CS226912B1 - Substituted phenols - Google Patents

Description

The invention relates to alkyl-substituted phenols and to a process for their preparation.

It is known that variously substituted phenols are used as stabilizers of various types of organic substances, especially polymers.

It follows from the theory of the branched chain oxidation mechanism of polymers that the basic condition for the effectiveness of a phenolic antioxidant is that it is able to provide hydrogen to the peroxyradical formed on the substrate and thereby limit the auto-catalyzed oxidation process. However, in addition to chemical reactivity, they must also meet certain requirements in terms of physical properties. It must be sufficiently non-volatile, compatible with the substrate to be stabilized and must comply with strict hygiene requirements.

These properties of phenolic antioxidants are just achieved by the introduction of suitable substituents, for example by alkylation of the basic structures with α-olefin oligomers, as already mentioned in U.S. Pat. However, the higher the molecular weight, the more difficult the alkylation with these oligomers is. The configuration of the double bonds in the olefin molecule also affects the degree of alkylation activity. Therefore, special catalysts have been sought to obtain economical alkylation yields. French Patent No. 2 031 357 discloses a boron trifluoride-phenol complex BF3.2 C6H5 as the alkylation catalyst. . OH, in U.S. Pat. No. 2,868,823, the AlCl2 complex. However, the removal of these catalysts from the reaction mixture is difficult and necessitates further technological operations, i.e., washing and neutralization.

In MS. No. 174,679 describes the preparation of alkylphenols. substituted oligomeric olefins using a variety of alkylation catalysts, the alkylation being achieved by such mild alkylation catalysts as bleaching earth, polyphosphoric acid or toluenesulfonic acid activated bleaching earth.

It has now been found that a condition for successful alkylation of phenols by olefin oligomers with mild alkylation catalysts is the presence of exomethylene groups in the oligomer. The branched substituents produced by the alkylation on the phenol nucleus also have a favorable effect on their stabilizing properties.

The present invention provides substituted phenols of formula (I)

228912

QH

Ru kde

R ¹ is alkyl of one to eight carbon atoms, alkoxy of one to four carbon atoms, styryl, alpha-methylstyryl or cycloalkyl,

R ² is a radical derived from propene oligomer having a polymerization degree of 5 to 50, having the structure corresponding to formula II

1 with H- CH.-CH- * 1 - e ^ -c - Z | CfL L V ^CH p

where m = 1 + ni + nz is in the numerical range of 5 to 50 and ni, nz have values of 1 to 48 and the index u is 0 to 2, the index is 1 to 2 and the sum u + v is not more than 3.

Method for producing compounds of formula I consists in that the phenol or phenols substituted by radicals R ¹ alkylated with catalysis of bleaching earth or bleaching earth modified phosphoric acids with a minimum 76 weight% of phosphorus pentoxide or p-toluenesulfonic acid at a temperature from 70 to 200 ° C either in the alkylating agent itself or in an aromatic hydrocarbon boiling up to 200 degrees Celsius, the alkylating agent consisting of propene oligomers of intermediate degree 5 to 50 contains at least 0.25 mol equivalents of vinylidene groups capable of forming a substituent R ² of the structure represented by the general formula II.

The obvious advantage of the described process of alkylation of propene oligomers containing exomethylene functional groups is not only that economically more advantageous alkylation catalysts are used, but also that alkylation can be carried out under milder conditions, thus limiting the formation of reaction byproducts that are hygienic. undesirable. When using milder alkylation catalysts, for example bleaching earth or bleaching earth activated with polyphosphoric acid or p-toluenesulfonic acid, no further technological operations, i.e. washing and neutralization, are eliminated and the catalyst is removed by simple filtration.

Fewer technological operations, simpler equipment, a non-corrosive and non-toxic catalytic system, and ease of alkylation of propene oligomers that contain decisive amounts of exomethylene structures for the alkylation activity are clear advantages of the new process.

Apart from the aforementioned advantages in terms of the alkylation reaction was further found that the branched structure of the substituent R ² is advantageous in terms of efficacy of the formulated antioxidant to polymeric substrates, especially those that are partially crystalline.

In some cases, R ¹ is preferably incorporated into the phenol molecule after the first alkylation by the propene oligomer and hence the compounds of formula (II).

