Palladium · CPC title

• C07C33/03

  in beta-position, e.g. allyl alcohol, methallyl alcohol · CPC title