US2522618A - Extraction of aromatic and sulfur compounds - Google Patents

Description

Sept. 19, 1950 c. E. JOHNSON ErAL EXTRACTION 0F AROHATIC AND SULFUR COMPOUNDS Filed Sept. 30. 1949 n Y mma w msm R mnd m MH JA.

r my wm Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE EXTRACTION F ABOMATIO AND SULFUR CQMPUUNDS Carl E. Johnson, Grlilith, and Arthur A. llarban, Hammond, Ind.. assigner: to Standard Oil 2mm, Chicago, Ill., a corporation of ln- Application September M, 1949, SerialNo. 118,745

This invention relates to the extraction o! aromatic hydrocarbons and organic sulfur compounds from mixtures oi either or both thereof with aliphatic hydrocarbons. for example, such mixtures as occur in various processed or unprocessed petroleum oils. More particularly. this invention relates to processes for the selective extraction of aromatic hydrocarbons and organic sulfur compounds from oils comprising aliphatic hydrocarbons by the employment of certain amine salts of sulfonic acids as selective extraction solvents.

Numerous so-called selective solvents have been proposed for removing aromatic and/or organic sulfur compounds from their solutions in various hydrocarbon oils. particularly for the reilning of lubricating oil stocks, burning oils and the like. While a number oi' selective solvents are in actual commercial use. no solvent has been round to be sufficiently satisfactory for all purposes to retard the general search for improved selective solvents.

We have discovered that certain amine suifonates are surprisingly enective selective solvents for aromatic hydrocarbons and sulfur cornpounds in admixture with aliphatic hydrocarbons, notably certain petroleum oil fractions. We have further found that said amine sulfonates can he prepared relatively cheaply, have relatively low toxicity, have relatively mild corrosive properties. permitting their employment in conventional equipment. are characterized by surprisingly low or negligible solubility thereof in the ramnate phase produced by the extraction process. are readily recoverable. and have physical properties which enable them to be employed as selective extraction solvents for aromatic hydrocarbons and sulfur compounds at readily attainable temperatures and pressures. Moreover. said amine sulionates are characterized by surprisingly great thermal stability permitting their employment as solvents in extractive distillation processes.

It is an object oi' this invention to provide a process for the selective extraction of aromatic hydrocarbons and organic sulfur compounds from their mixtures with aliphatic hydrocarbons, including both acyclic and alicyclic hydrocarbons which may be completely saturated or may contain one oleilnic unsaturation per molecule. Another object of this invention is to provide the art oi' selective extraction of aromatic hydrocarbons and organic sulfur compounds with novel solvents. viz., certain amine sulfonates. An additional object ot our invention is to provide solvents for selective extraction processes char- 13 Claim.. (Cl. ISG-14.35)

acterized by high selectivity for aromatic hydrocarbons and organic sulfur compounds while at the same time exhibiting little or no solvent capacity for aliphatic hydrocarbons, both saturated and unsaturated. A further object oi' our invention is to provide the art with a novel selective extraction process. These and other objects of our invention will be readily discerned from the ensuing description thereof and from the appended ligure.

The novel solvents employed in the selective extraction process ot this invention are amine sulfonates having the general formula:

wherein AR.: and Rs are selected from the class consisting ot hydrogen and saturated hydrocarbon radicals, R1 is a saturated hydrocarbon radical containing atleast two carbon atoms, and R4 is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals. Thus. the saturated hydrocarbon radlcal may be an alkyl radical containing at least two carbon atoms. a cycloalkyl radical. a cycloalkyl-alkyl radical. or an aralhrl radical.

R4 may be an alkyl, cycloalkyl, cycloalkyl-alkyl, aralkyl, aryl, alkaryi or cycloalkyl-aryl radical. The amine sulionate solvents oi' this invention contain between 4 and 20 carbon atoms. inclusive, per molecule.

Examples, given by way of illustration and not necessarily for limitative purposes, of suitable alkyl radicals are: ethyl. methyl. n-propyl, isopropyl, nbutyl. amyl, octyl. nonyl, hexadecyl and octadecyi.

Illustrative examples oi suitable cycloalkyl radicals include cyclopentyl, methylcyclopentyl, cyclohexyl. methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, ethylcyclopentyl, and endomethylenecyclohexyl (bicyclo [2,2,ll heptyl) and 2methylbicyclo [2.2.1] heptyl.

