DD266799A1 - PROCESS FOR THE ISOLATION OF HIGH-PURITY 4-AMINO-2,2,6,6-TETRAMETHYLPIPERIDINE - Google Patents

Abstract

The invention relates to the isolation of 4-amino-2,2,6,6-tetramethyl-piperidine (ATP) from mixtures obtained in the aminating hydrogenation of triacetoneamine. ATP is primarily used to make stabilizers. The isolation is carried out by reaction of contaminated ATPs with carbon dioxide, separation and washing of the precipitate and its thermal decomposition.

Description

739

Title of the invention

Process for the isolation of high purity 4-amino-2,2,6,6-i; etramethylplperldin

Field of application of the invention

The invention relates to a process for the workup and purification of 4-amino-2,2,6, b-tetramethylpiperidin (ATP) containing Ueaktlonsgemisohen,

ATP is primarily used for the production of UV stabilizers for plastics,

Characteristic of the known state of the art

It is known that ATP is prepared by aminating hydrogenation of 4-oxo-2,2,6,6-tetramethylpiperiane (triacetonamine or TAA) (EP 0 033 529).

The TAA is prepared by an acetone condensation in the presence of ammonia, Ale catalyst are ι Lewisoäuren (DE 2 429 745, DE 2 429 937, DE 2 429 936, JP 58-49363) or acidic ion exchanger (US 3,959,295 or, EP 0 013 865). The resulting by-products are mesityl oxide, water, acetone alcohol, acetone and higher condensation products. The TAA is very unstable and tends to form higher condensation products during prolonged storage as well as thermal stress · (A, 178, pp. 305-320). Therefore, it is advantageous to hydrate the TAA to the ATP immediately after production.

Wherein the pure TAA is recovered by distillation from the KondensationQßemisch (EP 0013865, EP 0033529) The known methods go off at the emitting hydrogenation of pure TAA ^·%

Üiel the invention

The aim of the invention is to produce a very pure and color-stable ATP when using crude I ¹ AA for aminating hydrogenation, which is suitable for the production of light stabilizers due to its color stability.

Explanation of the essence of the invention

The invention has the object to / basis, high-purity 4-Araino-2,2,6,6-tetramethyl-piperidine (ATP) from reaction mixtures dde 5 to S6 % (mass) of the ATP and in the aminating hydrogenation of undestilllertem 4th -0xo-2,2,6,6-tetramethylpiperidine (triacetoneamine).

This object is achieved dcduroh that 1 part by weight, of the reaction mixture obtained in the aminating hydrogenation, with 0.1 to 1.0 parts by weight of water and 1 to 2 parts by weight of acetone, the solution saturated with gaseous carbon dioxide until no more salt precipitates as a solid, then the precipitate filtered off, extracted with acetone or Mothylalkohol and then the salt heated to 90 to 200 ⁰ O until the C0 ₂ evolution is complete and the 4th -Amlno ~ 2,2,6,6-tetramethylpiperidine distilled off in vacuo.

Preferably, 1 part by weight of the RaktionsgeralsohoB to be used in 0j5 to 0.7 parts by weight of water and 1 to 2 parts by weight, acetone dissolved »The decomposition of the salt is best carried out at 120 to 140 ⁰ C,

Our own investigations have shown that losses of up to 25 % occur in the known distillation of TAA. The losses are considerably lower if only the acetone is driven off and the remaining sump is used for aminating hydrogenation, which leads to an improvement of the overall process.

TO

contributes. The experiments showed that the TAA in this vat is hydrogenated up to 90 % to ATP ·

Difficulties occur when distilling the hydrogenation product. The deacidylatants of ATP still contain impurities which turn brown when standing. For processing into UV stabilizers, these distillates are unsuitable. In order to be able to use the economically very favorable process variant of the use of undistilled TAA, there was the need for a suitable reprocessing technology of the Hydrler product,

Example embodiments Example 1

2265 g of a crude product having an ATP content of 25% (by mass) obtained by hydrogenation of a contaminated TAA was mixed with 2265 g of water and 4530 g of acetone. While stirring, so much carbon dioxide was introduced, that no more ausfiol pesticide. The white crystalline pesticide was filtered off and extracted with acetone for 2 hours. After air drying left 1096 g of a residue, which was slurried in 350 g of xylene. By heating to 120 to 140 ⁰ C, the ATP carbonate was decomposed. There remained a liquid residue, which was distilled off in vacuo.

