DE1793017B1 - Process for the production of phenylpropanals and phenylpropanols - Google Patents

Description

Similar to other olefins, styrene can be added with carbon as rhodium oxide, rhodium trichloride, as nitrate, monoxide and hydrogen to the corresponding sulfate or as ethyl hexanoate. Under the reaction conditions one carbon atom richer, soluble aldehydes are converted into catalytically soluble ones. When using cobalt catalysts, active rhodium carbonyl compounds, which are obtained naturally, are also produced and panals (H. Adkins, G. Krsek, JACS, 71, p. 383 in this form) may perform the reaction mixture. [1949] and JACS, 72, p 4339 [1950]. the yield carbon monoxide and hydrogen are, however, only 30 to 50 ° / ₀ of the theoretically available to ER- hydroformylation proportions anwartenden in the amounts in the amount , because large proportions of styrene are averted.

neither polymerize nor hydrogenated to ethylbenzene io The hydroformylation of styrene is in progress. As a result, this procedure is carried out for an inert diluent, a technical application is out of the question. Aliphatic and aromain proved to be suitable of the well-known Japanese patent applications hydrocarbons such as benzene, toluene, cyclodungene 1419/64 is the hydroformylation of styrene in hexane and cyclic ethers, e.g. B. tetrahydrofuran. Described presence of a rhodium catalyst. 15 The method of operation according to the invention allows However, the implementation only provides one of the two by simply varying the process conditions possible reaction products, namely to direct the reaction exclusively in such a way that uma-phenylpropanal, while technically likewise very settlement products optionally preferred «-Phenylprowertvolles / S-phenylpropanal is not formed. panal or ß-phenylpropanal or those made from these

Another disadvantage of the known process is aldehydes obtained by hydrogenation of alcohols in that only aldehydes can always be represented as reaction holes. To obtain a products are obtained and the representation of the an «-phenylpropanal or« -phenylpropanol strong corresponding alcohols always have an additional enriched reaction product in the Requires reaction stage. Hydroformylation stage pressures from 250 to 500 atm

The invention is based on the task of finding a back «5 and temperatures of 100 to 150 ° C as particularly visible yield and reaction control have proven to be essentially favorable. High proportions of ß-phenylpropanal borrowed improved process for the production of or / 5-phenylpropanol arise when styrene is used isomeric phenylpropanals and phenylpropanols, ins- pressures of 50 to 200 atm and temperatures of especially for the production of jS-phenylpropanal 160 to 200 ° C with carbon monoxide and hydrogen and /? - to supply phenylpropanol. 30 is implemented.

It has been found that the production of phenyl- The liberation of the aldehydic reaction product-

propanalen by hydroformylation of styrene at tes from the catalyst is carried out according to known increased pressure and increased temperature in the opposite direction. For example, the catalyst decomposes even when the rhodium catalysts are removed and the pressure apparatus is optionally released, and the subsequent hydrogenation of the aldehydes obtained can simply be filtered off. Another method for its removal to the corresponding alcohols with very good erosion consists in a treatment of the hydrous result can be carried out if one formylation product with water or steam styrene in the presence of 0.05 to 0.000125 by weight at elevated temperatures, whereby expediently 5 to percent rhodium, based on styrene, with carbon 50 percent by volume water or the corresponding monoxide and hydrogen at temperatures of 80 to 40 amount of steam, based on the 200 ° C used and pressures of 50 to 500 atm to form a reaction mixture and temperatures mixture of α- and ^ -phenylpropanal and between 80 and 200 ⁰ C are selected. If necessary, the hydroformylation product without the catalyst generally precipitates in the form of a separation of the rhodium-containing catalyst and a mixture of metallic rhodium and rhodium without the addition of other hydrogenation catalysts by means of oxides in the aqueous phase, from which the temperature is increased to about 180 to 250 ° C, ins- rhodium in a simple manner, for. B. by filtering special 190 to 210 ⁰ C with mixtures of coal can be recovered and then easily re-hydrogenated monoxide and hydrogen. can be used. After flash evaporation

The special advantage of the. The hydroformylation product according to the invention can also Process can be seen in the fact that with excellent 50 remaining residues of rhodium-containing material Total yields <x- and /? - phenylpropanals in addition to the distillation residue were recovered be won. In addition, it is the.

possible to use the aldehydes in the same reaction.

vessel and using the for the hydroformy of course in a known manner to the corresponding lation used catalyst can be hydrogenated by simple 55 alcohols, to achieve a Temperature increase selectively in the corresponding high selectivity, d. H. to avoid core alcohols convict. Particularly noteworthy is hydrogenation special catalysts such. B. Kupferin In this context, that a hydrogenation of the chromite must be used. The hydrogenation Benzene nucleus, as z. B. when using takes place under the usual conditions z. B. at Nickel catalysts in heterogeneous phase can be observed 60 temperatures between 20 and 200 ° C and pressures is careful, does not occur. It is another advantage of the 1 to 400 atmospheres.

