US2069294A - Manufacture of oil soluble phenols - Google Patents

Description

Patented Feb. 2, 1937 UNITED STATES MANUFACTURE OF OIL SOLUBLE PHENOLS Charles Patton Wilson, Jr., Houston, Tex.

No Drawing. Original application December 17,

' 1930, Serial No. 503,095. Divided and this application December 14, 1931,

581,068. Renewed November 27, 1934 18 Claims.

This invention relates to a method of preventing deterioration of oils, fats, and rubber, and is applicable to substances liable to oxidation. The

process and product will be described more particularly in relation to inhibiting auto-oxidation of motor fuels resulting from pyrolysis of heavy oils or coal.

Color deterioration and gum formation are known to be the result of oxidation. Color deterioration does not render motor fuel or motor oil unfit for use, but lowers its market value. Gum formation is the result of oxidation of unsaturated hydrocarbons, and when present in motor fuel in small quantities renders the fuel unfit for use in an internal combustion engine. To obtain gum-free and stable products, the usual practice is to remove a substantial quantity of the unsaturated hydrocarbons through treatment with sulfuric acid, or through the control of the crack- 20 high concentration of the unstable unsaturated hydrocarbons. Control of the cracking process in this way sometimes results in a lower percentage of cracked fuel, and the sulfuric acid treatment always results in a loss, which in many cases runs as high as 5% of the motor fuel produced. This treatment is costly and wasteful, and also results in a lowering of the anti-knock value of the motor fuel.

The primary object of the invention is the manufacture and use of an oxidation inhibitor which, when added in minute quantities, prevents deterioration of hydrocarbons and various oils liable to oxidation. It is particularly useful in the manufacture and marketing of motor fuel containing unsaturated hydrocarbons liable to oxidation, since it not only inhibits gum formation in storage, but actually reduces the gum yield when the cracked product to which the inhibitor has been added is tested for gum by the copper dish method. minute quantity of. the inhibitor, the cost of which is almost negligible, is required to reduce the result of the copper dish test to any desired specification. Results of tests made with identical cracked gasolines with and without the addition of the stabilizing compound are shown hereunder:

Copper dish tests Sample I Amount of inhibitor Gum (gms. added (gins. per 100 cc.)

per 100 cc.)

Nil

ing plant in such a manner as not to produce a In the majority of cases only a.

Serial No.

Sample II Amount of inhibitor Gum (gms. added (gms. per 100 cc.)

per 100 cc.)

Nil 0.183 0. 0007 0.101 0. 0014 0.066 0. 0035 0. 008 0.007 0. Oil

I have found that the following substances are effective in preventing gum formation when added in minute quantities to oils: pyrogallol, para-aminophenol, catechol, para-phenylene diamine, hydroquinone, methylaminophenol, orthoaminophenol, alpha-naphthol.

Numerous other compounds, such as cresol, dimethylaniline, etc., have a slight stabilizing effect, but my experience has been that as a general rule only aromatic compounds with two hydroxyl and/ or amino groups in the ortho or para positions of the benzene ring will completely prevent oxidation, although it will be noted that alpha-naphthol, which has only one hydroxyl group, is an exception. The presence of other groups in the benzene ring in addition to the above mentioned does not destroy the inhibiting action.

All of the above mentioned substances except alphanaphthol are more soluble in water than in oil, in which they are nearly insoluble, and they are not satisfactory for use in practice for the commercial stabilizationcf motor fuels on account of the fact that it is diflicult to prevent the latter from coming into contact with water. Naphthol cannot be used, since it causes motor fuel to deteriorate in color, although it is satisfactory as regards solubility.

I have found that if an alkyl or aryl group is substituted for a hydrogen atom in these compounds, their solubility in water is decreased and their solubility in oil is increased without an appreciable loss in their power to inhibit oxidation. The greater the number of alkyl or aryl groups which can be substituted in the benzene ring, the more soluble is the resulting compound in the hydrocarbon to be stabilized and the less soluble in water.

The new and novel features of the present invention are: the production of oil-soluble oxidation inhibitors from certain types of oil-insoluble phenolic or amino compounds, by substitution of one or more alkyl or aryl groups for hydrogen atoms; an improved method of introducing an alkyl group into a phenol; and the utilization of turpentine, a liquid sulfur dioxide extract of an oil, or the unsaturated hydrocarbons derived from the pyrolysis of oil or coal, as the base or stock from which the substituted phenolic or "mixed unsaturated hydrocarbons are very much cheaper than the pure unsaturated compounds,

but are equally satisfactory for the preparation of the substituted compound.

