HU186878B - Process for preparing 2-phenyl-ethylalcohol - Google Patents

Abstract

Field of the Invention The present invention relates to a process for the preparation of 2-phenylethyl alcohol from a styrene oxide / benzaldehyde mixture formed by the oxidation of styrene at atmospheric pressure with air, with a 0.1 to 10% Raney-Ni, supported or non-carrier Pd catalyst, to be reduced. hydrogenation. The process according to the invention is characterized in that the styrene oxide / benzaldehyde mixture is a C 1-3 aliphatic alcohol having from 0.5 to 15% water, or a C 3-5 C aliphatic ketone solvent in two stages at a reduction of 10-30 ° C. They start at 1-5 bar, then gradually increase the temperature to 70-140 'C in 1-5 hours, and the pressure to 10-20 bar, then in the second phase the pH is 2-6 after the loss of hydrogen disappears. is added by adding mineral acid, organic acid or acidic salt, and the reduction is continued at 10-30 ° C, at a pressure of 1-3 bar until hydrogen uptake ceases, and the resulting products are separated in a known manner. -1-

Description

The present invention relates to 2-phenylethyl alcohol. Hydrogenation of a styrene oxide-benzaldehyde mixture obtained by air oxidation of its filters.

There are several ways to synthesize 2-phenylethyl alcohol from styrene via styrene oxide. Styrene oxide can be prepared by direct oxidation of styrene with air or peroxide-containing compounds. (H ₂ O ₂ , peracids, organic hydroperoxides) and indirect oxidation of bipohalogenic acid (addition and alkaline elimination) The simplest of these is the use of oxygen in the air.

A number of processes are known for the air oxidation of styrene. Styrene oxide production is, in the most favorable cases, about J.0-70% depending on the experimental conditions.

According to one process (Spadlo, M., Bunkowski, W. Przethysysl Chemiczny 58, 40, 1979), 69% conversion of 133% styrene oxide can be achieved in dichloropropane solvent, benzaldehyde initiator, at 20 ° C and 3 bar. , but also 33% benzaldehyde is present in the east. In the presence of toluene and phenyl cyanide, O ₂ transfer at 110 ° C yields 43% styrene oxide with 85% conversion (USG 2,255,510 (1974)). In the presence of an alkylbenzoyl solvent and an acetaldehyde initiator at 55 ° C and 18 bars, a maximum of 55% of the oxidized product is formed, the main weight of which is styrene oxide (US 3,281,433 (1965)). Alternatively, by circulating at 40 ° C in the presence of isobutyl aldehyde and cobalt ethylhexanate, styrene was obtained, 91% conversion and 73% styrene oxide production. Styrene oxide can be produced in 65% yield by treating a solution of styrene in ethylene glycol diacetate with molecular oxygen (Belgium 628 810 61963).

In a continuous reactor, butyl acetate solvent, at 80 ° C and 50 bar, a yield of 52% styrene oxide is obtained with 65% conversion of styrene (US 3 275 '662 (1966)).

There are also many processes for the hydrogenation of pure styrene oxide (U.S. Pat. No. 2,822,403 (1958); Japan, 74,05,933 (1974); Brit. 681,183 (1952); Brit. 760,768 (1956); USG 1,918,852 (1970)). Raney-Ni, using a supported Pt or Pd catalyst, at 20-100 ° C and 1-200 bar in an alkaline additive (NaHCO ₃ , Na ₂ CO ₃ , Ba / OH / ₂ ) in water, aqueous alcohol or alcohol solvent and optionally in the presence of an emulsifier, 90-99% of 2-phenylethyl alcohol production is achieved.

However, it is difficult to purify highly contaminated styrene oxide formed during air oxidation before reduction. This is also indicated by the base used in the reduction processes to absorb acidic impurities.

The main contaminant of styrene oxide is benzaldehyde, which, due to its near boiling point and many similar chemical properties, makes it quite difficult to release styrene oxide. The volatility of the two materials in the presence of water vapor is more pronounced, but there is a large loss of styrene oxide during aqueous boiling due to the inevitable hydrolysis. A process was proposed (Spadlo, M., Bunikowski, N. Przemysl Chemiczny 58 (1979) 40, 40) consisting of steam distillation, vacuum distillation, hydrazine treatment and steam distillation again.

this mode is complicated, expensive and has a great deal of loss.