Examples of suitable aralkyl radicals in the above general formula include benzyl, 2-phenylethyl. 2-phenylpropyl. w-xylyl. naphthomethyl, and the like.

Examples of suitable cycioallwl-alhl radicals include cyclohexymethyl. cyclohexyethyi. cyclopentylpropyl. and the like.

Examples o! suitable R4 aryl radicals include phenyl, naphthyl and derivatives containing nucclearly substituted chlorine atoms, etc.

Examples of suitable R4 alkaryl radicals for substitution in the above general formula are 3 tolyl. xylyl. dimethylphenyl, ethylphenyl, isopropylphenyl. butylphenyl. methylnaphthyl. dimethylnaphthyl, and the like.

Examples of suitable cycloalkyl-aryl radicals include cyclohexylphenyl, methylcyclopentylphenyl, cyclohexyltolyl, and the like.

It is not intended to imply that all the amine sulfonates contemplated for use in this invention are precisely equivalent and indeed the speciflc examples hereinafter presented demonstrate that they are not. However. they are all generally useful and suitable for the purposes of the claimed invention.

Certain properties of some o! the airline sulfonates which are useful for the purposes of the present invention are shown in the following table:

Tanna I Amine sulfonate Bulionic Acid Amine Radll ma 'lriethylamlne -r We have found that equal volumes of the salts of Table I and the following solvents are mlscible at -25" C.: water, methanol, 95% ethanol, acetone and benzene, and that the salts are insoluble in hexane.

We have discovered that certain triethylamine sulfonates are particularly desirable for the purposes of the present invention because they are relatively non-viscous, non-volatile liquids at normal temperature, exhibit high selectively for automatic hydrocarbons and sulfur compounds, and are characterized by relatively little change of viscosity with temperature. Certain properties of triethylamine salts of the lower alkanesulfonic acids which are particularly desirable for employment in the claimed process are set forth in Tables II and III.

Tsar.: II

Properties of triethylamine sdlts of sullcmic acids alkane- 1 Period r emux m mds from swoon Universal vlseimem' l As supsrocolod liquid.

TAsLlIII E'Jeet of added water on the viscosity of triethulamine (Ci-C4) mixed alkanesulfonates W W W7 15 H16 nl?) n.6

245. 0 174. 9 71. 5 ma 100.2 ne 52. 8 47. 7 35. 5 1%. 5 133. 6 21. 8 -50 50 -66 The amine sulfonates deilned by the above general formula are either normally liquid or relatively low melting solids and may be used for the purposes of the present invention without auxiliary solvents or diluents. However, because of their solubility in water, methanol, ethanol, etc., it may be desirable to employ the amine sulfonate solvents of the present invention together with more or less of such diluents or co-solvents, to modify the selectivity of the amine sulionates. to lower their melting points, or for other reasons. The amount of auxiliary solvents employed can be selected with reference to specific cases; ordinarily, only between about l and about 20 weight per cent based on the amine sulfonate will be employed. If desired, the amine sulfonates may` be employed together with between about l and about 20 per cent of a. sulfonic acid, preferably the sulfonic acid that is combined in the amine sulfonate.

In the process of the present invention the selective solvent is employed as a liquid, melt or solution; the feed stock may be charged to the process as a liquid, solution or vapor. The present invention, therefore, relates to liquid-liquid or liquid-vapor extraction processes employing the above-defined amine sulfonate solvents. When the feed stock is charged to the process as a vapor, the process is one of extractive distillation.

By the term extraction," as employed in the appended claims, lt is intended to include not only liquid-liquid extraction processes, but also extractive distillation employing the above-defined solvents. It is well appreciated that these processes diier somewhat from each other in eiiiciency or applicability in specific instances, but they are actually and theoretically related (note, for example, H. J. Hibshman, Ind. Eng. Chem. 4l, 1366 (1949 i.

In general, the extraction operations of the present invention are conducted at temperatures between about 0 and about 180 F, the particular extraction temperature depending upon the specific amine sulfonate solvent, the melting point of the solvent, whether or not it is used alone or with an auxiliary solvent or dlluent, the degree and selectivity of extraction sought to be effected. etc.

