CA1106852A - Benzofuranylphenol stabilizers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Novel benzofuranylphenols are provided and in particular 2-(5-t-butyl-3-benzofuranyl)-4-t-butylphenol;
2-(5,7-dimethyl-3-benzofuranyl)-4,6-dimethylphenol, 2-(5,6-dimethyl-3-benzofuranyl)-4,5-dimethylphenol; 2-(4,6-di-methyl-3-benzofuranyl)-3,5-dimethylphenol; 2-(5,7-di-t-butyl-3-benzofuranyl)-4,6-di-t-butylphenol and 2-(5-methylthio-6-methyl-3-benzofuranyl)-4-methylthio-5-methylphenol; the novel compounds are useful as stabilizers in a wide variety of organic materials, against the deleterious effects of oxygen, heat and visible or ultra-violet light; they may be used as non-staining stabilizers for dienic polymers and styrene-acrylonitrile copolymers.

Description

111P6~S2 This invention relates to novel benzofuranylphenols.
This application is a division of Canadian Patent Application S.N. 251,889, filed April 22, 1976.
Several benzofuranylphenols are described in the prior art without discussion of utility. For example, Coxsworth, 45 Can. J. Chem. 1777 (1967), teaches preparation of 2-(5-methyl-3-benzofuranyl)-4-methylphenol and 2-(5-methyl-7-t-butyl-3-benzofuranyl)-4-methyl-6-t-butylphenol. Coxworth, 44 Can. J. Chem. 1092 (1966), teaches preparation of chlori-nated 2-(3-benzofuranyl)phenols. New stabilizers and new stabilized organic compositions are desired.
Some benzofuranylphsnols are effective stabilizers of a wide variety of organic materials against the deleter-ious effects of oxygen, heat and visible or ultraviolet light.
The benzofuranylphenols are especially useful as nonstaining stabilizers for dienic polymers and styrene-acrylonitrile copolymers. Benzofuranylphenols suitable for use as such stabilizers have the formula Y ~Y

wherein each X and Y may be hydrogen, halogen, hydroxyl, or an alkyl, alkoxyl or alkylthio group containing from 1 to 8 carbon atoms, but if any X is an alkyl, alkoxyl or alkylthio group, then at least one Y must also be an alkyl, alkoxyl or alkylthio group. Also suitable are the products of a process comprising (1) reacting glyoxal with a dihydroxy-lated compound in the prese~ of an acidic catalyst, the dihydroxylated compound having the formula 5~

~H OH

[~M

M

wherein each M is hydrogen, halogen or an alkyl group con-taining 1 to 8 carbon atoms, and (2) thereafter hydrolyzing the step (1) reaction product with an acidic or basic .
catalyst.
The present invention is particularly concerned with novel benzofuranylphenols of the above.~formula and in particular 2-(5-t-butyl~3-benzofuranyl)-4-t-butylphenol, 2-(5,7-dimethyl-3-benzofuranyl)-4,6-dimethylphenol; 2-(5,6-dimethyl-3-benzofuranyl)-4,5-dimethylphenol; 2-(4,6-di-methyl-3-benzofuranyl)-3,5-dimethylphenol; 2-(5,7-di-t-butyl-3-benzofuranyl)-4,6-di-t-butylphenol and 2-(5-methyl-thio-6-methyl-3-benzofuranyl)-4-methylthio-5-methylphenol.
, . ~ In another aspect of the invention there is provided a stabilized composition comprising (a) 100 parts by weigh* of an organic material subject to the deleterious effects of oxygen, heat and light and (b) from about O.l parts to about 10 parts by weight of at least one compound of the ! invention as set forth in the preceding paragraph.
~ .

.

.

~, .
: - 2 -., . ~ , . ~ .

-Preferred benzofuranylphenols for use as stabilizers include those of the above formula in which each X and Y is hydrogen, bromo, chloro, hydroxyl or an alkyl or alkylthio group containing from 1 to 8 carbon atoms, but if any X is an alkyl or alkylthio group, then at least one Y must also be an alkyl or alkylthio group, . Even-more preferably each X and Y is hydrogen, hydroxyl or an alkyl or alkylthio group containing from 1 to 4 carbon atoms, ~?6~352 but if any X is an alkyl or alkylthio group, then at least one Y must also be an alkyl or alkylthio group. Examples of suit-able benzofuranylphenols include 2-(6-methyl-3-benzofuranyl)-5-methylphenol, 2-(5-methyl-3-benzofuranyl)-4-methylphenol,

