US1928832A - Medicinal oil and method of preparation - Google Patents

Description

Patented Oct. 3, 1933 MEDICINAL OIL AND METHOD OF PREPARATION Seymour W. Ferris, Aldan, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application August 14,

Serial No. 1933 18 Claims.

The present invention relates to the art of refining mineral oils, with particular reference to a method of producing white mineral oils, such, for example, as those used for medicinal purposes.

The product resulting from such method, which is characterized by certain particularly desirable properties, also comes within the purview of this.

invention.

In accordance with prior practice, white mineral oils are prepared by subjecting a carefully selected fraction of a crude petroleum to treatment with large quantities of acid, usually fuming sulphuric acid, the quantity of acid required for the preparation of the most highly refined medicinal oils being of the order of 75% or more by weight of the oil treated. By such processes the yield of final product in general does not exceed 50% of the amount of the fraction used in its preparation, the'remaining 50% comprising acid sludge which is of little value. Furthermore, the product or products obtained have less desirable physical characteristics than do products obtained in accordance with this invention. A comparison of the characteristics of my product with white oils heretofore produced will be brought out in another part of this specification.

White mineral oils such as those used for medicinal purposes are substantially water-white viscous products which, in accordance with the prior practice, have been obtained by subjecting a carefully selected fraction of a crude petroleum, as for example, a fraction from Pennsylvania crude, to a drastic acid treatment as aforesaid. This treatment, due to the large quantities of strong acid used, results in the destruction of the less stable constituents contained in the oil, which probably accounts for the high oil loss incident to such treatment. This loss is referred to as an oil loss since the portion of the oil which reacts with the acid to form a sludge is only partially recoverable, and even when recovered it is usable only as a low grade fuel oil which has a very low market value.

Furthermore, processes in accordance with the produce a white mineral oil from a petroleum' fraction having a viscosity greater than 450 seconds Saybolt Universal at 100 F., as far as I am aware. I

' prior practice whereby white mineral oils are 1928, Renewed February 16,

An object of my invention is the preparation of white mineral oils, particularly oils to be used for medicinal purposes, which have properties materially and distinctly different from the properties of such oils as are now on the market. For example,.white mineral oils which have a viscosity as high as 500 seconds Saybolt Universal at 100 F., have not heretofore been known, whereas, such oils may be prepared in accordance with my invention.

This invention contemplates a process more efficient than processes for the manufacture of white mineral oils which have been known heretofore.

In accordance with my invention, a petroleum oil distillate or residuum is extracted with an aromatic nitro-compound, for example, nitrobenzene, whereupon there is produced a highly refined oil substantially all of which is of a saturated compound character, and which contains the most stable constituents of the distillate or residuum. Further, in accordance with this invention, the oil produced is of good stability and may be of higher viscosity than white mineral oils heretofore found on the market.

It desirable that a white mineral oil should comprise for the most part, saturated hydrocarbons, particularly hydrocarbons of those series in which the hydrogen to carbon ratio is high. It is generally recognized that petroleum oil is essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example as the parafiins of general formula CnH2n+2, the olefines, whose general formula is CnHB-n, the hydro-aromatics and the polymethylenes of the same empirical formula. and various other series of hydrocarbons in which the hydrogen to carbon ratio is less than in these compounds just mentioned. some of which may be of a chain structure and others of a ring structure. A large number of individual compounds of each series and of different boiling points are present in petroleum oil. 7

The various types of crude petroleiun which are generally classified into the three groups, namely, paraffine base, naphthenic or asphalt base, and mixed base, contain the various series of hydrocarbons heretofore mentioned, in different proportions. For example, in the paraffine base crudes, such as those produced in the oil fields of Pennsylvania. there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the so-called naphthenic or asphalt base crudes there is a relatively large proportion of hydrocarbons having ring structures, and a low hydrogen to carbon ratio. The mixed base crudes such as are obtained from the Mid-Continent oil fields contain hydro-carbons in proportions intermediate these two extremes.

