US2035584A - Process for separating nitrogen bases - Google Patents

Description

Patented Mar. 31, 1936 UNIT-ED, STATES PROCESS FOR SEPARATING NITROGEN BASES James R. Bailey, Austin, Tex., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application July 30, 1932, Serial No. 627,134

28 Claims.

This invention relates to a process for separating organic nitrogen bases. More especially it relates to a process for separating mixtures of nitrogen bases such as might be obtained from petroleum distillates, shale or by pyrolysis of cottonseed meal.

These substances, particularly petroleum oil, especially the asphaltic petroleums found in California and South America, contain varying amounts of nitrogen compounds. Attempts to remove these nitrogenous compounds from crude oils before distillation by using inorganic acids of varying strength resulted in the extraction of only negligible amounts of basic nitrogenous material. The result showed clearly that the crude oil itself does not contain any substantial amounts of basic nitrogen compounds. I have discovered that the process of distillation generates basic organic nitrogen compounds not present in the original crude oil. The temperatures at which this conversion occurs are the usual distillation temperatures for the separation of crude oil into its fractions such as gasoline, kerosene, gas oil,

lubricating oil and are usually below the cracking temperatures used in the conversion of heavier hydrocarbons into lighter hydrocarbons. While these cracking temperatures are eflicient for the generation of basic nitrogen compounds, the lower non-cracking temperatures also produce organic nitrogen bases from the non-basic compounds present in the oil. Undoubtedly the efiicient agent is heat, and this conversion of non-basic to basic nitrogen compounds may be obtained as well by merely heating to the temperatures usually employed in distillation. The above temperatures vary from 275 F. to and including 740 F., while the cracking temperatures are much'higher, varying from 800 F. to 1200 F. In the process ofdistillation oil is heated to different temperatures to recover various fractions. These temperatures vary, depending on the distillation system employed. Representative temperatures are. however, as follows: for the removal of primary gasoline, oil is heated to about 275 F.; for the removal of secondary gasoline the oil is heated to about 350 F. Oil is heated to from about 500 to 680 F. to removekerosone. Gas oil is recovered at about 680 F. and up, while lubricating oils are distilled at about 740 F.

The nitrogen bases formed by the distillation, cracking or heating of the petroleum oils constitute only a small fraction of the particular distillates in which they are present and must be isolated therefrom before being subjected to the process of separation hereinafter disclosed.

In separating the nitrogen bases from their oil content, I have found it desirable to first remove the hydrocarbon oil and thus concentrate the bases. There are several methods by which this can be accomplished. For instance, the nitrogen bases may be extracted from the crude petroleum distillates by repeated washing with dillute acid, preferably diluted sulphuric acid. Another method for extracting the nitrogen bases from crude petroleum distillates consists in treating these distillates with liquid sulphur dioxide according to the well known Edeleanu process (U. S. Patent No. 911,553). The extract phase thus obtained contains large amounts of liquid sulphur dioxide, the nitrogen bases and the S0: soluble hydrocarbons present in the distillate. The major portion of the sulphurdioxide is varemaining after the major portion of the sulphur dioxide has been removed contains a much higher concentration 'of nitrogen bases (partly as sulphur dioxide addition compounds, partly as free nitrogen bases) than was' present in the original crude distillate. This extract is then treated with a dilute acid or water for instance on'countercurrent contact to extract the bases as water soluble salts and the free nitrogen bases are obtained from these salts by the addition of an inorganic basesuch as sodium hydroxide. This method of extracting the nitrogen bases from petroleum distillates has been fully described and claimed in my co-pending application Serial No. 590,913.

The nitrogen bases extracted from petroleum distillates, as well as those obtained from shale or by pyrolysis of cottonseed meal, are complex mixtures of compounds of carbon, hydrogen and nitrogen. They may be classified in a general manner into aromatic bases, such as methylated quinolines which are present in considerable numbers in most fractions of nitrogen bases, and hydroaromatic bases such as the pyrindacine base CmHzsN The proportion of aromatic to' hydroaromatic nitrogen bases in any particular complex mixture porized from the extract phase. The extract 1 depends upon the source from which the latter was isolated and increases with the boiling point of the petroleum fraction. Thus for instance, in

mixtures of nitrogen bases extracted from pehibit a much lower refractive index than the aromatic ones. Experiments conducted showed that substituted quinolines or isoquinolines have a refractive index of N25/D of approximately 1.600 while two hydroaromatic bases, namely the pyrindacine base CreHssN referred to above and a pyrindine base CraHzrN have refractive indices of N20/D=1.5129 and N25/D=1.4833 respectively.

