ELECTROCHEMICAL TRANSFORMATIONS

Abstract

A process for synthesising a defined compound, such as solketal, wherein the process comprises subjecting a solution comprising another defined compound, such as glycerol, to a potential difference. A compound and a composition obtainable by the process, and a product comprising the compound or the composition.

Claims

1. A process for synthesising a compound according to Formula (I): ##STR00013## wherein the process comprises: subjecting a solution comprising a compound according to Formula (II): ##STR00014## to a potential difference, wherein, for the compounds according to Formulae (I) and (II): each X is independently selected from the group consisting of O, S, NR.sup.Y and PR.sup.Y, each of R.sup.1 to R.sup.6 and R.sup.Y is a group selected from the list consisting of hydrogen, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl, C.sub.6-C.sub.12 aryl, and C.sub.3-C.sub.12 heterocyclyl, each of R.sup.1 to R.sup.6 and R.sup.Y optionally contains one or more heteroatom containing groups, and wherein Formulae (I) and (II) include tautomeric and stereochemically isomeric forms thereof.

2. The process of claim 1, wherein the solution comprises a Brnsted base.

3. The process of claim 2, wherein the Brnsted base is selected from the list consisting of KOH, NaOH, LiOH, Li.sub.2CO.sub.3, LiHCO.sub.3, Na.sub.2CO.sub.3, NaHCO.sub.3, K.sub.2CO.sub.3, and KHCO.sub.3.

4. (canceled)

5. The process of claim 1, wherein the solution comprises and/or is contacted with carbon dioxide.

6. The process of claim 1, wherein the pressure whilst the potential difference is applied is 5 MPa or less.

7. (canceled)

8. The process of claim 1, wherein the potential difference is applied across two or more electrodes that are in contact with the solution, and wherein the electrodes are made of a material selected from the list consisting of graphite, zinc, copper, platinum, gold, rhodium, lead, copper, nickel, palladium and/or silver.

9. The process of claim 8, wherein material is coated onto a substrate.

10. The process of claim 8, wherein the two or more electrodes comprise a first electrode and a second electrode, and wherein either: a) the first electrode is made of copper and the second electrode is made of graphite, or b) the first electrode is made of copper-coated graphite and the second electrode is made of copper-coated graphite, or c) the first electrode is made of copper-coated graphite and the second electrode is made of graphite, or d) the first electrode is made of zinc-coated graphite and the second electrode is made of graphite.

11. The process of claim 10, wherein the first electrode is the anode and the second electrode is the cathode.

12-13. (canceled)

14. The process of claim 1, wherein each of R.sup.1 to R.sup.6 and R.sup.Y is a group selected from the list consisting of hydrogen, C.sub.1-C.sub.8 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.2-C.sub.8 alkynyl, C.sub.6-C.sub.8 aryl, and C.sub.4-C.sub.8 heterocyclyl.

15. (canceled)

16. The process of claim 1, wherein X is O.

17. The process of claim 1, wherein the or each heteroatom containing group is an alcohol.

18. The process of claim 14, wherein the compound according to Formula (I) is solketal: ##STR00015##

19. The process of claim 14, wherein the compound according to Formula (II) is glycerol: ##STR00016##

20. The process of claim 1, wherein the process comprises isolating the compound according to Formula (I).

21. (canceled)

22. A compound of Formula (I), as defined by claim 1, wherein the compound is obtainable by the process according to claim 1.

23. A composition comprising a compound of Formula (I), as defined by claim 1, wherein the composition: is obtainable by the method of claim 1; and/or comprises a by-product characteristic of the method of claim 1.

24. The composition of claim 23, wherein the by-product has the molecular formula C.sub.7H.sub.12O.sub.2 and/or is formic acid.

25. The compound of claim 22, wherein the compound is present in or as: a) a solvent; b) a fuel; c) a pharmaceutical intermediate; d) a pharmaceutical carrier; e) an air care product; f) a paint or varnish; g) an ink; h) a cleaning agent; and/or i) a leather treatment agent.

26. The process of claim 1, wherein the solution comprises a carbonyl group-containing molecule.

Description

DESCRIPTION OF THE DRAWINGS

[0141] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0142] FIG. 1 shows a batch reactor that can be used to perform the process of the present invention;

[0143] FIG. 2 illustrates a suitable exemplary flow reactor;

[0144] FIG. 3 shows the .sup.1H NMR spectrum of the reaction product, which correlates with literature data for solketal;

[0145] FIG. 4a shows the GC-MS chromatogram for the reaction product; and

[0146] FIG. 4b shows the mass spectrum of the peak at 5.283 minutes in the chromatogram of FIG. 4a.

EXAMPLES

Preparation of Coated Graphite Electrodes

[0147] A saturated aqueous solution of CuCl.sub.2 (10 mL) was prepared. A potential difference of 10 V was passed for 10 min across two graphite electrodes with fixed poles using an IKA ElectraSyn 2.0 cell. The resulting copper-coated electrode was dried at 110 C. overnight.

