US2763672A - 2,2'-methylene-bis-tert, butylhydroquinone and fats and oils stabilized therewith - Google Patents

Description

United States PatentC 2,2'-lVIETHYLENE-BIS-TERT. BUTYLHYDROQUI- NONE AND FATS AND OILS STABILIZED THEREWITH No Drawing. Application January 5, 1953,

Serial No. 329,718

4 Claims. (Cl. 260-3985) This invention relates to the stabilization of fats, oils and other organic materials subject to deterioration employing a series of compounds as antioxidants which include 2,2-methylene-bis-tertiarybutyl-hydroquinone, to a process for preparing the same, to the compounds per se, and to compositions containing the same as antioxidants.

Various derivatives of his (phenyl) alkanes are known and the antioxidant properties of some of these compounds have been described in the prior art, e. g. the dimethyl ether of 2,2-methylene-bis (tertiary butyl hydroq-uinone), nordihydroguaiaretic acid (N. D. G. A.), etc. However, the antioxidants of this invention are clearly superior to such known antioxidants. Thus, the compounds of this invention have four unetherified hydroxy radicals which contribute to their antioxidant efficacy. Partial ethers of these compounds are of markedly less potency as antioxidants. Thus, the applicants have made the valuable discovery that when all four hydroxy radicals are unsubstituted the resulting compounds are unexpectedly superior antioxidants. These compounds cannot be properly considered as isomers or homologs of the known compounds because of the clearly distinct molecular structure.

In accordance with our invention we have found that compounds which possess the following formula are extremely effective antioxidants for fats and oils:

wherein R represents a substituent selected from the group consisting of a hydrogen atom and an alkyl radical containing from 1 to 6 carbon atoms and each of the tertiary butyl groups is positioned in either of the 5- or 6-positions. The compound which we have found to be most advantageously suitable is that defined by the general formula wherein R represents a hydrogen atom, namely, 2,2-methylene-bis (S-tertiarybhtyl-1,4-dihydroxyphenyl) and'the isomers of this comp'ound wherein the tertiarybutyl groups are in the 6,6 and 6,5 positions, which three isomeric compounds can be generically designated as 2,2'-methylene-bis-tertiarybutyl-hydroquinone. The production of this novel compound generally results in a mixture of these three isomers which probably in-- clude lesser quantities of other isomers wherein the tertiary butyl group is positioned in the 3-position on either or both of the benzene rings.

The novel antioxidants of this invention are quite valuable in the stabilization of fats and oils. Preliminary tests relating to toxicity data indicate that the compounds of this invention can be incorporated into edible fats and oils. A known antioxidant suitable for the stabilization of edible fats and oils is butylated hydroxyanisole which is commercially available and is frequently referred to as BHA. The compound 2,2'-methylene-bis-tertiarybutyl-hydroquinone is a superior antioxidant for fats and oils as compared to BHA.

It is an object of this invention to provide new and useful compounds. Another object of this invention is to provide novel antioxidants which are especially valuable for the stabilization of fats and oils. A further object of this invention is to provide a process for preparing the novel compounds of this invention. A still further object of this invention is to provide stabilized fats and oils containing the novel compounds of this invention. Additional objects will become apparent elsewhere in this specification.

According to one embodiment of this invention a simple procedure is provided whereby the compounds defined by the general formula set forth above can be prepared by reacting monotertiarybutyl hydroquinone with an aldehyde dissolved in an inert solvent in the presence of an acidic condensing agent under inert atmosphere.

Examples of aldehydes which can be employed in this process include formaldehyde, acetaldehyde, n-butyraldehyde, isobutyraldehyde, valeroaldehyde, etc. These aldehydes include those which contain from 1 to 6 carbon atoms. Most advantageously, formaldehyde is employed.

The solvents which can be employed in this process include the lower alkanoic acids containing from 2 to 6 carbon atoms and various other inert solvents which do not interfere with the condensation of monotertiarybutyl hydroquinone with an aldehyde. Most advantageously, acetic acid can be employed as the solvent.

The acidic condensing agents which can be advantageously employed in accordance with this process include hydrochloric acid, sulfuric acid, phosphoric acid, etc. Most advantageously, concentrated hydrochloric acid or anhydrous hydrogen chloride can be employed.

Temperatures which can be advantageously employed in conducting this process can generally be in the neighborhood of room temperatures and include temperatures of from 20 to 50 C. Higher and lower temperatures can also be employed.