Method according to the invention that is very low However, it is particularly simple according to the method

Amounts of catalyst both for the hydroformylation of the invention, the hydrogenation without prior de-aling also for the subsequent hydrogenation of the aldehyde removal of the rhodium carbonyl compounds from the Sufficient reaction product. 65 hydroformylation product. At this

The rhodium used as a catalyst is hydrogenated in the procedure with mixtures of the reaction mixture as metal or in the form of carbon monoxide and hydrogen, preferably in inorganic or organic compounds e.g. B. a molar ratio of 1: 2 to 1: 4. The Rea-

tion temperature is preferably increased to about 180 to 25O ⁰ C, to 190 to 21O ⁰ C. The hydrogenation is generally carried out in the same pressure range as the hydroformylation. It is expedient to work at pressures above 250 atm.

When the hydrogenation has ended, the reaction mixture is worked up in the customary manner. In the By hydrogenation using the hydroformylation catalyst, the reaction product is cooled after the hydrogenation off and relaxed. The catalyst decomposes and separates almost quantitatively as a powder. The precipitate can easily be removed by filtration, blow-down, etc. and without further treatment to be used again. Small amounts of catalyst still remaining in the crude product decompose during distillation. However, the method of the invention can also be used in batches. or perform fully continuously. Both hydroformylation and hydrogenation can by taking samples from the pressure equipment with ao subsequent, for example, gas-chromatographic analysis to be tracked.

κ- and ß-phenylpropanal are used in the manufacture of fragrances. The alcohols produced from the aldehydes are important for the production of special plasticizers for plastics.

The following examples illustrate the invention.

B e i s ρ i e 1 1

Representation of a predominantly -phenylpropanol containing Mixture of the isomeric phenylpropanols

In an autoclave, 1250 g benzene, 0.025 g Rh ₂ O ₃ with the addition of a small amount of hydroquinone with carbon oxide and hydrogen in a ratio of 1: 1 are heated to 100 ° C. under 180 atm pressure. The pressure is then increased to 290 atm and 250 g of styrene, dissolved in 250 g of benzene, are pumped into the autoclave over the course of 5 minutes. The course of the reaction is followed by gas chromatographic analyzes of the reaction material, which is taken from the reaction vessel at regular intervals. As soon as styrene can no longer be detected, the contents of the autoclave are heated to 190 ° C. under the same pressure to convert the aldehydes formed into the corresponding alcohols. After the hydrogenation has ended, the mixture is cooled to room temperature, filtered to remove precipitated catalyst components and distilled. 290 g = 88.5% of the expected yield, based on the styrene used, of a mixture containing α-phenylpropanol are obtained.

By distillation through a packed column, the Phenylpropanolgemisch, which consists of 83.5 ° / ₀ of "-Phenylpropanol and 16.5% ^of ß-phenylpropanol, can be separated into its constituents. a-phenylpropanol boiling at 107.5 to 109 ⁰ C, ^ -Phenylpropanol at 121 ° C, measured at a pressure of 10 Torr.

Example 2

Representation of a predominantly /? - phenylpropanol containing Mixture of the isomeric phenylpropanols

In an autoclave, 1250 g of benzene and 0.025 g of Rh ₂ O _{3 are} heated ^{to 180 °} C. under 180 atm pressure with the addition of a small amount of hydroquinone with carbon oxide and hydrogen in a ratio of 1: 1. The pressure is then increased to 250 to 260 atm and 250 g of styrene, dissolved in 250 g of benzene, are pumped into the autoclave within 5 minutes. The course of the reaction is monitored in the manner described in Example 1. For the hydrogenation of the aldehyde reaction product of the pressure to 290-300 atm, and the temperature to 200 to 21O ⁰ C is increased. The reaction product is worked up as in Example 1. 219 g = 67% of the expected yield, based on the styrene used, of a mixture containing 3-phenylpropanol are obtained.

The mixture can be converted into α-phenylpropanol by separation by distillation in a packed column (48%) and / 3-phenylpropanol (52%) are decomposed.

Claims (4)

Patent claims: 1. A process for the preparation of phenylpropanals by hydroformylation of styrene at elevated pressure and temperature in the presence of rhodium catalysts and, if appropriate, subsequent hydrogenation of the aldehydes obtained to the corresponding alcohols, characterized in that styrene is used in the presence of 0.05 to 0.000125 percent by weight Rhodium, based on styrene, is reacted with carbon monoxide and hydrogen at temperatures of 80 to 200 ⁰ C and pressures of 50 to 500 atm to form a mixture of α- and ß-phenylpropanal and optionally the hydroformylation product without separating off the rhodium-containing catalyst and without adding other hydrogenation catalysts hydrogenated by increasing the temperature to about 180 to 250 ⁰ C, in particular 190 to 210 ⁰ C, with mixtures of carbon monoxide and hydrogen. 2. The method according to claim 1, characterized in that preferably for the preparation of a-phenylpropanalhaltigen aldehyde mixtures in the Hydrof ormylierungsstuf e pressures of 250 to 500 atm and temperatures of 100 to 15O ⁰ complies C. 3. The method according to claim 1, characterized in that one for the production of preferably / J-phenylpropanals containing aldehyde mixtures in the hydroformylation stage pressures from 50 to 200 atm and temperatures from 160 to 200 ° C. 4. The method according to claim 1 to 3, characterized in that the hydrogenation of the phenylpropanals with mixtures of carbon monoxide and hydrogen, preferably in a molar ratio from 1: 2 to 1: 4.