US2932677A - Purification of alkyl aryl hydrocarbons - Google Patents

Description

di er N United States Patent PURIFICATION OF A'LKYL ARYL HYDROCARBONS James C. Kirk, Lake Charles, La., and Edsel L. Miller, Houston, Tex., assignors to Continental Oil Company,

Ponca City, Okla., a corporation of Delaware No Drawing. Application January 8, 1958 Serial No. 707,686

10 Claims. (Cl. 260-674) The present invention relates to the production of alkyl aryl hydrocarbons which are substantially free of color precursors. Somewhat more particularly this invention provides a method for producing such alkyl aryl hydrocarbons which, upon sulfonation andneutralization, yield a substantially color-free salt.

Sulfonation of alkyl aryl hydrocarbons has generally followed the procedure wherein about 1.3 to 2 parts by weight of 100 to 105 percent sulfuric acid or olepm is used per part by weight of the alkyl aryl hydrocarbon. Other sulfonating agents have been used but whatever agent was used, the resulting sulfonic acid when neutralized witha base such as sodium hydroxide, yields a dark-colored sulfonate. Since dark-colored sulfonates can be used only in relatively few applications, various methods have been heretofore suggested for removing such color bodies which impart color to the sulfonate. These methods have involved treating the aqueous solution of the sulfonate with bleaching agents such as peroxide or acidic reagent such as sulfuric or hydrochloric acid. Other methods have involved blowing the aqueous sulfonate solution with oxidizing gases such as free oxygen. None of these methods have been entirely satisfactory, generally because they have involved an undesirable expenditure of materials and time, and furthermore the final product so obtainedhas not been improved greatly in color and the resulting improvement is only transitory in nature.

It is, therefore, a principal object of this invention to provide an improved process, which process obviates the disadvantages of the prior art methods. It is another object of our invention to provide a method for the removal of color precursors from alkyl aryl hydrocarbons whereby substantially colorless sulfonates can be produced by the sulfonation of such alkyl aryl hydrocarbons followed by neutralization. Further objects and advantages of the invention will become apparent from the following description.

In its broadest aspects the invention comprises the alkylation of an aromatic hydrocarbon such as benzene or toluene with an olefin containing from 8 to 18 carbon atoms in the molecule in the presence of an alkylation catalyst under alkylation conditions. Following the alkylation reaction the resulting mixture is allowed to remain quiescent until 2'layers are formed, an organic layer and a catalyst sludge layer. The catalyst sludge is removed and then the alkyl aryl hydrocarbon recovered from the organic layer by fractional distillation. The alkyl aryl hydrocarbon is then treated with an oxidizing agent in the presence of acid and water andat a temperature varying from 20 to 100 C. for a period of time varying from to 60 minutes. The oxidizing mixture is then allowed to remain quiescent for a period of time until the oxidizing materials have settled out. The oxidizing materials are withdrawn and the alkyl aryl hydrocarbon which is partially freed of color precursors is treated with about l to 5 weight percent of sulfuric acid based upon the, Weightofthe alkyl aryl hydrocarbon (2,932,677 Patented Apr. 12, 1960 at a temperature varying from 25 to C. for a period of time varying from 5 to 30 minutes. The resulting mixture is allowed to remain quiescent until the acid has settled out. By this procedure two layers are formed, the lower acid layer which contains oxidized color precursors and an upper layer'which consists of the alkyl aryl hydrocarbon substantially free of color precursors.- The alkyl aryl hydrocarbon is then recovered and upon subsequent sulfonation and neutralization there is obtained an alkyl aryl sulfonate which is, substantially colorless.

While We do not wish to be bound by any particular theory regarding the reactions which take place during the chemical treatment of the aromatic hydrocarbon, we believe that in the preparation of alkyl aryl hydrocarbons by the reaction of an alkylating agent with an aromatic hydrocarbon in the presence of a Friedel-Crafts catalyst such as aluminum chloride, side reactions occur which lead to the formation of polynuclear aromatic hydrocarbons. These polynuclear hydrocarbons impart a blue fluorescenceto the alkyl aryl hydrocarbon and are in part responsible for the dark color of the product obtained on sulfonation and neutralization of the alkyl aryl hydrocarbon. Analysis indicates that the polynuclear hydrocarbons are primarily 9-alkyl anthracenes and 9,10-dialkyl anthracenes and may be present in the alkyl aryl hydrocarbon in concentrations up to .125 gram per liter and .075 gram per liter respectively. 9

Before proceeding with specific examples illustrating our invention, it may be well to indicate in general the nature and the amounts of the difierentmaterials required in the process.