While the majority of the nitrogen bases found in petroleum are essentially water insoluble, some of the bases present in crude gasolines exhibit a rather high degree of solubility. It is believed that this solubility is due to the presence of a considerable amount of methylated pyridines.

The bases vary from low boiling liquids which solidify only at low temperatures to high boiling liquids, some of which are solids at room temperature. The lower boiling petroleum distillates contain bases with maximum boiling point below 450 C. whilehigher boiling point bases, some of which are solid at room temperatures, are found in the heavier petroleum distillate such as gas oil or lubricating oil.

As previously stated, the fractions of nitrogen bases obtained from the petroleum distillates, and other analogous sources, represent complex aggregates of nitrogen compounds. The individual compounds present in any mixture of bases have similar boiling points but differ widely in physical and chemical properties. Fractional distillation of nitrogen bases, such as may be extracted from kerosene, even under the most favorable conditions, can only separate certain cuts having a relatively narrow boiling point range but does not allow the separation of any particular base from "its admixtures. Therefore, fractional distillation, while useful in resolving a complex mixture into fractions of narrow boiling point range, must be supplemented by other methods of partial resolution of the bases..

I have discovered that some of the nitrogen bases in a complex mixture either in the free state or as certain salts possess a selective solubility in one solvent in preference to another solvent with which the first is immiscible. Thus, by extracting a mixture of nitrogen bases or their salts with two immiscible solvents. it may be resolved into two or more fractions each containing a smaller number of bases than was present in the original mixture. Some of the pairs of soltures of nitrogen bases, the presence of water is essential for a separation into two layers.

The basic principle of this resolution is to use two immiscible liquids having selective solvent properties for certain of the nitrogen bases or their salts. In the case of nitrogen bases extracted from gasoline, certain of said bases are soluble in water but are more soluble in petroleum ether. Consequently, in this combination of solvents, it is preferable to extract with water and extract the water solution with petroleum ether, while in the case of the other solvent pairs herein suggested, extraction of the bases may be made by a mixture of solvents to cause a partition of the bases between the two solvents. In the case of organic solvents such as chloroform or ethylene dichloride when used with water, the insolubility in water of the nitrogen bases derived from such fractions as kerosene or gas oil makes necessary the conversion of the bases into a form in which they are more soluble in water than they are in their free state. Thus, by converting the bases into salts and extraeting a water solution of these salts with certain organic solvents, for instance, low boiling chlorinated solvents such as chloroform or ethylene dichloride, a partition of the salts between the two liquids occurs and in the latter case, it is found that the salts of hydroaromatic bases dissolve in the organic solvents, while the salts of the aromatic bases remain in the water solution.

It is, therefore, an object of my invention to provide an easy, cheap and efficient method for resolving mixtures of organic nitrogen bases.

It is another object of my invention to separate the aromatic from the hydroaromatic nitrogen bases.

It is still another object of my invention to isolate an individual hydroaromatic nitrogen base or aromatic nitrogen base free from admixture.

Broadly stated, my invention comprises a process for the resolution of mixtures of organic nitrogen bases either in the free state or in the form of certain salts characterized by extracting these mixtures with a number of mutually immiscible solvents to obtain a plurality of solvent phases each containing a fraction of the nitrogen bases present in the original mixture and subsequently separating the solvents.

Thus, in a narrower sense, my invention comprises a process for the resolution of a mixture of nitrogen bases into aromatic and hydroaromatic bases by extracting an aqueous solution of the hydrochlorides, acid sulphites, acid sulphates, nitrates or other salts of the bases with water insoluble organic solvents for instance chloroform or ethylene dichloride, to obtain the salts of the hydroaromatic bases dissolved in the organic solvent and the salts of the aromatic bases dissolved in the water and separating the aqueous solution from the organic solvent solution. Of the salts enumerated above, the acid sulphites and hydrochlorides are preferred for the separation of the bases as to types.

