US3865889A - Process for alkenylation of alkylbenzenes - Google Patents

Process for alkenylation of alkylbenzenes Download PDF

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US3865889A
US3865889A US411563A US41156373A US3865889A US 3865889 A US3865889 A US 3865889A US 411563 A US411563 A US 411563A US 41156373 A US41156373 A US 41156373A US 3865889 A US3865889 A US 3865889A
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xylene
alkylbenzene
reaction
adduct
mono
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Richard E Mitchell
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Sun Ventures Inc
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Sun Ventures Inc
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/54—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition of unsaturated hydrocarbons to saturated hydrocarbons or to hydrocarbons containing a six-membered aromatic ring with no unsaturation outside the aromatic ring
    • C07C2/72—Addition to a non-aromatic carbon atom of hydrocarbons containing a six-membered aromatic ring

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  • 260/668 B 260/671 A kyl nzene recycl i hout increasing the size of the [51] Int. Cl. C07c 3/52 di illation column normally used to separate the al- [58] Field of Search 260/668 8. 671 A kyl enzene from the mono-adduct in the reaction product.
  • alkenylation of alkylbenzenes can be used as a route for preparing various alkylnaphthalenes by following the alkenylation reaction with a ring closure step to
  • This invention relates to the catalyzed reactions of alkylbenzenes with conjugated alkadienes to produce the mono-adduct product, i.e. the one-to-one addition product of the alkylbenzene and diene.
  • alkali metals for promoting the addition of alkadienes to alkylbenzenes is known in the prior art. This kind of reaction is shown for such reactants as toluene or xylene with butadiene or isoprene in the following U.S. Pat. Nos: 1,934,123 issued Nov. 7, 1933, F. Hofmann ct al.; and 2,603,655, issued July 15,1962, D. E. Strain.
  • Such alkenylation reactions have also been described by R. E. Robertson et al., CAN. .1. RES, 263, 657-667 (1948).
  • the conditions disclosed in these references result in the production of large amounts of adducts of higher molecular weight than the mono-adduct product. These references fail to provide conditions under which the mono-adduct product could be obtained in high yield.
  • the alkenylated product typically contains 80-85 percent by weight of mono-adduct (i.e. odolylpentene) with the remainder being mainly di-adducts.
  • mono-adduct i.e. odolylpentene
  • the principal by-product formed is the di-adduct addition product formed by the combination of two alkadiene molecules with one alkylbenzene molecule, although even higher adducts are formed in small amounts.
  • One method of reducing by-product formation is to reduce the concentration of mono-adduct in the reaction zone. Since the amount of higher adducts formed is proportional to the concentration of mono-adduct in the reaction zone, procedures for reducing the monoadduct concentration will reduce by-product formation and improve mono-adduct yield.
  • the average concentration of monoadducts in the slurry for the serially arranged reaction zones is less than the mono-adduct concentration would be for a single stage reaction system.
  • the final mono-adduct concentration is also the concentration always maintained in the reactor; whereas in a plurality of successive zones the final mono-adduct concentration is only that in the last zone and the average concentration thereof for all zones is considerably less. Since the amount of higher adducts formed is proportional to the concentration of mono-adducts in the reaction zone the use of a plurality of stages in the manner described substantially improves selectivity for the desired product.
  • My aforesaid copending application also discloses carrying out the alkenylation reaction in the presence of excess alkylbenzene. This also has the effect of reducing the mono-adduct concentration in the reaction zone and thereby, for the reasons mentioned previously, increasing mono-adduct yield.
  • the reactor cffluent is sent to a distillation column (after removal of any catalyst particles) and the excess alkylbenzene is separated from the adduct products. The latter are sent to another distillation column where pure monoadduct is distilled. The separated excess alkylbenzene is recycled to the reaction zone.
  • alkylbenzenezalkadiene weight ratios of greater than, say, 20:1 are desired to maximize monoadduct yield a distinct disadvantage arises at such a high ratio. This is because all the excess alkylbenzene must be distilled in the above-mentioned distillation column. A point is reached where the increase in column size resulting from an increase in the alkylbenzenezalkadiene ratio is not justified even though this increased ratio begets a significant increase in monoadduct yield.
  • the invention provides a means for increasing the alkylbenzenezalkadiene ratio that can be employed in the alkenylation reaction without excessive costs. Stated in another manner the invention provides a means of increasing the maximum economical alkylbenzene recycle ratio in the alkenylation of alkylbenzenes with an alkadiene.
  • the method involves reacting the alkadiene with excess alkylbenzene, which excess includes recycle alkylbenzene, and, at the end of the reaction, introducing the reaction mass into a flash chamber, flashing off some of the alkylbenzene for use as some of the recycle, introducing the remaining reaction mass into a distillation column to separate adduct product plus more alkylbenzene and utilizing the latter also as recycle.
  • the flash chamber is considerably cheaper than additional multiplate distillation capacity and functions just as well. As a result the distillation column for the same 3 recycle ratio is smaller or, better yet, additional recycle can be achieved with the same distillation column.
