CN1036388C - Method for the synthesis of aldehydes by hydroformylation of olefins - Google Patents

Abstract

The invention discloses a method for synthesizing aldehydes through hydroformylation of olefins. C ₃ or _above olefins, carbon monoxide and nitrogen, using dicobalt octacarbonyl as a catalyst, quaternary ammonium salt as a catalyst stabilizer, and generating aldehydes under the reaction conditions of 100-130°C and 5.5-8.5MPa. The normal isomerization ratio of the product is above 1.2, and the aldehyde yield is 71.7-90.1%.

Description

Method for the synthesis of aldehydes by hydroformylation of olefins

The invention relates to a method for synthesizing aldehydes by olefin hydroformylation, in particular, the invention relates to a method for preparing aldehydes by carbonylation of olefins, carbon monoxide and hydrogen.

Olefin hydroformylation is a well-known chemical process in which an olefin, usually a terminal olefin of the general formula:

In the RCH=CH ₂ formula, R represents a hydrogen atom or any substituted hydrocarbon group. Under the conditions of increasing temperature and pressure, and in the presence of a suitable catalyst, it can react with carbon monoxide and hydrogen according to the following reaction formula to generate aldehyde:

R generally represents a hydrogen atom or an alkyl group.

Alkene hydroformylation of ethylene can produce a single aldehyde product, that is, propylene. However, if propylene or higher olefins are subjected to olefin hydroformylation, due to the regioselectivity of the reaction, the product contains the required normal aldehyde, It also always contains a certain proportion of the corresponding isomeric aldehyde, which is formed according to the following reaction formula:

The ratio of normal isoaldehyde (normal/iso) is determined by the catalyst and reaction conditions, and it is an important index to measure the reaction result. In general, the desired product of olefin hydroformylation reactions is normal aldehydes rather than isomeric aldehydes, whose sales are relatively limited. For example, the normal product of butene hydroformylation, n-valeraldehyde, is the key raw material for the synthesis of methyl dihydrojasmonate, one of the most popular and valuable fragrances in the world, and one of the main fragrances of jasmine. It is imported and supplied; while its isomer product 2-methylbutyraldehyde is only used in the synthesis of general spices with the fragrance of white orchid head.

Cobalt catalyst and rhodium catalyst are widely used in oxo industry at present, and different synthesis processes are divided into high-pressure method and low-pressure method. The classic one is the high-pressure method. Since the catalyst is easy to decompose at high temperature to produce metal deposition, it is necessary to increase the partial pressure of carbon monoxide in the synthesis gas during the reaction to ensure the stability of HCo(CO) ₄ and HRh(CO) ₄ ; later it was found that there are phosphine ligands in the catalyst The low-pressure method appears after greatly increasing the stability of the catalyst. Using a rhodium catalyst, the main product of olefin hydroformylation is aldehyde, regardless of the high-pressure or low-pressure method, but the rhodium catalyst is prone to poisoning, and there are strict requirements on the purity of the synthesis gas and raw material olefins, and there are many problems in the supply, loss and recovery of precious metal rhodium. Larger limitations. The high-pressure cobalt method has low requirements on the purity of synthesis gas and raw material olefins, but requires high compression and reaction equipment, and high investment costs; while the low-pressure cobalt method increases the hydrogenation performance of the system, and the main product is aldehyde hydrogenation product alcohol. In recent years, iron-cobalt cluster catalysts (CH ₃ ) ₃ C ₆ H ₅ CH ₂ N|FeCo ₃ (CO) ₁₂ | have been widely used in hydroformylation reactions, with good catalytic activity and selectivity. Not harsh (medium-pressure synthesis), but the normal isomerization ratio of aldehyde is not ideal (about 1), the catalyst life is short, and it needs to be destroyed to recover cobalt after one use. U.S. Patent 4,209,643 describes the method of preparing acetal by C ₃ or higher α or internal olefin, carbon monoxide, hydrogen and C ₁ -C ₅ alcohol with octacarbonyl dicobalt as catalyst, quaternary ammonium salt as speed accelerator, and olefin conversion The yield can reach 100%, and the acetal yield is over 80%.

The object of the present invention is to provide a method for synthesizing aldehydes by hydroformylation of olefins, the normal isomerization ratio of aldehydes in the product is large, the yield is high, and the reaction conditions are mild.

In the invention, the quaternary ammonium salt is used as the stabilizer of the cobalt catalyst to _jointly catalyze the hydroformylation reaction of aldehydes prepared from _C3 or above olefins, carbon monoxide and hydrogen. This reaction can be expressed as:

R represents a hydrogen atom or an alkyl group.