My invention also comprises any of the speciilc processes hereinafter disclosed.

, most part dissolved in the aqueous layer while the hydroclilorides'of the hydroaromatic bases predominate in the organic solvent layer. The

aqueous solution of the aromatic hydrochlorides may then be extracted with some of the pure organic solvent to separate some of the remaining hydroaromatic hydrochlorides and the organic solvent solution may then be extracted with water to remove any aromatic hydrochlorides carried over. By this operation, the original mixture of nitrogen bases is resolved into fractions containing a high concentration of either aromatic or hydroaromatic bases. The process as outlined above has been called cumulative extraction. As stated earlier in this specification, the

presence or absence of either type of'bases may be observed from their refractive indices which allows an operator to observe the extent to which the separation referred to above has been carried out. Should the refractive indices indicate that the separation is notcomplete'the process as outlined above may be repeated.

Sincethe degree of purity, i. e. separation of the hydroaromatic bases from the aromatic bases depends upon the'exhaustiveness of the extraction with chloroform or the other solvents previously referred to. it may be desirable limit this extraction to obtain highly concentrated but impure fractions of aromatic and hydroaromatic bases as the case may be'and tofurther purify these partially resolved nitrogen base types by the following procedure:

The hydrochlorides of the bases are treated with sodium hydroxide to liberate the free bases. The latter-are dissolved in acetone or alcohol and concentrated sulphuric acid is slowly added to the solution. The aromatic bases precipitate as acid sulphates while the acid sulphates of the hydroarornatic bases remain in solution. The two types of acid sulphates may be separated by filtering and washing the filter cake with a little acetone or alcohol to remove the acid sulphates of. the hydroaromatic bases. I may also add sulphuric acid directly to the free bases and extract the acid sulphates of the hydroaromatic bases with alcohol or acetone; and subsequently separate the two types of bases by filtration. These latter processes which may supplement any of the specific processes for separating hydroaromatic from aromatic nitrogen bases have been described and claimed in a continuation of my copending application Serial No. 590,913, the continuation bearing the Serial No. 638,195.

The following constitutes a modification of my process for resolving a mixture of nitrogen bases as salts into hydroaromatic and aromatic bases.

The aqueous solution of the acid sulphites of the nitrogen bases, obtained by treating a partially S02 freed extract with a countercurrent wash of water, as described earlier in this specification, is extracted with a water immiscible solvent, for instance chloroform. The acid sulphites of the'bases distribute themselves exactly like the hydrochlorides previously referred to, i. e.

theacid sulphites of the aromatic bases are present in preponderant amounts in the aqueouslayer, ,while the. hydroaromatic acid sulphites are concentrated in the chloroform layer. Withthe exception of extracting the acid sulphites of the bases instead of the hydrochlorides to bring about a resolution of the mixtures of bases into aromatic andhydroaromatic, the former process may becarried out in-an identical manner as the latter.

The free bases-may be obtained from any of their salts such as'the-hydrochlorides or acid sulphites by the addition of aninorganlcbase such as sodium hydroxide. I

The following is a specific example of the above mentioned method of resolution of fractions of nitrogen bases into aromatic and hydroaromatic bases. r 1

A mixture of nitrogen bases was extracted with liquid sulphur dioxide from a California kerosene distillate by one of the processes outlined earlier in this specification. The kerosene distillat'e "had a boiling pont range of from '350 550*F and was derived from a McKittrick asphaltic crude oil. The ai'oresaid'mixture o-f nitrogen' 'bases was carefully fractionally distilled underreduce'd" pressure and a fraction boiling at 260 C. (atmospheric pressure) was collected. This' fraction had a refractive index of N28/D=l.5190. Two hundred (200) c. c. of this fraction was dissolved in c. c. of 1: 1 hydrochloric acid and the resuiting aqueous solution was extracted with 265 c. c. of chloroform. The hydrochlorides of the bases distributed themselves between the two imbase. The bases in the chloroform layer were of the acid sulphates-of the aromatic bases came down. Afterchilling and filtering, 22 grams of snow white crystalline acid sulphates were obtafned. The bases liberated from these acid sulphates with ammonium hydroxide had a refractive index N28/D -1.5900 indicating a high concentration of aromatic nitrogen bases. The bases remaining dissolved as acid sulphates in the acetone were recovered by distilling off this solvent and were then taken up in water and the free bases liberated with ammonium hydroxide. The N28/D reading of this fraction of bases was 1.5315. By comparing the refractive indices given above and remembering that the refractive indices of the aromatic bases are somuch higher than those of the hydroaromatic bases it may be clearly seen how this process operates in concentrating the bases as to types.

