US2450652A - Alkyl benzenes - Google Patents

Description

. Oct 5, l948. A. w. FRANCIS Erm. 2,450,652

ALKYL BENZENE S Filed July 20, 1944 Al. A024708 0xff/lys l5 ATTORNEY of benzene. To isolate the benzene from petroy out .the alkyigtienff t Y nauytne sameboiiinj "pointes benzene-.2.;-

f first fractionally'distlled 'and a out is 'obtain Patented oef. s, 194s OFFICE ALKYL BENzENEs v Alfred W. Francis, Woodbury, and carleton H.

Sehlesman, Camden, N. J., assignors to Socony- Vacuum Oil Company, poration of New York Incorporated, a cor-v Application July 20, 1944, Serial N0. 545,885

10 Claims. (Cl.

This invention relates to the manufacture of alkyl benzenes and more particularly to the preparation of such compounds from petroleum distillates. The invention is principally concerned with benzene derivatives having an alkyl group. 5 of at least two carbon atoms asthe side chain.

The large demand for alkyl derivatives of benzene, such as ethyl benzene, cumene, diethyl ben-. zene, is well known. These compounds are useful principally as solvents'and. as raw materials for1o the synthesis of other organic compounds"- Ben- 1 zene ordinarily is obtained from coal tar or may.1. Y beseparated from petroleum by kn'own' isolation" methods, but the expense of these methods warf rents their use only when a sumciently high-115:' market exists. Compounds such as ethyl benzene; Y. cumene, and diethyl benzene do not occur in eitherf; coal tar or petroleum in substantialquantities.;`

Alkyl benzenes maybe synthesized-'fr'oi'n` the benzene obtained from coal tar or from petroleum, '20 but this is expensive because f the difiicultygof isolating'` the 'benzene from other hydrocarbons vj' present having approximately the'boiling vpoint leum by distillation. lorexampleand' then al-1 25' kylatethebenzene, would be an expensivepro-wcedure, l An object-ofgthepresent'invention is to xrf facture andjrecovfer,trom-the benzene ofV petroleum, alkylderivatives thereof. According tothe 30 invention;.'.the-Qdesiredbenzene homologues are vprepared 'andseparatdjfrom tlimixture-of"hy \-m droca'rbons occurring withthe benzene by a. process of selective lalk'y-lation and distillation.` `This involves, asaieaturefo 'theinventiom carrying 35 *lshr Ocibimwith whihit troleumland having' lsubstan-A 11S'. lo ed in a range appro'ximat'in'lg:'the boiling point of vbenzene but below,90'C. This fractional distillation To carry lout" fthe v`i ntl" 'n,f the :petroleum eliminates' other` aromatics as toluene and also saturated hydrocarbons having boiling points .45 quite distinct from benzene. However the cut which is obtainedy contains not onlyy benzene but saturated hydrocarbons' having boiling .points close to benzene. This cut is then subjected to a lselective'alkylation process with gaseous ole- 50 fins to alkylate the benzene therein. This lproduces the desired alkyl-benzene of higher boiling vpoints than benzeneand does not alkylate any parailins or naphthenesthat may be present. Thebenzene which is present in the fraction 55 which is obtained yis alkylated in preference to the paraiilns or naphthenes that may be present because as is well known, aromaticsvin general are moreeasily alkylated than are aliphatic `or alicyclic compounds. l f

-After the alkylation step'the 'res u ltant prod'- uct is distilled to substantially the same end-point as'used to prepare the fraction', so asto distil off the non-aromatic.Jmaterial which` was not a1- kylated *and to leave as` the:residual liquidy the alkylated benzene;y The alkyl benzenesoobtained can be'firactionated'fif desiredl to obtain-theindividual'-alkylation-.products v`oi-r can be zused'for treated in' 'any` 'manners-that siiiiilafm "compoundsv obtainediirom-otherisources mayb e employed.' '.While, as statedbthe inventionmay beapplied venden isi-concerned principally ywith sweating i ,petroleum distillatesgxand, as fknownl. manyi petro1eum'"'distiliates. .ar available whichaeontain taining' as little as A4% benzene -hasfgivenf auseful alkylationz- But for. -ecoonicaloperations it is 'betten to select. `a material with as .hishfa-fcontent .aS the iinal'productgg;