The alkyl aromatic hydrocarbons which may be freed of polycyclic aromatic compounds by the process of this invention are those alkyl aromatic hydrocarbons prepared by the condensation of an aromatic hydrocarbon and an alkylating agent in the presence of a Friedel-Craft catalyst, particularly aluminum chloride. The aromatic hydrocarbon may be benzene or a low molecular weight alkyl benzene or dialkylbenzene such as toluene, ethyl benzene, cumene, 0-, m-, and p-xylene, mixtures of xylenes, naphthalene, alpha-methyl naphthalene, beta-methyl naphthalene, diphenyl, the aromatics contained in petroleum fractions, and the like. The alkylating agent may be an alkyl halide, alkanol, or olefin having from about 10 to about 20 carbon atoms. Included among the alkyl halides are l-chlorodecane, lauryl chloride, 1- chloro-octadecane, and l-bromodecane. Suitable alkanols are lauryl alcohol, decanol, and stearyl alcohol. Suitable olefins are decene-l, decene-2, dodecene-l, dodecene-2, pentadecenes, octadecenes, and olefins obtained by the polymerization of ethylene, propylene, isobutylene and their mixtures such as tetrapropylene, pentapropylene and hexapropylene.

The oxidizing agents suitable for use in the process of this invention are the sulfuric acid solutions of the chromates including sodium and potassium chromate and dichromate and chromium trioxide. Ozone may also be used. The preferred oxidizing agents are sulfuric acid solutions of chromium trioxide or ozone. Generally for treatment of parts of the alkyl aromatic hydrocarbon an oxidizing solution containing from 0.25 to 0.75 parts of oxidizing agent, 1.5 to 5 parts of water and 2 to 6 parts of 96% sulfuric acid is efiective in removing polycyclic hydrocarbons. A larger amount of oxidizing solution may be used but is unnecessary for treatment of alkyl aromatic hydrocarbons prepared as described above.,

prefer to etfect the purification at 60 C. for a period of minutes. When ozone is used as the oxidizing agent, from about 0.3 to 0.6 grams-of ozone is used per 100 parts of hydrocarbon. The. ozone is. passed into the hydrocarbomduring a period of item about 20..to; 60 minutes.- Eollowing the oxidation treatment, the treated mixture is allowedfto settleand a dark-colored sludge withdrawnzusing, if; desired, a small. amount, ofa. filter inggaidtoqassist in. coagulating the. sludge- The. hydroca ghon isgthen agitated vigorously.with 1, to 5%, and preferably 2%, by weight of concentrated sulfuric, acid at a tempifirature' ot from 25 to 80. C. for from 5 to. 30 minutes. The sludge is. then removed and.the. hydro.-

' carbon treated with a basic clay such as Attapulgus clay on, a :Klett-Summerson Photo-electric Colorimeter using a4-centimete z cell and'a Klett Color Filter No. 42. The is. then equal to'the reading otthesamplerdie dedby. e ad ao thestandard. Obviously, the hi he e RQ-Q. numbe th more nten th y ow lor I'Qfj thes dium alky yl ulton te l r s n o r: t d scl se h x f l lllfi; f. t e p esent; invcnztion still more clear1y,ythefollowing illustrative examples will be given. It is to be understood, howeventhat the examples given hereinafter are not intended; for limiting the invention but rather to illustrate the principles and practices to be observed in producingthe improvement according to my invention. Parts given are parts by weight.

Example 1 A vessel equipped with a high speed agitator was charged with. 100 parts of pentadecylbenzene prepared by v the condensation of pentapropylene with benzene in hep sen e of a uminum. c l r d Wh e. gitating, 5 p r s i. an. ox d in s luti n. p p d y addin 4 Parts ot' h omium. r oxide o :6. pa t lo't w ter. w s. added an h agit pn nt nuedfor' 0 m nu es t.3.0." '0 Tw parts of Attapulgusclay was added to, the. agitating mixt r.e ..andjthen the; mixture was allowed, to. stand, quiescent allot; which. the hydrocarbon was decantedfrom, the dark sludge, The hydrocarbonwasthen agitated for min,- utes .at=,1 .00,? C. with, 5. parts of Attapulgus clay andfilteredthrough. a Hyflomat, to yield hydrocarbon having no. fluorescent bloom.