A further example of this method of resolut'on is as follows:

from a California kerosene distillate by the process outlined earlier in this specification. This mixture was carefully fractionated under reduced pressure and a fraction boiling at 269 C. (atmospheric pressure) was isolated. The refractive index of this fraction was 1.5270 when observed at 28 C. A sample'thereof, measuring 125 c. c., was dissolved in 100 c. c. of 1:1 hydrochloric acid to form the hydrochlorides of the bases in aqueous solution and this solution was extracted with 165 c. c. of chloroform. The mixture separated into two phases namely an aqueous solution containing a high concentration of the hydrochlorides of the aromatic bases and a chloroform solution containing a high concentration of the hydrochlorides of the hydroaromatic bases.

On addition of an inorganic base such as sodium hydroxide to the aqueous solution referred to above the latter was found to contain 35 c. c. of bases having a refractive index of N28/D=1.5588 which indicated the presence of considerable amounts of aromatic nitrogen bases. The chloroform solution was then extracted with three separate portions of water of c. c., 100 c. c. and 200 c. 0., respectively. The nitrogen bases dissolving in the first 100 c. c. of water measured 16 c. c. and had a refractive index N28/D=1.5260. The nitrogen bases d ssolving in the second 100 c. c. of water measured 12 c. c. and had a. refractive index of 1.5162 while the bases in the last 200 c. c. of water measured 12 c. c. and had a refractive index of 1.5138, the last two refractive indices being also taken at 28 C. The bases remaining in the chloroform layer after the water extraction, measured 50 c. c. and had a refractive index of N28/D=1.5085, which indicated a pre'ponderant amount of hydroaromatic bases present.

The 35 c. c. of aromatic nitrogen bases which were present in'the aqueous layer referred to above were dissolved in 56 c. c. of acetone and 9 c. c. of concentrated sulphuric acid was added to the solution. 21 grams of'nicely crystalline white acid sulphates of the aromatic bases were precipitated and yielded upon separation from the solution and by add'tion of sodium hydroxide 15 c. c. of free bases with N28/D=1.5820. The bases remaining as acid sulphates in' the acetone solution were chiefly hydroaromatic bases. They measured 20. c. c. and had a refractive indexof N28/D=1.5250. Remembering that the refrac tive index of the nitrogen bases is inversely proportional to the degree of hydrogenation one may clearly observe the resolution of the original mixture of bases into aromatic and hydroaromatic bases. from the data given above and ar-" ranged in the following table:

Table I Refractive Amount index Original free bases cc. 1. 5270 Bases in aqueous layer 35 1.5588 Bases in aqueous layer precipitated as acid 7 sulphates in acetone solution 15' l. 5820 Bases in aqueous layer remaining in acetone solution as acid sulphates 20 l. 5250 Bases from first water extraction of chlorm form layer 16. l. 5260 Bases from second water extraction of chloroform layer 12 l. 5162 Bases from third extraction of chloroform yer l2 1. 5138 Bases remaining in chloroform layer after water extraction"; so 1. 6085 As has already been stated earlier in this specification, the process of resolving mixtures of nitrogen bases into aromatic and hydroaromatic bases by extracting an aqueous solution of their salts with solvents such as chloroform. ethylene dichloride, etc. operates equally well. on complex mixtures of bases as on narrow fractions thereof. In a number of cases, especially where the mixture contains only few aromatic and hydroaromatic bases, the process of resolving the bases'as to types, as previously outlined, may be applied in separating a single aromatic or hydroaromatic-base free from admixture.