The 'amount offga'se'ousgfol y benzene present,v and uprithegalkylation product desired.'y Thus c the gaseous olen; reagent does f'- not polymerize as "longlzaas any; appreciable i amount.v of incompletelyv alkylatedaromatio is present.- However; 'if more'y than: three moles `of olefin is added for each molejof benzene-present,

the excessf'olfin'wcontinues to: be'rjabsorbed. but Asome .of it may result 4in'hign boilingunsaturated' polymers. Therefore.theoncentratioriof-olens i to benzene should' be kept below 3 moles to '-I'mole.

Liquid oleiin`s' cause lundesirable side@ reactions, so that if present, in anyof the reagentsgfth'ey should-be eliminated 'rst by mild acidtreatment. As noted, the degree. of alkylationmayfbe regulated by controlling themenconcentraton. I ACL I cordinglyr'if a mono-alkylated' product; such as cumene or .ethyl benzene, is desired, the amount of olefin added mustbe limited `to not over a be fa j. .gelainounts suitableoleisfnot-:desired added-aime alkylation process will dependj-uponfthe amountfof halt` a mole for one ol benzene, since mono-alkylated benzenes are alkylated further much more readily than are the original aromatics. In such a process the mono-alkylate may be separated from the unrcacted material and the latter recycled for further treating.

Processes for alkylating benzene with olefins are well known and understood in the art. The only requirement of the present operation is that conditions are used which will not result in alkylation of the less reactive parains and naphthenes that may be present. Because of the difference in reactivity the conditions may be regulated quite feasibly so that this latter type alkylation does not occur at all or occurs so slowly that it can be neglected.

In our operations we prefer; to alkylate the benzene in the presence of an aluminum chloride catalyst. Using such a catalyst, room temperature (-30 C.) is a suitable reaction temperature for propylene and higher oleiins, although higher temperatures are permissible, and a reaction temperature of at least C. should be used for alkylating with ethylene.

A further detailed understanding of the principles 0f this invention may be had by reference to the appended drawing and the following detailed description thereof.

In the single gure of the drawing there is diagrammatically illustrated an assembly of apconnection I3 and aluminum chloride and olefins are added to the alkylator in suitable amounts fronrsources of supply I4 and l5, respectively. Thealkylated product passes through a connection I6 to a second fractionator I1 where all material boiling below about 90 C. is removed and the remaining material which comprises the al- 'kylatedt benzene is drawn oil through a connection I8 to a third fractionator I9 which separates .thefalkylated benzene into monoalkyl benzene,

then polyalkyl benzene. f "In order to illustrate the invention further the following specific examples are given:

Example I A benzene rich'fraction was obtained by iractionation (B. P. 'Z1-85 C.) of a straight run gasoline. This cut was found by analysis to contain 21% benzene by volume. The charge was then alkylated by heating it with 1.5% of its weight of anhydrous aluminum chloride to 60 C. and stirring vigorously, while adding a moderate stream of ethylene gas until 0.25 mole of ethylene for one of4 benzene present had been added. The product was distilled to 90 C. endpoint. The residue had a density of 0.8778 indicating that it was wholly aromatic. On further distillation practically nothing came over below 132 C. and then '70% of it distilled between 132 and` 136 C. (ethylbenzene). The residue solidified` on cooling, indicating that it was mostly hexaethylbenzene, M. P. 128 C.

Example II A charge similar to that of Example I was alkylated with propylene similarly except that no preliminary heating was necessary. For each mole of benzene present, 0.57 mole of propylene was added during about 30 minutes. The temperature rose spontaneously to 63 C. The product was washed and distilled as before, giving practically nothing between C. and 148 C. Seventy-five per cent of the remainder boiled at 148-153 (isopropylbenzene or cumene) and 22% at 20D-212 C. (di-isopropylbenzenes) It will be appreciated from these examples that if the original charge had been rst subjected to some physical separation process to isolate the benzene from the hydrocarbons of similar boiling point, so that then the isolated benzene could be alkylated, a lengthy and expensive isolation procedute would have been necessary. By taking advantage of the selective alkylation properties of benzene as compared to the saturated hydrocarbons present in the charge, a rapid and inexpensive method of manufacturing the alkyl benzenes may be carried out. By first obtaining a charge which boils in a range close to benzene, other aromatics not desired to be alkylated, are initially eliminated so that they are not present to consume some of the olen utilized to carry out the alkylation.