White mineral oils produced, in accordance with my process, are prepared from suitable fractions of a crude petroleum, and in particular, fractions which heretofore have not been used in the preparation of white mineral oils or oils of a similar character. For example, a heavy distillate from a mixed base crude from the Mid-Continent area may be used in the preparation of a white mineral oil in accordance with my process. It is not however my intention to be limited to a product made from any specific crude or fraction of a crude, but to include within the scope of this invention a product characterized by certain desirable properties hereinafter described, prepared from any crude petroleum or fraction thereof which it is found desirable to use for such purposes, as well as the particular process for preparing such product, as is herein set forth.

As before stated, the various types of crude petroleum and their fractions differ from one another in the proportion of the various series of hydrocarbons which each contains. This is evidenced by the physical properties of the various oils and particularly by the relationship of the specific gravity to the viscosity of one oil as compared with another. For example, oil from a Pennsylvania crude with a viscosity of 400 seconds Saybolt Universal at 100 R, will show a specific gravity at F. of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, as one from the Gulf Coast area, will show a specific gravity of about 0.933 at 60 F. The relationship between the viscosity and gravity indicates the degree of the paraflinic or naphthenic character of the oil.

If a given crude petroleum be distilled into successive fractions and the specific gravities and viscosities of the several fractions determined, it will be found that they conform to the general relationship 10 log(V 38) in which G is the specific gravity at 60 F., V is Saybolt Universal viscosity at 100 F., and a is a constant knownas the viscosity-gravity constant. Fractions from each of the different types of crudes have different viscosity-gravity constants. Such constants are lower for fractions of the paraflinic crudes than are the constants for fractions of the naphthenic crudes. This necessarily follows from the relation of the constants of the crudes themselves, since such constants are different for different crudes, and

, the paraflinic crudes have lower viscosity-gravity constants than do the naphthenic crudes. a ticle entitled The Viscosity-Gravity Constant f Petroleum Lubricating Oils", by J. B. Hill and B. Coats which will be found in volume 20,

page f64l et seq., Industrial and Engineering Chemistry for June, 1928, explains the determi- I nation ofthe constant for several typical oils.

'Ifheviscosity-gravity constant is, therefore, an

' find ex of the paraffinicness or naphthenicness of Yfanf oil 'since regardless of the fraction upon whichjthe specific gravity and the viscosity are tali'n. when the particular specific gravity and 7 viscosity are substituted in the formula and the viscosity-gravity constant determined, the constant will.be substantially the same for any given crude.

The viscosity-gravity constants for some of the I have found that the white oils produced by my process .are much more paraffinic than white oils which have heretofore been commercially produced. For example, the oils produced by my process may have a viscosity-gravity constant of 0.795, whereas the ordinary white min-.

eral oils have viscosity-gravity constants ranging from about 0.800 to about 0.840. White oils of high viscosities, for example of 100 seconds Saybolt Universal at 100 F. or above, which have been known heretofore, have viscosity-gravity constants greater than 0.8030. None of the white mineral oils heretofore known have viscosity-gravity constants as low as viscositygravity constants of oils of corresponding viscosities which may be produced by my process.

In accordance with my invention, the process of which Ihave set forth in its broadest aspect in my copending application Serial No. 206,388, filed on July 6, 1927, which issued into U. S. Patent No. 1,788,569 on Jan. 13,1931, the oil fraction to be treated is agitated with nitrobenzene. The mixture is allowed to separate into layers, one of which contains substantially all of the nitrobenzene and that portion of the oil which dissolved therein, the other layer comprising that portion of the oil which did not dissolve in the nitrobenzene. This last mentioned layer may be subjected to a further treatment with nitrobenzene in case it is desired to remove additional quantities of constituents soluble in the aforesaid solvent, which remain in the oil after the first extraction.