The present invention is based on the discovery that a mixture of styrene oxide-benzaldehyde obtained by air oxidation of styrene is hydrogenated in two stages without complicated rectification to form 2-phenylethyl alcohol from styrene oxide and toluene from benzaldehyde; the latter can be removed from the 2-phenylethyl alcohol by simple distillation.

The process of the present invention consists in the first step of oxidizing styrene from my offices with air in a known manner. Styrene for oxidation

A solution of 15-30% v / v in some of its esters (eg butyl acetate, amyl acetals) is used. The mixture is bubbled with air while stirring so that the molar ratio of oxygen to styrene introduced per hour is between i-3. The total amount of the styrene reacts at 110-140 ° C for 90-300 minutes. After distilling the mixture in vacuo and evaporating the solvent, the main distillate is a mixture of styrene oxide and benzaldehyde. Depending on the parameters, the production ranges from 48-59% for sirol and 12-20% for benzaldehyde.

According to the invention, the styrene oxide / benzaldehyde mixture is hydrogenated in a mixture of 1 to 3 aliphatic alcohols or 5 to 5 carbon atoms of aliphatic ketone containing 0.5 to 15% water, and in the first stage the reduction is 10 to 30 '. Starting at a pressure of 1-5 bar, the temperature is gradually increased to 70-140 ° C over a period of 1-5 hours and to 10-20 bar, and in the second stage the pH is reduced to 2-6 after the end of hydrogen depletion. The reaction is carried out at a temperature of 1 to 3 bar at 10-30 ° C until the hydrogen uptake ceases, and the resulting products are isolated by conventional means.

Preferably, the hydrogenation catalyst is Raney-Ni, palladium with or without support, preferably palladium on active support. The amount of catalyst is 0.1-10% by weight, preferably 0-2-1.0% by weight of the material to be reduced.

To adjust the pH of the reaction mixture, mineral acids (e.g. hydrochloric or sulfuric acid), organic acids (e.g. formic acid, acetic acid) or acidic salts (e.g. potassium bisulfate or sodium dihydrogen phosphate) are used in the form of an aqueous solution. After adjusting the pH, it is expedient to increase the amount of catalyst to 1-3% by weight. The reduction is continued at 10-30 ° C at a pressure of 1-3 bar until hydrogen consumption stops or drops dramatically. The reaction mixture was stripped of solvent and toluene and concentrated in vacuo to give 2-phenylethyl alcohol (97-99% purity). By fractional distillation, the purity of the product can be further increased. Styrene oxide and benzaldehyde are fully reactive under these conditions, and 2-phenylethyl alcohol production is 92-99%, based on styrene oxide.

The main advantages of the process according to the invention are:

- the styrene oxide obtained by air oxidation of styrene does not have to undergo complex and costly purification operations

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the reaction can be carried out under standard conditions in mild conditions using standard hydrogenation catalysts

- 2-phenylethyl alcohol of sufficient purity is produced at the end of the reaction, because 2-phenyl ethyl alcohol can be easily separated from the reaction mixture with much lower boiling point toluene and solvents.

The following examples illustrate the process of the invention without limiting it.

Was charged with 115 cm ³ of styrene Example 1 liter flask and 345 cm ^{3 of} butyl acetate heated to 115 ° C and introduced into 3 dm ³ / min of air for 5 hours with vigorous stirring. The solvent was evaporated from the reaction mixture and concentrated by fractional distillation

81.6 g of a 25:75 mixture of benzaldehyde and styrene oxide are obtained. To the mixture was added 2 cm ^{3 of} water, 70 cm ^{3 of} diethyl divone and 0.15 g of 10% Pd on carbon and autoclaved hydrogenation at 20 ° C and 2 to 3 bar for 3 hours. During this period, the temperature is gradually raised to 120 ° C and the pressure to 15 bar. After hydrogen depletion, the mixture was acidified to pH 2 with 10% hydrochloric acid, treated with additional 0.9 g of charcoal Pd and further hydrogenated at 20-30 ° C at atmospheric pressure. In about 3-4 hours, the benzaldehyde is completely reacted. The catalyst is removed by filtration. GC analysis showed 98% yield of 2-phenylethyl alcohol based on styrene oxide. The solvent and toluene were evaporated in vacuo; the main distillate is 2-phenylethyl alcohol having a purity of 97% by gas chromatography.