  • the alkylbenzene reactant for the present process can have one to four alkyl groups, and it should contain at least three benzylic non-tertiary hydrogen atoms per molecule.
  • benzylic hydrogen refers to a hydrogen atom attached to a carbon atom which is directly attached to the benzene ring.
  • toluene or diethylbenzene meets the requirement of containing at least three benzylic nontertiary hydrogen atoms, but ethylbenzene does not.
  • the size and configuration of the alkyl substituents on the benzene ring are immaterial as long as three or more benzylic hydrogen atoms which are non-tertiary are present. Generally the number of carbon atoms in each alkyl group will be in the range of l-10 and usually 1-2.
  • alkylaromatics which can be alkenylated in an improved manner by means of the present process: toluene; mor p-xylene; mesitylene; pseudocumene; hemimellitene; durene; isodurene; prehnitene; methylethylbenzenes; cymenes; di-n-propylbenzenes', tri-nhexylbenzenes; ethyldecylbenzenes; methyl-tbutylbenzenes; and the like.
  • the diene reaction is a C -C conjugated alkadiene, viz. 1,3-butadiene, 1,3-pentadiene and isoprene.
  • Both reactants should be substantially free of water, sulfur compounds or other impurities, as otherwise excessive loss of deactivation of catalyst may occur.
  • Water can conveniently be removed from the feed materials by treatment with a molecular sieve adsorbent.
  • Alkenylation of the alkylbenzene by reaction with the diene is preferably promoted by means of potassium, sodium or a potassium-sodium mixture but other catalysts known in the art may be employed.
  • the alkali metal promoter is composed of a major proportion of sodium and a minor proportion of potassium on a weight basis, such as 75-98 parts sodium to 2-25 parts potassium.
  • a small proportion of alkali metal to the alkylbenzene reactant is employed, such as 0.015.0 g. moles alkali metal per liter of alkylbenzene and preferably 0.1 to 1.0 g. and a minor proportion of potassium on a weight basis, such as 75-98 parts sodium to 2-25 parts potassium.
  • alkali metal to the alkylbenzene reactant Normally only a small proportion of alkali metal to the alkylbenzene reactant is employed, such as 0.0l5.0 g. moles alkali metal per liter of alkylbenzene and preferably 0.1 to 1.0 g. mole per liter.
  • the catalyst is not considered to be the alkali metal per se but rather the metallo-organic product resulting from reaction of at least part of the alkali metal with the alkylbenzene.
  • the effective catalyst is believed to he the reaction product, benzyl potassium, which forms when a dispersion or slurry of molten potassium in heated toluene stands.
  • the alkali metal needs to be in contact with the alkylbenzene at a temperature above the melting point of the metal for enough time to permit substantial reaction.
  • the respective melting points of K and Na are 623C and 975C but alloys of these metals exhibit lower melting points.
  • a 50:50 by weight mixture of the two has a melting point of 10C.
  • the reaction between the metal and alkylbenzene is slow at low temperatures, it is advantageous to maintain the temperature of the dispersion at least above 50C to form the metallo-organic catalyst.
  • the latter is slightly soluble in the aromatic hydrocarbon but mainly will be present as a dispersed solid.
  • the accompanying drawing illustrates the improved method of alkenylating alkylbenzenes in accordance with the invention.
  • the reactants are considered to be o-xylene and butadiene and the promoter.
  • the desired reaction for producing the monoadduct product is illustrated by the following equation (hydrogen atoms being omitted for simplicity):
  • o-xylene butadiene 5-o-tolylpentene-2 As shown, the desired product from these reactants is 5-o-tolypentene-2, which can be converted to 1,5-dimethyltetralin by treatment with an acid catalyst. During this reaction substantial amounts of higher adducts tend to form due to the reaction of more than one mole of butadiene per mole of o-xylene reacted. Reaction of the additional butadiene can occur in several ways to produce higher adducts of various structures. The present method minimizes the formation of these higher adducts by carrying out the alkenylation reaction in the presence ofa large excess of o-xylene which is obtained by a much more economical procedure than heretofore employed. This excess results in substantially higher selectivity in conversion of the oxylene to the desired mono-adduct than otherwise can be secured.
  • o-xylene feed in line 10 is mixed with recycled o-xylene from line 11 and then continues through line 10 to heater 12 wherein it is heated to the desired temperature.
  • a minor proportion of the o-xylene is diverted through line 13 to a catalyst preparation tank 14 containing heater 15.
  • Molten alkali metal obtained from a source not shown is drawn through line 16 into catalyst preparation tank 14.
  • the latter is provided with a motorized stirrer not shown for effectively dispersing the alkali metal in the hydrocarbon.
  • the temperature in tank 14 is usually held in the range of 50-l70C, more preferably 140C, to facilitate reaction of the alkali metal and o-xylene and form the metallo-organic catalyst.