This is illustrated in the following example:

A mixture of nitrogen bases extracted with liquid sulphur dioxide from a California kerosene in the manner outlined above was carefully fractionally distilled under reduced pressure and a fraction boiling at approximately 276 C. (atmospheric pressure) was isolated. This fraction contains large amounts of a hydroaromat-ic base CreHzsN and an aromaticbase 2,3,8 trimethyl quinoline. A portion ofthis fraction was dissolved in a sumcient amount of 1:1 hydrochloric acid to form an aqueous solution of the hydrochlorides of the bases and the solution was ex tracted with chloroform.

A separation into two phases took place soon after the introduction of the chloroform. The 2,3,8 trimethyl quinoline hydrochloride dissolved in the aqueous phase while the hydrochloride of the CreHssN base dissolved in the chloroform phase. The two phases were then separated and each reduced by evaporation to a small volume. On cooling the aqueous solution of, the hydrochloride of the 2,3,8 trimethyl quinoline, the latter crystallizes out, while the hydrochloride of the CmHzsN base may be obtained by crystallizing from the cooled chloroform solution. Addition of small amounts of acetone to both the aqueous and chloroform solution will precipitate any of the hydrochlorides'of the bases remaining in a dissolved state. The free bases may be recovered from their respective hydrochlorides obtained as described above, by the addition of a base such,

as sodium hydroxide or ammonium hydroxide.

The bases produced from petroleum or on pyrolysis of protein materials and found in the chlorinated solvent layer are not of the truethydroaromatic type of the character of piperidine or coniine as is evidenced by the.fact that they are not susceptible to. dehydrogenation (see Bailey et al., Journal American Chemical Society 55, 4145, 1933). The structural formula: given for the CreHzsN base and the C13H21N base also illdlcate that they are not wholly hydroaromatic.

The difficulty in classifying these compounds A crude mixture of nitrogen bases obtained from petroleum or any of the analogous sources referred to earlier in this specification is dis-- solved in a light petroleum solvent such as petroleum ether and methyl alcohol is added to the aosasas solution. A small amount of water is then added and the original solution immediately-separates into two layers. A fraction of the nitrogen bases dissolves in the upper or petroleum ether layer whilethe remainder dissolves in the lower or alcohol layer. The two layers are then separated, the solvents vaporized and two aggregates of nitrogen bases are obtained, each aggregate being simpler in nature'than the original mixture. The-process as ou'tlinedabove'may be re- 'peated on any of the fractions of nitrogen bases obtained from either the alcohol or the petroleum ether and by doing so the original mixture of nitrogen bases may be'resolved into a number of more simple aggregates.

As stated earlier in this specification, some of the nitrogen bases which are present in crude gasoline are quite readily soluble in" water. Crude gasoline may be defined and identified as all ma. terial having a boiling point up to approximately 450 F. and obtainedby simple distillation of a crude petroleum, by distilling the same under pressure, or by any of the well known cracking processes. The water soluble bases may be removed from the gasoline by extraction with water. Somebf the nitrogen bases which dissolve in the water are 'more soluble in petroleum ether so that by extracting an aqueous solution of these nitrogen bases with petroleum ether and separating the two immiscible solutions, the original mixture is resolved into two more simple ones. The free bases may be obtained from the aqueous or petroleum ether solutions by driving off the respective solvents. A substantial percentage of the bases obtained from either the petroleum ether or aqueous layer is made up out of methylated pyridines.

A fraction of the nitrogen bases originally present in the crude gasoline remains behind after the extraction with water. These bases may be extracted from the crude gasoline with a dilute acid such as sulphuric acid and the free bases obtained from their salts by the addition of a base such as sodium hydroxide or ammonium hydroxide. Thus, by applying the procedures as outlined above to the nitrogen bases present in crude gasoline, the original mixture. of bases present in the aforementioned petroleum distillate may be resolved into a plurality of more simple ones.