Suitable reaction temperature is 100-130°C, pressure 5.5MPa-8.5MPa, synthesis gas ratio (H ₂ :CO) 1:1-1:3, relative ratio of cobalt catalyst to olefin, cobalt/ene (mol ratio, expressed as cobalt atom Calculated) is 1/450-1/75, and the relative ratio ammonium/cobalt of stabilizer and catalyst is advisable between 1/40-3/4.

Cl(Br，I)   (I)其中R₁、R₂、R₃、R₄为C₁-C₁₆烷基、芳烷基或苯基。The quaternary ammonium salt used in the present invention is represented by following general formula (I):

Cl(Br, I) (I) wherein R ₁ , R ₂ , R ₃ , R ₄ are C ₁ -C ₁₆ alkyl, aralkyl or phenyl.

The quaternary ammonium salt selected by the present invention has benzyltrimethylammonium chloride, benzyltrimethylammonium iodide, benzyltrimethylammonium bromide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium bromide, Methylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, dimethyl phenyl benzyl ammonium chloride, tetradecyl dimethyl ammonium chloride, cetyl trimethyl ammonium bromide.

The most notable feature of the present invention is to add a small amount of quaternary ammonium salt as a stabilizer for the cobalt catalyst in the general hydroformylation reaction system. In the carbonylation reaction, dicobalt octacarbonyl and hydrogen are firstly combined to form the active body HCo(CO) ₄ of the carbonylation reaction, and the quaternary ammonium salt is immediately combined with it in situ to form (CH ₃ ) ₃ C ₆ H ₅ CH ₂ N( Co(CO) ₄ ) (with (CH ₃ ) ₃ C ₆ H ₅ CH ₂ NCl as the quaternary ammonium salt) stabilizes the catalytic active body, thereby increasing the stability of the catalyst and enabling hydroformylation at low CO partial pressure was carried out and the catalyst and reaction products were separated by simple distillation.

Alkenes which may be used as starting materials in the present invention are optionally substituted alkenes having 3 to 9 carbon atoms.

The olefins selected by the present invention have propylene, 1-butene, cis and trans-2-butene, 1-pentene, cis and trans-2-pentene, 1-hexene, cis and trans -2- and -3-hexene, 1-heptene, cis and trans-2- and -3-heptene, 1-octene, cis and trans-2-, -3- and -4 -octene, 1-nonene, cis and trans-4-nonene, 2-, 3-, 4- and 5-methyl-1-hexene, 2-methyl-2-pentene, cis formula and trans-3-methyl-2-pentene.

The hydroformylation reaction involved in the present invention needs to be completed under certain temperature and pressure. The suitable temperature range is 100-130°C, and the pressure range is 5.5MPa-8.5MPa. As the temperature decreases or the pressure increases, the normal isomerization ratio of the product aldehyde increases. The reaction pressure (total pressure) is related to the partial pressure (ratio) of H ₂ and CO, and the ratio of the two (n ₂ :CO) is more suitable between 1:1-1:3.

In terms of cobalt atoms, the relative ratio of the catalyst (dicobalt octacarbonyl) to the olefin is in the range of 1/450-1/75, cobalt/olefin (molar ratio).

The concentration of the quaternary ammonium salt may conveniently be expressed as a molar ratio of ammonium to cobalt based on the amount of cobalt in the dicobalt octacarbonyl. The suitable range of ammonium/cobalt is 1/40-3/4. When the amount of quaternary ammonium salt is large, the heavy components obtained from aldehyde condensation in the product will increase.

Because general quaternary ammonium salts are easy to absorb water and have high solubility in water, the quaternary ammonium salts of the present invention can be fed directly in solid form or in the form of hot saturated aqueous solution without affecting the reaction result.

Corresponding to the current non-rhodium catalytic system for olefin hydroformylation to synthesize aldehydes, the present invention has significant advantages: the hydroformylation reaction conditions are not harsh, the temperature and pressure are moderate, and the one-time investment cost of equipment is relatively low, which is superior to the high-pressure cobalt method ; Catalytic activity and selectivity are good, the main product of the reaction is aldehyde and the yield is better, which is better than the low-pressure cobalt method; the normal isomerization ratio of aldehyde is higher, which is better than the iron-cobalt cluster catalytic system. But the catalyst life of the present invention is short, needs to be destroyed and reclaimed cobalt after one-time use; Stabilizer quaternary ammonium salt is alkaline, easily causes the condensation reaction of product aldehyde to generate heavy component, for this reason after hydroformylation reaction finishes, should distill immediately , to separate the aldehyde from the catalyst residue, ammonium salt, etc. dissolved in it. The normal isomerization ratio of aldehydes in the product prepared according to the method of the invention can reach 1.2-1.6, the olefin conversion rate (mol%) is 84.5-94.4, and the product yield (mol%) is 71.7-90.1.