2-(5-t-butyl-3-benzofuranyl)-4-t-butylphenol~ 2-(5-methyl-7-t-butyl-3-benzofuranyl)-4-methyl-6-t-butylphenol, 2-(5-t-butyl-7-methyl-3-benzofuranyl)-4~butyl-6-methylphenol, 2-(5,7-dimethyl-3-benzofuranyl)-4,6-dimethylphenol, 2-(4,7-dimethyl-3-benzofuranyl)-3,6-dimethylphenol, 2-(5,6-dimethyl-3-benzofuranyl)-4,5-dimethylphenol, 2-(4,6-dimethyl-3-benzo-furanyl)-3,5-dimethylphenol, 2-(5,7-di-t-butyl-3-benzofuranyl)-4,6-di-t-butylphenol, 2-(5-methylthio-6-methyl -3-benzofuranyl)-4-methylthio-5-methylphenol and the like. The reaction products of hydroquinone or 4-t-butyl catechol with glyoxal by the process described herein, are also suitable. Excellent results were obtained using 2-(5-methyl-3-benzofuranyl)-4-methylphenol, 2 (5-t-butyl-3-benzofuranyl)-4-t-butylphenol, 2-(5,7-dimethy1-3-benzofuranyl)-4,6-dimethylphenol, 2-(5,6-dimethyl-3-benzofuranyl)-4,5-dimethylphenol, 2-(4,6-dimethyl-

3-benz~furanyl)-3,5-dimethylphenol, 2-(5,7-di-t-butyl-3-benzofuranyl)-4,6-di-t-butylphenol, 2-(5-methyl-7-t-butyl-3-benzofuranyl)-4 methyl-6-t-butylphenol, and 2-(5-methylthio-6-methyl-3-benzofuranyl)-4-methylthio-5-methylphenol.
Excellent results were also obtained using the reaction products of hydroquinone or 4-t-butyl catechol with glyoxal described herein. In contrast, 2-(7-methyl-3-benzofuranyl)-6-methylphenol is not covered by the above formula and was found to be an ineffective antioxidant. Suitable benzofuranyl-phenols may be used in an amount from about 0.1 to about 10 parts by weight, more preferably from about 0.5 part to about 5 parts by weight, per 100 parts by weight of organic material to be stabilized.

-4-..
.

Benzofuranylphenols are produced by first reacting glyoxal with a phenol in the presence of an acidic catalyst at a temperature from about 0C to about 100C, more preferably from about 0C to about 50C. An acetal is formed during the first step of the reaction, with acetal yield decreasing substantially if reaction temperature is above 50C during the first step. After acetal formation is completed the second reaction step is performed. Water may be added to the reaction mixture, and the mixture is refluxed in order to hydrolyze the acetal and form a benzofuranylphenol . Alterna-tively, a solld acetal may be separated from the reaction mixture by filtration in some cases and the acetal thereafter hydrolyzed by refluxing in the presence of an acid or base catalyst.
Phenols used in the above process pre~erably have one unsubstituted position ortho to a hydroxyl group, but certain groups such as t-butyl and the like may occupy an ortho position and are displaced during acetal formation if the other ortho position is occupied by another substituent.
Suitable phenols for use in the above process include m-cresol, p-cresol, 4-ethylphenol, 4-n-propylphenol, 4-t-butyl-phenol, 2-methyl-4-t-butylphenol, 2-t-butyl-p-cresol, 2,4-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-di-t-butylphenol, 2,4-di-t-pentyl-phenol, 2,6-di-t-butyl-4-methylphenol, 4-(methylthio)-m-cresol, 4-chloro-3-methylphenol and the like. Excellent results were obtained using p-cresol, 4-t-butylphenol, 2,4-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2-t-butyl-p-cresol, and 4-(methy~thio)-m-cresol. In contrast, o-cresol was used to produce 2-(7-methyl-3-benzo~uranyl)-6-methylphenol, which was an unsatisfactory stabilizer and not within the scope of the formula given heretofore.

, . ' . .

~68S2 Furthermore, Bisphenol A was reacted with glyoxal by the process of this invention to form a product which was an unsatisfactory stabilizer and not within the scope of the formula given heretofore.
Also suitable as phenolic starting materials for the process described herein are dihydroxylated compounds having the formula - ~H
OH