Boiling point: K _p3 «64 to 65 ⁰ C

Parbo: colorless - pale yellow

Yield: 94%, based on the ATP amount of the starting material. Purity: 99.9 %

The ATP content in the carbonate-derived pilgrim was 2 %

Example 2

Analogously to the workup of Example 1, 357 g of a crude product having an ATP content of 7.5 % (mass), which had been obtained by aminating hydrogenation of a crude TAA, mixed with 180 g of water and 540 g of acetone and treated with carbon dioxide , Wake up the workup, the following product values were obtained:

Boiling point: K ₃ = 64 to 65 ⁰ C

Color: colorless - light yellow

Yield j 90%, based on ATP amount des'Einsatzproduktes

Purity: 99.9 %

Example 3

In otherwise the same procedure as in Example 1 is obtained from 100 g of a non-color-stable ATP distillate with an ATP content of 96 % (mass) (distillation section of Example 4) after mixing with 100 g of water and 200 g of acetone 93.5 g pure ATP ·

Boiling point: K ₃ 62 to 66 ⁰ C

Color: colorless

Yield: 97.4 %, based on ATP amount of the starting material

Purity: 99.9 %

Example 4 Comparative Example

Ee wurdo the workup of the product obtained in the aminating hydrogenation of crude TAA according to the prior art by fractional distillation. The following distillation parameters were used:

TO Ϊ99

Column:

Pilling:

Length χ

Inner diameter:

Number of plates: reflux ratio:

Vacuum:

Amount used:

silver sheath

Glass rings, diameter 3 mm

400 mm

25 mm

about 13 theoretical plates

Vi 5

3 Torr

1150 g (with 25 % ATP)

Result:

Destillatlonöabschnitte

Quantity S

1150

Quality dos main run

ATP content % g

solvent 560 0.1 5 0.56 leader 84 42 35.2 main run 184 98 180.3 trailing 170 26 44.2 Zörsetzungöprodukte 84 - - (Cold template) swamp 60 3.4

263.7

Boiling point: Ko = 61 to 64 ⁰ C

Color t yellow; brown after 4 weeks of service

Purity: 98 %

Yield: 68.3%, based on ATP amount of Einaatzproduktea

Claims (3)

To claims 1. A process for the isolation of high purity 4-amino-2,2,6,6-tetramewyi-piperidine from reaction mixtures containing 5 to 98 % (by weight) of the 4-amino-2,2,6,6 tetramethylpiperidin and obtained in the preparative hydrogenation of distilled 4-0XO-2,2,6,6-tetramethylpiperidine (triacetonamine), characterized in that 1 part by weight of the Reaktlonsgeminchee that in the aminating hydrogenation is added, mixed with 0.1 bio 1.0 parts by weight of water and 1 to 2 parts by weight of acetone, the solution is saturated with gaseous carbon dioxide until no more salt precipitates as a solid, then the precipitate is filtered off with acetone or methyl alcohol and then the salt heated to 90 to 200 ⁰ O until the C0 ₂ -Niungiung is completed and distilled off the 4 ^ mino-2,2,6,6 - tetramethyl-piperidln in vacuo. 2 «method according to claim 1, characterized in that 1 part by weight of the Reaktlonsgemisches to be dissolved in 0, 'j to 0.7 Gew _# parts of water and 1 bia 2 parts by weight, acetone dissolves. 3 · The method of claim 1, characterized in that one carries out the decomposition of the salt at 120 to 140 ⁰ C.