Since the novel antioxidants produced in accordance with this invention are sensitive to airoxidation, air is advantageously excluded during the process of their preparation in order to obtain a light colored product. An inert atmosphere is advantageously employed during the course of the reaction, examples of which include nitrogen, hydrogen, helium, etc. Other inert atmospheres can also be employed. Upon the completion of the initial condensation, the condensation product can be separated by any suitable process and purified in accordance with customary procedures. tion product can be poured into a large quantity of water followed by filtration, after which the product can be Acetic acid (1000 cc.) and cc. of concentrated hydrochloric acid were mixed thoroughly in a reaction vessel under a nitrogen atmosphere. Monotertiarybut'yl hydroquinone (83 grams, viz. 0.5 mol.) was added with agitation. A quantity of 21 g. of 36 percent formaldehyde' (0.25 mol.) was then gradually introduced over Advantageously, the condensa-v a period of 1 hour at a temperature of 20 to 30 C. The rea tipn mixture was agitated for an additional period of 3 hours. This reaction mixture was then poured into 8 liters of water. The product obtained was filtered, washed with water and 'dii'e'd. This product was a mixture of isomers which can be called 2,2' inethylene-bis-tertiarybutyihydroquinone and was found to' weigh 78.6 g. This product is a light tan solid which has a softening temperature of about 78 C. and melts at from about 96100 C.

Example 2 A quantity of 83.0 g. (0.5 mol.) of monotertiarybutylhydroquinohe', 15'0 of acetic acid and 7.75 g. of parafoi'maldehyd (0.258 hrbl.) were thoroughly mixed and niai'ritainedat to 10 C. for 12 hours While passing anhydrous hydrogen chloride through this mixture. This reaction mixture was allowed to stand at from O to -10? C. over night following whioh it was introduced into '4 liters of cold water and stirred for 1 hour. The product obtained was filtered, water-washed and dried in air. The product obtained weighed 81.6 g. and was a mixture of isomers \vhich can be called 2,2-m'ethylenebis-tertiarybutyl-hydroquinone.

The procedures set forth in the above examples can be suitably modified whereb other aldehydes, other solvents, and other condensing agents can be employed to produce other 'compoun'ds having the general formula set forth herein above.

The compounds described by the general formula set forth above are useful as antioxidants in fats, vegetable oils, etc., and can also be employed in the stabilization of the carotene content of alfalfa. Moreover, these compounds constitute satisfactory stabilizing agents for use in organic compounds in general, e. g. petroleum products such as gasoline, turbine oils, etc., materials which have been polymerized, e. g. acrylic acid ester polymers, methacrylate polyni'e'rs, polyvinyl compounds, polystyrene, etc. The fats and oils which can be advantageously stabilized include animal 'oils, fish oils, vegetable oils, animal fats, butter, etc.

When employed as antioxidants, frat'ztions of a percent of the compounds "co vered by the generic formula can be incorporated into such 'sub'strate materials as lard, cottonseed oil, peanut oil, soybean oil, etc., by admixing such antioxidant with the fats or oils whereby a solution or suspension of the antioxidant in the substrate is obtained. Alternatively, the antioxidant can be blended with suitable solvents to rom an antioxidant solution which can then be advahtag eously'admixed with the substrate. Examples of olvents for such solutions include glyceiin, propylene glycoh etc. Such antioxidant solutions can be more readily dissolved in the fat or oil to be stabilized with less necessity for prolonged mixing of the fat or oil with the undissolvcd antioxidant. Similarly, synergists can be admixed with the fats or oils along with the pure antioxidant compounds of this invention or, in order to facilitate the incorporation of the antioxidant and synergist into the fat or oil, they can both be dissolved in such solvents as propylene glycol, glycerin, or other similar solvents which are inert insofar as concerns both the antioxidant and/or the synergist components in the ultimately prepared stabilized fat or oil. Examples of s'ynergists which can be employed include citric acid, tartaric acid, phosphoric acid, ascorbic acid, etc.; other synergists can also be employed. In addition to the presence of a single antioxidant'of the above generic formula in the fat'or oil, it is possible to employ two or more of such antioxidants simultaneously; moreover, such antioxidants either alone "or in combination can be employed together with other antioxidants which are known in the prior art, e. .g. ;butylated hydroxyanisole, propyl ga'llate etepwhich can be added for their supplemental efiects if such be desired. I

In addition to the fats and oils mentioned above which can be stabilized by the antioxidants of our invention,

' shortening for the particular AOM test.

4 l other representative fats and oils include linseed oil, menhade'n oil, corn oil, cottonseed 'oil, peanut oil, soyabean oil, cod liver oil, castor oil, olive oil, rape-seed oil, cocoanut oil, palm oil, sesame oil, babassu oil, lard, beef tallow, etc., a well as hydrogenated oils and fats prepared from any of the foregoing. Furthermore, various other edible-type oils and fats may be similarly treated within the scope of the present invention.