+ M
~ M
wherein each M may be hydrogen, halogen or an alkyl group containing 1 to 8 carbon atoms. More preferably each M
may be hydrogen or an alkyl group containing 1 to 4 carbon atoms. The process comprises (1) reacting glyoxal with a dihydroxylated compound in the presence of an acidic catalyst and (2) thereafter hydrolyzing the step (1) reaction product with an acidic or basic catalyst. Products of the process just described may be the benzofuranylphenols described heretofore. However, complex polymeric benzofuranylphenols tend to form because of the presence of several reactive hydroxyl groups in each dihydroxylated compound molecule.
Examples of suitable dihydroxylated compounds include hydro-quinone, catechol, resorcinol, 4-t-butyl catechol and the like.
Excellent results were obtained using hydroquinone and 4-t-butyl catechol.
The glyoxal may be used in the anhydrous form but the commercial aqueous solutions of glyoxal are more prefer-ably used. Derivatives of glyoxal which can generate glyoxal in situ may also be used, such as glyoxal NaHS04. The ~68S2 glyoxal may be used in a molar ratio to the phenol from about 1/10 to about 10/1. More preferably, the ratio is about 1/2.
Acids which may be used to catalyze the reaction of glyoxal with phenols to form acetals include organic acids containing l to 12 carbon atoms SUCil as acetic acid, propionic acid, benzoic acid, monoesters and diesters of orthophosphoric acid, alkaryl sulfonic acids such as p-toluenesulfonic acid, and the like; inorganic acids capable of releasing protons such as boric acid, hydrochloric acid, phosphoric acid, sulfur-ic acid and the like; acid activated clays capable of releas-ing protons such as Retrol (produced by Filtrol Corp.), benton-ite and the like; acidic resins capable of releating protons such as Dowex 50-X10 ~a cationic exchange resins which is a sulfonated copolymer of styrene and divinylbenzene and is produced by Dow Chemical Conpany) and the like; and Lewis acids capable of accepting electrons such as aluminum chloride, zinc chloride, boron trifluoride and the like. me amount of acid catalyst used may be as little as about 0.01% based on total reactant weight, or the catalyst may be used as the solvent in which the reaction is run. Mixtures of acids may also be used. Excellent results were obtained using mixtures of acetic acid and sulfuric acid, zinc chloride and hydro-chloric acid, and p-toluenesulfonic acid and acetic acid.
The acids described above may also be used at higher temperature to catalyze hydrolysis of the acetal in the second reaction step, thereby forming benzofuranyl-phenols. Bases may be used in place of acids in the second reaction step. Suitable bases include inorganic bases such as sodium hydroxide, potassium hydroxide and the like.
Excellent results were obtained using potassium hydroxide.
Acetic acid is a preferred solvent for these reactions because of its availability, boiling point, water * trademark 7 1~1D685~: `

miscibility, ability to dissolve a wide variety of phenols, and catalytic effect on the reaction. The reaction may also be run in other solvents which include carboxylic acids s~Lch as o-toluic acid, esters such as n-butyl acetate, ethers such as bis[2-(2-methoxyethoxy)ethyl]ether, alcohols such as l-pentanol, ketones such as benzophenone, and the like. The réaction may also be run in a two-phase system where one reactant is soluble in one phase and the other reactant is soluble in a second phase, such as a hydrocarbon and water system. An emulsifying agent may be u~ed to facilitate the reaction in the two-phase system.
A preferred method for producing benzofuranylphenols compr~ises mixing glyoxal and a phenol with a major amount of acetic acid and a minor amount of sulfuric acid. The reaction mixture is stirred and cooled below 30C for about one to three hours. After that time, the temperature is raised to about 50C, and the reaction is continued for about 0.5 to three more hours in order to complete acetal formation.
The second reaction step is performed by adding water to the acetal reaction mixture and heating it to reflux temperature.
After about one to five hours the acetal is acid-hydrolyzed substantially to a benzofuranylphenol.
Another preferred method for performing the second reaction step (hydrolysis) comprises separating a solid acetal from the reaction mixture by filtration, mixing the acetal with water and an acid or base, and ac~d-hydrolyzing or base-hydrolyzing the acetal to a benzofuranylphenol.
Refluxing is generally required for acidic hydrolysis, but basic hydrolysis can be performed by simply warming the mixture to be hydrolyzed at about 50 - 100C in a dimethyl sulfoxide solution.
The benzofuranylphenol product may be separated from the hydrolysis mixture ~y any of ceveral methods. If the product is a solid it can be filtered and optionally washed with a solvent such as hexane or water. If the product is an oil it can be extracted with an aromatic solvent such as benzene. If acidic hydrolysis is used, the extract can be washed with a weak base or a basic salt solution such as ~a2C03 in water. If basic hydrolysis is used, the extract can be washed with a weak acid or an acidic salt solution in water such as (NH4)2S04 in water. The extract can then be distilled to obtain a substantially pure benzofuranylphenol.
Benzofuranylphenols within the scope of the formula recited heretofore are effective stabilizers of a wide variety of organic materials against the deleterious effects of oxygen, heat and visible or ultraviolet light.
The benzofuranylphenols are nonstaining stabilizers of both natural and synthetic polymers, such as uncured and vulcanized dienic polymers. The dienic polymers are sulfur-vulcanizable and m~y cont~in about 0.5% to a~)out 50~0 by weight of olefinic (~C=C<) unsaturation based upon total polymer weight.
The olefinic groups may be in the polymeric main chain (back-bone) or in pendant (side-chain) groups, or both. Examples of suitable dienic polymers include polymers such as natural rubber, cis-polyisoprene, cis-polybutadiene (CB), acrylonitrile-butadiene-styrene copolymers (ABS), butadiene-acrylonitrile rubbers (NBR), isoprene-acrylonitrile rubbers, polyisobutylene, polychloroprene, butadiene-styrene rubbers (SBR), isoprene-styrene rubbers and the like. Also suitable are polymers such as isoprene-isobutylene (butyl) rubbers, copolymers of conjugated dienes with lower alkyl and alkoxy acrylates such as ethyl acrylate, butyl acrylate, methoxyethyl acrylate and the like, and ethylene-propylene-diene polymers _9 '~ , ~1~6852 (EPDM) containing from about 0.5 percent to about 20 percent by weiF~ht of at least one dienic termonomer. ~ultable ~.PI)M
dienic termonomel~s include conjugated dienes such as butadiene, 1,3-pentadiene, and the like; nonconjugated dienes such as 1~4-pentadiene, 1,4-hexadiene, and the like; cyclic dienes such as cyclopentadiene, dicyclopentadien~ and the like; and alkenyl norbornenes such as 5-ethylidene-2-nor-bornene and the 11ike.
The dienic polymers may be ~ulcanized by methods known to the art. Suitable vulcanizing agents include elemental sulfur and compounds capable of yielding elemental ,~ sulfur such as tetramethylthiuram disulfide, tetraethylthi-uram disulfide, dipentamethylenethiuram hexasulfide, and the like.
A broad ran~e of compounding ingredients can be used in the dienic polymer vulcanizates, including sulfur-containing and nitrogen-containing accelerators. Examples of suitable accelerators include metal salts of dialkyl, diaryl and alkaryl dithiocarbamates, such as bismuth, copper, lead and zinc dimethyl dithiocarbamates, cadmium, selenium, tellurium and zinc diethyl dithiocarbamates, sodium and zinc dibutyl dithiocarbamates, zinc ethyl phenyl dithio-carbamate, zinc dibenzyl dithiocarbamate, and the like;
other dithiocarbamates such as piperidinium pentamethylene dithiocarbamate, N-cyclohexylethyl ammonium cyclohexylethyl dithiocarbamate, N-pentamethylene-ammonium-N-pentamethylene dithiocarbamate, and the likej benzothiazoles such as 2-mercaptobenzothiazole and the zinc salt thereof, 2,2'-benzothiazyl disulfide, 2-morpholinothiobenzothiazole, 3~ 2-(2,(-(limethyl-4-morpholinothio)benzotlliAzole and the Like;
I-enzothiazole-sulfenamides such as N-diethyl-2-benzottliazyl sulfenamide, N-t-butyl-2-benzothiazole sulfenamide, N-cyclo-g~ 68sZ

hexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzo-thia.zole sulfenamide and the like; thiuram sulfides such as tetramethyl thiuram disulfide, tetraethyl thirlram llisull`:ide, dimethyl diphenyl thiuram disulfide, dipentalnet}lylenc thiuram hexasulfide and the like; thioureas such as ethylene thiourea, trimethyl thiourea, N,N'-diethyl thiourea, N,N'-dibutyl thio'urea, N,N'-diphenyl thiourea, and the like; morpholines such as 4,4'-dithiomorpholine and the like; polyamines such as triethylene diamine, hexamethylene tetraamine, tricreto-nylidene tetraamine, and the like; aldehyde-amine condensa-tion products such as acetaldehyde-ammonia, heptaldehyde-ammonia, butyraldehyde-aniline, and the like, imidazolines such as 2-mercaptoimidazoline, and the like, and guanidines such as diphenyl guanidine, di-o-tolyl guanidine, and the ].ike. Excellent results were obtained using 2-morpholino-thiobenzothiazole.
Benzofuranylphenols within the scope of the formula recited heretofore are also effective nonstaining antioxi-dants in styrene-acrylonitrile copolymers. Suitable copolymers for use in the compositions of this invention contain polymer-ized therein (l) from about 50% to about 90% by weight based upon total copolymer weight of styrene, or at least one alkyl styrenc~ alkoxy :;tyrene or halostyrenc, r ~ lixt;~lle thereof, wherein the alkyl or alkoxy group contains from 1 to 8 carbon atoms, (2) from about lO~ to about 50% by weight based upon total copolymer weight of at least one vinyl nitrile having the formula ,R
CH2=C-C_N
wherein R is hydrogen or an aIkyl radical containing from 1 to 3 carbon atoms, and (3) from 0~ to about 20% by weight based upon total copolymer weight of at least one other 85;~