Anaylsin-The, initial pentadecylbenzene analyzed 0. .2 2,. per. lit r o .9- a .y anthracenes and. 0- 7 p iter; o 9.,lfl ialky an hracenes- Qn. fon tion. n neutralization a sulfonate-having an R.C.D. of 2 .70'was obtained.

The pent-adecylbenzene treated above analyzed0000 eve iterof nthr cenes. Onz ulfonation. ndne ra ization a sulfonate having an R.C .D. of 1.76 was obtained. 7

Although the use. of the: clay. treatmentgivesa somewhat bettenproduct. as. far as color is. concerned, it may be desirable to eliminate the, clay treatment in; many cases; This is truebecauseof the operatingditiiculties inyolyedwhenaclay treatment is used.

Example 2' 4 I Example 3 When treated only with clay and no oxidation or sulfuric acid treatment, the hydrocarbon gave a sulfonate having an R.C.D. of 2.70.

Example! When treated with. 3 .partstof'concentrated; sulfuric acid and then 5 partsoficlay, the hydrocarbon gave a sulfonate havingzan R.C.D of 2.68..

The. foregoing experiments demonstrate that it is neces-' sary to treat the alkyl benzene prepared by the condensation of an alkylation agent with benzene in the presence of aluminum chloride'with both an'oxidizing solution and sulfuric acid in order to obtain a sulfonate having excellent color. Either the use of the oxidizing solution or sulfuric acid alone does not give as good a result as when both are used.

Example 5 Dodecylbenzene. prepared by the alkylation of benzene with dodccenein thepresence of aluminum chloride was treated as in thepreceding 4examples. The -sulfonates obtained had the following colors:

and clay 2.58

From dodecylbenzene treated. with oxidizing agent,

sulfuric acid and clay 1.l1

Example 6- Into 130' parts of pentadecylbenzene'preparedas described in Example 1,05 parts. of ozone was bubbled over a period of 3.0 minutes at 25 C. The mixture was then agitated with 2parts of Attapulgus clay and a dark sludge removed by decanting the hydrocarbon. The hydrocarbon was thentreated at 60 C. for 20 minutes with 5 parts. of sulfuric acid (96% ),'the.,s1udge removed by decanting, the. hydrocarbon was then contacted with 2' parts ofjAttapulgusclay and" filtered. The product was, clear, colorlessand bright, and had an R.C;D. of 1.70.

Wehave found. thatinthose. few cases .wherethe met at salt o. .the,alky1-.ary1su1fonic acid produced by the. process of this.;in venti on is still slightly colored that product may be bleached.,.very easily by methods well known toithoseskilledinnthe.art.. Such. bleaching meth: ods includethe, treatmentof the. product with a. bleaching ent. such as a peroxide. o1.v bleaching by meansv of electrolysis. We. have. found further that: if. these color. precursprshave. not been; removedby theprocessv of this invention, it is rather diflicult to bleachtheresulting product andthe resultisonly-transitory.

While particular embodiments of the. invention. have been, described, it will .beunderstood, of course, that the invention is not, limited. thereto. since many modifications may be; made, and. it is-, ther.efore, contemplated to cover by theappended, claimsany such modificationsasfall withinthe, true spirit and,v scope of the invention.

he invention, having; thus. been described, what is claimed and, desired, to besecured by LettersLPatent is:

