DEHYDROGENATION PROCESS

Abstract

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

Claims

1. Compound of formula (I) ##STR00012##

2. 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. Dehydrogenation according to claim 2, wherein the oxidative reactant of formula (III) is chosen from the group consisting of the compounds of formula (IIIa), (IIIb) and (IIIc) ##STR00016##

4. Dehydrogenation according to claim 2, wherein the oxidative reactant is the compound of formula (IIIc) ##STR00017##

5. Dehydrogenation according to anyone of the preceding claim 2, wherein the amount the amount of the oxidative reactant of formula (III) goes from 0.5 mol-equivalent up to 5 mol-equivalent (in relation to compound of formula (I)).

6. Dehydrogenation according to claim 2, wherein the amount of the oxidative reactant of formula (III) goes from 0.5 mol-equivalent up to 3 mol-equivalent (in relation to compound of formula (I)).

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

8. Dehydrogenation according to claim 7, wherein the additive compound is chosen from the group consisting of triethanolamine, pyridine, butylhydroxyltoluene, hydroquinone and triethoxyamine.

9. Dehydrogenation according to claim 7, wherein the additive compound is added in amount of 0.001-1 mol-equivalent (in relation to compound of formula (I)).

10. Dehydrogenation according to claim 7, wherein the additive compound is added in amount of 0.003-1 mol-equivalent (in relation to compound of formula (I)).

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

12. Dehydrogenation according to claim 11, wherein the solvent is chosen from the group consisting aromatic hydrocarbon (i.e. benzene or toluene), ethyl acetate, THF, 2-methyltetrahydrofuran or 1, 4-dioxane.

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

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

Description

EXAMPLES

Example 1

[0043] (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.