Content of vinylidene groups

CH2 = c \

in propene oligomers it is characterized by absorbance in the IR spectrum at 890 cm ^-1 . A minimum of 0.25 mol is sufficient to achieve the effect according to the invention. equivalents. The alkylation yield increases with increasing content of exomethylene groups, as will be further exemplified in the examples.

The structure of the compounds represented by the general formula (I) was verified and characterized by NMR spectra. The structure of the substituent R ² has been established finding that protons CH-groups attached to the quaternary C atom resonate in the 1.10 and 1.13 ppm.

According to the described process for the preparation of alkyl-substituted phenols, for example, the following compounds were prepared:

2,6-Dimethyl-4-dodecakis (propen-1-yl) -phenol

2-methyl-4-dodecakil (propen-1-yl-phenol and its additional tert-butylation)

2-methyl-4-dodecakis (propen-1-yl-6-tert-butyl-phenol),

2-hexakis (propen-1) yl-4-methoxyphenol

2,6-dicyclohexyl-4-octadecakis (propen-1-yl-phenol),

2-Tetradecakis- (propen-1) yl-4-methylphenol

4-dodecakis (propen-1-yl-phenol and its additional tert-butylation)

2,6-di-tert-butyl-4-dodecakis (propen-1-ylphenol),

4-ethoxy-2-hexadecakis (propen-1) yl-phenol and the like.

The following examples illustrate the invention. Parts and% in the examples are by weight. Example 1

To 1000 parts of a propene oligomer, characterized by a mean number polymerization degree of P _c 15 and a content of 0.68 molar equivalents

OF

CH2 = c \

300 parts of o-cresol (with a minimum purity of 98% / oj) were added in portions and a total of 80 parts of bleaching clay as an alkylation catalyst was metered in. The mixture was heated to 140 ° C under inert gas for 10 hours. After cooling to 70 [deg.] C., the catalyst on a pressure filter was separated, and excess unreacted o-cresol was distilled off from the filtrate under reduced pressure of 1.86 kPa at 160 [deg.] C. Filtration and distillation were carried out under inert gas shielding.

Yield:

1084 parts of o-cresol, alkylated at the p-position with a propene oligomer. The product is a pale yellow, viscous clear liquid, specific gravity 0.854 kg / dm &^lt; ³ > and a dynamic viscosity of 422 mPa. with.

Under the same reaction conditions, o-cresol was alkylated with propene oligomers of different contents

CI-iz = C \

groups. The yield of the alkylation reaction on the physico-chemical properties of propene oligomers was found. Table 1 summarizes these results.

Table 1

Propene oligomer: number average molecular weight M _c content / CH2 = c \ molar equivalents % yield of o-cresol alkylated with propene oligomer designation mean number polymerization degree P _c AND 14 580 0.25 43 (B) 12 500 0.58 70 C 12 500 0.82 91

The product prepared according to Example 1 was added to powdered polypropylene at a concentration of 0.1% along with 0.25% dilauryllodipropionate and 0.15% calcium stearate. A film of 0.5 mm thickness was made from the mixture. The induction period of oxidation of the stabilized sample measured in O 2 atmosphere at 140 ° C in sealed tubes was 128 days. The end of the induction period was judged by the formation of cracks on the surface of the test specimen.

Example 2

25 parts of concentrated sulfuric acid (specific gravity 1840 kg / m ³ ) were dispersed in 2500 parts of the product (o-cresol, alkylated in the β-position with propene oligomer) according to Example 1, containing 12% of the o-cresol vase. Isobutene gas was introduced into the reactor at a temperature of 80 to 90 degrees Celsius through a tube located at the bottom of the reactor. Its mouth was provided with a turbine adapter for finely dispersing the gas in the reaction medium. The isobutene flow rate was adjusted and maintained such that the off-gas contained a minimum amount of isobutene. 165 parts of isobutene were introduced into the reactor within 6.5 hours.

After cooling the reaction mixture to 40 ° C, 30 parts of finely ground limestone were charged to the reactor, stirred vigorously for 2 hours, then an additional portion of 20 parts of limestone was added and stirred at 60 ° C for 90 minutes.

The mixture of the resulting calcium sulfate together with excess limestone was filtered off on a pressure filter, and the isobutene dimer formed as a by-product was removed from the filtrate by distillation at 130 ° C under a reduced pressure of 1.86 kPa.

A substantial improvement with respect to the final product is achieved by decolouring the crude alkylate with 100 parts of bleaching clay.

