FR2629817A1 - 3,5-Dialkyl-4-hydroxybenzyl hydrocarbyl sulphides and polysulphides, their preparation and their use as antioxidising additives - Google Patents

Abstract

A description is given of 3,5-dialkyl-4-hydroxybenzyl hydrocarbyl sulphide and polysulphide compounds, of their preparation and of their use especially as antioxidising additives. These compounds correspond to the general formula: in which R1 and R2, which are identical or different, are alkyl groups containing 1 to 8 carbon atoms, R3 is an alkyl group containing 1-20 carbon atoms, a cycloalkyl group having 5-12 carbon atoms, a phenyl or naphthyl group, optionally substituted by one or a number of alkyl groups containing 1-20 carbon atoms, or an alkylaryl group containing 7-20 carbon atoms, and n is a number from 1 to 5. They can be prepared by reacting a 4-halo-2,6-dialkylphenol with an alkali metal mercaptate or mercaptate-polysulphide. They are used as antioxidising additives in organic compounds, for example oils or certain polymers.

Description

dans laquelle R1 et R2 sont des groupes alkyles ayant de 1 à 8 atomes de carbone.The present invention relates to novel sulfurized phenolic compounds of the general formula

wherein R1 and R2 are alkyl groups having 1 to 8 carbon atoms.

R1 and R2 may be the same or different.

R3 is an alkyl group of 1 to 20 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, a phenyl or naphthyl group, optionally substituted with one or more alkyl groups of 1 to 20 carbon atoms each, or a alkylaryl group of 7 to 20 carbon atoms; n is a number from 1 to 5.

Preferably at least one of R1 and R2 is a tert-butyl group.

Compounds of structure (I) are for example: - 3,5-dimethyl-4-hydroxy-benzyl isobutylthioether - 3,5-dimethyl-4-hydroxy-benzyl tert.butylthioether - 3,5-dimethyl-4-hydroxy benzyl phenylthioether - 3,5-dimethyl-4-hydroxy-benzyl benzylthioether-3,5-dimethyl-4-hydroxy-benzyl tert.nonylthioether-3-methyl-5-tert-butyl-4-hydroxy-benzyl tert.butylthioether-3-methyl-tert-butyl 5-hydroxy-4-benzyl isobutylthioether - 3-methyl-5-tert-butyl-4-hydroxy-benzyl phenylthioether - 3-methyl-5-tert-butyl-4-hydroxy-benzyl benzylthioether - 3-methyl-5-tetbutyl-4-hydroxy-4-hydroxy benzyl tert.nonylthioether - 3,5-ditert-butyl-4-hydroxy-benzyl tert.butylthioether - 3,5-ditert-butyl-4-hydroxy-benzyl phenylthioether - 3,5-ditert-butyl-4-hydroxy benzyl benzylthioether - the 3,5-ditert-butyl-4-hydroxy-benzyl tert.nonylthioether-3-methyl-5-tert-butyl-4-hydroxy-benzyl tert.butyldisulfide-3-methyl-5-tert-butyl-4-hydroxy-benzyl phenyldi isulfide - 3-methyl-5-tert-butyl-4-hydroxy-benzyl benzyldisulphide - 3-methyl-5-tert-butyl-4-hydroxy-benzyl-tert.-n-butyl disulfide - 3,5-ditert-butyl-4-hydroxy-benzyl benzyldisulfide - ditert 3,5-butyl-4-hydroxy-benzyl tert.-n-butyl disulphide - ditert.buttl-3,5-hydroxy-4-benzyl tert.butyltrisulfide - 3,5-ditert-butyl-4-hydroxy-benzyl phenyltrisulfide - ditert.-butyl-3 4-hydroxy-benzyl benzyltrisulfide and 3,5-di-tert-butyl-4-hydroxy-4-benzyl tert.nonyltetrasulfide.

où X représente un halogène, par exemple Cl ou Br, Rl et R2 sont définis comme dans la formule (I): - soit avec un mercaptate de métal alcalin : R3 - S- N.I+ pour l'obtention de thioéthers, - soit avec un mercaptate polysulfure de métal alcalin : R3 S NI+ pour l'obtention de polysulfures, où R3 est défini comme dans la formule (I), NI est un métal alcalin et n est un nombre de 1 à 5. The compounds of formula (I) can be obtained by reaction of a halogeno-methyl-4-dialkyl-2,6-phenol (II)

where X represents a halogen, for example Cl or Br, R1 and R2 are defined as in formula (I): either with an alkali metal mercaptate: R3-S-N.I + for obtaining thioethers, - or with an alkali metal polysulfide mercaptate: R 3 S NI + for obtaining polysulfides, where R 3 is defined as in formula (I), NI is an alkali metal and n is a number from 1 to 5.

