JPS5835141A - Preparation of 2-cyclohexen-1-one - Google Patents

Abstract

PURPOSE:To inhibit the polymerization loss of an alpha,beta-unsaturated aldehyde effectively and obtain the titled substance in high yield without troublesome operations in reacting a ketone with the alpha,beta-unsaturated aldehyde in the presence of a catalyst, by carrying out the reaction in the vapor phase without using the liquid phase. CONSTITUTION:A ketone of the formula R<1>CH<2>COCH2R<2> (R<1> and R<2> are H, CH3 or C2H5) is reacted with an alpha,beta-unsaturated aldehyde of the formula R<3>CH= CHCHO (R<3> is H, CH3 or C2H5) in the vapor phase in the presence of a solid basic catalyst, e.g. sodium hydroxide or potassium hydroxide, to give the aimed compound. The reaction temperature is in the range of 200-400 deg.C. The feeding rate of the raw materials is in the range of 0.001-1.0mol based on the alpha,beta- unsaturated aldehyde and 1g catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the reaction of ketones and α,β-unsaturated aldehydes in the gas phase in the presence of solid base catalysts to produce the corresponding 2-cyclohexen-1-ones. 2-Cyclobexen-1-ones are chemical intermediates, such as 2,5,6-drimethyl-2-cyclohexene-1
-Onha is an important compound for vitamin E uses, etc.

Regarding conventional cyclohexenones, Large Organic Chemistry Volume 6 Alicyclic Compounds ■, Page 282, 1. According to (Asakura Shoten),
Methods such as oxidation of cyclohexene with chromic anhydride and selenium dioxide, and dehydrohalogenation of 2-halogen cyclohexanone are introduced as general production methods. By the way, regarding a technique similar to the method of the present invention,
According to 17223, crotonaldehyde and diethyl ketone are reacted in the liquid phase in the presence of an alkali, 2.5.6-
The company manufactures trimethyl-2-cyclohexen-1-one. However, according to this method, crotonaldehyde, which is alkaline and easily polymerized, is reacted in the liquid phase under an alkaline catalyst, resulting in a large polymerization loss.

Furthermore, if a similar reaction is carried out with acrolein, the acrolein will polymerize explosively, resulting in a large polymerization loss, and it will be difficult to carry out the reaction in a liquid phase, making it unsatisfactory as an industrial production method.

The inventors of the present invention have made extensive studies to solve these serious industrial deficiencies and have found that the objective can be achieved by employing a gas phase reaction.

That is, the present invention is based on the general formula R' CH2C0CH-z R2
Ketone represented by 'tl' and general formula R3CH=CHC
2- characterized in that an α,β-unsaturated aldehyde represented by HO is reacted in the gas phase in the presence of a solid base catalyst.
This is a method for producing chlorohexen-l-ones.

Here, R1, R2 and R3 may be the same or different and represent each #H, CH3 or C2H5.

According to the method of the present invention, α, β-
The polymerization loss of unsaturated aldehyde is efficiently suppressed, and the reaction proceeds smoothly because the complicated operations that occur as a side effect are not required, so 2-fuclohexene-1- is produced in good yield. You can get on types.

The reaction formula of the method for producing 2-cyclohex-7-1-ones of the present invention is as follows.

General formula R' CR2COCR2R2 applied in the present invention
The ketone represented by (here, RIR2 has the same meaning as above) is a saturated lower aliphatic ketone, for example,
Acetone, diethyl ketone, di-propyl ketone,
Examples include methyl ethyl ketone and methyl propyl ketone.

α,β-unsaturated aldehyde represented by the general formula R3CH=CHCHO (where R3 has the same meaning as above)
are lower aliphatic aldehydes, such as acrolein,
Examples include crotonaldehyde and 2-pentenal.

Solid base catalysts include alkali metal and alkaline earth metal oxides, hydroxides, carbonates, phosphates, etc., e.g.
Examples include sodium oxide, potassium oxide, magnesium oxide, barium oxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, lithium phosphate, sodium phosphate, potassium phosphate, and the like.

These solid bases may be supported as such or on a suitable carrier. Suitable carriers include, for example, silica, alumina, activated carbon, and silicon carbide.

The above catalyst can be prepared by a known method.

For example, alkali metal and alkaline earth metal nitrates,
Hydroxide and the like are dissolved in water, mixed with a carrier, and then dried. Next, it can be obtained by molding to a suitable particle size and firing. Powdered solid bases, such as carbonates and phosphates of alkali metals and alkaline earth metals, can be molded as is, or mixed with a suitable carrier, molded to an appropriate particle size, and then calcined. be able to.