Example:

Olefin, catalyst and stabilizer are added in an autoclave of appropriate size (volume), and the still is tightly sealed. After the kettle is replaced by vacuum, it is poured into the mixed gas of dehydrated and deoxygenated hydrogen and carbon monoxide. Stir and heat and properly replenish the synthesis gas to make the temperature and pressure in the kettle reach the requirements of the reaction. Under suitable temperature and pressure, the hydroformylation reaction starts, absorbs the synthesis gas, and the system pressure drops, replenishes the synthesis gas at any time to maintain the reaction pressure, so that the reaction proceeds, and the reaction is completed when the system no longer absorbs the synthesis gas. After cooling to room temperature, the pressure was released, and the tail gas and liquid samples of the reaction system were collected for gas chromatography analysis. In all examples, the component contents of synthesis gas, raw olefins, and hydroformylation liquid products were quantified by the corrected area normalization method, and the hydrocarbon component contents in the tail gas were quantified by the external standard method. In the reaction result, the conversion rate of olefin and the yield of aldehyde are given by mole percent according to the routine, and the normal isomerization ratio of product aldehyde is given by the absolute value of its content ratio. Table 1 has listed specific examples.

Table 1 specific embodiment example Olefin Quaternary ammonium salt Cobalene ratio mol Ammonium cobalt ratio mol temperature °C pressure MPa Conversion mol% Yield mol% positive/different 1 A D. 1/400 1/4 110 6.0 84.5 73.0 1.3 2 A D. 1/250 1/30 120 6.5 86.0 82.0 1.4 3 A D. 1/260 1/20 110 6.5 90.3 85.0 1.4 4 A D. 1/300 1/5 115 8.5 89.6 93.0 1.5 5 A E. 1/80 1/10 130 8.0 93.2 75.4 1.6 6 A f 1/250 1/8 110 6.5 93.7 90.1 1.4 7 B E. 1/90 3/4 110 6.0 92.2 88.0 1.5 8 C f 1/300 1/2 120 5.5 86.3 90.0 1.4 9 A D. 1/100 1/25 130 7.0 89.0 88.4 1.5 H ₂ /CO=1:1～1:3, A: 2-butene B: 1-hexene C: 1-nonene

D: Benzyltrimethylammonium Chloride, E: Tetraethylammonium Bromide F: Dimethylphenylbenzylammonium Chloride

Claims (3)

1. A method for the synthesis of aldehydes by hydroformylation of olefins, specifically, a method in which olefins with 3-9 carbon atoms, carbon monoxide and hydrogen carry out carbonylation reactions to generate aldehydes under the action of a catalyst, which is characterized in that using eight Dicobalt carbonyl as catalyst, quaternary ammonium salt as stabilizer, reaction temperature 100-130°C, pressure 5.5-8.5MPa, H ₂ /CO 1:1-1:3, relative ratio of dicobalt octacarbonyl to olefin cobalt/ Alkene (mol ratio, in terms of cobalt atoms) is 1/450-1/75, and the ratio ammonium/cobalt (mol ratio) of stabilizer and octacarbonyl dicobalt is 1/40-3/4, and the quaternary ammonium salt consists of the general formula (I) represents, wherein R ₁ , R ₂ , R ₃ , R ₄ are C ₁ -C ₁₆ alkyl, aryl or phenyl:

Cl(Br,I)(I) 2. The method according to claim 1, wherein the quaternary ammonium salt is benzyltrimethylammonium chloride, benzyltrimethylammonium iodide, benzyltrimethylammonium bromide, tetramethylammonium chloride Ammonium, Tetramethylammonium Bromide, Tetramethylammonium Iodide, Tetraethylammonium Chloride, Tetraethylammonium Bromide, Tetraethylammonium Iodide, Tetrabutylammonium Chloride, Tetrabutylammonium Bromide , Tetrabutylammonium iodide, dimethylphenylbenzyl ammonium chloride. 3. The method according to claim 1 or 2, characterized in that the olefins are propylene, 1-butene, cis and trans-2-butene, 1-pentene, cis and trans-2-pentene ene, 1-hexene, cis and trans-2- and -3-hexene, 1-heptene, cis and trans-2- and -3-heptene, 1-octene, cis and trans-2-, -3- and -4-octene, 1-nonene, cis and trans-2-nonene, 2-, 3-, 4- and 5-methyl-1-hexene , 2-methyl-2-pentene, cis and trans-3-methyl-2-pentene.