The following constitutes another method by which a mixture of nitrogen bases may be resolved by extracting it with selective solvents immiscible in each other:

A petroleum distillate containing dissolved nitrogen bases is extracted with liquid sulphur dioxide at low temperatures, preferably l( F. or lower. The extract phase so obtained contains large amounts of liquid sulphur dioxide, the nitrogen bases and the SO: soluble hydrocarbons present in the original distillate. A fraction of the sulphur dioxide is vaporized from the extract phase referred to above and the resulting extract still containing considerable liquid sulphur dioxide is extracted with a solvent preferably free from any components which tend to dissolve in the liquid sulphur dioxide. A typical solvent of this type is a light parafllnic petroleum distillate having a specific gravity from .685-.650 commonly called petroleum ether. On commingling the petroleum ether with the extract referred to above, the nitrogen bases distribute themselves between the two solvents. By repeating the pe-- troleum ether extraction of the sulphur dioxide extract, the original mixture of nitrogen bases may be resolved into any number of smaller asobtained from the petroleum ether solutions by driving off the solvent.

A fraction of nitrogen bases still remains dissolved in the liquid sulphur dioxide extract after the petroleum ether extraction. To obtain these bases the major portion of the sulphur dioxide is vaporized and the resulting extract commingled with a countercurrent stream of water or a dilute acid to form an aqueous solution oftheir salts. The free nitrogen bases may be obtained from their salts by the addition of an inorganic base such as sodium hydroxide.

The value of the process of resolution of mixtures" of nitrogen bases herein disclosed lies in the ease with which this resolution can be accomplished. By its application any person skilled in the art can obtain mixtures of nitrogen bases containing substantially only aromatic or hydroaromatic bases free from admixture. In the formation of'phthalone dyes from alkylated quinclines which are aromatic in character the presence'of hydroaromatic bases is undesirable H. QQJ. it has been deemeddesirable"'to"reinove' 'th e; hydroaromatic bases from the alkylated quinothey tend to'decrease the yield of the dye s herein disclosed and many variations maybe made within the scope of the appended claims.

I claim:

1. A process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale oil fractions and distillates resulting from the pyrolysis of cotton seed meal; which comprises forming salts of said mixtures and extracting an aqueous solution of said salts with a low boiling chlorinated hydrocarbon solvent immiscible with water. i

2. A process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale oil fractions and distillates resulting from the pyrolysis of cotton seed meal; which comprises commingling these mixtures with an inorganic acid to form corresponding salts of the nitrogen bases and extracting an aqueous solution of the said salts with a low boiling chlorinated hydrocarbon solvent immiscible with water.

3. A process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale oil fractions and distillates resulting from the pyrolysis of cotton seed meal which comprises chloroform from the aqueous phase containing. a

preponderant amount of bases soluble in water.

4. A process according to claim .3 comprising the additional steps of partially vaporizing the hydrochlorides of thechloroform and water from the separated chloroform and aqueous phases, adding a small amount of acetone to each phase to crystallize out the hydrochlorides of the bases present in each phase and recovering the free bases from their hydrochlorides by the addition of an alkaline hydroxide.

5. A process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale ,oil fractions, and distillates resulting from pyrolysis of cottonseed meal into aromatic and nonaromatic bases which comprises forming salts of the bases present in said mixtures and extracting 'an aqueous solution of said salts with a low boiling chlorinated hydrocarbon solvent immiscible with water, said chlorinated solvent dissolving substantially all of the salts of the non-aromatic bases and leaving substantially all of the salts of the aromatic nitrogen bases dissolved in the water.

6. A process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale oil fractions, and distillates resulting from pyrolysis of cottonseed meal which comprises forming the acid sulphite salts of the bases in aqueous solution and extracting said aqueous solution with a low boiling chlorinated hydrocarbon solvent.

'7. A process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale oil fractions, and distillates resulting from pyrolysis of cottonseed meal into aromatic nitrogen bases and non-aromatic nitrogen bases which comprises forming the hydrochloride salts of the bases in aqueous solution and extracting said aqueous solution with a low boiling chlorinated hydrocarbon solvent.