When the extraction with nitrobenzene is completed, separation from the solvent of that portion of the oil which dissolved therein is effected, as for example, by distillation, whereupon the extract results as a by-product and may be used in the manufacture of cable oil s, lubricating oils or the like. The oil which remains insoluble in the nitrobenzene, that is, that portion which is to be further treated to form the desired final product, is subjected to a light acid treatment to further remove objectionable compounds, which if allowed to remain in the oil might cause discoloration of the oil. Due to the fact that most of the undesirable constituents of the oil have by the nitro-benzene extraction already been removed, only a small amount of acid is required to produce a finished product.

It is to be understood that when circumstances warrant, as for example, in the treatment of a highly viscous oil, the nitrobenzene extraction may be carried out at elevated temperatures in order to effect a complete solution of the oil therein so that all portions of the oil may be brought into intimate contact with the nitrobenzene and ahomogenous liquid solution formed. After such treatment the mixture is cooled whereupon it separates into two layers, the upper being a solution of nitrobenzene in the more paraflinic portion of the oil, and the lower a solution of the more naphthenic portion of the oil in nitrobenzene.

However,.in lieu of this heating, I may simply agitate the cold mixture.

.Before removing the nitrobenzene from the upper layer of paraflinic oil obtained by the pro-. cedure just described, extraction of further naphthenic bodies from the paraflinic portion of the oil maybe efiected by adding a further quantity of nitrobenzene, allowing layers to form and separating the layers. Such extraction may be repeated two or three times, or as often as desired. In the manufacture of a white mineral oil in accordance herewith, it is preferable to use a dewaxed oil as the starting material. Such oil, for example, may be a high viscosity fraction from a Mid-Continent crude from which the wax has been removed by any of the well-known processes. It is not to be understood, however, that this process is to be limited to a dewaxed oil, since it may,

be used in the treatment of oil fractions containing large amounts of solid hydrocarbons, in which instance such hydrocarbons may be removed 'or partially removed after the oilhas been extracted with. nitrobenzene.

As an example ofmy process, but which is not to be considered as limiting my invention, a dewaxed distillate from a Mid-Continent crude, having a viscosity of 118 seconds Saybolt Universal at 210 F., and a specific gravity of 0.9200, is treated with nitrobenzene in the proportions of about one part of oil to about two parts of nitrobenzene by weight. After agitating, the mixture is allowed to settle and the portion of the oil which remains insoluble in the solvent is separated. Another portion of nitrozenzene in about the proportions used in the first extraction is added to the oil so removed, and the operation is repeated. In this manner four extractions with nitrobenzene are carried out. 1

The nitrobenzene soluble portion of the oil which amounts to about 65% of the original oil fraction is separated from the nitrobenzene by distillation, whereupon it is suitable for use, either alone or blended, in the manufacture of such valuable products as cable oils, lubricating oils or the like.

The portion of the oil fraction which remains undissolved in the nitrobenzene after the several extractions have been completed is separated by distillation from any nitrobenzene which remains admixed therewith. This insoluble portion represents about 35% by volume of the amount of the original fraction at the beginning of the process.

The nitrobenzene insoluble portion of the oil is treated with two pounds per gallon of 663B. sulphuric acid to eflect further purification thereof, whereupon the acid treatment removes the small amount of undesirable constituents still remaining in the oil after the nitrobenzene extraction. The acid sludge which forms is removed from the oil and the oilis treated with an adsorbent ,agentras fullers earth, to produce a water-white product.

The final product obtained by such treatment as has been described in detail, is an oil having a viscosity of 1031 seconds Saybolt Universal at 100 F., a specific gravity of 0.8805 at F., and a viscosity gravity constant of 0.797. I

While in the above example I have stated that nitrobenzene may be used as the solvent, I do not intend to limit my invention to this particular compound. It is to be understood that other solvents such as nitrotoluene, mono-nitronaphthalene or the like, or a mixture of them may be used and come within the scope of solvents contemplated by my invention.

