Method for producing 2-substituted 4-hydroxy-4-methyl-tetrahydropyrans, said method using recycling

Patent metadata

Field	Value
Publication number	US-9695142-B2
Application number	US-201414787312-A
Country	US
Kind code	B2
Filing date	Apr 28, 2014
Priority date	Apr 29, 2013
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

The present invention relates to a process for the preparation of 2-substituted 4-hydroxy-4-methyltetrahydropyrans.

First claim

The invention claimed is:

1. A process for the preparation of 2-substituted 4-hydroxy-4-methyltetrahydropyrans of the formula (I)

in which
R 1 is a straight-chain or branched C 1 -C 12 -alkyl, a straight-chain, or branched C 2 -C 12 -alkenyl, a cycloalkyl having in total 3 to 20 carbon atoms, optionally substituted with C 1 -C 12 -alkyl and/or C 1 -C 12 -alkoxy, or an aryl having in total 6 to 20 carbon atoms, optionally substituted with C 1 -C 12 -alkyl and/or C 1 -C 12 -alkoxy,
the process comprising a reaction of 3-methylbut-3-en-1-ol of the formula (III)

with an aldehyde of the formula (IV)
R 1 —CHO  (IV)

where R 1 in the formula (IV) has the meaning above, in a reactor with at least one downstream separating column in the presence of an acidic catalyst, wherein a portion of a discharge stream from the reactor is returned to the reactor, and another portion of the discharge stream is directed to the separating column;
wherein heat is removed from the portion of the discharge stream prior to returning to the reactor.

2. The process according to claim 1 , wherein the reaction takes place continuously.

3. The process according to claim 1 , wherein the reaction is conducted in the presence of a solvent.

4. The process according to claim 1 , wherein heat is supplied to the portion of the discharge stream that is directed to the separating column.

5. The process according to claim 1 , wherein at least one stream from the top of the at least one separating column is returned to the reactor.

6. The process according to claim 1 , wherein the reaction is carried out adiabatically.

7. The process according to claim 1 , wherein the reactor used is isothermal.

8. The process according to claim 7 , wherein the reactor comprises an internally arranged heat exchanger.

9. The process according to claim 1 , wherein the reactor is a fixed-bed reactor.

10. The process according to claim 1 , wherein the radical R′ is isobutyl or phenyl.

11. The process according to claim 1 , wherein the acidic catalyst is selected from the group consisting of hydrochloric acid, sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid and strongly acidic cation exchangers.

12. The process according to claim 1 , wherein the acidic catalyst is a strongly acidic cation exchanger.

13. The process according to claim 1 , wherein the alcohol of the formula (III) and the aldehyde of the formula (IV) are used in a molar ratio in the range from 0.7:1 to 2:1.

14. The process according to claim 1 , wherein the reaction is conducted in the presence of 3% by weight to 15% by weight of water, based on the amount of the reaction mixture of components formulae (III) and (IV) and the water.

15. The process according to claim 1 , wherein the reaction is carried out at a temperature in the range from 0° C. to 70° C.

16. The process according to claim 1 , wherein the reaction is carried out at a pressure in the range from 1 bar to 15 bar.

17. A process for the preparation of 2-substituted 4-hydroxy-4-methyltetrahydropyrans of the formula (1)

in which
R 1 is a straight-chain or branched C 1 -C 12 -alkyl, a straight-chain, or branched C 2 -C 12 -alkenyl, a cycloalkyl having in total 3 to 20 carbon atoms, optionally substituted with C 1 -C 12 -alkyl and/or C 1 -C 12 -alkoxy, or an aryl having in total 6 to 20 carbon atoms, optionally substituted with C 1 -C 12 -alkyl and/or C 1 -C 12 -alkoxy,
the process comprising reacting 3-methylbut-3-en-1-ol of the formula (III)

with an aldehyde of the formula (IV)
R 1 —CHO  (IV)

in a reactor, in the presence of an acidic catalyst, and the alcohol of the formula (III) and the aldehyde of the formula (IV) are present in a molar ratio in a range from 0.7:1 to 2:1, and the reaction is conducted in the presence of 3% by weight to 15% by weight of water, based on the amount of the reaction mixture of components formulae (III) and (IV) and the water, wherein a portion of a discharge stream from the reactor is recycled to the reactor, and another portion of the discharge stream is directed to at least one separating column;
wherein heat is removed from the portion of the discharge stream prior to returning to the reactor.

18. The process according to claim 17 , wherein the reactor is a fixed-bed reactor, and the acidic catalyst is selected from the group consisting of hydrochloric acid, sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid and strongly acidic cation exchangers.

19. The process according to claim 18 , wherein the reaction is carried out at a temperature in the range from 20° C. to 70° C., and a pressure in the range from 1 bar to 15 bar, and R1 is selected from the group consisting of a straight-chain or branched C 1 -C 12 -alkyl, a straight-chain or branched C 2 -C 12 -alkyl, and phenyl.

Assignees

• Basf Se

Inventors

• Stork Timon
• Beck Karl
• Gralla Gabriele
• Bey Oliver
• Ebel Klaus

Classifications

• C07D309/10 Primary

  Oxygen atoms · CPC title