The volume of selective solvent employed depends, among other things, upon the aromatic and/or sulfur content of the feed stock, the temperature of operation, and desired eillciency, but will generally fall within a range of about 0.3 to about l0 volumes of amine sulfonate per volume of charging stock. Usually, pressures within the range of about 0 to 100 p. s. i. g. are sufficient for this purpose, it being appreciated that the particular pressure necessary in a given case can readily be determined. When the feed stock is to be employed in the vapor phase, suitable pressures can readily be determined at which the feed stock will be a vapor at the extraction temperature.

Numerous hydrocarbon oil fractions derived from petroleum, coal, shale, etc., are known to contain aromatic hydrocarbons, organic sulfur compounds, and usually both of these constituents, whose removal is in numerous instances, desired in order to produce refined hydrocarbon oils. Such oils may boil within the boiling ranges of gasoline, naphtha, kerosene, gas oil, heater oil. or lubricating oil. 'I'he process of the present invention is particularly applicable to the refining of gasoline boiling range hydrocarbon oils conandere crude oils, such as West Texas crude oil, by

cracking or coking processes. The process of the present invention is particularly applicable to the selective extraction of polycyclic aromatic hydrocarbons, for example, monoand dimethylnaphthalenes, from hydrocarbon fractions containing the same, for example, hydroformer bottoms fractions and cracked gas oil boiling range stocks derived from the cracking i gas oil or higher boiling range hydrocarbon oils in the presence ot silica-alumina. silica-magnesio., or similar solid siliceous cracking catalysts. etc. The process ot the present invention is well adapted for the selective extraction of non-acidic sulfur compounds, such as thioethers, disulndes and cyclic sulildes, such as thiophene. alkyithiophenes, thiophanes. and the like.

Following are some speclilc examples of the process o our invention. which are furnished to illustrate, but not unduly to limit. the scope of our invention.

EXAMPLEI One volume of a mixture containing 0.5 volume of benzene and 0.5 volume of n-heptane was contacted with one volume oi' mixed alkane-sulfonic acid salts (C1-C4 alkanesulfonic acid mixture) of n-butyl amine at 35 C. The mixture was shaken and then allowed to settle into two layers. The amine salt layer consisted of 1.22 volumes and the hydrocarbon layer ot 0.78 volume. The oil was recovered from the extract by dilution of the extract phase with about an equal volume of water. The data summarized below show that the extract contained 62% benzene and 38% heptane and the ralnate contained 33% benzene and 67% heptane.

Charge Extract Raillnato dill 0.760 0.5M 0.749

EXAMPLE2 When the process oi' Example 1 was repeated, employing, in the place of the solvent of Example 1. one volume of a mixture of 0.3 volume n-butylamine C1-C4 alkanesulfonates. and 0.2 volume of methanol. at 23 C., the identical extraction resuits were obtained.

EXAMPLE 4 The feed stock was a light catalytic cycle' stock derived from the catalytic cracking of West Texas gas oil in the presence oi natural clay catalyst and having the following properties:

l ASTM Dlltillation rg-m* n.r.,r. l

1.11.1. on s 4m in as so 4u i.' s l0 so im an 1o n1 an an so sro n.1. m l5 ne 1.4963 Weight per cent B 1.15 Specific Dispersion. 156 Bromine No 11.3 2o A. P. I 20.3

so no Percent E Catalytic stock c l. 4063 i. l5 esta??? w l. $54 0. 85 Extract l. 571i 3. m

selectivity oi' the solvents for the extraction oi aromatic hydrocarbons, the following factor, termed the aromatic selectivity factor (ASF) has been developed:

A F nu feed-nb ranate s Volume percent extractedX 10"* A similar factor expressing the selectivity of a solvent for sulfur compounds. the so-called sulfur selectivity factor (BSF) is determined in accordance with the following equation: w

8SF=percent S in feed-percent S in ramnate Volume percent extracted X10 As a measure oi' the Taal.: IV

S Factor ses:

It will be obvious that methane aiorded raillnate yields as high as those attainable by the use of triethylamine ethanesulonly the use ot nitro- 7o fonate. It will also be noted that the ASF and BBF oi the amine sulfonate solvent compare very favorably with those of iurfurai and nitromethane. The amine sulfonate was more selective for aromatica than HF, suggesting the sequential 7 employment of the amine suii'onate and HF in refining hydrocarbon oils containing both aromatic hydrocarbons and organic sulfur compounds.