An advantage of my process, in addition to those heretofore mentioned, is that the amount of the oil fraction which is converted into acid sludge is very small as compared with the amount incident to the drastic treatments used in prior processes for the manufacture of white mineral oils. In the example given above, from a total of 100 parts of the fraction treated there were obtained parts of an oil of higher value than the general run of lubricating oils, and 32.7 parts of the final desired white mineral oil product,

leaving a loss of only 2.3 parts in the form of acid sludge. This compares with a loss of about 50% of the amount of the original oil fraction which "forms acid sludge when prior processes are used in the preparation of such oils. In my process this loss is low in spite of the fact that I am able to use a fraction whose viscosity is much higher than the viscosity of those oils customarily used in the preparation of white mineral oils. If the oils of high viscosity which I am able to use were used in the prior processes, a loss in the form of acid sludge much greater than 50% might be expected, provided, of course, that such higher viscosity fractions could be acid treated by such. prior process to an extent to produce a white mineral oil. The low treating loss incident to my process can be explained by the removal by the nitrobenzene of the chemically unstable compounds which normally react. withthe acid to form sludge. In my process, instead of large quantities of acid sludge being produced, practically all of the oil treated is converted into products of high marketable value.

Another advantage of producing a white mineral oil in the manner described is that the amount of sulphuric acid required is low compared with the amount of sulphuric acid required, or which would be required in the treatment of the high viscosity oils for which my process is particularly adapted, by methods for producing white mineral oils in accordance with prior practice. In producing the usual medicinal oils having viscosities of from around 100 to 300 seconds Saybolt Universal at 100 F., the fuming sulphuric acid required is of the order of 75% by weight of the oil treated. -As indicated by the above example, in my process, treatment with only about 25% of 66 B. sulphuric acid was necessary to produce a white medicinal oil of 1031 seconds SayboltUniversal at 100 F. To produce a water-white oil of this viscosity by straight acid treatment, assuming that such treatment could be accomplished satisfactorily would require a considerably greater quantity of acid.

It is to be noted that in the treatment of an oil in accordance with my invention, an oil of comparatively high value results as a by-product, whereas, in the sulphuric acid processes only acid sludge results, which even if recovered, is of little value.

It has long been recognized that the higher the viscosity of a medicinal oil, the more valuable it is, and as my process produces white mineral oil of higher viscosity than it has been possible heretofore to produce, both the process and the product represent a distinct and decided advance in the art.

It is to be understood that this process, in addition to being particularly adaptable for use in the preparation of white mineral oils to be used for medicinal purposes, is also suitable for I f I 4 the preparation of oils such as those commonly known as technical white oils, which are used in" various industries, as for example, ;the baking industry. v 1

In-the appended claims, the term white mineral oil is used-to include medicinal oils, technical white oils and other highly refined viscous oils jao of a" like character, the term "nitrobenzene 's employed in a genericsense to include that material and equivalent. aromatic nitro. compounds or mixtures thereof, and the term viscous oil comprehends oil of substantial viscosity, i. e., having a viscosity of the order of 50 seconds Saybolt Universal at F., and up-.-

wards.

What I claim is:

1. In the art of preparing a white mineral oil,

the step which comprises extracting a viscous mineral oil distillate containing paraifinic and naphthenic hydrocarbons with nitrobenzene thereby to remove from the distillate substantial amounts of its naphthenic hydrocarbon content. 2. In the art of preparing a white mineral oil, the step which comprises repeatedly extracting a viscous mineral oil distillate containing paraffinic and naphthenic hydrocarbons with nitrobenzene, thereby to remove from the distillate substantial amounts ofits naphthenic hydrocarbon content. l

. 3. In the art of preparing a whiteamineral oil having a viscosity -gravity constant not higher than 0.795, the step which comprises extracting a viscous mineral oil distillate containing paraffinic and naphthenic hydrocarbons with nitrobenzene, thereby to remove from the distillate substantial amounts of its naphthenic hydrocarbon content.