Inasmuch as it is well known in the art to employ antioxidants in the stabilization of fats and oils, it is not believed necessary to give numerous specific examples of how the antioxidants of this invention can be blended with the fats or oils nor specific proportions which can be employed. The methods of blending antioxidants and synergists with particular fats and oils can be readily determined by those skilled in the art. The range of antioxidant proportions which can be employed is from about 0.901 percent up to as much as 1.0 percent or more by weight of the antioxidants of this invention depending upon the effects desired. Generally, a range of proportions of from about 0.001 percent up to about 0.1 percent is advantageous with the upper limit being generally fully satisfactory if it does not exceed 0.05 percent. When solvents are employed in preparing antioxidant solutions, such solvents can be present in an amount just suificient to dissolve the antioxidant up to any larger amount which may be desired, especially if larger amounts are necessary to fully dissolve other supplementary antioxidants and/or synergists which may be incorporated into the antioxidant solution.

The following tabulation of data is presented in order to further illustrate our invention and show some of the properties 'ofi some of the antioxidants covered by this invention. Data are also presented in this tabulation regarding Bl-IA which is made up of a mixture of the following isomers: 2-tertiarybutyl 4 methoxyphenol and 3-tertiarybutyl-4 methoxyphenol. BHA .is a well-known antioxidant which is commercially available. The presentation of data regarding this known antioxidant in the tabulation shows the advantage of the compounds 'of this invention over the prior art.

Table l AOM Value (Hours) Sample No. Composition of Sample men. meq. rneq. men. men.

Lard (Control) 9 13.5 Lard+0.01% BELL-.- 22.5 40

Lard+0.01% 2,2f mothlene bis-tert arybutyl iydroquinone. 92.5 90 4 Cottonseed Shortening Oontr 24.25 48 '54 58.25 5 Cottonseed Shortening N +0.01% BHA. 18.75 43.50 54.50 62.50 6 Cottonseed Shortening +0 2. m th and bis-tertiarybutyl hydroquinoneuflcnn 72. 50 97 103 109 The data presented above is based on tests conducted under the same conditions employing similar samples in each instance of lard and cottonseed oil shortening. The numbers under the heading AOM Value represent the milliequivalent (meq.) peroxide value of the fat or The AOM figures are in hours.

It is clear from the tabulated data that the compounds of this invention are excellent antioxidants for lard and cottonseed oil. Bas'e'don this data, it is clearly apparent that the compounds of "this invention are quite efiective antioxidants 'for fats and Oils such as lard, cottonseed oil, peanut oil and soybean oil, etc., and that they are markedly superior to BHA in every instance tested.

In addition to the specific compound of the above generic formula which has been presented in the tabulation and thereby illustrated in accordance with this invention, it is obvious that other derivatives of the general formula set forth can also be employed.

The development of rancidity in fats and oils is followed by an increase in peroxide content when air is bubbled through fats and oils at 208 F. This accelerated test is known as the Active Oxygen Method (AOM) and is described by Riemenschneider, R. W., Turer, J., and Speck, R. M., in Oil and Soap 20, 169-- 171 (1943). Values are usually reported in hours required to attain peroxide numbers of 20, 50, etc. The longer the time required to attain these peroxide values, the more efiective the antioxidant is.

What we claim as our invention is:

1. A stabilized product comprising a substrate selected 6 from the group consisting of fats and fatty oils, containing from about 0.001% to about 1.0% by weight of 2,2'-methylene-bis- (tertiarybutyl-hydroquinone) 2. A stabilized product as defined in claim 1 which contains from about 0.001% to about 0.1% by weight of a synergist.

3. A stabilized product as defined in claim 2 wherein the synergist is citric acid.

4. 2,2'-methylene-bis-(tertiarybutyl-hydroquinone).

References Cited in the file of this patent UNITED STATES PATENTS 2,542,972 Thompson Feb. 27, 1951 2,591,651 Young Apr. 1, 1952 2,697,111 Bell et a1. Dec. 4, 1954

Claims (1)

1. A STABILIZED PRODUCT COMPRISING A SUBSTRATE SELECTED FROM THE GROUP CONSISTING OF FATS AND FATTY OILS, CONTAINING FROM ABOUT 0.001% TO ABOUT 1.0% BY WEIGHT OF 2,2''-METHYLENE-BIS-(TERTIARYBUTYL-HYDROQUINONE). 4. 2,2''- METHYLENE-BIS-(TERTIARYBUTYL-HYDROQUINONE).