monoolefin. Preferred alkyl styrenes are those wherein an aIkyl ~roup contains from 1 to 6 carbon atoms, more prefer-ably from 1 to 4 ca~bon atoms. Preferred alkoxy styrenes are those wherein an alkoxy group contains from 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms. Preferred halostyrenes are those ~herein a halogen group is chloro or bromo. Examples of suitable alkyl styrenes, alkoxy styrenes and halostyrenes include methyl styrene, ethyl styrene, methoxyethylstyrene, chlorostyrene, dichlorostyrene, and the like. F~mples of suitable vinyl nitriles include acrylonitrile, methacrylonitrile, ethacrylonitrile, and the like. Excellent results were obtained using copolymers of styrene and acrylonitrile.
Other compounding ingredients usable in the dienic pol~mer compositions and styrene-acrylonitrile copolymers include fillers such as carb`on blacks, calcium and magnesium carbonates, caIcium and barium sulfates, aluminum silicates, silicon dioxide, phenol-formaldehyde and polystyrene resins, asbestos, and the like; plasticizers and extenders including dialkyl and diaryl acid esters such as diisobutyl, diiso-octyl, diisodecyl and dibenzyl oleates, stearates, sebacates, azelates, phthalates, and the like~ and naphthenic and paraffinic oils, castor oil, tall oil and the like; and antioxidants, antiozonants and stabilizers such as di-~-naphthyl-p-phenylenediamine, phenyl-~-naphthylamine, N,N'-di-~2-octyl)-p-phenylenediamine, 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 2,6-di-t-butyl-p-cresol, 2,2'-thiobis(4-methyl-6-t-butylphenol), distearyl thiodipropion-ate, dilauryl thiodipropionate, 2,4-bis(4-hydroxy-3,5-t-butyl-phenoxy)-6-(n-octylthio)-1,3,5-triazine, tetrakis methylene 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate methane, 4-isopropylamino diphenylamine, tri(nonylated phenyl)phosphite, ~ 68~2 and the like, Other compounding ingredients may also be used, such as pigments, tackifiers, flame retardants, fungicides, and the ]ike.
In addition to polymeric materials, the present benzo-furanylphenols act to stabilize a wide variety of other organic materials. Such materials include: waxes' synthetic and petroleum-derived lubricating oils and greases, animal oils such as fat, tallow, lard, cod-liver oil, sperm oil and the like; vegetable oils such as castor, linseed, peanut, palm, cotton seed and the like; fuel oil; diesel oil; gasoline, and -the like.
The following examples illustrate the present invention more fully.

EXAMPLE 1 - Preparation of 2-(7-methyl-3-benzo-furanyl)-6-methylphenol o-cresol (44 g. or 0.4 mole), 40% aqueous glyoxal (30 g. or 0.2 mole), and acetic acid (200 ml.) were mixed together. Concentrated sulfuric acid (80 ml. or 1.5 mole) was added to the reaction mixture with stirring over a 60-minute period. The mixture was stirred for a total of about3 hours with cooling as needed to keep reaction temperature at about 30C. The mixture was heated thereafter to 50C and stirred for about 1 hour. Water (100 ml.) was added and the mixture refluxed for about 1.5 hours. The mixture then was cooled and poured into 2 liters of water, and a solid was separated therefrom. The solid was filtered and washed first with water and then with 0.1 normal Na2CO3 solution in water.
The product weighed 44 g. The 2-(7-methyl-3-benzofuranyl)-6-methylphenol was found to be an unsatisfactory stabilizer in a vulcanized rubber composition.

_ 13 -.

. :

6~S2 EXAMPLE 2 - Preparation of 2-(5-methyl-3-ben~o-fu ranyl)-4-methylphenol p-cresol (86.4 g. or o.8 mole), 40% aqueous glyoxal (80 g. or 1.4 mole), and acetic acid (200 ml.) were mixed together. Concentrated sulfuric acid (80 ml.) was added to the reaction mixture with stirring over a 60-minute period.
The mixture was stirred for a total of about 3 hours with cooling as necessary to keep reaction temperature at about 30C. The mixture was then allowed to stand overnight.
The acetal intermediate formed and was a solid. It was collected by filtration, washed with 400 ml. of water, and allowed to dry. It weighed 90 g. (95~ yield based on p-cresol) and melted at 150-165C. This solid was dissolved in 200 ml.
of acetic acid, 10 ml. of water, and 2 ml. of concentrated sulfuric acid. This solution was refluxed for 2 hours, cooled and neutrali~ed with a solution of 4 g. of sodium hydroxide in 10 ml. of water. The solvents were distilled to give 77 g. of a black viscous oil. This oll was distilled to give a light yellow oil(~.p. 120-145C/0.5 mm ).

EXAMPLE 3 - Preparation of 2-(5-t-butyl-3-benzo-furanyl)-4-t-butylphenol 4-t-Butylphenol (60 g. or 0.4 mole ), 4S~ aqueous glyoxal (30 g. or 0.2 mole), and 200 ml. of acetic acid were mixed together. Concentrated sulfuric acid (80 ml.) was slowly added (1 hour at 30C), and the mixture was stirred for another ? hours at 30C and thereafter heated to 50C
for 0.5 hour. ~00 ml. of water was added and the mixture was refluxed for 1.5 hours, cooled, poured into 1.5 liters of water, and the product separated. The oily product was washed with O.lN Na2C03 solution.