The mercaptate polysulfides of alkali metals can be obtained by reacting sulfur with an alkali metal mercaptate. Such a reaction is described for example by KULIEV, ZEINALOVA, GASANOV and ALIEV in the "Journal of
Organic Chemistry of the USSR 14,661 (1978) for the synthesis of alkyl disulfides, which consists in slowly introducing a stoichiometric amount of finely divided sulfur into a solution of sodium alkylmercaptate in isopropanol at a temperature of 600.degree. The reaction mixture is then brought to 75-800C for 5 hours.

The invention also relates to the use of the compounds of formula (I) as antioxidant additives for organic compounds, for example for hydrocarbon lubricating oils, for synthetic lubricating oils such as diacid esters, polyol esters, polyalphaolefins, alkylbenzenes and for polymers organic such as polyethylene, polypropylene. In these uses the compounds of formula (I) are used in a proportion of 0.05 to 5% by weight, preferably 0.1 to 1% by weight.

The following examples illustrate the invention. They should in no way be considered as limiting.

EXAMPLE 1
Ditert.butyl-3,5-hydroxy-4-benzyl tert.butylthioether (III)
The sodium tert.butylmercaptate is obtained by neutralization of 50 g (0.cl mole) of tert.butyl mercaptan dissolved in 500 ml of methanol with pelletized sodium hydroxide in a stoichiometric amount. 4-chloromethyl-2,6-dithiophenol (160 g, 0.63 mol) is introduced gradually into the mixture brought to light reflux. At the end of the addition. reflux is prolonged for 3 hours.
After returning to the temperature of the atmosphere, 300 cm3 of water are added and then the alcohol is distilled; ; the monosulfide is then extracted with ethyl ether, washed with water and dried. After evaporation of the solvent, 175 g of sulfide (III) are collected, which corresponds to a yield of 90%. The light yellow viscous product obtained was analyzed by proton NMR. The chemical shifts observed confirm the structure of the product

H 6 (ppm) a 5.1 b 1.45 c 3.75 d 1.35 e 7.1 EXAMPLES 2 TO 6
The synthesis of the sulphides of Examples 2 to 6 is carried out according to the process described in Example 1.

Table 1

<tb><SEP> Product <SEP> R1 <SEP> R2 <SEP><SEP> R3 <SEP> Yield <SEP> (%)
<tb> Ex <SEP> 2 <SEP> IV <SEP> methyl <SEP> tert.butyl <SEP> tert.butyl <SEP> 88
<tb> Ex <SEP> 3 <SEP> V <SEP> methyl <SEP> tert.butyl <SEP> isobutyl # e <SEP> 91
<tb> Ex <SEP> 4 <SEP> VI <SEP> tert.butyl <SEP> tert.butyl <SEP> phenyl <SEP> 85
<tb> Ex <SEP> 5 <SEP> VII <SEP> tert.butyl <SEP> tert.butyl <SEP> benzoyl <SEP><SEP> 96
<tb> Ex <SEP> 6 <SEP> VIII <SEP> ~ <SEP><SEP> tert.butyl <SEP> tert.butyl <SEP> tert.nonyl <SEP> (*) <SEP> 93
<tb> (*) <SEP> Blend <SEP> of <SEP> mercaptans <SEP> mainly <SEP> in <SEP> Cg <SEP><SEP> derivatives <SEP> of <SEP> tripropylene.
<Tb>

The products obtained were analyzed in proton RNIN and displacements
observed chemicals are in good agreement with the structure of the products.

EXAMPLE 7
Ditert.butyl-3,5-hydroxy-4-benzyl benzyldisulfide. (IX)
The sodium benzyl mercaptate is obtained by reaction of 132 g (1.1 moles) of benzyl mercaptan with 45 g (1.1 moles) of sodium hydroxide pellets dissolved in 500 ml of methanol. Sulfur flower (36 g - 1.1 mol) is then added to the vigorously stirred sodium benzylmercaptate solution. The mixture is then heated for 2 hours at 600 ° C. and then allowed to return to ambient temperature. 256 g (1 mole) of halogenated derivative (II) are introduced very slowly under violent stirring of the reaction medium. The temperature is brought gradually to the reflux of the methanol, reflux which is then maintained for two hours. After cooling, 500 cm3 of water are added, and then the methanol is distilled off. The organic phase recovered after decantation is refluxed with 200 ml of a 10% aqueous sodium hydroxide solution for three hours.