[0148] Other metal-coated electrodes can be prepared by the above method, exchanging the CuCl.sub.2 for the desired metal halide salt. For example, ZnCl.sub.2 can be used to prepare zinc-coated graphite electrodes.

Synthesis of Solketal

[0149] ##STR00012##

First Protocol:

[0150] Prior to the reaction, all equipment was new and dried to make sure that no trace of acetone was present. A mixture of glycerol (2 M, 2.5 mL) and KOH (2 M, 2.5 mL) was prepared and a constant stream of carbon dioxide was bubbled through the resulting solution at 1 atm pressure for 30 minutes to saturate the solution with carbon dioxide prior to the reaction taking place. The apparatus used for this experiment is shown in FIG. 1.

[0151] Whilst continuing the stream of carbon dioxide through the solution, the solution was electrolysed at room temperature using a potential difference of 2 V for 2 hours using an IKA ElectraSyn 2.0 cell. Water was subsequently removed under reduced pressure and the residue obtained was analysed by gas chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy and infra-red spectroscopy to confirm the presence of solketal. The yield of solketal was calculated by GC-MS, by comparison to a calibration curve.

[0152] FIG. 3 shows the .sup.1H NMR spectrum of the reaction product of the first protocol, which correlates with literature data for solketal. FIG. 4a shows the GC-MS chromatogram for the reaction product and FIG. 4b shows the mass spectrum of the peak at 5.283 minutes in the chromatogram of FIG. 4a, which shows solketal, with a M+H.sup.+ m/z of 133.

[0153] The electrodes used and yields obtained in the experiments are shown in Table 1, below.

TABLE-US-00001 TABLE 1 Electrodes Formic acid Solketal Current Anode/Cathode yield (%) yield (%) (mA) Cu/graphite 0.001 63.04 5-6 Cu-coated graphite/Cu-coated 0 56.35 70-100 graphite Cu-coated graphite/graphite 0.2 63.13 70-100 Zn-coated graphite/graphite 0.05 68.11 5-6

[0154] Solketal was successfully produced in calculated yields of from 56 to 68%. The amounts of the by-product, formic acid, that were produced were very low.

Second Protocol:

[0155] A solution (10 mL) containing glycerol (2 M), KOH (2 M) acetone (1 mL) was prepared. The solution was subjected to a potential difference of 2 V using an ElectraSyn 2.0 cell for 2 h using a carbon anode and a copper cathode, whilst being supplied with 20 SCCM of CO.sub.2. The resultant solution was collected in a GC vial and diluted (500 L sample+200 L 2-propanol+50 L internal standard) and was analysed by GC equipped with a Stabilwax column. The yield of solketal was calculated by GC-MS, by comparison to a calibration curve.

Third (i.e. Two Stage) Protocol:

[0156] An aqueous solution of H.sub.2O.sub.2 (500 L) and NaCl (35 ppm/0.35 g) in water (total volume 10 mL) was prepared. The solution was subjected to a potential difference of 2 V using an ElectraSyn 2.0 cell, using a carbon anode and a copper cathode, whilst being supplied with CO.sub.2 (20 SCCM). After 1 hour, glycerol (1 M) and acetone (1.0 mL) was added. After a further 1 hour, the reaction mixture was collected in a GC vial (500 L sample+200 L 2-propanol+50 L internal standard) and was analysed by GC equipped with a Stabilwax column. The yield of solketal was calculated by GC-MS, by comparison to a calibration curve.

[0157] Following this protocol solketal (20% yield) was obtained.

[0158] GC-MS analysis of the reaction mixture revealed that a compound having the molecular formula C.sub.7H.sub.12O.sub.2, which could have been ethyl cyclopentanolone, was generated as a by-product of the reaction. This was surprising and was postulated as perhaps being characteristic of the process of the first aspect as opposed to conventional condensation reaction being used to prepare solketal.

Comparative Experiment Without Potential Difference

[0159] In a comparative experiment performed under the first protocol as detailed above but with no potential difference applied across the electrodes, no reaction occurred.

Conclusions

[0160] Solketal was produced without any acids, let alone strong acids, or heterogeneous catalysts being added to the reaction mixture, as would be required by conventional processes for producing solketal. [0161] Solketal was produced at room temperature, rather than at the high temperatures that would be required by conventional processes for producing solketal. [0162] Solketal was produced at standard atmospheric pressure, rather than at the high pressures that would be required by conventional processes for producing solketal. [0163] Solketal was produced without requiring acetone to be added or requiring excess acetone to be removed by distillation to isolate solketal, unlike the conventional processes for producing solketal. The use of new, dry equipment ensured that acetone was not present before the potential difference was applied to the solution. [0164] This reaction requires a potential difference to be applied.

[0165] Therefore, the process of the present invention has a number of distinct advantages over conventional processes for producing compounds of Formula (I), such as solketal.