SU527425A1 - The method of obtaining 4-phenylpyridine - Google Patents

Description

one

This invention relates to a process for the preparation of 4-phenylpyridine used in the synthesis of physiologically active compounds.

A 1 j method is known for producing 4-phenylpyridine by the catalytic condensation of cinnamic aldehyde with acetaldehyde and ammonia in the vapor-gas phase over ZOO-4OO C over alumina or kaolin.

The disadvantage of this method is the low (22%) yield of the target product,

In order to increase the yield of the target product, it is proposed to conduct the process in the presence of water at a molar ratio between cinnamic aldehyde, acetaldehyde, ammonia, water and an inert diluent (for example, nitrogen, ethyl alcohol) equal to 1: 2-10: 2-100: 2-5: 1 - 2O. The reaction time is 1.5-6 seconds.

Gamma alumina modified with nitric or hydrofluoric acid, aluminosilicate, mixed cobalt phosphate and aluminum, calcium phosphate promoted with chlorine copper, which are activated by heating to ZOO-4OO C in ammonia and water, are usually used as catalysts.

The optimal molar ratio between cinnamic aldehyde, acetalde guide, ammonia and water is 1: 5: 25 - 50: 3.

The optimum time of the catalyst is 3–1 hours, then it is regenerated by burning carbon deposits by passing air through the catalyst bed at 400–55 ° C. In the initial period of regeneration, it is necessary to dilute the air with water vapor or EO nitrogen to avoid overheating of the catalyst.

When using reactors with a moving catalyst bed or circulating fluidized bed, in which the continuity of the contact cycle and the regeneration cycle is achieved, as well as using a system consisting of two alternating operating reactors with a fixed catalyst bed, the process can be carried out in a continuous pattern.

The target product is extracted from catalnzate by extraction with benzene, followed by distillation.

The yield of the purity product is 52 mol.% (Based on cinnamic aldehyde). In addition, valuable alkylpyridines are formed during the condensation process.

Example 1. Industrial aluminum gamma oxide {granule diameter 1–2 mm) is treated with 57% nitric acid at 65 ° C, washed with water to pH 5 in the washing water and dried at 120 ° C. 7 ml of the obtained catalyst are loaded into a glass reactor, heated using an electric furnace up to 40 ° C, passing 3 l / h of air through the catalyst bed simultaneously, then for 30 minutes activating the catalyst with ammonia (3 l / h) and water vapor (2 g / h) and lowering the temperature in the reactor. At 31 ° C for 4 hours, a mixture of cinnamic aldehyde (0.72 g) and acetaldehyde (1.21 g) is fed to the evaporator (2.2 ml / hour),

nitrogen and water are introduced, aldehyde vapors and water are fed to the reactor, where they are mixed with ammonia (b, b / h from a cylinder) over the catalyst bed. The molar ratio between cinnamic aldehyde, acetaldehyde, ammonia; ohm, nitrogen and water 1: 5: 50: 18: 3. Contact time 2.5 seconds The reaction products from the contact gases are condensed in traps at 0 ° C, homogenized by the addition of ethyl alcohol and analyzed by gas chromatography using quinoline as an internal standard. 4-Phenylpyridine 52 mol. .o (based on cinnamon a ldehyde). Alkylpyridine yield 40 mol.% (based on acetaldehyde).

Example 2. The experiment was carried out as in Example 1 using various catalysts. The results of the experiments are given in the table.

Gamete-alumina modified with 3% hydrofluoric acid

Mixed aluminum phosphate and cobalt

49

Example 3: The reaction was carried out in a pilot plant (volume of catalyst: gamma alumina, modified with nitric acid, 1.5 l). For 4 hours at 31 ° C, 640 ml / hour of a mixture of cinnamic aldehyde (840 g) with acetaldehyde (140O g), 1000 l / hour of ammonia, 185 ml / hour of ethanol, 86 ml / hour of water (molar the ratio is 1: 5: 26: 2: 3) with a contact time of 3.8 seconds. The reaction products are condensed in a heat exchanger. The aqueous layer was separated and extracted with benzene. The organic layer combined with the benzene extract is rectified in vacuo. At 118122 ° С / 2 mm, 382 g (38 mol.%) Of technical 4-phenylpyridine, containing more than 97% of the main product, is obtained. After

nineteen

6

sixteen

nineteen

12

ten

double recrystallization from ethyl alcohol so pl. 4-phenylpyridine picrate 194-45.

Claims (1)

1. A method for producing 4-phenylpyridine by the catalytic condensation in the vapor-gas phase of cinnamic aldehyde with acetaldehyde and ammonia in ZOO-400 ° C, characterized in that, in order to increase the yield of the target product, the process is carried out in the presence of water at a molar ratio between cinnamic aldehyde, acetaldehyde, ammonia, water and an inert diluent (for example, nitrogen, ethyl alcohol) equal to 1: 2 - 10: 2 - 100: 2 - 5: 1 - 20, 5 52742 2, A method according to claim 1, characterized in that gamma alumina modified with nitric or hydrofluoric acid or aluminosilicate is used as a catalyst or co-5 phosphate and alum phosphate, or calcium phosphate promoted with chlorine copper, which are activated by heating to 300-400 ° C in an ammonia and water environment. 5g 3. A way to pop. 1, which is carried out in that the process is carried out at a molar ratio of cinnamic aldehyde, acetaldehyde, ammonia and water 1: 5: 2550: 3. Sources of information taken into account in the examination of the application: 1. A. E. Chichibabin, DI Orochko, SRFHO, 62, 1201 (1930V