The organic phase is separated again, washed with water and dried. The mass of product IX collected is 398 g, a yield of 94%. The product obtained has a sulfur content of 16.4% (theory 17.1 rock).

The analysis by thin layer chromatography shows the absence of elemental sulfur. The sulfur of compound IX is therefore well bound, probably in the form of a mixture of mono and polysulfides corresponding statistically to n = 2.

EXAMPLES 8 TO 12
The synthesis of the compounds described in Examples 8 to 19 is carried out according to the method described in Example 7. The value of n is adjusted by the amount of sulfur added to the sodium mercaptate in the first phase of the reaction.

Table 2

<tb><SEP> - <SEP> s%
<tb><SEP> Product <SEP> Ri <SEP> R2 <SEP> R3 <SEP> n <SEP> Tr. <SEP> th. <SEP> Yield <SEP> (7G <SEP>
<tb><SEP> Ex <SEP> 8 <SEP> X <SEP> methyl <SEP> tert.butyl <SEP> tert <SEP> butyl <SEP> 2 <SEP> 21.1 <SEP> 21.5 <SEP> 91
<tb><SEP> Ex <SEP> 9 <SEP> XI <SEP> tert.butyl <SEP> tert.butyl <SEP> tert.butyl <SEP> 3 <SEP> 24.6 <SEP> 25.8 <SEP> 93
<tb> Ex <SEP> 10 <SEP> XII <SEP> tert.butyl <SEP> tert.butyl <SEP> benzyl <SEP> 3 <SEP> 22.9 <SEP> 23.7 <SEP> 95
<tb> Ex <SEP> 11 <SEP> XIII <SEP> tert.butyl <SEP> tert.butyl <SEP> isobutyl <SEP> 3 <SEP> 24.3 <SEP> 25.8 <SEP> 95
<tb> Ex <SEP> 12 <SEP> XIV <SEP> tert.butyl <SEP> tert.butyl <SEP> tert.nonyl <SEP> (*) <SEP> 2 <SEP> 14.2 <SEP> 15 , 6 <SEP> 96
<tb> (*) <SEP><SEP> Blend of <SEP> mercaptans <SEP> mainly <SEP> in <SEP> C9 <SEP><SEP>SEP> derivatives of <SEP> tripropylene.
<Tb>

Compounds X to XIV were analyzed by thin layer chromatography.

The presence of elemental sulfur has not been detected. Sulfur compounds
X to XIV was thus integrated into the polysulfide chain, probably as a mixture of polysulfides corresponding statistically to the value of n. Moreover, the nuclear magnetic resonance spectra of the proton are entirely in line with those of the expected products. Also for example, with
XII in the proton NMR, the following chemical shifts are observed

H 6 (ppm) at 5.1 b 1.5 c 3.7-4.1-4.2 d 7.3
The presence of several signals between 3.7 and 4.2 ppm confirms that we are dealing with a mixture of polysulfides corresponding on average to the value n = 3.

EXAMPLE 13
Antioxidant action in mineral oils.

The antioxidant efficacy of the compounds according to the invention was established according to the PSA-RENAULT method 1517. In this test, 300 ml of oil arranged in an Erlenmeyer flask are carried in an oil bath at a temperature of 1300C for 200 hours. . Throughout the duration of the test, a bubbling of 10-l / h of air is ensured at constant flow. At the end of the test the oil is analyzed from the point of view of increasing viscosity, acidity and deposit content. The results are shown in Table 3. The additives are used at a dose of 0.5 W by weight in a mineral oil consisting of a 350 Neutral mineral oil mixture.
Solvent and Bright Stock Solvent having a viscosity of 11.3 mm2 / s at 1000C and 101.4 mm2 / s at 400C corresponding to a viscosity index of 97.