Example 2 Into a 1 liter flask were weighed 90 cm ^{3 of} filters and 510 cm ^{3 of} butyl acetate, heated to 120 ° C, and air stirred at 2.5 dm ³ / min for 5 hours. Do we remove the solvent from the reaction mixture? and by fractional distillation as the main distillate

62.6 g of a 28: 72 mixture of benzaldehyde: styrene oxide are obtained. To the mixture, 1 cm ³ of water is suspended 0.7 g of 10 wt% Pd / Al2O3 catalyst and 200 cm ³ of isopropyl alcohol was added and the hydrogenation is started by autoclaving at 25 ° C and 3-5 bar pressure. The temperature was raised to 100 ° C over 4 hours and the pressure to 10 bar. After 2 hours, the mixture was cooled and treated with 1.4 g of 10% Pd / Al ₂ O ₃ and 5 cm ^{3 of} 10% KHSO ₄ . The hydrogenation is carried out at 10 to 20 ° C under a pressure of 1 bar until the benzaldehyde and benzyl alcohol are completely reacted. The mixture was filtered and analyzed by gas chromatography; the yield of 2-phenylethyl alcohol is 92% based on styrene oxide. After fractional vacuum distillation, the product is 97% pure.

Example ³ Into a one-liter flask were weighed 115 cm ^{3 of} filters and 460 cm ^{3 of} butyl acetate, heated to 125 ° C, and air stirred at 3.4 dm ³ / min for 3.5 hours. The reaction mixture was concentrated by distillation in vacuo, 81.0 g of a 1: 4 mixture of benzaldehyde and styrene oxide. This mixture, 12 cm ^{3 of} water, 0.8 g of Raney-Ni and 110 cm ^{3 of} methyl ethyl ketone was added to the autoclave and hydrogenation was started. The temperature was gradually increased from 20 to 140 ° C over 5 hours and from 3 to 18-20 bar. After cooling, 10 cm ^{3 of} acetic acid and another 1.5 g of Raney-Ni are added to the reaction mixture, and the reduction is continued at 20 ° C and 1 bar until hydrogen consumption stops. After filtration and vacuum distillation, the yield of 2-phenylethyl alcohol is 94% and the purity of the product is 98%.

EXAMPLE 4 Into a 1 liter flask was weighed 115 cm ^{3 of} filters and 345 cm ^{3 of} amyl acetate, heated to 120 ° C and air was bubbled for 2 hours at 2.1 dm ³ / min with vigorous stirring. The reaction mixture was concentrated in vacuo to a 81.5 g (22:78) mixture of benzaldehyde J: styrene oxide. This distillate and 100 cn ~ ³ 90 vol% aqueous ethanol and 0.7 g of Raney-Ni-l charged into the autoclave and the hydrogenation was started. Gradually increase the temperature from 20 to 70 ° C and the pressure from 2 to 13-15 bar over 1 hour. After 4 hours, the mixture was cooled and 10 cm ^{3 of a} 10% aqueous NaH ₂ PO ₄ solution and 1.8 g of Raney-Ni were added. The reaction was continued at 15 ° C and 2-3 bar until hydrogen depletion ceased. Gas chromatography analysis showed 2-phenylethyl alcohol to be 92% based on styrene oxide. The reaction mixture was worked up as in Example 1. The product was 97% pure 2-phenylethyl alcohol.

