Process for the preparation of a benzene derivative
A substituted benzene derivative is prepared in a process, which includes reacting a furan derivative of formula (I): wherein R is an alkyl group, with an olefin of formula (II): R 1 —CH═CH—R 2 (II) wherein R 1 and R 2 are the same or different and independently are selected from the group consisting of hydrogen, —CN, —CHO and —COOR 3 , wherein R 3 is selected from hydrogen or an alkyl group, or R 1 and R 2 together form a —C(O)—O—(O)C— group, with the proviso that R 1 and R 2 are not both hydrogen, to produce a bicyclic ether; and dehydrating the bicyclic ether to obtain a benzene derivative. The benzene derivative thus obtained can suitably be converted to a benzene carboxylic acid compound by oxidation.
1. A process for the preparation of a benzene carboxylic acid compound comprising:
reacting a furan of formula (I):
wherein R is an alkyl group,
with an olefin of formula (II):
R 1 —CH═CH—R 2 (II)
wherein R 1 and R 2 are the same or different and independently are selected from the group consisting of hydrogen, —CN, —CHO and —COOR 3 , wherein R 3 is selected from hydrogen or an alkyl group, or R 1 and R 2 together form a —C(O)—O—(O)C— group, with the proviso that R 1 and R 2 are not both hydrogen,
to produce a bicyclic ether;
dehydrating the bicyclic ether in the presence of a catalyst at a temperature in the range from −5 to 90° C. to yield a substituted benzene; and
oxidizing the substituted benzene thus obtained, to yield the benzene carboxylic acid compound.
2. The process according to claim 1 , wherein R is selected from an alkyl group containing from 1 to 6 carbon atoms.
3. The process according to claim 1 , wherein the furan of formula (I) has been obtained from the dehydration of a carbohydrate to yield furfural and the conversion of furfural thus obtained.
4. The process according to claim 3 , wherein the carbohydrate is selected from a pentose.
5. The process according to claim 3 , wherein the carbohydrate is selected from arabinose, ribose, ribulose, xylose, xylulose and lyxose.
6. The process according to claim 1 , wherein the furan of formula (I) has been obtained from the conversion of furfural that is formed during the dehydration of a hexose.
7. The process according to claim 1 , wherein the furan of formula (I) is reacted with the olefin of formula (II) at a temperature of from 0 to 150° C.
8. The process according to claim 1 , wherein the furan of formula (I) is reacted with the olefin of formula (II) in the presence of a Lewis acid that is used as a Diels-Alder catalyst.
9. The process according to claim 1 , wherein the molar ratio between the amount of furan of formula (I) to the amount of olefin of formula (II) ranges from 0.1:1 to 10:1.
10. The process according to claim 1 , wherein the bicyclic ether is dehydrated in the presence of a solvent.
11. The process according to claim 10 , wherein the solvent is selected from the group consisting of alcohols, esters, ketones, amides, aldehydes, ethers, ionic liquids and sulphoxides.
12. The process according to claim 10 , wherein the solvent is an aliphatic alcohol with 1 to 3 carbon atoms.
13. The process according to claim 1 , wherein the catalyst is a basic catalyst.
14. The process according to claim 1 , wherein the basic catalyst is selected from the group consisting of alkali metal hydroxides, alkanolates, carboxylates and carbonates.
15. The process according to claim 1 , wherein the bicyclic ether is dehydrated at a pressure ranging from 0.5 to 50 bar.
16. The process according to claim 1 , wherein bicyclic ether is dehydrated in a batch or continuous reactor wherein the residence time is from 0.1 to 48 hours.
17. The process according to claim 1 wherein the reaction of the furan of formula (I) with the olefin of formula (II) and the dehydration reaction are performed in one step.
18. The process according to claim 1 , wherein the oxidation is effected by an oxygen-containing gas in the presence of a catalyst comprising cobalt and manganese or by potassium permanganate or nitric acid.
19. The process according to claim 18 , wherein the catalyst comprises cobalt and manganese, and further comprises bromine.
20. The process according to claim 1 , wherein the oxidation is carried out at a temperature of from 60 to 220° C., at a pressure of from 5 to 100 bar and at a residence time of from 0.1 to 48 hours.