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Patented Mar.‘ 8,‘ 1938 2,110,330 j 1 UNITED ‘STATES PATENT ‘OFFICE 2,110,830 SIMIULTANEOUS PRODUCTION OF VINYL AROMATIC OOMPDUNDS AND ARYLACET YLENES Robert a. Dreisbach, Midland, Mich” assignm to The Dow Chemical Company, Midland, _ Mich, a corporation of Michiga No Drawing.v Application October 6, 1937, , , Serial No. 167,598 ' . 5 Claims. ,(01. 2604-168) This invention concerns the simultaneous pro passing isopropyl benzene alone or in admixture duction of a vinyl‘ aromatic compound and an arylacetylene by pyrolysis of a benzene deriva tive having the general formula 6, _ ‘- ‘ with a gaseous diluent such as steam‘ or carbon dioxide through an externally heated tube or a bath of-lead or other molten metal, but care must‘ be taken‘ to heat and promptly cool the‘ 5 vapors with suiilcient rapidity to avoid excessive X5 carbonizatlon. _In practice the pyrolysisv is pref Y.’ erably carried out according to the general meth _ wherein R. represents an isopropyl or isopropenyl od for pyrolyzing alkylated aromatic hydrocar 0 radical, X and Y each represent hydrogen, halo-. bons set forth in my co-pending application, 10 gen, or an alkyl radical containing not ‘more ‘ Serial No. 151,457, ?led .July 1, 1937, of which than 3 carbon atoms, and n and n’ are integers this application is a continuation-in-part. This having a sum not exceeding 5. The invention ‘preferred mode ofmpperation, described below, particularly concerns the simultaneousiproduc permits the desired ‘products to be formed inv , 15 tion of styrene and phenylacetylene‘by pyrolysis higher yield than I have found possible vby the 15. of one or both of the compounds isopropyl ben usual pyrolytic methods,v without appreciable. zene and alpha-methyl styrene. ‘ ‘ Isopropyl benzene has heretofore been pyro lyzed at temperatures up to, but not exceeding 90 700° 0., to obtain styrene‘ and alpha-methyl styrene, but phenylacetylene has not been re ported as a product of the reaction. In my own researches I have never obtained more than faint traces of phenylacetylene by pyrolyzing 25 isopropyl benzene at such temperatures. carbonizatlon or tarring of the reaction mix ture. , In my preferredmode of operation, liquid or @ vaporized isopropyl benzene and superheated 20 steam are passed continuously into admixture with one another, the steam being employed in the proportion'and at the temperature required to attain the reaction temperature and furnish the heat of pyrolysis. Usually, between 7 and 10 25 parts by weight of steam superheated to a tem However, I ‘have found that isopropyl benzene may satisfactorily be pyrolyzed at higher tem . perature between_800° and 1000° ‘C. is used‘ per peratures to obtain not only the usual products, part of isopropyl benzene, but the steam may of ‘styrene and alpha-methyl styrene, but also course be employed in other proportions and at . _ 30 phenylacetylene in appreciable yield. In general, even higher temperatures. The pyrolysis‘ mix- 30 the yield of phenylacetylene becomes higher and ture is promptly cooled; e. g. by ‘contact with ‘ , that of alpha~methyl styrene lower as the pyrol water or passage through suitable heat exchang- ‘ ysis temperature is raised and by the use of tem peratures above 900° C. the formation ‘of alpha ers or condensers, to a temperature below that at which rapid pyrolysis occurs, e. g. below 700° 35 methyl styrene may practically be eliminated. . I 1 0., and the cooling is continued to condense the 35 have also found that the styrene and phenylacet- ~ aromatic components of- the mixture. The or ylene, which boil together,'may readily be sep ganic condensate is then distilled to collect. as ’ arated by distillation‘ from any alpha-methyl styrene and unreacted isopr‘opyl benzene present one fraction a mixture ‘of styrene and phenylacet ylene and as other fractions alpha-methyl ‘sty 40 and that‘the alpha-methyl styrene, alone or ad rene (when formed) and any unreacted isopropyl 40 .mixed with isopropyl benzene, may be further‘ benzene. The alpha-methyl styrene may be col pyrolyzed‘ to produce additional styrene and lected as a ?nal product or it may be returned‘, phenylacetylene. The phenylacetylene serves as alone or in admixture with isopropyl benzene. an eifective’agent for preventing polymerization to the pyrolysis for the formation of additional 45 of the styrene‘, hence the mixture of these two ‘ compounds is a valuable and marketable prod- ' 50 styrene and. phenylacetylene.- » ~ 45 ~ As hereinbefore indicated, the phenylacetylene not. When desired, the phenylacetylene may be separated from the styrene by the chemical treat formed in the reaction distills together with the ments hereinafter described. ter during manufacture, distillation, storage, and shipment. Accordingly, this mixture of styrene‘ 50 ' I In. order to obtain phenylacetylene in appre ciable yield, the pyrolysis is conducted at tem peratures above 750° C. and below that at which excessive carbonizatlon occurs, preferably be ‘ tween 800° and ‘950° C. The pyrolysis may be 55 carried out in any of the usual ways, e.