8. A process for resolving mixtures of nitrogen gases derived from crude material selected from the class consisting of petroleum fractions, shale oil fractions and distillates resulting from the pyrolysis of cotton seed meal which comprises dissolving said mixtures in dilute hydrochloric acid to form an aqueoussolution of the hydrochlorides of substantially all the bases present, extracting said aqueous solution with a low boiling chlorinated hydrocarbon solvent immiscible with water to obtain an aqueous phase and a chlorinated hydrocarbon solvent phase, re-extracting the aqueous phase with portions of the chlorinated hydrocarbon solvent and re-extracting the chlorirated hydrocarbon solvent phase with portions of water and combining the individual'aqueous and individual chlorinated hydrocarbon solvent extracts. l

9. A process according to claim 8 in which the low boiling chlorinated hydrocarbon solvent is chloroform.

10. A process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale oil fractions, and distillates resulting from pyrolysis of cottonseed meal into aromatic and non-aromatic bases which comprises dissolving the said mixtures in diluted hydrochloric acid to form an aqueous solution of the hydrochlorides of at least a portion of the bases present, extracting said aqueous solution with ethylene dichloride to obtain two phases, the aqueous phase containing a high concentration of the hydrochlorides of the aromatic bases, while the ethylene dichloride phase contains a high concentration of a,oss,ss4

the hydrochlorides of the non-aromatic bases,.

separating the two phases, extracting the aqueous phase with small portions of ethylene dichloride to remove admixed hydrochlorides of the nonaromatic bases and the ethylene dichloride phase with small portions of water to remove admixed hydrochlorides of the aromatic bases, combining the individual ethylene dichloride and individual water solutions to obtain an aqueous solution containing substantially only hydrochlorides of the aromatic nitrogen bases and an ethylene dichloride solution containing substantially only hydrochlorides of the non-aromatic bases and recovering the free bases from their hydrochlorides.

of nitrogen bases than was present in the original kerosene, commingling this extract with water to obtain an aqueous solution of the'acid sul-.

phites of the nitrogen bases, liberating bases by the addition of an inorganic base to the aforesaid aqueous solution of the acid sulphites of the bases, separating the free bases as a crude mixture, fractionally distilling said mixture under reduced pressure, isolating a fraction boiling at approximately 276 C. (atmospheric pressure), dissolving this fraction in diluted hydrochloric acid to obtain an aqueous solution of the hydro chlorides of the nitrogen bases present in the said fraction, extracting the said aqueous solu-' tion with chloroform to obtain an aqueous phase containing the hydrochlorides of the aromatic bases and a chloroform phase containing hydrochlorides of the non-aromatic bases, separating the two phases, reducing each phase to a small volume .by evaporation, cooling the chloroform and water phase, adding a small amount of acetone to each individual phase to precipitate the aromatic 2,3,8 trimethyl quinoline hydrochloride in substantially pure form from the water and the hydrochloride of the non-aromatic pyrindacine base CmHzsN from the chloroform and obtaining the free bases by the addition of an alkaline hydroxide to the hydrochiorides thereoi.

12. A process for obtaining and separating 2,3,8 trimethyl quinoline and a pyrindacine base whose empirical formula is C1sH25N, which comprises extracting a kerosene produced from an asphalt base crude oil, with liquid sulphur dioxide to obtain an extract phase containing large amounts of liquid sulphur dioxide, the nitrogen bases present in the kerosene together with the S0: soluble portion thereof, vaporizing the major portion of the liquid sulphur dioxide to obtain an extract" containing a higher concentration of nitrogen bases than was present in the original kerosene, commingling this extract with water to obtain an aqueous solution of the acid sulphites of the nitrogen bases, liberating the free bases by the addition of an inorganic base to the aforesaid aqueous solution, separating the free bases as a crude mixture, fractionally distilling luted hydrochloric acid toobtain 'an aqueous solution of the hydrochlorides of the nitrogen bases present in the said fraction, extracting the said aqueous solution with ethylene dichloride to obtain an aqueous phase containing-the hydrochlorides of the aromatic bases and an ethylene dichloride phase containing hydrochlorides of the non-aromatic bases, separating the two phases, reducing each phase to a small volume by evaporation, cooling the ethylene dichloride and water phase, adding a. small amount of acetone to each individual phase to precipitate the aromatic 2,3,8 trimethyl quinoline hydrochloride in substantially pure form from the water and the hydrochloride of thepyrindacine base C16H25N from the ethylene dichloride and obtaining .the free bases by the addition of an alkaline hydroxide to the hydrochlorides thereof. I

13. A- process for separating 2,3,8 trimethyl quinoline from the pyrindacine base C1sH25N which comprises dissolving a mixture of nitrogen bases containing a high concentration of the said 2,3,8 trimethyl quinoline and CxcHzsN pyrindacine base in dilute hydrochloric acid to obtain the hydrochlorides of the said mixture of nitrogen bases in aqueous solution and extracting said aqueous solution with chloroform to separate a chloroform phase containing substantially only the hydrochloride of the CisHzsN base from an aqueous phase containing substantially only the hydrochloride of the 2,3,8 trimethyl quinoline.

