DE1695434C3 - Process for the catalytic production of alpha and gamma Picohn - Google Patents

Description

\ -

Hie invention relates to a method for catalytic see Production of γ-picoline and γ-picoline from a mixture from vapors of acetaldehyde and / or paraldehyde and ammonia in a molar ratio of Aldehyde: ammonia / wipe 1: 0.5 and 1: 3 at temperatures between 350 and 500 C, which means is characterized in that the catalyst consists of a fluorinated silica-alumina mixture with a TonerfAt 10 to 15% and a fluorine content from 2 to 10%.

There have already been methods of making
and γ-picoline in the gas phase from aldehydes and ammonia using catalysts made from silica alumina with or without promoters, such as. Ü. Salts or oxides of certain metals such as Th, Zn, Cd, Sn, Pb, Fe. Ni, etc., known.

If one works alone in the presence of silica clay, the y-picoline is produced in higher or almost the same yield as the \ -picoline. By adding some of the above-mentioned promoters to the silica clay, however, it became possible either to increase the overall yield of picolines or to slightly increase the amount of α-picoline compared to the amount of γ-picoline. In the latter case, the yield of-picoline almost corresponded to that of-picoline or was even slightly higher than this.

The most effective promoters are known to include some metal halides, e.g. B. ZnF. ,, 7nCl., Or PbF ₂ , which, however, under certain conditions can be subject to organic decomposition with the formation of hydrogen halides, which in turn can cause corrosion of the system.

In the method according to the invention, the x-picoline falls in a higher bulge than the y-picoline. One such The process is of great interest because the picolin is of greater technical importance than the y-picoline.

In fact, y-picoline is used almost exclusively in the manufacture of pharmaceutical products from isonicotinic acid. On the other hand, the / v-picoline is used extensively as an intermediate product for numerous technical applications, e.g. 13. in the synthesis of - »- vinylpyridine for rubber and synkohl -; - ^1:
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, '.' ,. n _ol | the peace lies there.: ,, that _; ,, ■; \ - and v-picoline also h ..:; ieht- -, ...; . .! - ι; and 2-methyl-5-ether chloride

, _r . . ,, ... · .economic Ievery time. :; = loading

... i.,. · :, ' ^! ,.; to cite, dah ί '-. τ er.,. ...: .---. final catalytic converter without ■ ";. , ·: ;; ■ '■, · υ rde -Cl cm se Ii au Ik; .: iner;. _; , \. ■ ·,. · ■ ksamkeit also a · large / ,,. ; c; / i and easy; ..: ene-

:.;,.; .: - was found, la '·: · itself

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uiiikie. who are w / hreti.i the

ι. . ivsatoroberllächc ab .: ^T .igert

; ■ · ■■; .e ·; ί, -.:Tt. without the fluorine content

■,) ■■ v .: nr.iii.Tt becomes.

; ii'ist- ^{: ll} ing the catalyst verv.ende-:.:, ■ -! on.'de mixtures can be created by ge -.-> j, f..ii.üiL 'and by mixing the jriiestellt. Your clay

cehali btträsü ■ i'ii;! ..: according to 10 to 15 weight pro / em.

To the fluoriiruii »of the silica-alumina-chemical aqueous solutions of hydrofluoric acid can be used. Ammoniumiluond or -bitluorid or also Hydrogen fluoride or other compounds which, under suitable working conditions, give rise to hydrogen fluoride develop ability to be used.

The fluorine neck! Finished catalyst is preferably located / between 1 and 10 percent by weight, since the best yields with a higher one in this area Value of the ratio of Λ-picoline to γ-picoline be achieved.

In order to increase the activity of the catalyst and thereby the howling at \ - and y-picoline further can increase the fluorinated silica-alumina mixture promoters, e.g. B. cadmium oxide, in technical can be added in the usual way.

A preferred catalyst preparation takes place, for. B. using commercially available silica Alumina with an alumina content of 13 percent by weight and aqueous solutions of hydrofluoric acid, the concentration of which gives the desired fluorine content in the catalyst.

The following examples are intended to explain the invention in more detail. Here example 7 gives that without any use performed by fluorinated silica clays was to do a comparative test again.

example 1

50 ecm of an aqueous 50% hydrofluoric acid solution were diluted with distilled water until the volume obtained equals the total volume of the Pores of 300 g of commercially available silica-alumina with an alumina content of 13% in small cylinders with the dimensions 1.587 x 1.587 mm.

The silica-alumina was mixed with the hydrofluoric acid solution impregnated and left at room temperature for 8 hours. The impregnated silica- Alumina was then evaporated to dryness on the water bath under the hood. Subsequently was

mc 3 hours in a muffle furnace at 500 ("activated. The catalyst prepared in this way had an fluorgelial ■■ on 4.7 percent by weight.

This catalyst was brought into a 300 ecm Steel reactor with an inner diameter of 30 mm and conducted for 6 hours at a temperature of 400 C per hour 1.25 mol of acetaldehyde and 2.94 mol of ammonia over the catalyst.