1. A,meth0d;10f. removing colon precursors, of the typewhichadversely afiectalkyl ary l; sulfonates, from anyalkylaryl-hydrocarbon mixture, produced ina Friedel- Craftspallcylation,reactionandcontaining 8. to 18 carbon atoms; in. the alkyl. group-, saidmethod comprising the treatmenkof. said mixturewith. an oxidizing agent selected fromrthe group. consisting of-sodium chromate, potassium chromate. sodium dichromate, potassium, dichromate, chromium trioxide, and ozonein the presence ofwaterand sulfuricacid at a temperaturevarying from acclimate- 100 C2 and for -aperiod varying from about 5 to 60 minutes, allowing the oxidized products to settle out thus forming two layers, an upper layer comprising the alkyl aryl hydrocarbon partially freed of color precursors and substantially freed of color precursors of the alkyl anthracene type and a lower layer comprising the oxidized products, separating the two layers, contacting said recovered upper layer with 1 to 5 weight percent sulfuric acid based on the weight of said alkyl aryl hydrocarbon at a temperature varying from about 25 to 80 C. for a period of time varying from about 5 to 30 minutes, allowing the mixture to separate into a lower layer consisting predominantly of the alkyl aryl hydrocarbon, and then separating the layers to recover thereby the alkyl aryl hydrocarbon substantially free of color precursors.

2. The method of claim 1 wherein the oxidizing agent is a chromium trioxide.

3. The method of claim 2 wherein the alkyl aryl hydrocarbon mixture comprises pentadecylbenzene.

4. The method of claim 2 wherein the alkyl aryl hydrocarbon mixture comprises dodecylbenzene.

5. The method of claim 1 wherein the oxidizing agent is ozone.

6. The method of claim 5 wherein the alkyl aryl hydrocarbon mixture comprises pentadecylbenzene.

7. The method of claim 1 wherein the oxidizing agent is a sodium chromate.

8. The method of claim 1 wherein the oxidizing agent is a potassium chromate.

9. The method of claim 1 wherein the oxidizing agent is a sodium dichromate.

10. The method of claim 1 wherein the oxidizing agent is a potassium dichromate.

References Cited in the file of this patent UNITED STATES PATENTS 1,963,555 Morrell .a June 19, 1934 2,688,633 Cohen Sept. 7, 1954 2,806,875 Geiser Sept. 17, 1957 2,875,257 Thompson Feb. 24, 1959 FOREIGN PATENTS 143,193 Great Britain Feb. 3, 1921

Claims (1)

1. A METHOD FO REMOVING COLOR PRECURSORS, OF THE TYPE WHICH ADVERSELY AFECT ALKYL ARYL SULFONATES, FROM AN ALKYL ARYL HYDROCARBON MIXTURE, PRODUCED IN A FRIEDELCRAFTS ALKYL LATION REACTION AND CONTAINING 8 TO 18 CARBON ATOMS IN THE ALKYL GROUP, SAID METHOD COMPRISING THE TREATMENT OF SAID MIXTURE WITH AN OXIDIZING AGENT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHROMATE, POTASSIUM CHROMATE, SODIUM DICHROMATE, POTASSIUM DICHROMATE, CHROMIUM TRIOXIDE, AND OZONE IN THE PRESENCE OF WATER AND SULFURIC ACID AT A TEMPERATURE VARYING FROM ABOUT 20 TO 100*C. AND FOR A PERIOD VARYING FROM ABOUT 5 TO 60 MINUTES, ALLOWING THE OXIDIZED PRODUCTS TO SETTLE OUT THUS FORMING TWO LAYERS, AN UPPER LAYER COMPRISING THE ALKYL ARYL HYDROCARBON PARTIALLY FREED OF COLOR PRECURSORS AND SUBSTANTIALLY FREED OF COLOR PRECURSORS OF THE ALKYL ANTHRACENE TYPE AND A LOWER LAYER COMPRISING THE OXIDIZED PRODUCTS, SEPARATING THE TWO LAYERS, CONTACTING SAID RECOVERED UPPER LAYER WITH 1 TO 5 WEIGHT PERCENT SULFURIC ACID BASED ON THE WEIGHT OF SAID ALKYL ARYL HYDROCARBON AT A TEMPERATURE VARYING FROM ABOUT 25 TO 80*C. FOR A PERIOD OF TIME VARYING FROM ABOUT TO 30 MINUTES, ALLOWING THE MIXTURE TO SEPARATE INTO A LOWER LAYER CONSISTING PREDOMINANTLY OF THE ALKYL ARYL HYDROCARBON, AND THEN SEPARATING THE LAYERS TO RECOVER THEREBY THE ALKYL ARYL HYDROCARBON SUBSTANTIALLY FREE OF COLOR PRECURSORS.