CS250592B1 - Dialkylesters of 2,3-bis(1,2,2,6,6-pentamethyl-4-piperidyloxy)butadiene acid ane method of its preparation - Google Patents

Abstract

The present invention relates to dialkyl esters of an acid 2,3-bis (1,2,2,6,6-pentamethyl-4-piperidyloxy) - butanediate and their preparation. The hindered amines are new a group of light stabilizers. Vzhl'adom to the nature of stabilization Their high efficiency is extremely important especially for products with a large surface area as are films and fibers. In addition to application in polyolefins these stabilizers are also effective polystyrenes, polyurethanes and polyamides. The invention relates to a dialkyl acid ester 2,3-bis (1,2,2,6,6-pentamethyl-4-piperidyloxybutanedioic acid) of Formula I

Description

The invention relates to dialkyl esters of 2,3-bis (1,2,2,6,6-pentamethyl-4-piperidyloxy) butanedioic acid and a process for their preparation.

Sterically hindered amines represent a new family of light stabilizers. Due to the nature of the stabilizing action, their high efficiency is of particular importance, especially for products with large surface areas such as films and fibers. In addition to their application in polyolefins, these stabilizers are also effective in polystyrenes, polyurethanes and polyamides.

The present invention provides a 2,3-bis (1,2,2,6,6-pentamethyl-4-piperidyloxy) butanedioic acid dialkyl ester of formula I

where

R is methyl or ethyl.

The present invention further provides a process for the preparation of a compound of formula I which is characterized in that the 2,3-dibromobutanedioic acid dialkyl ester of formula II

O: O \ /

C — CH — CH — C / III.

RO Br Br OR (Π) where

R is methyl or ethyl, acting on the sodium salt of 4-hydroxy-1,2,2,6,6-pentamethylpiperidine of formula III

ONA

CH 3 (III) in dry benzene, toluene or xylene at a temperature of 80-90 ° C most preferably under a nitrogen atmosphere.

An advantage of the present invention is the preparation of intermediates for the synthesis of a polymeric light stabilizer of the polyalkylpiperidine type, with reduced extractability and elimination of volatility.

Example 1

To a 4-hydroxy-1,2,2,6,6-pentamethylpiperidine III sodium salt of 3.88 g (0.02 mol) in 70 mL dry toluene was added a catalytic amount of KI (0.02-0.03). g) and at 80-90 [deg.] C. under a nitrogen atmosphere, 3.03 g (0.01 mole) of 2,3-dibromobutanedioic acid dimethyl ester in 30 ml of dry toluene are added dropwise, and the reaction is allowed to proceed for 5 hours under unchanged conditions. the reaction mixture was washed three times with distilled water. after drying the toluene solution over anhydrous sodium sulfate, the solvent was vacuum evaporated to afford the crude product as a yellow viscous liquid which when divided by the cliromatografickej silica has a refractive index of n _D = 1.4972 ^Z0.

Elemental analysis for:

C26H48O6N2;

M _r = 484.68 calculated:

% C, 64.43;% H, 9.98;% N, 5.78; found:

63.97 C / C, 9.61 C / H, 5.59 C / N.

IR spectrum (chloroform)

Vmax

980, 2 920, 2 815, 1 745, 1 635, 1 460,1 450,

390, 1370, 1320, 1280, 1255, 1190, 1150 cm ^{_1 X} to H-NMR (chloroform-d)

5:

1.01 1.1 (wide band of doublets — 24 H, gem.

CH3);

1.45, 1.72 (2 doublet - 8H, - CH2 -);

2.18 (s-6 Η, —N — CH3);

3.25 (k-2H, -C-H);

3.32 (s-6H, -O-1OH3);

5.01 (m-2H, α-hydrogen) ppm

Example 2

100 wt. parts of unstabilized powdered polypropylene are impregnated in dichloromethane with 0.1 wt. % of 2,6-di-tert-butyl-4-methylphenol, 0.15 wt. % of calcium stearate and 0.2 wt. After evaporation of the solvent, 0.15 mm thick films are pressed from the mixture at 20 MPa at 190 ° C. The films are irradiated with a 125 W mercury lamp provided with a glass sheath, the polymer degradation being monitored by the development of the hydroperoxide and carbonyl bands in the infrared spectra. Under these conditions, the residence time of the carbonyl index of 0.2 for the polypropylene not containing the light stabilizer is reached in 140 hours, while for the stabilized polymer this value is reached in 1,740 hours.

The invention has applications for the light stabilization of polymers, especially polyolefins, as well as for the preparation of polymeric light stabilizers of polyalkylpiperidine-type polymers.

Claims (2)

1. 2,3-Bis (1,2,2,6,6-pentamethyl-4-piperidyloxy) butanedioic acid dialkyl ester of formula I bX CH ₃ x A / 3 O O \ Z C — CH — CH — C / I \ RO Br Br OR (Π) BA · Ί · ~~ C '(Ί where R is methyl or ethyl, acts with the sodium salt of 4-hydroxy-1,2,2,6,6, -pentamethylpiperidine of formula III RO * C - CH About Where (III) R is methyl or ethyl. 2. A process for the preparation of a compound of the formula I according to claim 1, characterized in that it is preferable to use a dialkyl 2,3-dibromobutanedioate of the formula II in dry benzene, toluene or xylene at a temperature of 80 to 90% most preferably under nitrogen.