EXAMPLE 5 150 cm ³ filters and 350 cm ³ butyl acetate were weighed into a one liter flask, heated to 110 ° C and air stirred at 7.5 dm ³ / min for 3.5 hours with vigorous stirring. The reaction mixture was evaporated and the residue was fractionated by vacuum distillation to give benzaldehyde: styrene oxide (108 g, 29:71). This distillate, along with 35 cm ^{3 of} water, 90 cm ^{3 of} acetone and 0.1 g of Pd carbon black, were added to the autoclave and hydrogenation was started at 15 ° C and 3-5 bar. After 4 hours, the mixture was cooled and 5 cm ^{3 of} acetic acid and 0.7 g of Pd-carbon were added. The reduction is continued at 25 ° C and 1-2 bar until the hydrogen consumption drops sharply. Gas chromatography analysis showed 2-phenylethyl alcohol to be 92% based on styrene oxide. After purification of the reaction mixture, the product was found to be 98% pure by gas chromatography.

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Was charged with 115 cm ³ of styrene and 345 cm ³ of amyl acetate, heated to 130 ° C and with vigorous stirring 3.2 dm ³ / min of air was passed into ^five leaders for 2 hours Example 6 liter flask. The solvent was evaporated from the reaction mixture and fractionated by vacuum distillation to give 86.3 g (18: 82) of benzaldehyde: styrene oxide. This distillate, as well as 15 cm ^{3 of} water, 83 cm ^{3 of} methanol and 0.4 g of ¹ θ 10 s% charcoal fd are weighed into the alumina and hydrogenation is started at 30 ° C and 2-4 bar. . After 5 hours, the temperature was raised to 100 ° C, the pressure increased to 12 bar, and then cooled, the mixture was ^{treated with} 1.2 g of charcoal Pd and adjusted to pH 2-3 with 5% sulfuric acid. t. The reduction is continued at ambient temperature and at a pressure of 1-2 bar until the hydrogen consumption drops significantly. Gas chromatography analysis showed 2-phenylethyl; 99% alcohol production based on styrene oxide. The reaction mixture was worked up as in Example 1; the purity of the product is 99%.

EXAMPLE 7 115 cm ^{3 of} styrene and 460 cm ^{3 of} amyl acetate were weighed into a ²⁵ liter flask, heated to 140 ° C and air at 4.5 dm ³ / min with vigorous stirring for 1.5 hours. The reaction mixture was subjected to fractional vacuum distillation of the reaction mixture to give 86.6 g; A mixture of benzaldehyde: styrene oxide (79) was obtained. This mixture, along with 10 cm ^{3 of} water, 100 cm ^{3 of} methanol and 0.5 g of 5% Pd / C catalyst, were charged into the autoclave and hydrogenation was started at 3 ° C and 3 to 5 bar. The temperature was raised to 90 ° C and pressure to 14 bar over 4 hours and then cooled to room temperature. 2 g of 5% Pd / C catalyst are added and the pH is adjusted to 3-4 with 10% sulfuric acid.

The reduction is continued at <RTI ID = 0.0> C </RTI> and 1.5-2 bar until the hydrogen consumption drops significantly. Gas chromatography analysis showed 2-phenylethyl alcohol to be 97% based on styrene oxide. The reaction mixture was worked up as in Example 1; the purity of the product is 98%.

Claims (1)

A patent claim A process for the preparation of 2-phenylethyl alcohol by the hydrogenation of styrene oxide / benzaldehyde obtained by air oxidation of styrene at atmospheric pressure with 0.1 to 10% by weight of Raney-Ni, with or without Pd catalyst, on the material to be reduced. hydrogenating the styrene oxide / benzaldehyde mixture in a C 1 -C 3 aliphatic alcohol or C 5 -C 3 aliphatic ketone solvent containing 0.5 to 15% v / v water in two stages, the first stage being reduced at 10 to 30 ° C. , Starting at a pressure of 1-5 bar, gradually increasing the temperature to 70-140 ° C over a period of 1-5 hours, to a pressure of 10-20 bar, and in the second stage, after depletion of hydrogen, to a pH of 2-6. is adjusted by addition of a mineral acid, an organic acid or an acidic salt, and the reduction is carried out at a pressure of 10-30 ° C, 1-3 bar until hydrogen uptake ceases, followed by isolated in a known manner.