The present invention provides a process for the preparation of cyclic ketones.
Background of the invention
The catalytic hydrogenation of phenols to cyclic ketones is widely known. The EP Publication No. 0,889,019 Al and EP Publication No. 0,890,565 Al describe methods for preparing cyclohexanones by hydrogenation of the corresponding phenols in the presence of alkanes or water as solvent. The EP Patent No. 2,607,345 describes a process for preparing cyclohexanones by hydrogenation of the corresponding phenols in the presence of alcohol as solvent.
Summary of the invention
The present invention provides a process for the preparation of a compound of Formula II, comprising;
a) contacting a compound of Formula I with hydrogen in the presence of a hydrogenation catalyst to obtain the compound of Formula II, and
OH

Formula I Formula II
b) isolating the compound of Formula II obtained from step a), wherein the step a) takes place in the absence of a solvent.

Detailed description of the invention
The present invention provides a process for the preparation of a compound of Formula II, comprising;
a) contacting a compound of Formula I with hydrogen in the presence of a hydrogenation catalyst to obtain the compound of Formula II, and


OH

H3C

H3C

Formula I Formula II
b) isolating the compound of Formula II obtained from step a), wherein the step a) takes place in the absence of a solvent.
The compound of Formula I, which is used as a starting material in step a) may be obtained commercially.
The hydrogenation catalyst used in the step a) may be 1 to 30% by weight of the palladium supported on a carrier. The alkali metal-containing palladium catalysts are preferred. The carrier of the palladium catalyst or an alkali metal-containing palladium catalyst is preferably a carbon or alumina. The alkali metal component may be selected from the group consisting of alkali metal hydroxides e.g., sodium hydroxide and potassium hydroxide or alkali metal carbonate e.g., sodium carbonate and potassium carbonate.
The preferred alkali metal components are selected from the group consisting of sodium hydroxide and sodium carbonate.

The hydrogenation reaction of step a) can be performed by using 0.1 to 5.0mole equivalents of the alkali metal component with respect to the palladium catalyst and 0.00005 to 0.1 mole equivalents of palladium catalyst with respect to the starting material i.e., compound of formula I.
The hydrogenation reaction can be carried out at a pressure selected in the range from atmospheric to 20 barand at a temperature selected in the range from 60°C to 150°C. The catalyst used in the step a) can be recycled back after isolation from reaction mass by filtration.
Sodium hypochlorite and acetic acid are added in the process of the present invention.
The compound of Formula II is isolated by any method known in the art, for example, chemical separation, acid-base neutralization, distillation, evaporation, column chromatography and filtration or combination thereof.
While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.

PREPARATION OF 4-METHOXYCYCLOHEXANONE
Example:
The 4-methoxyphenol (100 g) and palladium-carbon catalyst (l.Og, 5% Pd containing sodium carbonate) were taken together in 400 mL hydrogenation reactor. The hydrogenation was conducted at 130°C and the pressure was maintained at 2 to 4 Bar. The progress of the reaction was monitored with gas chromatography. The reaction mass was cooled and filtered to isolate the catalyst. The sodium hypochlorite (62g, 11%) and acetic acid (3g) was added. The crude product thus obtained was distilled to get the title compound.
Yield(%): 95

WE CLAIM:
1. A process for the preparation of a compound of formula II, comprising;
a) contacting a compound of Formula I with hydrogen in presence of a hydrogenation catalyst to obtain the compound of Formula II, and
OH

Formula I Formula II
b) isolating the compound of Formula II obtained from step a), wherein the step a) takes place in absence of a solvent.
2. The process as claimed in claim 1, wherein the hydrogenation catalyst is selected from 1 to 30% by weight of a palladium catalyst supported on carbon or alumina.
3. The process as claimed in claim 2, wherein the palladium catalyst is an alkali metal-containing palladium catalyst.
4. The process as claimed in claim 3, wherein the alkali metal is selected from the group consisting of alkali metal hydroxides and alkali metalcarbonates.
5. The process as claimed in claim 4, wherein the alkali metal hydroxide is selected from the group consisting of sodium hydroxide and potassium hydroxide.

6. The process as claimed in claim 4, wherein the alkali metalcarbonate is selected from the group consisting of sodium carbonate and potassium carbonate.
7. The process as claimed in claim 1, wherein the process is carried out at a pressure in the range from atmospheric to 20 bar and at a temperature in the range from 60°C to 150°C.