2615 parts of 2-methyl-4-dodecakis- (propen-1) yl-6-tert-butylphenol were obtained.

The induction period of polypropylene stabilized with 0.1% of this product, 0.25% of distearyl thiodipropionate and 0.15% of calcium stearate determined by the method given in Example 1 was 169 days.

Example 3

1.25 equivalents of β-cresol are dissolved in 1 mol at 90 ° C with stirring. equivalents of propene oligomer (which is characterized by a mean number polymerization degree of P _c 12, a mean number molecular weight of M _{c of} 500 and a content of 0.82 molar equivalents)

CH2 = c \

groups).

Bleaching earth impregnated with 32 parts of H6P4O13 was added to the solution. The amount of this alkylation catalyst is chosen so that in the first stage of the alkylation process it corresponds to 4 to 7%, in the second stage a minimum of 9, at most 16%, based on the weight of the propene oligomer used. It is alkylated at a temperature of 130 to 170 ° C under a blanket nitrogen atmosphere with a stirring method which ensures a completely homogeneous dispersion of the catalyst throughout the reaction volume. The first alkylation phase lasts 2 to 6 hours. The second phase is then 4 to 9 hours. The conversion is monitored by determining the content of free, unalkylated β-cresol in the samples taken at specified time intervals from the reaction mixture.

After conventional operations, i.e., filtration from the catalyst and distillation of the unalkylated β-cresol, 0.93 to 0.95 molar equivalents of the alkylate are obtained. According to NMR spectra, the product of β-cresol, alkylated in the 2- position to the phenolic OH group, corresponds to a propene oligomer. The signal of the proton at position 6 is about 5 to 6 linear% lower, corresponding to x the degree of substitution of this H-atom on the nucleus by the second molecular oligomer.

The product was added to powdered low pressure polyethylene at 0.1% along with 0.1% distearyl thiodipropionate. A film of 0.5 mm thickness was made from the mixture. The oxygen absorption induction period measured at 180 ° C was 584 minutes.

Example 4

4-dodecakis (propen-1) yl-phenol obtained according to Example 1 by alkylation of 104 kg of phenol, 520 kg of propene oligomer containing 0.84 molar equivalents)

CH2 = c \

groups at 65-75 ° C were further alkylated with a mixture of isomeric octenes (with an average composition of about 75% 2,4,4-trimethylpentene-1, 20% 2,4, -trimethylpentene-2 and 5% / higher boiling fractions) for a total of 5 hours per catalysis of 60 kg of bleaching earth containing 7 to 9% reversibly bound water.

After removing the catalyst by filtration and distilling off the excess isobutene dimer, 2- (2 ', 4', 4'-trimethylpentyl-2 -) - 4-dodecakis- (propen-1) yl-phenol was obtained in a yield of 81% based on weight of starting phenol alkylated with propene oligomer.

The product was added to 0.1 L / O along with 0.1% tris (nonylphenyl) phosphite to low pressure polyethylene. The induction period determined in the same manner as in Example 3 was 637 minutes.

Claims (2)

OBJECT OF THE INVENTION where Substituted phenols of general formula I R ³ is an alkyl of one to eight carbon atoms, an alkoxy of one to four carbon atoms, a styryl or alphamethyl styryl or cycloalkyl, a R ² radical derived from a propene oligomer having a degree of polymerization of 5 to 50 having a structure corresponding to formula II H- ch ₉ -ch- ^from 1 1 -ch ₂ -c- ť I ² I CH- ch ₃ * f _n ^CH * ^and 1 where η - 1 + ni + Π2 is in the number range 5 to 50 and ni and nz are 1 to 48 and the index u is 0 to 2, the index is 1 to 2 and the sum u + v is not more than 3. 2. A process for producing compounds of formula I wherein the phenol or phenol substituted with longer radicals R ¹ are alkylated under the catalysis of bleaching earth or bleaching earth modified phosphoric acids with a minimum 76 weight% of phosphorus pentoxide or p-toluenesulfonic acid at a temperature from 70 to 200 ° C either in the alkylating agent itself or in an aromatic hydrocarbon boiling up to 200 Celsius by an alkylating agent consisting of propene oligomers of an average number polymerization degree of 5 to 50 containing a minimum of 0,25 mol equivalents of vinylidene groups capable of forming a R ² substituent II.