The accumulated condensate was mn 50 "," itier Treated sodium hydroxide solution and distilled with steam. After further treatment with 5% sodium hydroxide solution the distillate was separated into an aqueous and an oily phase.

The aqueous phase was extracted repeatedly with mil Methylene chloride, combined the extracts with the oily phase, and the solvent was evaporated therefrom analyzed the residue by gas chromatography.

The following yields were determined based on the acetaldehyde introduced:

\ -Picoline 31 mole percent, y-picoline 22.6 mole percent, Pyridine 4 mole percent, 2 - methyl - 5 - ethylpyridine 2.3 mole percent.

The total conversion of aldehyde was 98.6 "/".

25 Examples 2 and 3

Table Il

Jinsci / lingings example 4

1 luorine content of the catalyst in percent by weight

Temperature in C

1: Request for loan
in hours

Introduced acetaldehyde
in moles / hour

Introduced ammonia
in moles / hour

Acetaldehyde conversion

in ⁰ A, '

Bulging in molprozeni,
based on the imported acetaldehyde:

• \ -Picoline

y-picoline

Pyridine

2-methyl-5-ethylpyridine

2.6 390

2.27 1, ('7 99.7

27.4

23.8

2.5

3 2

1.25 3.5S 9 «. 9

27.4

23.7

3.1

2.5

Example 6

In two separate experiments, 2.27 mol of acetals ^1. ~ 1 yd and 1.96 mol of ammonia per hour were passed over a catalyst prepared according to Example 1 with a fluorine content of 4.7 percent by weight for 6 hours.

Table I below shows the reaction conditions and the results of the two examples compiled.

Table I.

Implementation conditions

of the catalyst weight pro

Fluorine content

sators in

cent

Temperature in ^U C

Acetaldehyde conversion

in 7o

Yields in mole percent,
based on the imported acetaldehyde

Λ-picoline

y-picoline

Pyridine

2-methyl-5-ethylpyridine

Example 2

4.7
418

97.5

28.8

20.1

4.1

2.5

Examples 4 and 5

Silica-alumina with an alumina content of 13 weight percent was following the procedure of Example 1 with aqueous hydrofluoric acid solution treated. Two different catalysts were produced from it, which were activated after three hours the air at a temperature of 500 ° C an analytical one determined fluorine content of 2.6 or 7.6 percent by weight.

The results obtained with these two catalysts and the respective conversion conditions are shown in Table II below.

From a weight percent cadmium nitrate hydrate containing aqueous solution, ig was concentrated with Caustic soda cadmium hydroxide precipitated. The cadmium hydroxide has been washed for so long until there were no more nitral ions in the wash water, and then dissolved in ammonia.

Silica - alumina with an alumina content of 13 percent by weight and a fluorine content of 7.6 percent by weight was repeatedly impregnated with this ammoniacal cadmium hydroxide solution, whereby after each impregnation drying at 110 ° C

Example 3 was done.

After three hours of activation in a muffle furnace at 400 ° C., the finished catalyst contained 5 percent by weight Cadmium oxide. 1.25 moles of acetaldehyde per hour were passed over 268 g of this catalyst for 6 hours and 3.53 moles of ammonia at a temperature of 400 ° C.

Based on the acetaldehyde introduced, the following yields were obtained:

\ -Picoiin 31.4 mole percent, y-picoline 27.8 mole percent, 2-methyl-5-ethylpyridine 2.6 mole percent. The total acetaldehyde conversion was 93.5%.

Example 7

A reactor was charged with 300 ecm of silica clay with a clay content of 13 percent by weight, and 2.27 mol of acetaldehyde and 1.76 mol of ammonia were then passed in per hour. The implementation was carried out for 6 hours at <i30 ⁿ C.

The accumulated condensate was after. Treated method of Example 1 and then analyzed by gas chromatography, based on on the imported acetaldehyde, received the following buckling values:

Λ-picoline 22.8 mole percent !,} - picoline 24.2 mole percent, Pyridine 3.9 molpro / .eu. 2-methyl-5-ethylpyridine 2.6 mole percent.

The acelaldehyde conversion hetrun as a whole 97.5%.

4.7
450

98.7

29.2
20.3

5.7

2.3

Claims (2)

1 695 4. Patent claims: . Process for the analytical production of \ - and} '- l'icolin. from a mixture of vapors of acetaldehyde and or paraldehyde and ammonia in a molar ratio of aldehyde: ammonia / wipe 1: 0.5 and 1: 3 at temperatures / wipe 350 and 500 C. d a d u ich g e k e η η- ίο / eic Ii nc ι. that the catalyst consists of a Fluorinated silica-alumina mixture with an alumina content of 10 to 15% and a fluorine hall from 2 to 10%. 2. \ experienced according to claim 1, characterized in that that the catalyst contains 5 percent by weight of CdO as a promoior.