Process for producing prenol and prenal from isoprenol

Patent metadata

Field	Value
Publication number	US-2019077736-A1
Application number	US-201716084285-A
Country	US
Kind code	A1
Filing date	Mar 14, 2017
Priority date	Mar 15, 2016
Publication date	Mar 14, 2019
Grant date	—

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

1 .- 17 . (canceled)

18 . 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 Al2O3 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.

19 . The process according to claim 18 , wherein the catalyst used in step ii) is a Pd catalyst comprising SiO 2 and/or Al 2 O 3 as support material.

20 . The process according to claim 18 , wherein the gas mixture used in step i) comprises 3% to 10% by volume of oxygen.

21 . The process according to claim 18 , wherein the gas mixture used in step ii) comprises 8% to 15% by volume of oxygen.

22 . The process according to claim 18 , 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).

23 . The process according to claim 18 , 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.

24 . The process according to claim 18 , 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.2 and i.3.

25 . The process according to claim 18 , 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.

26 . The process according to claim 18 , wherein step i) is conducted without supply of an external solvent.

27 . The process according to claim 18 , 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.

28 . The process according to claim 18 , 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).

29 . The process according to claim 18 , 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).

30 . The process according to claim 18 , wherein step ii) is conducted without supply of an external solvent.

31 . The process according to claim 18 , 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.

32 . The process according to claim 18 , wherein the process is performed continuously.

33 . The process according to claim 18 , 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.

34 . The process according to claim 33 , 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

• B01J21/04

  Alumina · CPC title

• B01J23/44

  Palladium · CPC title

• C07C29/56 Primary

  by isomerisation · CPC title

• C07C45/38

  being a primary hydroxyl group · CPC title

• C07C47/21

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