sz EXAMPLE 4 - Preparation of 2-(5-t-butyl-7-methyl-3-benzofuranyl)-4-t-butyl-6-methyl-phenol 2-Methyl-4-t-butylphenol (~4 g. or 0.4 mole) and acetic acid (200 ml.) were mixed together. Concentrated sulfuric acid (80 ml.) was added to the reaction mixture with stirring over a 60-minute period. The mixture was stirred for a total of about 2 hours with cooling as needed to keep reaction temperature at about 30C. The mixture was - 10 heated thereafter to 50C and stirred for about 0.5 hour.
Water (lO0 ml) was added and the mixture refluxed for about l.5 hours. The mixture then was cooled and pured into 1.5 ! - liters of water, and a black oil was separated therefrom.
The oil was washed with a 0.1 normal Na2C03 solution in water~
and unreacted 2-methyl-4-t-butylphenol was removed by dis-tillation. The product weighed 76 g. The product's IR
8pectrum was consistent with the assigned structure of 2-(5-t-butyl-7-methyl-3-benzofuranyl?-4-t-butyl-6-methyl-phenol.
PLE 5 - Preparation of 2-(5,7-dimethyl-3-benzo-- furanyl)-4,6-dimethylphenol 2,4-Dimethylphenol (49 g. or 0.4 mole), 40%
aqueous glyoxal (29 g. or 0.2 mole), and acetic acid (250 ml.) were stirred together and 80 ml. of concentrated sulfuric acid added in 1 hour. The reaction temperature was maintained between 20 - 30C by cooling during the addition.
The temperature was raised to 50C for 1 hour. The mixture was cooled, fiItered~ and washed with water to separate an acetal intermediate, which was refluxed for 4 hours with 250 ml. of acetic acid and 5 ml. of concentrated hydrochloric acid. The cool reaction mixture was poured into 1.5 liters of water and the oil separated. It weighed 32 g., and its IR spectrum was consistent with the assigned structure of ; 2-(5,7-dimethyl-3-benzofuranyl)-4,6-dimethylphenol.

"' ' ' ~61352 EXAMPLE 6 - Preparation of 2-(5-methyl-7-t-butyl-3-benzofuranyl)-4-methyl-6-t-butylphenol A mixture of zinc chloride (3 g.), 2-t-butyl-p-cresol (65.7 g. or 0.5 mole), and 30~ aqueous glyoxal (20 g. or 0.5 mole), and 30~ aqueous glyoxal (20 g. or 0.1 mole) was stirred and gaseous HCl bubbled into the mixture for 0.5 hour. The temperature was kept below 35C by cooling. The mixture stood overnight, after which HCl was bubbled through the mixture for 3 hours more with the temperature maintained between 10 - 20C by cooling.
A light gray solid formed. This solid was filtered and washed first with water and then O.lN Na2C03 solution.
The white solid melted at 188 - 192C and was the acetal described in U.S. Patent 2,515,909. The acetal, weighing 11 g., was slurried in 100 ml. of dimethylsulfoxide. A solu-tion of potassium hydroxide (10 g.), ethanol (100 ml.), and dimethylsulfoxide (100 ml.) was added directly to the acetal slurry. This mixture was heated to reflux under nitrogen for 4 hours. The mixture was poured into 1 liter of water which contained 15 ml. of concentrated hydrochloric acid.
A solid formed and was collected by filtration and washed with water. It weighed 9 g. and melted at 132 - 134C.
Its paramagnetic resonance and IR spectra were consistent with the assigned structure of 2-(5-methyl-7-t-butyl-3-benzofuranyl)-4-methyl-6-t-butylphenol.
EXAMPLE 7 - Preparation of 2-(5,6-dimethyl-3-benzo-furanyl)-4,5-dimethylphenol To a mixture of 3,4-dimethylphenol (62 g. or 0.5 mole), 40~ aqueous glyoxal (23 g. or 0.15 mole 3, and acetic acid (200 ml.), was slowly added (0.5 hour) 30 ml. of con-centrated sulfuric acid. The mixture was stirred at 50C

.
.