4. In ,the art of preparing a white mineral oil having a viscosityof at least 500 seconds Saying the nitrobenzene from that portion of the oil which remains undissolved therein and treating the undissolved portion of oil with sulphuric acid.

6. In the art of preparing a white mineral oil, the process which comprises repeatedly adding nitrobenzene to a viscous mineral oil and agitating the mixture, separating the nitrobenzene from that portion of the oil which remains undissolved therein thereby to dissolve from the .oil a substantial part ofthe components thereof which react with sulphuric acid and treating the undissolved portion of the oil with sulphuric acid.

7. In the art of preparinga white mineral oil the process which comprises extracting a viscous mineral oil distillate with nitrobenzene to dissolve from the oil a substantial part of the components thereof which react 'with sulphuric acid,

separating the nitrobenzene from that portion of the distillate which remains undissolved there in, treatingthe undissolved portion with a fur- 'ther quantity of nitrobenzene, and again separating the nitrobenzene to further dissolve from the oil components thereof which react with sulphuric acidtherefrom, treating the undissolved oil with sulphuric acid, separating the acid sludge,

from the oil, and treating the oil with an adsorbent agent.

8; In the art of preparing a white mineraloil the process which comprises repeatedly extracting a viscous mineral oil distillate with nitrobenzene to dissolve from the oil a substantial part of the components thereof which react with sulphuric acid, separating the nitrobenzene from the portion of the oil which remains undissolved therein, treating the undissolved portion of oil with sulphuric acid, separating the acid sludge from the oil, adding fullers earth to the treated oil, and filtering the oil.

9. A white mineral oil having a viscosity between 500 seconds Saybolt Universal at 100 F. and 1031 seconds Saybolt Universal at 100 F.

10. A white mineral oil having a viscosity-gravity constant not higher than 0.797 and a viscosity between 500 seconds Saybolt Universal at 100 F. and 1031 secondsSaybolt Universal at 100 F.

11. A white mineral oil having a viscosity 'greatefthan 100 seconds Saybolt Universal'at 100 F. and viscosity-gravity constant not higher than 0.8030. v

12. A white mineral oil having a viscosity of at least 500 seconds Saybolt Universal at 100 F. and a viscosity-gravity constant not higher than 0.8030. g

I 13. In the art of refining mineral oils, the process which comprises extracting a viscous mineral oil distillate with nitrobenzene to dissolve from' the oil a substantial part of the components thereof which react with sulphuric acid, separating the; nitrobenzeneirom that portion of the distillate which remains undissolved therein.

treating the undissolved portion with a further quantity of nitrobenzene to further dissolve from the oil components thereof which react with sulphuric acid, and again separating the "nitrobenzene therefrom, treating the undissolved oil with "substantial part of the components thereof which react with sulphuric acid, separating the nitrobenzene from that portion of the 'oil which remains undissolved-therein and treating the 'undissolved portion of oil with sulphuric acid.

16. In the art of refining mineral oils, the process which comprises repeatedly adding nitrobenzone to a viscous mineral oil and agitating the mixture, separating the nitrobenzene from that portion of the oil which remains undissolved the-rein, thereby to dissolve from the oil a substantial part of the components thereof which react with sulphuric acid, and treating themdissolved portion of the oil with sulphuric acid.

17. In theart of refining mineral oils, the process which comprises repeatedly extracting a viscous mineral oil distillate with nitrobenzene to. dissolve from the'oil a substantial part of the components thereof'which react with sulphuric acid, separating the nitrobenzene from the portion of the ofl which remains undissolved thereoil a substantial part of the components thereof which will react with a sludge forming agent,

separating the nitrobenzene trom the portion of the oil which remains undissolved therein, and

treating theundissolved portion 01' the oil with a sludge forming agent. 1 L

n SEYMOUR W. FERRIS..