The reaction temperature used in the present invention can generally be carried out in the range of 200 to 400°C. If the temperature is too low, the reaction temperature will drop extremely; if it is too high, side reactions will occur.

The feed rate of the raw material is 0001 to 1.00 per gram of catalyst based on α,β-unsaturated aldehyde. The amount is selected from the range of 0 mol/hour and determined experimentally depending on the reaction temperature and the like. Further, the molar ratio of ketone/α,β-unsaturated aldehyde is preferably 1 or more, particularly preferably in the range of 5 to 30.

Inert gas such as water vapor and nitrogen may be present in the reaction. The reaction method is usually carried out in a fixed bed under normal pressure, and satisfactory results can be obtained, but in some cases, it may be carried out in combination with pressure such as reduced pressure or increased pressure, and equipment such as a fluidized bed or moving bed. .

Embodiments are operated continuously, for example by sequentially feeding both feedstocks into a reaction zone maintained at a predetermined temperature. The crude product obtained can be easily purified by condensation and subsequent distillation using known methods.

Next, the present invention will be explained in more detail with reference to Examples. Note that the yield was determined by gas chromatography analysis.

Example 1 775 g of barium nitrate was dissolved in 50 g of water and added to 500 g of 20 ml sol while stirring well, and then concentrated to obtain a cake-like substance. 1 of this cake-like substance
After thoroughly drying at 10°C, it is heated at 350°C for 3 hours to decompose the nitrate. Next, this is 5mm) (X511m
After molding into a tablet shape, it was calcined at 500°C for 3 hours to obtain a catalyst.

The catalyst 50- thus prepared had an inner diameter of 28.4 m.
A +++ stainless steel U-shaped reaction tube is filled with a raw material solution of diethyl ketone/acrolein at a molar ratio of 23 at 1 hourly.
Charge at the speed of Ornl, reaction temperature 300℃, 325℃
As a result of reaction with acrolein, 2,6-dimethyl-2-7 chlorohexen-1-one was obtained in a yield of 912% at 300°C and in a yield of 966% at 325°C.

Examples-2 to 4 Nitric acid mag Example-4 instead of barium nitrate in Example-1
) The catalyst was prepared in the same manner and reacted in the same manner (reaction temperature: 300°C). The results are as follows.

Examples 5 and 6 Using the catalyst of Example 4, diethyl ketone/acrolein of Example 1 was replaced with diethyl ketone/crotonaldehyde (Example 5) and acetone/acrolein (Example 6). The reaction was carried out in the same manner except that (
Reaction Temperature Examples 7 and 8 100 g of 20% silica sol was added to 50 g of lithium phosphate, and after thorough kneading, it was dried at 110°C.
HX 5 III After molding into a tablet shape of 4 g
A catalyst was obtained by firing at 00°C for 3 hours.

Using diethyl ketone/crotonaldehyde of Example-5 (reaction temperature: 275°C) (Example-7) and diethylketone/acrolein of Example-1 (reaction temperature: 335°C) (Example-8), and Same Example-9 except that the catalyst prepared above was used. The reaction was carried out in the same manner as in Example-8 except that the molar ratio of diethyl ketone/acrolein was changed to 23.10.5 (reaction temperature: 325°C). ) Result, 2,6. -dimethyl-2
-7 Chlorhexen-l-one at the same molar ratio of 23 yields 8
32%, 10 with a yield of 675%, and 5 with a yield of 570%.

Comparative Example-1 In the same manner as in Example-1 without using a catalyst, 2.
No 6-dimethyl-2-cyclohexen-1-one was formed.

Comparative Example-2゜When using 13% alumina-containing silica (trade name N-631L, manufactured by JGC Chemical Co., Ltd.) as a solid acid catalyst in the same manner as in Example-1, 26-dimethyl-2-cyclohexene-
The yield of 1-one was 51%, and a large amount of by-products were produced.

Claims (1)

[Claims] A ketone represented by the general formula R'CH2COCH2R'' and α, β represented by the general formula R3CH=CHCHO
-2-cyclohexene-1- characterized in that an unsaturated aldehyde is reacted in the gas phase in the presence of a solid base catalyst.
On-type manufacturing method. Here, R1, R2 and R3 may be the same or different and each represents H, CHs or CzHs.