IE47923B1 - Production of unsaturated carbonyl compounds - Google Patents

Description

This invention relates to the use of an aluminium oxycarbonate catalyst in the production of unsaturated carbonyl compounds with simultaneous removal of water of reaction to maintain the catalytic activity of the oxycarbonate catalyst.

According to the invention, there is provided a process for producing an unsaturated carbonyl compound, which compris es contacting at least one ketone or aldehyde with an aluminium oxycarbonate catalyst, the water formed by the reaction being removed as it is formed.

The invention can be used, for example, in an aldol condensation and dehydration process for increasing the molecular weight of carbonyl compounds. The catalyst commonly used for such a process is sodium hydroxide. This 1.5 process generally yields hydroxy carbonyl compounds which are often dehydrated to form unsaturated carbonyl compounds in the presence of an acid catalyst. For example, acetone is condensed in the presence of an alkaline compound to yield diacetonc alcohol which is then dehydrated to yield 2o mesityl oxide.

In accordance with the present invention, the aldol condensation and dehydration-pro'Cess' can be carried out using an aluminium Oxycarbonate catalyst in either a fixed or in a fluidised bed. Degradation Of the aluminium oxycarbonate catalyst can Be avoided,' when the reaction is stopped, by the application of C0_ to the catalyst.

As used herein, the term aldol condensation means a 4-7 9 2 3 - 3 combined condensation-and-dehydration reaction utilizing carbonyl compounds (i.e, aldehydes and/or ketones), the term fixed bed means a stationary catalyst bed through which vapours and liquids move, and the term fluidised bed means a suspension of catalyst particles, the suspension being maintained by agitation.

The aldol condensation produces alpha-beta unsaturated carbonyl compounds. The aluminium oxycarbonate catalyst, maintained in either a fixed or fluidised bed, is also useful in the substitution of other carbonyl groups into such alpha-beta unsaturated carbonyl compounds. The substitution occurs at the alpha carbon of the unsaturated carbonyl compound.

The process of the present invention can be used to condense a wide variety of aldehydes and ketones. Carbonyl compounds containing from two to twenty carbon atoms are particularly desirable for condensation, but higher molecular weight carbonyl compounds can be used.

By the process of the present invention, it is now possible to condense higher molecular weight ketones.

If only one carbonyl compound is used in the aldol condensation process according to the present invention, it preferably has the following general formula: II HCH —C —Rj Ci) R2 wherein R^ and R2 are the same or different and each is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkaryl group or an aralkyl group, or R^ and together form an alkylene group.

If two distinct aldehydes and/or ketones are used, at least one of them preferably has the general Formula (I).

The aluminium oxycarbonate catalyst can be prepared by heating aluminium hydroxide in a carbon dioxide atmosphere. The catalyst may also be prepared by heating Al20g 473 23 - 4 __in a CO2 atmosphere, or by treating aluminium oxide or hydroxide with C02, while the aluminium compound is wetted with water or with a carbonyl compound. Other methods of combining aluminium with carbon dioxide will be apparent to those skilled in the art.

The catalytic activity of the aluminium compound improves rapidly with the initial addition of COg but soon reaches a very efficient state that improves little thereafter. The ratio of A1:CO2:O can vary widely. Some C02 is essential to ensure the catalytic activity of the catalyst.

The aluminium oxycarbonate catalyst may be used in various forms, for example as granules, pellets or powders.

In the process of the invention, the catalyst is preferably maintained in a suitable reaction tube or chamber. The catalyst may be employed in a fixed bed over which the carbonyl compound in vapour and/or liquid form may be passed while carrying out the aldol condensation reaction.

The catalyst may also be employed as a fluidised bed.

The temperature at which the aldol condensation reaction is carried out can be up to 200°C or higher. The preferred temperature range is between 80°C and 150°C. The reaction speed decreases with temperature. At higher temperatures more undesired side reactions occur. The aldol condensation reaction should be conducted at a temperature at which the reactant and product remain stable. For example, aldehyde begins to decompose at about 250°C.

The pressure at which the aldol condensation reaction is carried out may be, for example, from sub-atmospheric to about 50 atmospheres. The preferred pressure range is between 1 and ID atmospheres. During the reaction, the carbonyl compound may be in the vapour phase and/or the liquid phase, but preferably it is a mixture of vapour and liquid with the vapour and liquid components of· the mixture moving in opposite directions through the bed of the catalyst.

The preferred reaction conditions are such that the water of reaction is azeotropically removed from the catalyst chamber. Removal of water is essential to maintain the required catalytic activity of the catalyst. When using 7 9 2 3 - 5 carbonyl compounds that readily form an azeotrope with water, it is convenient to operate at atmospheric pressure and at a tenperature at or near the normal boiling point of the carbonyl conpound. When using conpounds such as acetone which do not readily form an azeotrope with water at such pressure and tenperature, then the pressure and tenperature may be raised. A solvent can be added to aid in the formation of an azeotrope and in separating the water.

