United States Patent L M116 “Patented Jan

‘I. i" a ‘l " 2,819,322 United States Patent l M116 “Patented Jan. 7., “1958 .11 .2 catalysts for the process, particularly‘the group VI metal sul?des, as, for example, the sul?des of tungsten, molyb ‘2,819,322 denum and chromium, and the sul?des of metals of atomic number from 25 to 28, especially nickel sul?de. PRODUCTION OF AROMATIC COMPOUNDS l ‘Composites of a metal sul?de from each of these. groups Lloyd C. Fetterly,”El'Cerrito, Cali?, a'ssigno'r to Shell Del are especially preferred. Corresponding oxides and com velopment Company, New York, N. Y., a corporation posites thereof are also suitable catalysts for'the'present of Delaware purpose, as well'as composites of oxides and sul?des. No Drawing. Application December '21, 1953 ‘ The diaryl methane compounds which are to be cracked 10 in accordance’with the invention, in generalare prepar Serial No. 399,570 able by the “alkylation” of the corresponding aryl com 9 Claims. (Cl. 260—668) pound with formaldehyde. ‘For example, it is known to prepare diphenylmethane, ditolylmethane " (mixture of isomers) and dixylylmethane, by reacting the correspond This invention relates to’ thepro'duction of methylaro 15' ing benzene/compound with formaldehyde in- the pres matic compounds,‘ and more'particularly to the produc ence of an acidic catalyst, such as sulfuric acid. _Simi tion of such‘compounds‘which contain a further alkyl larly, other compounds can be prepared,- such as di-beta radical, such as a second methyl radical, such as para 1 naphthylmethane from naphthalene, ~di§beta-5,6,7,8-tetra xylene, 2,6-dimethylnaphthalene and 'durene. 'hydronaphthylmethane from tetralin, 'di—2,4,5-trimethyl Various methods have been proposed for the prepara .20 phenylmethane from pseudocumene, bis-(2,4-dimethyl tion of such compounds vas the methylbenzene com phenyl)methane from meta-xylene, bis-(betaaG-methyl pounds. Thus, it has been proposed to chloromethylate naphthyl)methane and bis-(beta-7-methylnaphthyl)meth toluene to chloromethyltoluene (alpha-chloro-xylene) and ane from beta-methylnaphthalene. , > then to replace the chlorine by hydrogen, to obtain the Other diarylmethane compounds to; be converted-by net result of the substitution of a methyl radical for a 25 the present invention can bemade by theindicated alkyla nuclear hydrogen atom in a substituted benzene. On the ‘ tion with formaldehyde, as will‘ be understood. In gen ‘other hand, it has been proposed to alkylate aromatic eral, the diarylmethane compound is‘ preterablyrvolatile hydrocarbons in vapor phase with methanol, in the pres ‘at the conditions of the reaction to be utilized. ence of a phosphoric acid catalyst. ‘However, none-of 'As ‘already indicated,the'diarylmethane compounds, the methods previously proposed for [the “methylation” 3.0 ~which may be represented by the iformula‘Ar-éCHz-éAr’, of aromatic compounds has proven to be entirely satis wherein the “Ar” groups are usually the’ same aryl, radi factory, for one reason or another. The methods here cals having the same'empirical formulas, although they tofore available have failed to provide a simple, effective -may be diiferent position isomers ‘and can be even dif and economic method for the methylation of a given aro~ fferent types of radicals, are cracked inthe practicelof the matic compound to form the monomethyl‘ derivative 35 invention, with hydrogenation, ‘to yield two substances, thereof. one an arylmethane (AI‘—-CH3) and the other‘ a corre It is, therefore, a principal object of the present inven "nsponding aryl compound, Ar'H. The gross reaction can tion to provide an improved process forthe production ‘be-represented by the equation =of methyl-substituted aromatic compounds. A’ further AT—CH2--AI'+H2=AI§CHs+1AI'H ‘object is to provide, an improved process for ‘the intro 40 :duction of a methyl radical in substitution for a nuclear Thus,v the‘ not result of the reaction ‘is-:the cleavage-pf La hydrogen atom of an aromatic compound. A more ‘spe -, C-—-C'bond between the methylene (—€Hz-—) - carbon and ci?c object of the invention is to provide an e?ectivegand . a carbon atomof one of thearomaticringsand a satura economicalmethod' for the production of’ nuclear methyl tion withv hydrogen of the‘ two .bond fragments. ‘The derivatives of benzene and naphthaleneivand of benzene ‘kinetics or methanism whereby this result; is-effeetedis compounds and naphthalene compounds. A ‘still-more not clear, although it is considered.to-involvo-more than speci?c object is to provide a method for the conversion a mere carbon-to-carbon cleavage and hydrogenation. In of aromatic compounds which contain benzene or naph any case, the invention is not to be limited by any theory as to its operation. thalene nuclei and only hydrogenlatoms and/or lower In the preparation of