PROCESS FOR THE PREPARATION OF ALKOXYLATED 2,5-DIHYDROFURAN

Abstract

The present invention relates to a process for the preparation of alkoxylated 2.5-dihydrofuran. The process is carried out in an electrochemical cell reactor with a vertical flow.

Claims

1. Process for the preparation of a compound of formula (I) ##STR00007## wherein R is a linear or branched C.sub.1-C.sub.6 alkyl group, which comprises electrochemically reacting the compound of formula (II) in Z-form ##STR00008## with at least one mono alcohol of formula (III) ##STR00009## wherein R has the same meaning as in compound of formula (I) wherein the process is carried out in electrochemical reactor with a vertical flow.

2. Process according to claim 1, wherein R is CH.sub.3 or CH.sub.2CH.sub.3.

3. Process according to claim 1, wherein R is CH.sub.3.

4. Process according to claim 1, wherein the process is carried out in a non-aqueous medium.

5. Process according to claim 4, wherein the at least one alcohol of formula (III) is used in an amount of at least 2 mol-equivalents in regard to the compound of formula (II).

6. Process according to claim 4, wherein the non-aqueous medium is (or comprises) at least one linear or branched C.sub.1-C.sub.10 alcohol.

7. Process according to claim 4, wherein the non-aqueous medium is the mono alcohol of formula (III) ##STR00010## wherein R is a linear or branched C.sub.1-C.sub.6 alkyl group.

8. Process according to claim 1, wherein the process is carried out in a cuboid electrochemical reactor.

9. Process according to claim 1, wherein the cathode is not made from graphite.

10. Process according to claim 1, wherein the cathode is made from materials chosen from the group consisting of metals and metal alloys.

11. Process according to claim 1, wherein the anode is made from materials chosen from the group consisting of noble metals, oxides, graphite, highly oriented pyrolytic graphite (HOPG), boron-doped diamond (BDD), dimensionally stable anodes (DSA) and glassy-carbon

12. Process according to claim 1, wherein the current density applied in the process is between 1-1000 mA/cm.sup.2.

13. Process according to claim 1, wherein the process is carried out in the presence of at least one supporting electrolyte.

14. Process according to claim 13, wherein at least one electrolyte is not phosphoric acid and/or a salt, thereof.

15. Process according to claim 13, wherein the at least one electrolyte is chosen from the group consisting of HCl, H.sub.2SO.sub.4, Na.sub.2SO.sub.4, NaCl, sodium dodecyl sulfate, methyltributylammonium methylsulfate, triethylammonium bisulfate, tetrabutylammonium bisulfate, tetramethylammonium bisulfate, tetrabutylammonium acetate (NBu.sub.4OAc), tetrabutylammonium sulfate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, methanesulfonic acid, ammonium bisulfate, tetrabutylphosphonium methanesulfonate, 1-methylimidazolium bisulfate, tetrabutylammonium perchlorate and LiCIO.sub.4.

16. Process according to claim 1, wherein the reaction is carried out batchwise or in a continuous way.

Description

EXAMPLES

Example 1

[0096] Electrochemical oxidation reaction of 1 M Z-2-butene-1,4-diol (compound of formula (la) to 2,5-dihydro-2,5-dimethoxyfuran was carried out in an undivided flow-cell (V=10 mL, surface area 100 cm.sup.2, 1 mm electrode distance) in methanol, 5.6 wt % methyltributylammonium methylsulfate was used as electrolyte. Graphite (100 cm2) electrode was used as anode and stainless steel (100 cm.sup.2) was used as cathode. Electrolysis was carried out galvanostatically by applying current of 100 mAcm.sup.2 at 20 C. (measured cell potential 5.9 V). The reaction mixture was pumped vertically from bottom to top with a flowrate of 400 mL/min through the flow-cell. After 90 min, a conversion of 96% Z-2-butene-1,4-diol was achieved, and the methanol was distilled of. The evaporated reaction mixture was distilled to get DMDF in the distillate with an overall 70% yield and a 62% Faraday efficiency was achieved. In the residue quantitative amount of MTBS was obtained with a purity of 73%.

Example 2

[0097] Electrochemical oxidation reaction of 2 M Z-2-butene-1,4-diol (compound of formula (la) to 2,5-dihydro-2,5-dimethoxyfuran was carried out in an undivided flow-cell (V=10 mL, surface area 100 cm.sup.2, 1 mm electrode distance) in methanol, 5.1 wt % methyltributylammonium methylsulfate was used as electrolyte. Graphite (100 cm.sup.2) electrode was used as anode and stainless steel (100 cm.sup.2) was used as cathode. Electrolysis was carried out galvanostatically by applying current of 100 mAcm.sup.2 at 20 C. (measured cell potential 6.5 V). The reaction mixture was pumped vertically from bottom to top with a flowrate of 400 mL/min through the flow-cell. After 190 min, a conversion of 97% Z-2-butene-1,4-diol was achieved. The reaction mixture had a content of 63% DMDF and a 52% Faraday efficiency was achieved.

