CS261084B1 - 4- (alpha,. Alpha.-dimethylbenzyl) dlphenylamine and its preparation - Google Patents

Abstract

The solution concerns 4-(alpha,alpha'-dimethylbenzyldiphenylamine and the method of its preparation. Diphenylamine is allowed to react with alpha-methylstyrene in a molar ratio of 1:1 at a temperature of 80 to 120 ĎC in the presence of a catalyst - bleaching clay. The solution can be used in the chemical industry.

Description

The invention relates to 4-(alpha ^, alpha'-dimethylbenzyl diphenylamine) and the method of its preparation.

Among the secondary aromatic amines, diphenylamine derivatives still have a technically significant position. Alkylated and aralkylated compounds are of practical importance — they are effective as antidegradants in polymeric materials (JP 5 674 176, US 3 649 690). They are prepared mainly by alkylation of diphenylamine either with alpha-methylstyrene at a temperature of 200——230 °C in the presence of a fluoroboron catalyst, by neutralization with calcium hydroxide (JP 5 674 176) or by alkylation with another alkylating agent (JP 5 554 249).

Now 4-(alpha,alpha'-dimethylbenzyl)diphenylamine of formula I has been discovered

as a] method of preparing this new substance, the essence of which consists in reacting diphenylamine with alpha-methylstyrene in a molar ratio of 1:1 at a temperature of 80 to 120 °C and in the presence of a catalyst - bleaching clay.

The compound according to the invention can be used in natural rubber and other polymeric materials as a stabilizer and antidegradant against the degrading effects of heat, light, oxygen and ozone. The compound can also be used as a starting compound for the preparation of other stabilizers and antidegradants.

The above example illustrates, but does not limit, the subject matter of the invention.

Example

In a 250 ml four-necked flask equipped with a stirrer, reflux condenser, thermometer and dropping funnel, 0.418 mol (70.7 g) of DFA was placed, which was heated to 70 degrees Celsius. After dissolving the diphenylamine, 10% bleaching earth was added to the reaction mixture. After mixing the bleaching earth with diphenylamine, 0.418 mol (49.4 g) of alpha-methylstyrene was added dropwise so that the temperature was in the range of 80 to 120 °C. After 6 hours, the reaction mixture was filtered, the filter cake was washed with benzene heated to 60 °C. The benzene was distilled off under vacuum and pure 4-(alpha,alpha'-dimethylbenzyl)diphenylamine was obtained by fractional distillation at a temperature of 190-192°C and a pressure of 266.10 ³ kPa. The product thus obtained was crystallized from hexane.

The reaction yield is 74% of theory.

M.p.: 61 °C

ID:

390 cm ^-1 υ(Ν—H)

010—3 060 cm ^-1 in(C—H Aromatic

960 cm' ¹ in(C—H)

590—1 490 cm ^-1 p(C=C)aromatic

340 tin-' in(C—N)

820—880 cm ¹ 5(C—H] for 1,4 substituted benzene 700 cm ¹ y(C—H) aromatic

NMR: (ppm)

1.58 --CH ₃

5.3 — NH

6.58 — 7.42 — aromatics % N:

4.70% measured;

4.87 °/o calculated Example 2

The thermooxidative activity of 4-(alpha,alpha'-dimethylbenzyl)diphenylamine (stabilizer A), prepared according to Example 1, was verified in the stabilization of a vulcanizate based on a combination of natural (66%) and styrene-butadiene rubber (34%). The vulcanizate further contained a light mineral filler of the Blanc-Fix type (70 parts by weight, based on rubber), a combination of white pigments based on zinc and titanium oxides (10 and 10 parts by weight), processing additives of the stearin, paraffin and vaseline oil type and a sulfur accelerator system (N-cyclohexyl-2-benzothiazolesulfenamide (2 parts by weight) 1 part by weight).

The stabilizer was added in an amount of 2.0 parts by weight, calculated on the rubber, while for comparison, phenyl-beta-naphthylamine (Stabilizer B) and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (Stabilizer C) were used in the same concentration commonly used in practice.

The aging process of vulcanizates prepared by pressing at 160 °C was monitored based on the change in the basic tensile and physico-chemical properties of test specimens in a stream of hot air at a temperature of 90 °C, using the method according to ČSN 621 511 for 1 to 12 days.

About

Table 1

Thermo-oxidative aging of vulcanizates, 90 °C, 3—12 days

Monitored parameter Vulcanizate

residual strength ductility (%) unstabilized with stable A with stable B with stable C 3 days 67/58 80/81 83/78 80/74 6 days 41/56 67/71 65/70 61/67 9 days 23/43 59/68 46/63 46/60 12 days 20/34 39/56 44/60 27/48

Table 2

Dynamic fatigue of vulcanizates under de Mattia

Monitored parameter Vulcanizate unstabilized with ¹ stable A with stable B with stable C crack growth from 2 to 12 mm, CZK 6.9 17.6 22.6 16.0 same after aging 7 days/70°C 2.2 6.8 9.2 8.8 4-(alpha,alpha’-dimethylbenzyl) diphenylamine namic properties before and after thermal shows high stabilizing effects on the dy- stress.

Table 3

Change in whiteness of vulcanizates after exposure to UV radiation, Leukometer (% MgO)

Exposure time Vulcanizate (h) unstable with stable A with stable B with stable C

0 68 70 60 65 2 54 49 34 35 4 48 44 26 29 8 46 40 19 27

SUBJECT OF THE INVENTION

Claims (2)

1. 4- (alpha, alpha, alpha-dimethylbenzyl) diphenylamine of formula I Νμ (l) 2. A process for the preparation of 4-alpha, .alpha.-dimethylbenzyl] diphenylamine according to claim 1, wherein the diphenylamine is reacted with alpha-methylstyrene at a molar ratio of 1: 1 at 80-120 [deg.] C. in the presence of a bleaching clay catalyst.