EXAMPLEB One volume of the catalytic cycle stock employed as a feed stock in Example 4 was extracted. using the same technique as in Example 4, with an equal volume of molten triethylamine p-toluenesuifonate, a crystalline solid which melts at 65 C. The amount oi extract was i0 volume per cent based on the feed stock. The following data were obtained:

Taste V nn* PercentB charge 1.4968 1.15 gligi 1.4863 0.92

The above data indicate that the aromatic selectivity factor of the solvent under the above conditions was 104 and the sulfur selectivity factor was 230.

IXAIMPLE One volume of the catalytic cycle stock employed as feed stock in the above examples was contacted with two volumes of the n-butylamine salt of a mixture of Ci-C4 alkanesulfonic acids in two extraction treatments at 50 C. The following data were obtained:

Tsai.: VI

Vol. nul Percent Percent 8 Charge Catalytic Cycle Stock 1. 4963 l. l nal Rafllnato l. 4901i 0.8i Extract l l M29 l0 2.12 Extract 2 l. 5302 4. 5 2. l0

The data in the following table show the results obtained when one volume o! the iight catalytic cycle stock employed as feed stocks in the above examples was extracted with one volume of amine salt at 'l0' C.

One volume of the mixture of 0.525 part by volume of thiophene and 0.475 part by volume of n-heptane was extracted at 25 C. with one volume oi.' triethylamine Cl-Cl alkanesulfonates. The extraction mixture was allowed to stratify into a railinate layer containing 20% by volume of thiophene and 80% by volume ci n-heptane. and an extract layer from which an oil was separated by dilution with water, said oil containing 93% by volume of thiophene and 1% by volume ci n-heptane. The raiiinate yield was 56% oi the feed stock.

An illustrative process flow and equipment are indicated in the ngure. The .hydrocarbon mixture to be extracted, containing aromatic hydrocarbons and/or sulfur compounds. for example. a light cycle stock from silica-alumina cracking of a West Texas gas oil. is passed through valved line l! into the contacting sono il.

We may employ conventional contacting and separation equipment such as has heretofore been employed in eiiecting selective solvent extraction of lubricating oils, illuminating oils. etc..

or in the processes for the extractive distillation of hydrocarbon oils. The contacting equipment may comprise a vertical tower. which is preterably provided with packing or spacing materials to insure thorough contacting of the hydrocarbon feed stock and the amine sufonate solvent. Suitable materials of construction for the contacting zone are aluminum and stainless steel. which have proven strongly resistant to corrosion by alkyl ammonium sulfonates, although it should be understood that we may employ other construction materials. for example. giass. ceramicor carbon-lined iron towers. Suitable spacing materials comprise shaped fragments. for example Berl saddles or Raschig rings made of carbon, porcelain. glass, aluminum. stainless steel. etc.; stainless steel jack chain; stainless steel or aluminum screens which may be shaped, for example. in the form of Scofield. McMahon or Stedman packing, etc. I! desired. the contacting tower may be jacketed or provided with heat exchange coils to permit maintenance of the desired temperature.

In a desirable method of operation. the feed stock is passed into the lower portion of sone ll against a counter-now of an amine sulfonate. for example, triethylammonium ethanesuifonate. which is introduced into the upper portion of tower Il through valved line II. Diluents. e. g., pentane or hexane. or modifying solvents. e. g. methanol. may be introduced with the feed stock. the amine sulfonate solvent or separately through a line not shown. into zone il.

The contacting of the amine sulfonate and hydrocarbon feed stock results in the production of ramnate and extract phases whose common boundary or interface is indicated at i3. The countercurrent extraction zone may be operated with either the feed stock or solvent as the continuous phase. In the mode of operation. illustrated in the figure, the extract phase is shown as the continuous phase through which the h!- drocarbon feed stock is introduced as the dispersed phase.