for 2 hours, cooled, and poured into 1.5 liters of water to give 44 g. of a solid acetal. 40 g. of this acetal was slurried in 250 ml. of dimethylsulfoxide, and a solution of 40 g. of potassium hydroxide in 250 ml. of methanol and 250 ml. of dimethylsulfoxide was added. This mixture was refluxed for 2 hours, cooled, poured into 2 liters of water, and extracted with benzene. The benzene was removed by distillation to give 44 g. of a dark oil. Its IR spectrum was consistent with the assigned structure of 2-(5,6-dimethyl-3-benzofuranyl)-4,5-dimethylphenol.
EXAMPLE 8 - Preparation of 2-(4,6-dimethyl-3-benzo-furanyl)-3,5-dimethylphenol A stirred mixturé of 3,5-dimethylphenol (25 g. or 0.2 mole), 40% aqueous glyoxal (15 g. or 0.1 mole) and acetic acid (150 ml. ? was maintained at 30C while 15 ml. of concen-trated sulfuric acid was added in 0.5 hour. The mixture was stirred 2 hours more at room temperature and then at 50C
for 0.5 hour. Water (35 ml.) was added and the mixture refluxed for 1.5 hours. It was cooled and poured into 1 liter of water to give 18 g. of a black solid . The solid was separated by filtration and had an IR spectrum consistent with its structural assignment of 2-(4,6-dimethyl-3-benzo-furanyl)-3,5-dimethylphenol.
EXAMPLE 9 - Preparation of 2-(5,7-di-t-butyl-3-benzofuranyl)-4~6-di-t-butylphenol A mixture of 2,4-di-t-butylphenol (82 g. or 0.4 mole), 40% aqueous glyoxal (30 g. or 0.2 mole), and acetic acid (400 ml.) was treated with 80 ml. of concentrated sulfuric acid while maintaining the temperature at 30C.
After 2 hours, the solid was collected by filtration.
Vapor phase chromatography showed that it was 30~ starting phenol and 70~ acetal. The phenol was removed by washing 6~S2 with methanol. The substantially pure acetal remained, melted at 236-238C, and weighed 51 g. This acetal (30 g.) was dissolved in 100 ml. of benzene and 200 ml of dimethylsulfox-ide. The acetal solution was treated with a solution of 20 g.
of potassium hydroxide in 200 ml. of methanol and 200 ml. of dimethylsulfoxide. This mixture was refluxed for 2 hours, cooled, poured into 1 liter of water, acidified with concen-trated hydrochloric acid and extracted with ether. The ether extract was washed with water and distilled to give 34 g. of a yellow oil (b.p.220C/ 1 mm ). Its VPC and IR spectra were consistent with the assigned structure of 2-(5,7-di-t-I butyl-3-benzofuranyl)-4,6-di-t-butylphenol.
EXAMPLE 10 - Preparation of 2-(5-methylthio-6-methyl-3-benzofuranyl)-4-methylthio-5-methyl-phenol A mixture of 4-(methylthio)-m-cresol (31 e or 0.2 mole), 40~ aqueous glyoxal (15 g. or 0.1 mole), and 150 ml.
of acetic acid was treated with 15 ml. of concentrated sulfuric acid while maintaining the temperature below 30C for 2 hours.
Temperature was raised thereafter to 50C for 0.5 hour, 30 ml-of water was added to the mixture, and it was refluxed for 1.5 hours, cooled, and poured into 1 liter of water.
An oil was separated and washed with a 0.lN Na2C03 solution to yield 2-(5-methylthio-6-methyl-3-benæofuranyl)-4-methyl-thio-5-methylphenol.
EXAMPLE 11 - Reaction of hydroquinone and glyoxal, followed by hydrolysis A mixture of hydroquinone (66 g. or 0.6 mole), 40 aqueous glyoxal (90 g. or o.6 mole), and 500 ml. of acetic acid was treated with 60 ml. of concentrated sulfuric acid while maintaining the temperature at 30C for 2 hours.
The mixture was then heated for 2 hours at 40 - 50C., poured into 2 liters of water, ~iltered, washed with O.lN Na2C03, and dried to yield 62 g. of a gray solid acetal. This acetal (25 g.) was stirred with 100 ml. of dimethylsulfoxide. To th~is mixture was added a solution of 25 g. of potassium hydroxide, 200 ml. of methanol, and 200 ml. of dimethylsulf-oxide. A dark brown ~ixture resulted and was stirred and re~luxed for 4 hours. It was poured into 2 liters of water and acidified with concentrated hydrochloric acid. A black resin was collected by filtration and washed with O.lN
Na2C03. The resin's IR spectrum was consistent with a polymeric benzofuranylphenol structure.
EXAMPL~ 12 - Reaction of 4-t-butyl catechol and glyoxal, followed by hydrolysis A mixture of 4-t-butyl catechol ~32.3 g. or 0.2 mole) 40/' aqueous glyoxal (15 g. or 0.1 mole) and acetic acid (150 ml.) was treated with 15 g. of concentrated sulfuric acid while maintaining the temperature at 30C for 2 hours.
The mixture was then heated for 0.5 hour at 50C, poured into 35 ml. water and stirred and refluxed for 1.5 hours.
The mixture was cooled and poured into 1 liter of water .
- 20 A black oil formed and was extracted with benzene and washed with a O.lN Na2C03 solution. The extract was distilled to give 21 g. of product.

