Dehydrogenation process

Abstract

The present invention relates to a new compound and the dehydrogenation of that compound to produce retinal.

Claims

1. A compound of formula (I): ##STR00012##

2. A dehydrogenation process which comprises conducting dehydrogenation of the compound of formula (I): ##STR00013## to the compound of formula (II): ##STR00014## in the presence of at least one oxidative reactant of formula (III): ##STR00015## wherein R.sup.1 is CN, Cl or F, R.sup.2 is CN, Cl or F, R.sup.3 is H, CH.sub.3, Cl or F, and R.sup.4 is H, CH.sub.3, Cl or F.

3. The dehydrogenation process according to claim 2, wherein the at least one oxidative reactant of formula (III) is selected from the group consisting of the compounds of formula (IIIa), (IIIb) and (IIIc): ##STR00016##

4. The dehydrogenation process according to claim 2, wherein the at least one oxidative reactant is the compound of formula (IIIc): ##STR00017##

5. The dehydrogenation process according to claim 2, wherein the at least one oxidative reactant of formula (III) is present in an amount from 0.5 mol-equivalent to 5 mol-equivalent in relation to compound of formula (I).

6. The dehydrogenation process according to claim 2, wherein the at least one oxidative reactant of formula (III) is present in an amount from 0.5 mol-equivalent to 3 mol-equivalent in relation to the compound of formula (I).

7. The dehydrogenation process according to claim 2, wherein the process is carried out in the presence of at least one additive compound.

8. The dehydrogenation process according to claim 7, wherein the at least one additive compound is selected from the group consisting of triethanolamine, pyridine, butylhydroxyltoluene, hydroquinone and triethoxyamine.

9. The dehydrogenation process according to claim 7, wherein the at least one additive compound is present in amount of 0.001-1 mol-equivalent in relation to the compound of formula (I).

10. The dehydrogenation process according to claim 7, wherein the at least one additive compound is present in amount of 0.003-1 mol-equivalent in relation to the compound of formula (I).

11. The dehydrogenation process according to claim 2, wherein the process is carried out in the presence of at least one inert solvent.

12. The dehydrogenation process according to claim 11, wherein the at least one inert solvent is selected from the group consisting aromatic hydrocarbons, ethyl acetate, tetrahydrofuran (THF), 2-methyltetrahydrofuran and 1, 4-dioxane.

13. The dehydrogenation process according to claim 2, wherein the process is carried out at a temperature of from 0 C.-150 C.

14. The dehydrogenation process according to claim 7, wherein the process is carried out at a temperature of from 6 C.-150 C.

Description

EXAMPLES

Example 1

(1) (3E,6E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-1-en-1-yl)nona-3,6-dienal (88 mg, 0.3 mmol; 1.0 eq), triethanolamine (3.1 mg, 0.02 mmol, 0.07 eq) and dry toluene (4.0 mL) were placed in a dried two necked round bottom flask equipped with a magnetic stirrer and condenser under an argon atmosphere. Solution of DDQ (71 mg, 0.3 mmol, 1.0 eq), in 1.0 mL dry toluene was added. The reaction was stirred at room temperature for 24 h. The reaction mixture was heated to 90 C. and a solution of DDQ (73 mg, 0.3 mmol, 1.0 eq), in 1.0 mL dry toluene was added. The reaction was stirred at 90 C. for 30 min. Subsequently cooled to room temperature and filtered over a glass fibre filter. All volatiles were evaporated under reduced pressure (40 C., 5 mbar) to obtain the product as dark red oil.