The raiilnate phase forms a supernatant layer above interface i3 in zone Il whence it is discharged from said zone through vaived line il. The ramnate phase contains a substantially reduced content of aromatic and sulfur compounds as compared with the feed stock. It should be understood, however. that the raiiinate phase may be further treated to reduce its content of sulfur and aromatic compounds. if it is so desired. For this purpose, a portion at least of the raffinate phase may be recycled from line i4 by a line not shown to re-enter zone ll with fresh feed stock. Alternatively. or in addition. the ramnate in line i4 may be sent to another contacting zone, identical in all substantial respects with zone il, for treatment in a second stage with fresh solvent, which may be the same amine sulfonate or a diilerent amine suli'onate from that passing into line l2, or may be an entirely different type of solvent. e. g.. liquid hy drogen uoride. HIL-BEI. liquid a, phenol.

asaasis furfural. bis- (beta-chloroethyl) ether, etc. It should be noted that further extraction of the raiiinate passing through line Il with solvents different from the amine suli'onate passing through line I2 is greatly facilitated by the fact that the amine sulfonate is substantially insoluble in said raihnate. averting the necessity of special procedures tor the removal of said amine sulfonate from said raiiinate. The inappreoiable solubility of the amine sulfonates of this invention in the raiilnate phase is noteworthy and substantially diii'erent from the behavior heretofore observed in extraction processes employing conventional solvents. such as phenol. furi'ural, nitromethane, etc.

The extract phase. a solution of aromatica and/or sulfur compounds in the amine sulfonate solvent. is withdrawn from the lower end of tower Il through valved line Il, whence it is passed into separation zone I6. Ii' desired, a part of the extract phase may be recycled from line I Il to i'eed line I2 by means of a line not shown in the drawing. Zone i8 may be a separating vessel into which water or aqueous solvents are introduced by valved line I'I, in suitable amounts, e. g. between about 0.5 and about 3.0 volumes per volume of extract, to etl'ect the resolution oi the extract into an aqueous amine suli'onate layer and a layer of aromatic hydrocarbons and/or organic sulfur compounds. Alternatively, the separation zone I6 may take the form of a distillation vessel, preferably a steam distillation vessel in which the aromatic and/or sulfur compounds are vaporized and pass overhead, usually as azeotropes with water, through line IB into a settling vessel I9, whence the water layer is withdrawn through valved line and aromatics and/or sulfur compounds are withdrawn through valved line 2|.

A bottoms fraction containing the amine sulfonate is withdrawn from zone IB through valved line 22 for recycle to line I2 and extraction zone I I. The amine sulfonate stream withdrawn from zone I6 may be puriiled before recycle to contacting zone II, for example, by blowing with hot inert gases such as flue gas, nitrogen, carbon dioxide. or other inert gas to effect substantial dehydration thereof, in a step not shown in the which the treated amine sulfonate may be recycled to extraction zone II. Alternatively, the recycle stream of amine sulfonate may be dehydrated by azeotropic distillation of water therefrom with yarious azeotroping agents. e. g. benzene, toluene, n-heptane, etc. At least partial dehydration of the recycled solvent is necessary when the extract is sprung by means of water or wet steam.

Although the figure represents a continuous countercurrent, single-stage extraction operation, it will be apparent that the process of the present invention is amenable to batch processing. multi-stage operation, concurrent flow of solvent and feed stock, the use of knot-hole or other mechanical mixers for feed and solvent in series with one or more settling zones and other variations that will no doubt occur to those skilled in the art, without departing from the spirit of this invention.

Having thus described the process of our invention, what we claim is:

1. A process for the selective extraction of a compound selected from the class consisting oi' aromatic hydrocarbons and organic sulfur compounds from a mixture comprising a compound oi said class and an aliphatic hydrocarbon, which hydrocarbon with l l0 process comprises contacting said mixture with a selective solvent consisting essentially of an amine salt of a sulfonic acid. said salt having the formula wherein R1 and R.: are selected from the class consisting of hydrogen and saturated hydrocarbon radicals, Ra is a saturated hydrocarbon radical containing at least two carbon atoms. and Ra is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals, said amine salt containing between 4 and 20 carbon atoms, inclusive, per molecule. and separating an extract phase comprising said 8elective solvent and a compound of said class.

2. The process oi claim 1 wherein said mixture comprises alight cracked gas oil containing polycyclic aromatic hydrocarbons and sulfur compounds. said gas oil being derived by cracking high boiling hydrocarbon oils containing sulfur and aromatic compounds in the presence of a solid siliceous cracking catalyst.