Table 3

<tb> Additives <SEP> Without <SEP> VII <SEP> VIII <SEP> XIV
<tb> Increase <SEP> of <SEP> Viscosity <SEP> Wo <SEP>
<tb><SEP> to <SEP> 1000C <SEP> 5.6 <SEP> 3.9 <SEP> 4.5 <SEP> 3.2
<tb><SEP> to <SEP> 400C <SEP><SEP> 9.3 <SEP> 5.1 <SEP> 6.8 <SEQ> 4.2
<tb> Acidity <SEP> in <SEP> end <SEP> assay <SEP> 2.6 <SEP> 1.1 <SEP> 0.7 <SEP> 0.6
<tb><SEP> (mg <SEP> NOH / g) <SEP>
<tb> Insoluble <SEP> (ro <SEP><SEP> mass) <SEP> 0.22 <SEP><SEP> 0.07 <SEP> 0.05 <SEP> 0 * 14 <SEP>
<Tb>
EXAMPLE 14
This example shows the behavior of the product VIII of Example 6 as a stabilizing agent against the thermooxidation of polyolefins. The method consists in measuring the inhibition time of the exothermic oxidation reaction in the presence of oxygen. 2100C. After mixing on Haake mixer
Rheocord EUS at 1800C for 5 minutes at 32 revolutions / minute of a medium density virgin polyethylene (d = 0.948) with the product VIII, the induction time of the mixture is measured by differential thermal analysis under oxygen at 2100C. Comparative tests are carried out with commercial products.

 The results obtained are shown in Table 4.

Table 4

<tb><SEP> Content <SEP> time <SEP> induction
<tb> Antioxidant <SEP> Antioxidant <SEP> to <SEP> 2100C
<tb><SEP> (ppm) <SEP> (min)
<tb> Trimethyl-1,3,5 <SEP> Tris-2,4,6
<tb>(<SEP> ditert <SEP> .butyl-3,5 <SEP><SEP> 4-hydroxybenzyl) <SEP> 1250 <SEP> 16
<tb> benzene
<tb> Pentaerythrityl <SEP> tetrakis
<tb> [3 <SEP> (ditert.butyl-3,5 <SEP> hydroxy- <SEP> 1250 <SEP> 17
<tb> phenyl-4) <SEP> propionate
<tb> Product <SEP> VIII <SEP> 1250 <SEP> 17
<Tb>

Claims (7)

 in which R 1 and R 2 are alkyl groups of 1 to 8 carbon atoms R 3 is an alkyl group of 1 to 20 carbon atoms, a cycloalkyl group of 5 to 19 carbon atoms, a phenyl or naphthyl group, optionally substituted by a or several allyl groups of 1-20 carbon atoms. or an alkyl group of 7-20 carbon atoms, n is a number from 1 to 5.

 CLAIMS 1 - Phenolic sulfur compound of general formula  2 - A compound according to claim 1, wherein at least one of R1 and R2 is a tert.butyl group. 3 - Compound according to one of claims 1 and 2 characterized in that it is selected from 3-methyl-tert.butyl-4-hydroxy-4-benzyl tert.butylthioether. 5-methyl-5-tert-butyl-4-hydroxy-isobutylthioether, ditert-but-3,5-hydroxy-4-benzyl tert-butylthioether, 3,5-ditert-butyl-4-hydroxy-benzyl phenylthioether, ditertylbutyl- 3,5-hydroxy-4-benzyl benzylthioether, 3,5-ditert-butyl-4-hydroxy-benzyl tert.nonylthioether, 3-methyl-5-tert.butyl-4-hydroxy-benzyl tert.butyldisulphide, 3,5-ditert-butyl-hydroxyethyl 4 benzyl benzyldisulphide, ditert butyl 3,5-hydroxy-4-benzyl tert.nonyl disulphide, ditert.b # tyl-3,5-hydroxy-4-benzyl tert.butyltrisulfide, 3,5-ditert-butyl-4-hydroxy benzyl isobutyltrisulfide and the 3,5-butyl-4-hydroxy-benzyl benzyltrisulfide.  4 - Process for the preparation of a phenolic compound according to one of revendi cations 1 to 3, wherein is reacted a 4-halomethyl-2,6-dialkyl phenol of formula

 where X is a halogen and R1 and R2 are defined as in formula (I), with a mercaptate of formula R3-S-M + or a mercaptate-polysulfide of formula R3-S M +, where R3 is defined as in formula ( I), M is an alkali metal and n is a number from 1 to 5. 5 - Use of a phenolic compound according to one of claims 1 to 3 as an antioxidant additive for organic compounds. 6 - Use according to claim 5 in a hydrocarbon lubricating oil. 7 - Use according to claim 5 in an organic polymer.