The introduction of alkylgroups is effected by amodiflcation of the method of Koenigs (Ber. 23, 3144; 24, 1'79, 3889; 25, 2649) who prepared alkyl substituted phenols by allowing a mixture of one part of the phenol with the equivalent amount of an unsaturated hydrocarbon to stand for several days in the presence of one part of concentrated sulfuric acid and nine parts of acetic acid. My improvements that are new to the art are as follows:

1. The use of a mixture of unsaturated hydrocarbons, such as turpentine, a liquid sulfur dioxide extract of an oil, or an oil derived from the pyrolysis of oil or coal. Such oils should preferably contain a large percentage of unsaturated hydrocarbons, as high concentrations of the latter cause the reaction to take place more readily.

2. The use of dilute sulfuric acid (about 50%) instead of concentrated acid. This prevents loss of the phenolic compound by eliminating side reactions such as the formation of acetates.

3. The use of a much smaller quantity of sulfuric and acetic acid, thus reducing the cost of manufacture.

4. Carrying out the reaction at an elevated temperature with agitation. This reduces the time required to a few hours.

5. The use of a considerable excess of unsaturated compounds, in order to avoid loss of the more costly phenol.

6. Incomplete removal of acetic acid from the solution of alkyl substituted phenol. A trace of acid present in the solution acts as a preservative, preventing oxidation of the compound itself before is is added to the oil to be stabilized.

7. The use of a dilute solution of a mineral acid for extracting the acetic acid instead of water or ammonium carbonate. Oxidation of the compound during the washing is thus prevented.

It will be noted that by alkylation of the various oil-insoluble oxidation inhibitors, such as pyrogallol and aminophenol, in various ways, an almost infinite number of diiferent compounds can be obtained which would be suitable for inhibiting the oxidation of oils. For the preparation of the various types of compounds, 9. number of different methods are available. For example, amyl pyrogallol may be prepared by the action of amyl alcohol on pyrogallol in the presence of anhydrous zinc chloride; and aminophenol can be alkylated by heating under pressure with alcohols; or the reaction between pyrogallol and unsaturated hydrocarbons will take place to some extent without a catalyst, or with aluminium chloride. I have, however, found that the cheapest and easiest compounds to manufacture are those prepared from pyrogallol by the method described above. Catechol also gives good results by this method, but is more expensive. Examples of the preferred method of preparation using 1cracked distillate and turpentine are given be- Five parts by weight of powdered pyrogallol, ten parts of glacial acetic acid, one part of 50% sulfuric acid, and ten parts of cracked distillate are placed in an acid-resisting container fitted with a stirrer and a reflux condenser, and supplied with facilities for heating. The mixture is agitated violently, and heated to boiling. The agitation and heating are continued for t o amino compound is produced; oils containing hours, '75 parts of cracked distillate being gradually added during this period. After two hours, when substantially all of the pyrogallol should have entered into combination with the unsaturated hydrocarbons present, the agitation is stopped and the product allowed to cool in an oxygenfree atmosphere. The reaction which occurs is probably as follows:

The resulting mixture consists of a solution of the oxidation inhibitor and acetic acid in the oil which supplied the unsaturated hydrocarbons, and a layer of sludge on the bottom of the containing vessel. Twenty parts of 0.1% sulfuric acid are introduced, and the mixture is agitated for fifteen minutes for the purpose of removing excess acetic acid. The washing also causes any substituted compound contained in the sludge to return to the oil solution. The lower layer is drained oif, and the extraction repeated twice. The solution of oxidation inhibitor thus prepared is then run into a storage vessel, preferably of copper or wood.

When turpentine is used, forty parts of pyrogallol are dissolved by heating and agitation in sixty parts of glacial acetic acid. One part of 50% sulfuric acid is added, and a hundred parts fresh turpentine introduced while the mixture is being agitated. Heat is evolved, and care must be taken that the temperature does not rise above 100 C. When all the turpentine has been added, the mixture is maintained at about C. until the reaction is substantially complete. After cooling, it may be diluted by a suitable oil. It is then washed as in the previous example. The amount of the substituted compound formed is substantially twice the weight of pyrogallol used. I have found that acetic acid acts as a preservative of the compound, but most of it must be removed, as it would cause the motor fuel to which the above described inhibitor has been added to become corrosive. The acetic acid may be removed by extraction with any suitable solvent, such as water or a mineral acid, or by other suitable methods such as distillation, instead of by dilute sulfuric acid as described in the above examples.

It has been found that the substituted compound when prepared as described above may be stored for a long period of time, at least as long as two years as shown by practical tests, without losing activity as a stabilizer.

I have found that a compound as thus prepared is acidic and that it can be removed or destroyed by shaking with alkalis, such as sodium carbonate or caustic soda. It is, therefore, necessary to prevent the motor fuel from coming into contact with alkaline substances after the addition of the inhibitor. The compound is also destroyed by organic peroxides, and to prevent this the motor fuel must be perfectly fresh and free from peroxides when the compound is added.