.
Examples 13 - 31 demonstrate stabilizing properties of benzofuranylphenols in cured rubber vulcanizates. A master-batch was prepared by mixing the following materials in a banbury mixer:
TABLE I
MaterialsParts by Wei~ht Ribbed Smoked Sheet100.0 Natural Rubber HAF Carbon Black 50.0 Zinc Oxide 5.0 Stearic Acid 3.0 Sulfur 2.5 160.5 -lg~
'~
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6~i2 In each example, 176 g. of the masterbatch described in Table I was compounded and cured with 1.1 gram of 2-morpholinothiobenzothiazole accelerator and 1.1 gram of a given stabilizer. The compounding and curing procedure was as follows. A 4-inch, 2-roll mill was heated to 160F
and each ingredient was charged to the mill in the order listed, with thorough milling between each addition.
Each milled rubber composition was sheeted off the mill and cut into approximate 6 in. x 6 in. x 0.090 in. sections.
The sections were wrapped separately in aluminum foil and cured for 35 minutes at 302F.
Physical testing of the vulcanizates was performed, and the results are set forth in Tables II, III and IV.
300~ modulus, tensile strength and ultimate elongation were determined according to ASTM D412-68 using Die C dumbbells.
Test tube aging was performed according to ASTM Do65-62 for 24 hours at 100C. Crack Growth Test results in Table II
were measured using the B.F.Goodrich Rotating Ring Crack Growth Test described in 38 Rubber Chemistry & Technology 714 (1965). Standard conditions used for the latter test were 70C., 3 lbs. load and 300 cycles/minute.
The data in Tables II, III and I~ indicates that thc benzofuranylphenols tested have stabilizing properties as good as or better than control stabilizers when tested in cured rubber vulcanizates.

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Examples 35 - 42 demonstrate stabilizing properties of benzofuranylphenols in a styrene-acrylonitrile (SAN) copolymer composition. The SAN copolymer contained about 30~ by weight acrylonitrile based upon total copolymer weight and had a weight-average molecular weight of about 118~000 and a number-average molecular weight of about 51,000.
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Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A compound selected from the group consisting of (a) 2-(5-t-butyl-3-benzofuranyl)-4-t-butylphenol, (b) 2-(5,7-dimethyl-3-benzofuranyl)-4,6-dimethylphenol, (c) 2-(5,6-dimethyl-3-benzofuranyl)-4,5-dimethylphenol, (d) 2-(4,6-dimethyl-3-benzofuranyl)-3,5-dimethylphenol, (e) 2-(5,7-di-t-butyl-3-benzofuranyl)-4,6-di-t-butylphenol and (f) 2-(5-methylthio-6-methyl-3-benzofuranyl)-4-methylthio-5-methylphenol.

2. 2-(5-t-Butyl-3-benzofuranyl)-4-t-butylphenol.

3. 2-(5,7-Dimethyl-3-benzofuranyl)-4,6-dimethyl-phenol.

4. 2-(5,6-Dimethyl-3-benzofuranyl)-4,5-dimethyl phenol.

5. 2-(4,6-Dimethyl-3-benzofuranyl)-3,5-dimethyl-phenol.

6. 2-(5-Methylthio-6-methyl-3-benzofuranyl)-4-methylthio-5-methylphenol.

7. 2-(5,7-Di-t-butyl-3-benzofuranyl)-4,6-di-t-butylphenol.

8. A stabilized composition comprising (a) 100 parts by weight of an organic material subject to the deleterious effects of oxygen, heat and light and (b) from about 0.1 parts to about 10 parts by weight of at least one compound selected from the group consisting of (a) 2-(5-t-butyl-3-benzofuranyl)-4-t-butylphenol, (b) 2-(5,7-dimethyl-3-benzofuranyl)-4,6-dimethylphenol, (c) 2-(5,6-dimethyl-3-benzofyranyl)4,5-dimethylphenol, (d) 2-(4,6-dimethyl-3-benzofuranyl)-3,5-dimethylphenol, (e) 2-(5,7-di-t-butyl-3-benzofuranyl)-4,6-di-t-butylphenol and (f) 2-(5-methylthio-6-methyl-3-benzofuranyl)-4-methylthio-5-methylphenol.

9. A composition of claim 8, wherein the organic material is a polymer.

10. A composition according to claim 9,wherein the polymer is a dienic polymer.

11. A composition according to claim 10, wherein the dienic polymer is an isoprene homopolymer or copolymer.

12. A composition according to claim 11, wherein the dienic polymer is poly-isoprene.

13. A vulcanized composition of claim 10.

14. A composition according to claim 8, 9 or 10, wherein (b) is 2-(5-t-butyl-3-benzofuranyl)-4-t-butylphenol.

15. A composition according to claim 8, 9 or 10, wherein (b) is 2-(5,7-dimethyl-3-benzofuranyl)-4,6-dimethyl-phenol.

16. A composition according to claim 8, 9 or 10, wherein (b) is 2-(5,6-dimethyl-3-benzofuranyl)-4,5-dimethyl-phenol,

17. A composition according to claim 8, 9 or 10,wherein (b) is 2-(4,6-dimethyl-3-benzofuranyl)-3,5-dimethyl-phenol.

18. A composition according to claim 8, 9 or 10, wherein (b) is 2-(5-methylthio-6-methyl-3-benzofuranyl)-4-methylthio-5-methylphenol.

19. A composition according to claim 8, 9 or 10, wherein (b) is 2-(5,7-di-t-butyl-3-benzofuranyl)-4,6-di-t-butyphenol.