14. A process for obtaining aromatic nitrogen I bases substantially free from admixture which comprises extracting a crude mixture of nitrogen bases from a petroleum fraction, contacting said mixture with hydrochloric acid to form an aqueous solution of the hydrochlorides of all the bases present in said mixture, extracting said mixture with a low boiling chlorinated hydrocarbon solvent, removing the said solvent together with the hydrochlorides of the bases soluble therein from the aqueous solution containing substantially only hydrochlorides of the aromatic nitrogen bases and subsequently recovering the free aromatic nitrogen bases from the aqueous solution by the addition of an inorganic hydroxide.

15. A process according to claim 14 wherein the low boiling chlorinated hydrocarbon is chloreform.

16. Process according to claim 1 in which the low boiling chlorinated hydrocarbon solvent is chloroform.

17. Process according to claim 2 in which the low boiling chlorinated hydrocarbon solvent is chloroform. i

18. A process for resolving mixtures of nitrogen bases derived from crude materials selected from the class consisting of petroleum fractions. shale oil fractions and distillates resulting from the pyroysis of cotton seed meal which comprises forming salts of said mixtures in aqueous solution, extracting said aqueous solution with a low boiling chlorinated hydrocarbon solvent immiscible with water to form an aqueous phase and a chlorinated hydrocarbon solvent phase, separating said phases, re-extracting the aqueous phase 7 chlorinated hydrocarbon solvent extracts so obtained.

' low boiling chlorinated hydrocarbon solvent is ethylene dichloride.

23. A,process for resolving mixtures of nitrogen bases derived from a crude material selected from the class consisting of petroleum fractions, shale oil fractions and distillates resulting from pyrolysis of cottonseed meal which comprises, forming salts of said bases in aqueous solution, extracting said aqueous solution with a low boiling chlorinated hydrocarbon solvent to obtain two phases and separating a low boiling chlorinated hydrocarbon solvent phase containing a preponderant amount of salts of the bases soluble therein from an aqueous phase containing a preponderant amount of salts of the bases soluble in water.

24. A process for separating 2,3,8 trimethyl quinoline from the pyrindacine base CmHaaN which comprises dissolving a mixture of nitrogen bases containing a high concentration of the said 2,3,8trimethyl quinoline and CrsHasN pyrindacine base in dilute hydrochloric acid to obtain the hydrochlorides of the said mixture of nitrogen bases, in aqueous solution and extracting said aqueous solution with ethylene dichloride to separate an ethylene dichloride phase containing substantially only the hydrochloride of the CisHzsN base from an aqueous phase containing substantially only the hydrochloride of the 2,3,8 trimethyl quinoline. v

25. A process according to claim 23 in which the solvent used isethylene dichloride.

26. A process for resolvingmixtures of nitrogen bases into aromatic and non-aromatic bases which comprises extracting with liquid sulphur dioxide a crude material selected from the class consisting of petroleum fractions, shale oil fractions and distillates resulting from pyrolysis of cottonseed meal, to obtain an extract phase containing liquid sulphur dioxide, nitrogen bases and non-basic portions of the crude material soluble in liquid sulphur dioxide, removing sulphur dioxide from the said extract phase, contacting the remaining extract phase with water to obtain an aqueous phase containing acid sulphites of the nitrogen bases, extracting said aqueous phase with a low boiling chlorinated hydrocarbon immiscible with water to obtain a chlorinated hydrocarbon phase containing a preponderant amount of acid sulphites of the non-aromatic nitrogen bases and an aqueous phase containing apreponderant amount of acid sulphites of the aromatic nitrogen bases and separating said phases. v

27. A process as defined in claim 26 wherein the chlorinated hydrocarbon solvent is chloroform.

28. A process 'as defined in claim 26 in which the chlorinated hydrocarbon solvent is ethylene dichloride.

JAMES R. BAILEY.