3. A process for the selective extraction of an aromatic hydrocarbon from a mixture of said an aliphatic hydrocarbon, which process comprises contacting said mixture with a selective solvent consisting essentialLv of an amine salt of a sulfonic acid, said salt having the formula a ns-Risoul wherein Ri and Rz are selected from the class consisting o! hydrogen and saturated hydrocarbon radicals, Rs is a saturated hydrocarbon radical containing at least two carbon atoms. and R4 is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals, said amine salt containing between 4 and 20 carbon atoms, inclusive, per molecule, and separating an extract phase comprising said selective solvent and said aromatic hydrocarbon.

4. A process for the selective extraction of an organic sulfur compound from a mixture comprising said sulfur compound and an aliphatic hydrocarbon, which process comprises contacting said mixture with a selective solvent consisting essentially oi' an amine salt of a sulfonic acid. said salt having the fomula Ri RNJnsoin R( wherein R1 and Rz are selected from the class consisting of hydrogen and saturated hydrocarbon radicals, Rs is a saturated hydrocarbon radlcal containing at least two carbon atoms, and R4 is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals, said amine salt containing between 4 and 20 carbon atoms, inclusive, per molecule, and separating an extract phase comprising said selective solvent and said organic sulfur compound.

5. A process for the selective extraction of a compound selected from the class consisting ot aromatic hydrocarbons and organic sulfur compounds from a mixture comprising a compound of said class and an aliphatic hydrocarbon, which process comprises contacting said mixture with a li selective solvent consisting essentially c! a triethylamine salt ot an alksnesuli'onic acid containing from 1 to 4 carbon atoms, inclusive. per molecule, and separating an extract phase comprising said selective solvent and a compound of said class.

6. A process for the selective extraction of a compound selected from the class consisting or aromatic hydrocarbons and organic sulfur compounds iroxn a mixture comprising a compound of said class and an aliphatic hydrocarbon, which process comprises contacting said mixture with a selective solvent consisting essentially of the triethylamine salt of p-toluenultonic acid, and separating an extract phase comprising said selectivo solvent and a compound oi' said class.

'1. A process for the selective extraction oi' a compound selected from the class consisting of aromatic hydrocarbons and organic sulfur compounds from a mixture comprising a compound o! said class and an aliphatic hydrocarbon, which process comprises contacting said mixture with between about 0.3 and about l0 volumes, per volume o! said mixture. of n. selective solvent consisting essentially of an amine salt of a sulfonic acid, said salt having the formula Br- -RsBOsB wherein R1 and Rn are selected from the class consisting of hydrogen and saturated hydrocarbon radicals, R: is a saturated hydrocarbon radical containing at least two carbon atoms. and R4 is selected from the class consisting of saturated hydrocarbon radicals and aromatic hydrocarbon radicals, said amine salt containing between 4 and 20 carbon atoms, inclusiveI per molecule. eilecting said contacting at a temperature between about 0 C. and about 180 C. under a pressure suilicient to maintain said mixture and said selective solvent in the liquid phase. and separating an extract phase comprising said selective solvent and a compound oi said class.

8. 'Ihe process of claim 3 wherein R4 is a saturated hydrocarbon radical.

9. The process ci claim 3 whereinRl is an aromatic hydrocarbon radical.

l0. The process ot claim 4 wherein R4 is a saturated hydrocarbon radical.

l1. The process of claim 4 wherein R4 is an aromatic hydrocarbon radical.

l2. The process o! claim 'i wherein R4 is a saturated hydrocarbon radical.

13. The process of claim 'l wherein R4 is an aromatic hydrocarbon radical.

CARL E. JOHNSON. ARTHUR A. HARBAN.

No references cited.

Claims (1)

1. A PROCESS FOR THE SELECTIVE EXTRACTION OF A COMPOUND SELECTED FROM THE CLASS CONSISTING OF AROMATIC HYDROCARBONS AND ORGANIC SULFUR COMPOUNDS FROM A MIXTURE COMPRISING A COMPOUND OF SAID CLASS AND AN ALIPHATIC HYDROCARBON, WHICH PROCESS COMPRISES CONTACTING SAID MIXTURE WITH A SELECTIVE SOLVENT CONSISTING ESSENTIALLY OF AN AMINE SALT OF A SULFONIC ACID, SAID SALT HAVING THE FORMULA

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