Under the preferred reaction conditions, the hot vapours moving up through the catalyst bed contain the water of reaction, Upon condensation, the water separates frcm the organic condensate.

Ihe organic condensate is refluxed through the catalyst thereby removing the reaction product. Removal of the product from the catalyst bed is desirable to minimize formation of undesirable by-products.

Keeping the catalyst wetted With the liquid reactant also suppresses the foimation of such by-products.

When using a fluidised bed, it is preferred to . remove the reaction mixture solution at reaction product concentrations of 75% or less, to limit the formation of such by-products.

In general, pressures of 1 to 10 atmospheres are preferred to establish the boiling points of the carbonyl compounds in the desired 80°C to 150°C temperature operating range.

In the presence of the aluminium oxycarbonate catalyst, the aldol condensation dehydration process is reversible, which is an important advantage of the invention. Due to this reversibility of the aldol condensation process, it is now possible to produce additional unsaturated carbonyl compounds by contacting the aluminium oxycarbonate catalyst with alpha-beta unsaturated carbonyl compounds, either alone or in the presence of another carbonyl compound. The reaction conditions previously described can be used to produce these additional compounds but temperatures below 80°C can also be used.

The present invention will be illustrated by the following Examples.

Example 1 There was used an aldol condensation dehydration pilot plant consisting of (1) an autoclave fitted with beating 7 9 2 3 - 6 steam coils, (2) a 15 cm diameter vertical tube having a catalyst chamber extending above the autoclave, sections of this tube above and below the catalyst chamber being packed with ceramic saddles, (3) a condenser, and (4) a condensate receiver.

Methyl isobutyl ketone (MIBK) was refluxed in the autoclave at atmospheric pressure. The 2,6,8-trimethyl-5nonen-4-one (TMNO) formed was removed from the bottom of the autoclave. The catalyst chamber was packed with the aluminium oxycarbonate catalyst.

The water by-product from the reaction was removed from the receiver while the MIBK from the receiver was returned to the top of the vertical tube as reflux.

The operating conditions were as given in the following 15 Table 1: Table 1 Catalyst Depth Run Time TMNO Conversion Rate TMNO (cm) (Hours) (kg) (gm/cm^/hr*) (%) 24 il 9 4.4 100 81 260 977 20 98 208 80.5 536 36 96.6 305 - - 46 - ♦Gram/cm of cross sectional area of the catalyst chamber.

Example 2 The plant described in Example 1 was used. Acetone was refluxed through the catalyst bed while mesityl oxide was removed from the autoclave. Normal pentane was refluxed to the top of the tube to aid in the removal of water from the refluxing acetone. Water was removed from the receiver.

The operating conditions were as given in the following Table 2: 7 9 2 3 Catalyst Depth (cm) Pressure (Atmospheres) Conversion Rate 2 (gm/cm /hr) 142 3 3.7 - 5.4 142 3.7 4.4 - 7.3 142 4.4 6.3 142 5.1 7.8 - 9.3 142 5.8 11 142 6.4 14.6 - 16 305 7.8 49 Example 3 There was used a plant as described in Example 1 with a catalyst depth of 305 cm. The plant was pressurised overnight with COg at 3.7 atmospheres. This COg treatment enhanced the catalytic activity of the .aluminium oxycarbonate and the conversion rate to TMNO increased to more than 50 gm/cm /hr.

Example 4 A three litre flask equipped with a stirrer to produce a fluidised bed was used. A receiver and condenser extended upward from the flask. To the flask, 1 kg of MIBK and 100 gm of aluminium oxycarbonate (fine powder) were added, and heated to an initial boiling point of 115°C. The MIBK and water formed an azeotrope, and 67 ml of MIBK saturated with water was removed. Thereafter, MIBK was continually refluxed to the flask. Over a ten hour period, the temperature of the flask increased from 115°C to 145°C, and 760 gm of product were removed from the reaction flask. Distillation produced 250 gm of MIBK and 410 gm of TMNO. Remaining from the distillation was 100 gm of residue. The conversion of MIBK was 70%. The reaction product was 80.4% TMNO.

This Example illustrates that the aluminium oxycarbonate catalyst can be utilized in a fluidised bed as well as in a fixed bed.

Example 5 A three litre flask was used to carry out an aldol condensation process. Extending from the flask was a 50 mm diameter column. The column was packed at the bottom with 7 9 2 3 - 8 ceramic saddles. The centre 25 cm section of the column was packed with aluminium oxycarbonate. The top 12 cm section of the column was packed with ceramic or porcelain saddles.

A receiver and a water-cooled condenser were operatively coupled to the top section of the column.

The flask was charged with 1,800 ml of methyl ethyl ketone (MEK) and refluxed at atmospheric pressure. A small amount of n-hexane, added to the condenser, aided in the water separation. After refluxing for 13 hours, approximately 70% of the original MEK was condensed to a product having a distinct spicy odor. The condensation products were -methyl-4-hepten-3-one and 3,4-dimethyl-3-hexen-2-one.