diarylmethanes by alkylation of hydrocarbon radicals (1 to 6 carbon atoms), attached 50 to nuclear carbon atoms of the benzene and naphthalene aromatic compounds with formaldehyde,» particularly the nuclei, into nuclearly substitutedmethyl derivativeslthere alkylation of alkylaromatics (e. g., toluene), generally of. A particular'object is to provide‘a practical method there will be produced more or less of further alkylation for the synthesis of durene. These‘objects will be better products thereof. Thus, some of‘the'diarylmethanecom pound is converted into a triarylv dimethane compoundha understood and others will become apparent from ‘the 55 detailed description of *the invention. so-called “trimer,” represented by ' ' Now, in accordance with the-present invention, ithas been ‘found that diarylmethane (Ar2CH2) compounds These diarylmethane (arylmethyldiarylmethane) .-_.com (methylenediaryls) can‘be converted ‘into corresponding pounds are also cracked in the samepmanneryand, under arylme'thane (ArCH3) compounds and aryl‘ (ArH) com 60 ‘similar conditions to yield .two;;molecu1es-».of~methy1 pounds by cracking the compounds in, admixture with hy aromatics and one molecule of _the~- original aromatic. drogen with hydrogenation at an elevated temperature and 'Evenhigher polymers are crackedgsimilarly. ~-It is con pressure-and in contact ‘with a catalyst active'foraryl .templated, in the present invention to crackthe mixture "methylene-carbon and'a‘r'yl-carbon linkage cleavage and of dimer, trimer and other polymerswhich ‘maybe .ob "having hydrogenation activity. ~'In_general the high melt~ 65 tained by ‘the alkylation, the polymer ‘preferably being ing compounds of‘thegroup-VI-VIII metalsrhaving an , .kept to a minimum. atomic number of at: leasti-24:~;jare suitable, particularly .-An examination of the equations for the-reactions for ' the variable valence metals. A particularly suitable cata '(1) the formation of the. dimer and ,(2):>the~cra_cking= o lyst‘forthispurposeis, forle'xample, a tungsten-nickel sul?de' catalyst such as is utilized commercially forv the dehydrogenation of-méthylcyclohexane 10'10111311‘3- {The 70 dehydrogenating metal sul?des are a preferred class "of _. (2). 2819,3255 shows that the overall result is the conversion of one thus giving by hydrocracking primarily durene as the mole of aromatic compound (ArH) to one mole of tetramethyl benzene compound, one molecule of pseudo corresponding methylaromatic or arylmethane (ArCH3) cumene being regenerated. A minor portion of the for each two moles of initial aromatic feed. However, Pseudocumene goes to bis-(2,3,5-trimethylphenyl)-meth one mole of the aromatic compound is produced in the ane, which on hydrocracking yields isodurene and pseu second stage, which can be recycled to the ?rst stage. documene. And a further minor portion alkylates to Thus, the theoretical net consumption of aromatics is the mixed Cm-isomer, 2,2’,3,4’,5,5’-hexamethyldiphenyl one mole for each mole of desired methylaromatic pro methane, some of which on hydrocracking yields durene, duced. Therefore, a preferred method of practicing the in addition to “regenerated” Pseudocumene, while the invention comprises: (1) alkylating the aromatic com 10 other yields isodurene, depending on which aromatic pound, such as toluene, with formaldehyde to produce ring is cleaved from the methylene carbon atom. The the diarylmethane (ditolylmethane), which will normal mesitylene alkylates essentially to only one dimer, bis~ ly be a mixture of isomers (p-p’, o-p, m-p) predominat (2,4,5-trimethylphenyl)methane, which hydrocracks to ing in the p-p' isomer; (2) cracking the diarylmethane isodurene and mesitylene. The hemimellitine present product, either the total alkylate, or the portion from 15 alkylates to three dimers, which hydrocrack to “regen which the higher polymers have been removed, as by erate” hemimellitine and a mixture of isodurene and distillation, to yield a mixture of isomeric methylaromatic prehnitene. The “regenerated” trimethylbenzenes are compounds (xylenes, predominantly the para-isomer) and readily separated by distillation and recycled to the of corresponding aromatic compound (toluene); (3) sepa alkylation, where desired. The durene (M. P. 79-80" rating the produced methylaromatics from “regenerated” 20 C.) is readily crystallized in good yield from the isodurene aromatic as by distillation whereby the “regenerated” (M. P. —24° C.) and prehnitene (M. P. ——4° C.) in aromatic (toluene) is recovered as overhead distillate; the separated fraction. (4) and recycling the “regenerated” aromatic to the The cracking-hydrogenation of the diarylmethanes is alkylation step. When the alkylation results in an ap readily effected by passing a suitable mixture of the feed preciable

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