Example 3

[0098] Electrochemical oxidation reaction of 1 M Z-2-butene-1,4-diol (compound of formula (la) to 2,5-dihydro-2,5-dimethoxyfuran was carried out in an undivided flow-cell (V=10 mL, surface area 100 cm.sup.2, 1 mm electrode distance) in methanol, 8.2 wt % triethylammonium bisulfate was used as electrolyte. Graphite (100 cm.sup.2) electrode was used as anode and graphite (100 cm.sup.2) was used as cathode. Electrolysis was carried out galvanostatically by applying current of 100 mAcm.sup.2 at 20 C. (measured cell potential 6.2 V). The reaction mixture was pumped vertically from bottom to top with a flowrate of 400 mL/min through the flow-cell. After 90 min, a conversion of 97% Z-2-butene-1,4-diol was achieved. The reaction mixture had a content of 66% DMDF and a 58% Faraday efficiency was achieved.

Example 4

[0099] Electrochemical oxidation reaction of 1 M Z-2-butene-1,4-diol (compound of formula (la) to 2,5-dihydro-2,5-dimethoxyfuran was carried out in an undivided flow-cell (V=10 mL, surface area 100 cm.sup.2, 1 mm electrode distance) in methanol, 8.2 wt % triethylammonium bisulfate was used as electrolyte. Graphite (100 cm.sup.2) electrode was used as anode and graphite (100 cm.sup.2) was used as cathode. Electrolysis was carried out galvanostatically by applying current of 150 mAcm.sup.2 at 20 C. (measured cell potential 7.3 V). The reaction mixture was pumped vertically from bottom to top with a flowrate of 400 mL/min through the flow-cell. After 60 min, a conversion of 98% Z-2-butene-1,4-diol was achieved. The reaction mixture had a content of 68% DMDF and a 60% Faraday efficiency was achieved.

Example 5

[0100] Electrochemical oxidation reaction of 1 M Z-2-butene-1,4-diol (compound of formula (la) to 2,5-dihydro-2,5-dimethoxyfuran was carried out in an undivided flow-cell (V=10 mL, surface area 100 cm.sup.2, 1 mm electrode distance) in methanol, 8.2 wt % triethylammonium bisulfate was used as electrolyte. Graphite (100 cm.sup.2) electrode was used as anode and stainless steel (100 cm.sup.2) was used as cathode. Electrolysis was carried out galvanostatically by applying current of 150 mAcm.sup.2 at 20 C. (measured cell potential 6.0 V). The reaction mixture was pumped vertically from bottom to top with a flowrate of 400 mL/min through the flow-cell. After 60 min, a conversion of 98% Z-2-butene-1,4-diol was achieved. The reaction mixture had a content of 65% DMDF and a 57% Faraday efficiency was achieved.

Example 6

[0101] Electrochemical oxidation reaction of 0.5 M BED (Z-2-butene-1,4-diol) to DMDF (2,5-dihydro-2,5-dimethoxyfuran) was carried out in an undivided flow-cell (V=10 mL, surface area 100 cm.sup.2, 1 mm electrode distance) in methanol, 3.1 wt % Sodium dodecyl sulfate was used as electrolyte. Graphite (100 cm.sup.2) electrode was used as anode and stainless steel (100 cm.sup.2) was used as cathode. Electrolysis was carried out galvanostatically by applying current of 50 mAcm.sup.2 at 20 C. (measured cell potential 5.6 V). The reaction mixture was pumped vertically from bottom to top with a flowrate of 400 mL/min through the flow-cell. After 360 min, a conversion of 98% BED was achieved with an overall 70% yield DMDF and a 61% Faraday efficiency was achieved.

Examples 7-15

[0102] Electrochemical oxidation reaction of 0.5 M BED (Z-2-butene-1,4-diol) to DMDF (2,5-dihydro-2,5-dimethoxyfuran) was carried out in an undivided flow-cell (V=1 mL, surface area 10 cm.sup.2, 1 mm electrode distance) in methanol, using various electrolytes. Graphite (10 cm.sup.2) electrode was used as anode and various electrode materials (10 cm.sup.2) were used as cathode. Electrolysis was carried out galvanostatically by applying current between 17-50 mAcm.sup.2 at 20 C. (varying cell potentials). The reaction mixture was pumped vertically from bottom to top with a flowrate of 50 mL/min through the flow-cell.

TABLE-US-00001 Current Cell Conversion Content Faraday density potential BED DMDF efficiency Exp Electrolyte Cathode [mA/cm.sup.2] [V] [%] [%] [%] 7 3.1 wt % Stainless steel 34 4.3 81 36 37 1-Methylimidazolium bisulfate 8 3 wt % Sodium dodecyl sulfate Platinum 34 5.4 90 70 80 9 3 wt % Sodium dodecyl sulfate Stainless steel 34 5.4 95 72 77 10 3 wt % Tetramethylammonium Platinum 17 4.0 94 53 57 bisulfate 11 2 wt % Sulfuric acid Platinum 34 3.8 56 43 42 12 3 wt % Methyltributylammonium Graphite 17 4.2 98 71 80 methylsulfate 13 3 wt % Tetrabutylammonium Graphite 17 4.3 92 45 53 bisulfate 14 3 wt % Tetrabutylammonium Platinum 17 4.7 97 56 60 bisulfate 15 6 wt % Tetrabutylammonium Platinum 34 4.3 95 56 61 bisulfate