Example 6 The same equipment as described in Example 5 was used.

The flask was charged with 11,600 ml of n-butanal and 200 ml of n-hexane. Refluxing at atmospheric pressure, the n-butanal was condensed to 2-ethylhexanal at a rate of approximately 20 gm/hr.

Example 7 The same equipment as described in Example 5 was used.

The flask was charged with 2,500 ml of mesityl oxide.

Refluxing at atmospheric pressure resulted in a mixture of Cg di-unsaturated ketones. The conversion rate was approximately 300 gm/hr. Removal of water was accomplished by reversal of the aldol condensation reaction to form acetone. The acetone was removed from the reaction while it was being formed.

Example 8 The equipment of Example 1 was used. The catalyst had a depth of 24 cm. It was allowed to stand overnight.

The reaction was restarted the next day. The rate of formation of TMNO was slightly greater than 3.9 gm/cm /hr. After standing again overnight, the rate of TMNO formation was less than that amount. Loss of activity of the catalyst continued with subsequent stops and starts. To prevent such degradation of the catalyst, C02 treatment of the catalyst at each shutdown was used. After such CO2 treatment, no apparent loss of catalytic activity reoccurred.

Example 9 TMNO was heated in the presence of aluminium oxycarbonate using the same equipment as described in Example 4.

The resulting products were decanted and distilled. The distillate consisted of MIBK, unreacted TMNO, C18 di-unsaturated ketones, and distillation residues.

Example 10 Using the equipment as described in Example 4, 1500 ml of cyclohexanone and 100 gm of aluminium oxycarbonate were added to the flask, and heated to an initial boiling point of 142°C. Water evolved quickly and the temperature of the flask rose to 200°C in three hours. The liquid was decanted, and -distilled to yield unreacted cyclohexanone, cyclohexylidene cyclohexanone, and a higher molecular weight condensation product, CjgHggO, believed to be di-cyclohexylidene cyclohexanone.

Example 11 Using the equipment as described in Example 5, 1500 ml of cyclohexanone were added to the flask, and heated to boiling. After seven hours the temperature of the flask was 210°C. Distillation yielded about 80% cyclohexylidene cyclohexanone together with unreacted cyclohexanone. Very little of the higher molecular weight condensation products were produced.

Example 12 Using the equipment as described in Example 4, 1700 ml of acetophenone were added along with 300 gm of the catalyst. Also added, as a solvent, were 100 ml of hexane to suppress the boiling point and to. form an azeotrope with the water. The aldol condensation was rapid. The yield was 65% phenyl beta-methylstyryl ketone.

As will be apparent to those skilled in the art, the invention provides a process which can be very efficient and economical. Simplicity of the process and the required equipment make it possible to utilize small and, therefore, relatively inexpensive production plants. Accordingly, these smaller plants can be more advantageously located near the source of materials or markets. In addition, the process of the invention can produce products for which no previously known process was commercially suitable.

Claims (10)

CLAIMS :

1. A process for producing an unsaturated carbonyl compound, which comprises contacting at least one ketone or aldehyde with an aluminium oxycarbonate catalyst, 5 the water formed by the reaction being removed as it is formed.

2. A process according to claim 1, wherein the ketone or aldehyde or at least one of the ketones or aldehydes has the general formula: wherein R^ and are the same or different and each is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkaryl group or an aralkyl group, or R^ and R 2 together form an alkylene group. 15

3. A process according to claim 2, wherein methyl isobutyl ketone is contacted with the catalyst to produce trimethylnonenone.

4. A process according to claim 2, wherein acetone is contacted with the catalyst to produce mesityl oxide. 20 5. A process according to claim 2, wherein cyclohexanone is contacted with the catalyst to produce cyclohexylidene cyclohexanone. 6. A process according to claim 2, wherein acetophenone is contacted with the catalyst to produce 25 phenyl beta-methylstyry1 ketone. 7. A process according to claim 2, wherein an alpha-beta unsaturated ketone or aldehyde, or a mixture thereof with a different ketone or aldehyde, is contacted with the catalyst. 47933 - 11 8. A process according to claim 7, wherein mesityl oxide is contacted with the catalyst to produce a Cg-diunsaturated ketone. 9. A process according to any of claims 1 to 8,

5. Where the reaction is carried out in the presence of a solvent to aid in the removal of water.

6. 10. A process according to any of claims 1 to 9, wherein the catalyst is in the form of a fixed bed or a fluidised bed. 10

7. 11. A process according to any of claims 1 to 10, wherein the process is effected at a temperature of from 80 to 150°C.

8. 12. A process according to any of claims 1 to 11, wherein the activity of the catalyst is maintained and/or 15 enhanced by treating it with

9. 13. A process for producing an unsaturated carbonyl compound, substantially as described in any of the foregoing Examples.

10. 14. An unsaturated carbonyl compound, when produced 20 by a process according to any of claims 1 to 13.