The gum content of Samples 3 and 4 shown hereunder has been determined by the U. S. Bureau of Mines steam oven method, in which a 20 cc. sample of. motor fuel is evaporated in a. steam oven from which oxygen is excluded. The gummy residue obtained in this manner is considered to represent the actual or inherent gum present in the fuel.

my application,.Serial No. 503,095, flied December I 60 the evaporation and although a sample of cracked gasoline gives a considerable residue by .this method, the same sample might be found to be entirely free from inherent gum as determined by the steam oven method.

Results of storage tests made on identical cracked gasolines, withand without addition of inhibitor, are given below. The samples consist of cracked gasoline stored in dark in glassbottles vented to atmosphere:

Sample No. 3

Steam oven gum (gms. Color Saybolt chro per 20 cc.) mometer Time of storage Without With 0.001% Without With 0.001%

inhibitor inhibitor inhibitor inhibitor Plus 25 Ylus 25 25 25 2s 2s 25 25 25 2a 25 25 25 25 11 2s 25 2s 24 22 23 2s 25 Without With 0.0mm Without With 0.00057 inhibitor inhibitor inhibitor inhibitor Plus 25 2s 2s 25 25 25 2A 24 aa 21 ferred embodiment of the invention, it is to be understood that I reserve the right to make all changes properly falling within the spirit of the invention and without the ambit of the prior art.

This application is a continuation in part of Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made 'without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A process for the manufacture of a mixture of oil-soluble phenols which comprises condensing a polyhydric phenol with a cracked hydrocarbon distillate in the presence of heat and dilute sulfuric acid thereby combining unsaturated hydrocarbon components of the distillate with the phenol to form alkyl substituted derivatives of said phenol.

2.,A process for the manufacture of a mixture of oil-soluble phenols which comprises condensing apolyhydric phenol with a cracked'petroleum distillate in the presence of heat and dilute sulfuric acid whereby oleflnic hydrocarbon constituents of said distillate are combined with the phenol to form alkyl substituted derivatives of said phenol.

3. A process for the manufacture of a mixture of alkyl substituted oil-soluble phenols which comprises condensing cracked naptha with a phenol in the presence of acetic and a small amount of dilute sulfuric acid.

4. A process for the manufacture of a mixture of alkyl substituted oil-soluble phenols which comprises condensing cracked petroleum with a polyhydric phenol in the presence of acetic acid.

and a trace of 25-100% sulfuric acid.

5. A process for the manufacture of a mixture of alkyl substituted oil-soluble phenols which comprises condensing cracked petroleum with a polyhydric phenol in the presence of acetic acid and a trace of 25-100% sulfuric acid, and removing most of the acetic acid by washing with a very dilute mineral acid.

6. A process for the manufacture of a mixture of alkyl substituted phenols which comprises condensing cracked naphtha with a dihydric phenol in the presence of heat and dilute sulfuric acid.

7. A process for the manufacture of a mixture of alkyl substituted phenols which comprises condensing cracked naphtha with catechol in the said phenols being oil-soluble and consisting es-' sentially of a polyhydric phenol containing unsaturated hydrocarbon components of a cracked hydrocarbon distillate as substituent groups.

11. A composition of matter comprising essentially a mixture of alkyl substituted phenols, said phenols being oil-soluble and consisting essentially of a polyhydric phenol containing oleflnic constituents of a cracked petroleum distillate as alkyl substituents.

12. A composition of matter comprising essentially a mixture of alkyl substituted phenols, said phenols being oil-soluble and consisting essentially of a dihydric phenol containing hydrocarbon constituents of cracked petroleum naphtha as alkyl groups.

13. A composition according to claim 12 in which the dihydrlc phenol is catechoi.

14. A composition of matter comprising essentially a mixture of alkyl substituted phenols, said mixture being oil-soluble and consisting essentially of a trihydric phenol containing hydrocarbon constituents of cracked petroleum naphtha as alkyl groups.

15. A composition according to claim 14 in 17. A composition of matter consisting essentially of a relatively concentrated solution of a mixture of oil-soluble polyhydric phenols in a cracked hydrocarbon distillate, said phenols containing olefin constituents of the distillate as alkyl substituent groups.

18. A composition of matter consisting essentially of a relatively concentrated solution of a mixture of oil-soluble phenols, of the class of dihydric and trihydric phenols, in a cracked petroleum naphtha, said phenols containing unsaturated hydrocarbon constituents of said naphtha as alkyl substituents.

CHARLES PA'ITON WILSON, JR-