‘ g. by styrene and inhibits polymerization of the lat and phenylacetylenev is a valuable product having 1 properties not possessed by styrene alone. When desired, part or all of the phenylacetylene may be removed from the ' styrene eithem-(l‘), by agi-' tating the mixture at ‘room temperature or there- 55 2,1 10,880 (2., about with a mixture of mercuric oxide and a actor suf?'ciently to condense the aromatic prod- " 30-50 per cent concentrated aqueous sulphuric acid solution to convert the phenylacetylene into lower aliphatic hydrocarbons. The organic layer ucts, leaving a gaseous mixture of hydrogen and of the condensate was separated and dried. It consisted of 18.7 pounds of a mixture containing approximately 43 per cent by weight of styrene, 16 other compounds, readily separable from styrene by distillation, or (2) by treating the mixture of styrene and phenylacetylene with an aqueous. per cent of alpha-methyl styrene, and 4.3 per‘ cent ammoniacal solution of a salt of a metal belong ing to group. 1, family 2, 'of the periodic system, of phenylacetylene, the remainder being largely e. g. silver chloride, silver sulphate, cuprous chlo unreacted isopropyl benzene and some benzene. 10 Example 3 10 ride, cuprous sulphate, etc., to precipitate the phenylacetylene as its metal salt, e. g. as silver 64.5 pounds of isopropyl benzene was gradually or . cuprous phenylacetylide. The ammoniacal vaporized and the vapors were passed continu ‘metal salt employed in this treatment is pref erably one containing the metal in its lowest ously into admixture with a , stream of steam 15 superheated to 890°, C., the respective rates of 15 ?ow being such that the mixture had atempera The ?rst of said methods for removing phenyl acetylene is simple-and practicable, ‘but does not ture of about 825° C. The time of passage'was 3 permit recovery of the phenylacetylene as such. hours 30 minutes. The mixture was immediately After said treatment the styrene is separated and cooled and condensed and the organic layer 0! the 20 20 puri?ed by permitting the treated mixture to condensate was separated and dried as in Example stand and stratify, separating the organic layer 2. There was obtained 48.8 pounds of a’ liquid thereof, washing this layer free of acid with water organic mixture containing approximately 52.8 or dilute aqueous alkali ‘solution, and distilling per cent by weight of styrene, 9.3 per cent of alpha-methyl styrene, 8.5 per cent of phenyl the same, e. g. with steam or under vacuum. . The ‘second. of the above-mentioned methods acetylene, and 12.5 per cent of unreacted isopropyl 26 for removing the phenylacetylene does permit benzene, the remainder being largely benzene and recovery of the latter. After precipitating the ethylbenzene. The yields of styrene, alpha phenylacetylene as its metal salt, the latter isv methyl styrene, and phenylacetylene were 52.6 per cent, 7 .9 per cent, and 8.1 per cent, respective - separated by ?ltration or decantation to recover 30 the liquid styrene. 'The precipitate may then be ly, based on the isopropyl benzene consumed in valence. _ - acidi?ed with a strong mineral acid, e. g. an the reaction. aqueous sulphuric or hydrochloric acid solution, to regenerate the phenylacetylene. The latter Isopropyl benzene was vaporized and preheated forms a distinct layer and may be separated me to a temperature of about 440° C. and the pre chanically from the acid and puri?ed by washing with water. The invention, accordingly, permits production of styrene and phenylacetylene either in admixture or as the individual compounds. The following examples illustrate certain ways 40 in which the principle or the‘invention has been applied, but are not to be construed as limitin I the invention. - Example 4 ’ Example 1 Isopropylbenzene was passed, in continuous 45 ?ow at a rate of approximately 50 grams per 36 heated vapor was passed continuously into ad mixture with a stream of steam superheated'to about 1070° C. at such rate‘that the temperature of the resultant mixture was approximately 900° C. The mixture was cooled and condensed im 40 mediately after ~formation and the organic layer _ of condensate was separated, dried, and analyzed. It contained 53 per cent by weight of styrene, 2 per cent of alpha-methyl styrene, and 8.3 perv cent of phenylacetylene, the remainder being un reacted isopropyl benzene and by-products such minute, ?rst through a heated chamber wherein. . as benzene and probably naphthalene. it was vaporized and preheated to about 285° C. Example 5 and thence into admixture with a current of steam superheated to approximately 825° C., the 50 [rate of‘steam ?ow being such that the mixture formed had a temperature of approximately 750° ' Meta-chloro-isopropyl benzene was pyrolyzed at 820° C. by procedure similar to that in Exam me 3. The liquid organic product contained ap C. The vapor mixture was passed in less than proximately 39 per cent by weight oi.’ meta ~ 0.03 second through the mixing zone directly‘ chloro-styrene, 5.1 per cent of meta-chloro-phen into condensers wherein it was rapidly cooled and ylacetylene, 3.9 percent or meta-chloro-alpha 55 - condensed. The organic layer of the condensate methylstyrene, and 3.5 per cent of styrene, the was separated and dried.’ It‘ contained approxi mately 45.4 per cent by weight of unreacted isopropyl benzene, 27.3 per cent- of-styrene, 14.8 per cent of alpha-methyl styrene, and 0.43 per 60 remainder being largely unreacted meta-chloro cent 01' phenylacetylene. ’ ‘ Example 2 isopropyl benzene and some by_-products such as vchlorobenzene and meta-chloro-ethylbenzene. I have also pyrolyzed meta-ethyl-isopropyl benzene as hereinbeiore described to obtain a product comprising styrene homologues, e. g. meta-ethyl styrene, meta-divinyl benzene, etc., and arylacetylenes, e. g.-phenylacety1ene, meta vinyl-phenylacetyle'ne, etc. The arylacetylenes benzene vapors and approximately 205 pounds of . in the mixture inhibited polymerization of the highly superheated steam were passed in steady I styrene homologues. Other nuclear substituted ‘ ?ow through a tubular iron reactor, wherein they isopropyl benzene compounds such as ortho-, formed a mixture having a temperature of 805° , meta-,' or para-bromo-isopropyl benzene, 3-ch1o Isopropyl benzene was vaporized and preheated to about 220° C. 24,2 pounds of the isopropyl ro-S-ethyl-isopropyl benzene, ortho-chloro-iso 70 C. The time of passage was 1 hour 20 minutes. . propyl benzene, para-methyl-isopropyl benzene, The‘ ‘mixture passed through the reactor and into ’ suitable cooling apparatus at such rate as to be 'ldiethyl-isopropyl benzene, di-isopropyl benzene, maintained at temperatures above ‘700° C. i'or'less than 0.05 second, probably about 0.03 second. 75 The mixture was cooled asit issued from the re ‘ "lo etc. may be pyrolyzed according to the inven tion to obtain a product comprising homologues or-analogues of'styrene and an arylacetylene. 75 3 2,110,880 ' In the claims the term “styrene-like compound" radical, x and Y each represent hydrogen, halo refers to a compound of the ‘class consisting of gen, or an alkyl radical containing not more than 3 carbon atoms, and n and n’ are integers having, a sum- not exceeding 3. styrene and its homologues and analogues, Other modes of applying’ the principle of the ._ invention may be employed instead of those ex _ 3; A method for the-simultaneous production plained, change being made as regards the meth- , of a styrene-like compound and an arylacetylene 0d herein disclosed, provided‘the step. or‘ steps which comprises simultaneously passing separate stated by any of the following claims or the equiv streams of superheated steam and of a benzene alent of such stated step or steps be employed. derivative having the general formula ‘ 10 I therefore particularly point out and distinctly _ i 10' .claim as my inyention:-.— ‘ '. ' 1, A method for the simultaneous formation of ' _a styrene-like compound and an arylacetylene which comprises pyrolyzing at a temperature o!v _' , 50“ Y.’ ‘ , 15 at least 750° C. a benzene derivative having the wherein R represents an isopropyl or isopropenyl 15 ‘ radical, X and Y each represent hydrogen, halo general formula I 4 , gen or an alkyl radical containing not more than 3 carbon atoms, and n and n’lare integers having a sum not exceeding 5, into, admixture to form Y,’ _ a mixture having a temperature between 800° wherein R represents an isopropyl or isopro'pe and 900° C. and promptly cooling the mixture 20, nyl radical, X and Y each represent hydrogen, to a temperature below I100" 0., the steam em halogen, or an alkyl radical containing not more ployed being superheated sufficiently to attain 4 than 3 carbon atoms, and n and 1],’ are integers said pyrolysis temperature. I a sum not exceeding 5. r 4. Aimethod for the simultaneous formation of 25 2.5 having v 2. A method for the simultaneous formation of styrene and phenylacetylene which comprises py a styrene-like compound and an arylacetylene rolyzing isopropyl. benzene at a temperature of which comprises heating to a pyrolyzing tem at least 750° C. ' ' . ' perature of at least 750° C‘. and cooling su?‘l 5. A method for the simultaneous formation of - x»v ‘ g8 .R. ciently rapidly to avoid appreciable carboniza tion, a benzene derivative having the general I formula ‘ mixture with steam superheated su?iciently' so ' _ X‘ atyrene and phenylacetylene which comprises 30 continuously passing isopropyl benzene into ad ' I ‘Y.’ wherein R represents an isoprop'yl or ‘iso'propenyl that the mixture is formed at a pyrolyzing tem perature between 800° and 950° C. and cooling the .mixture to a temperature below ‘700° C., within 0.05 second after formation. 1* ‘ . , ROBERT R. DREISBACH.