This application is a continuation-impart of application Serial No. 356,648, led September 13, 1940 (now, United States Letters Patent No. 2.371,163, issued March 13, 1945).

What is claimed is:

1. The process of obtaining alkyl benzenes substantially free of non-aromatic hydrocarbons from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling points of the benzene and the non-aromatic hydrocarbons are so close together that they cannot be separated feasibly by conventional fractional distillation, which process comprises distilling the oil to prepare a fraction boiling below about 907 C., subjecting the fraction to selective alkylation with a single normally gaseous olefin in the presence of aluminum chloride so as to alkylate only the benzene, and then fractionally distilling the mixture formed by said alkylation step to produce a fraction reduced in benzene content boiling below 90 C. and a fraction boiling above 90 C. which consists of alkyl benzenes substantially free of non-aromatic hydrocarbons.

2. The process of obtaining alkyl benzenes substantially free of non-aromatic hydrocarbons from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling points of the benzene and the non-aromatic hydrocarbons are so close together that they cannot be separated feasibly by conventional fractional distillation, which process comprises distilling the oil to prepare a fraction boiling substantially between about 71 C. and 85 C., subjecting the fraction to selective alkylation with a single normally gaseous olefin in the presence of aluminum chloride so as to alkylate only the benzene, and then fractionally distilling the mixture formed by the alkylation step to produce a fraction reduced in benzene content boiling below about 90 C. and a fraction boiling above about 90 C. which consists of alkyl benzenes substantially free of non-aromatic hydrocarbons.

3. The process of obtaining alkly benzenes substantially free of non-aromatic hydrocarbons from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling tial points of the benzene. Vand-'fthe non-aromatic hydrocarbons are so close together that they cannot be separated feasibly by conventional fractional distillatin, which process comprises distilling the oil to prepare a fraction boiling below 90 C., subjecting the fraction to selective alkylation with a single normally gaseous olefin in the presence of aluminum chloride so as to alkylate only the benzene, the olefin being present in the molar ratio of not more than 3 to 1 with reispect to the benzene, and then fractionaliy distilling the mixture formed by the alkylation step to produce a fraction reduced in benzene content boiling below about 90 C. and a. fraction boiling above about 90 C. which consists of alkyl benzenes substantially free of non-aromatic hydrocarbons.

4. The process of obtaining alkyl benzenes sub-v stantially free of non-aromatic hydrocarbons from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling points of the benzene and the non-aromatic hydrocarbons are so close together that they cannot be separated feasibly by conventional fractional distillation, which process comprises distilling the oil to prepare a fraction boiling substantially between about '71 C. and 85 C., sub-I y jecting thefraction to selective alkylation with a single normally gaseous oleiln at a'temperature not substantially in excess of 60 C. in the presence of aluminum chloride so as to alkylate only the benzene, the olen being present in the molar ratio of not more than 3 to 1 with respect to the benzene, and then fractionally distilling the mixture formed by the alkylation step to produce a fraction reduced in benzene content boiling below about 90 C. and a fraction boiling above about 90 C. which consists of alkyl benzenes substantially free of non-aromatic hydrocarbons.

5. The process of obtaining alkyl benzenes substantially free of non-aromatic hydrocarbons from a petroleum oil comprising a substantial amount of benzene and a substantial amount of nonaromatic hydrocarbons wherein the boiling points of the benzene and the non-aromatic hydrocarbons are so close together thatthey cannot -be separated feasibly by conventional fractional distillation, which process comprises distilling the oil tol prepare a fraction boiling between about 71 C. and 85 C., subjecting the fraction to selective alkylation with a single normally gaseous olefin in a molar ratio of not more than three mols of olefin to one mol of benzene in the presence of aluminum chloride so as to alkylate only the benzene, and then fractionally distilling the mixture formed by the alkylation stepto produce a fraction reduced in benzene content boiling below about 90 C. and a fraction boiling above 90 C. whichconsists of alkyl benzene substantially free of non-aromatic hydrocarbons.

6. The process of obtaining substantially pure ethyl benzene from a petroleum oil comprising a substantial amount of benzene and a substanamount of non-aromatic hydrocarbons wherein the boiling point o f the benzene and the nent-aromatic hydrocarbons are so close to- -gether that they cannot be separated feasibly by a conventional fractional distillation, which process comprises distilling the oils to prepare a fracroducea fraction reduced ',ir'r benzenepcontentfboiling' below ".'abtf C.. a fraction boiling near 136 C. consisting of substantially pure ethyl benzene and a higher boiling fraction consisting of higher ethylated benzenes.

7. The process of obtaining substantially pure cumene from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling point of the .benzene and the nonaromatic hydrocarbons are so close together that they cannot be separated feasibly by a conventional fractional distillation, which process comprises distilling the oils to prepare a fraction boiling below about 90 C. subjecting the fraction to selective propylation with propylene in the presence of aluminum chloride so as to propylate only the benzene and then fractionally distilling the mixture to produce a fraction reduced in benzene content boiling below about 90 C., a fraction boiling near 152 C. consisting of substantially pure cumene and a higher boiling fraction consisting of higher propylated benzenes.

8. A processor obtaining mono alkyl benzenes substantially free of non-aromatic hydrocarbons from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling points of the benzene and the non-aromatic hydrocarbons are so close together that they cannot be separated feasibly by conventional fractional distillation, which process comprises distilling the oil to prepare a fraction boiling below about 90 C., subjecting the fraction to selective alkylation with a single normally gaseous olen in a molar ratio of about one-half a mol of olefin to one mol of benzene in the presence of aluminum chloride so as to alkylate only the benzene and then fractionally distilling the mixture to produce a fraction reduced in benzene content boiling below about 90 C. and a fraction boiling above about 90 C. which consists of alkyl benzenes substantially free of non-aromatic hydrocarbons.

9. The process of obtaining substantially pure ethyl benzene from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling point of the benzene and the nonaromatic hydrocarbons are soclose together that they cannot be separated feasibly by a conventional fractional distillation, which process comprises distilling the oils to prepare a fraction boiling below about 90 C, subjecting the fraction to selective ethylation withethylene in a molar ratio of about one-half a mol of ethylene to one mol of benzene in the presence of aluminum chloride so as to cthylate only the benzene and then fractionally distilling the mixture to produce a fraction reduced in benzene content boiling below about 90 C., a fraction boiling near 136 C. consisting of substantially pure ethyl benzene and a. high boiling fraction consisting of higher ethylated benzenes.

10. The process of obtaining substantially pure cumene from a petroleum oil comprising a substantial amount of benzene and a substantial amount of non-aromatic hydrocarbons wherein the boiling point of the benzene and the non- -aromatic hydrocarbons are so close together that they cannot be separated feasibly by a conven- 4tional'fractional distillation, which process comprises distilling the oils to prepare a fraction boiling below about 90 C. subjecting the fraction to 8 selective propylation with propylene in a. molar ratio oi' about onefhalf a. m91 of propylene to one REFERENCES 'CITED m01 of benzene in the presence' gf aluminum The following references are of record in the chloride so as to propylate only the benzene and me 0f this Patenti then Iractionally distilling the mixture to produce a fraction reduced in benzene content boiling d UNITED STATES PATENTS below about 90 C., to a fraction boiling near Number Name Date 152 c. consisting o: substantially pure cumene 1301.988 Torrey. Jn. et al. Feb-12, 1929 and a high boiling traction consisting o1' higher 2,001,907 ptie' May 21, 1935 propylated benzenes lo stanley et al. Jam 10, 2,260,279 d'Ouville et 9,1. Oct. 21, 1941 ALFRED W. FRANCIS. 2.396.683 Carmody et al Mar. 19, 1946 CARLEI'ON H. scHLEsmN. 2396966 Fassino Mar. 19, 1945

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