  • the alkali metal can be potassium or sodium or any mixture or alloy of these two metals.
  • the effective catalyst tends to form more readily when potassium is used than when sodium alone is employed and the selectivity for mono-adduct production appears to be somewhat better. However mixtures of sodium and potassium containing even as much as percent or more sodium are about as effective as potassium alone.
  • the alkali metal utilized be composed of a major proportion of sodium and a minor proportion of potassium on a weight basis.
  • the proportion of alkali metal to alkylbenzene in catalyst preparation tank 14 is not critical and can vary widely. Generally from 5 to 20 parts by weight of the alkylbenzene per part of alkali metal are used in preforming the catalyst dispersion.
  • the minimum residence time in tank 14 for forming the catalyst will vary with temperature, decreasing as higher temperatures are employed. Typically, for a temperature level of 1 C, a residence time of 0.5-2.0 hours is employed.
  • the catalyst dispersion flows from tank 14 through line 17 to line 18 where it meets the stream of o-xylene from heater 12. Also meeting the stream of o-xylene from heater 12 in line 18 is o-xylene recycle in line 19 from flash chamber 20. As will be explained hereafter this recycle is normally at about the boiling point of oxylene (144C) and will usually be vapor. In any event the heat input in heater 12 should be such that the oxylene feed in line 10 plus the recycle in line 11, both of which are usually well below the o-xylene boiling point, plus the line 19 recycle and line 17 catalyst addition, yield a total mixture at about 144C at the inlet to reactor 21.
  • the amount of o-xylene recycled should be such that the total o-xylene (i.e., recycle plus makeup) is at least pounds per pound of total butadiene (i.e., line 31 butadiene). Normally this ratio will be at least 20:1, preferably at least :1.
  • the data below show the improved mono-adduct yield (moles momo-adduct per mole of butadiene times 100) at different o-xylene ratios (pounds total o-xylene divided by pounds butadiene) at typical operating conditions. By employing my invention yields of at least 84 percent are obtained, usually at least 86-88 percent.
  • o-Xylene Mono-a dduct Ratio Yield Reactor 21 is preferably divided into several independently stirred reaction zones.
  • the number of such zones can vary, for example, from 2-10 but preferably is in the range of 3-6.
  • five independent zones designated by A, B, C, D and E, are utilized.
  • the zones are separated by baffles 22, 23, 24 and 25 each of which is somewhat spaced from the top of tank 21 to permit overflow of the reaction mixture to the next zone.
  • the zones are provided with motorized stirrers 26, 27, 28, 29 and 30 and with individual spargers not shown at the bottom of each zone for independently admitting a continuous stream of butadiene from feed line 31 to each reaction zone via lines 32, 33, 34, 35 and 36.
  • Effective mixing conditions are maintained in each of zones A, B, C, D and E by the respective motorized mixers, and the butadiene is fed relatively slowly through the sparger provided in each zone.
  • the butadiene in each zone is thus immediately dispersed into the slurry at a rate whereby a low concentration of the diene therein is maintained.
  • each zone has about the same volumetric capacity and the rates of butadiene addition to the zones are approximately the same, although this is not essential.
  • the amount of total diene to all five zones is preferably controlled so as to provide less than 0.5 mole diene per mole of o-xylene feed.
  • reactor 21 is exothermic and, if necessary, reactor 21 can be provided with cooling coils or other heat removal means (not shown) to keep the temperature constant from inlet to outlet.
  • the process can also be conducted, however, by introducing the slurry through line 18at somewhat below the average desired temperature and allowing the temperature to rise above the average level as the mixture flows to outlet line 37.
  • staged reactor system is the preferred manner of carrying out the present invention and is described and claimed in my aforesaid copending application.
  • staged reactor system is not essential to the success of the present invention and insofar as the latter is concerned it can be employed with either a one-stage or a multistage reactor.
  • My aforesaid copending application shows the improved mono-adduct selectivity that can be achieved by staging. The data hereinabove show the improvement achieved by higher recycle ratios.
  • the reaction mixture next passes to settler 38 wherein the alkali metal, including that in the form of undissolved metallo-organic catalyst, is allowed to settle from the bulk of the hydrocarbon phase.
  • the alkali metal solid material is removed from the settler 38 by line 39 and discarded.
  • the catalyst can be recycled by means not shown to catalyst preparation tank 14 for reuse but in most cases very small amounts of catalyst are employed and it will be more economical to discard the catalyst rather than recycle it.
  • a cooler not shown, will be employed in line 37 between reactor 21 exit and settler 38 but the reaction mixture is preferably not cooled much below the o-xylene boiling point.
  • Flash chamber 20 is in effect a single stage vaporizer as opposed to a distillation column which has many stages to achieve desired purities. However in one stage o-xylene recycle containing 90+% o-xylene can be obtained by heating the catalyst-free reaction product mixture to its boiling point by heating means 41. The vapor exits the flash chamber through line 19 to meet o-xylene feed in line 18.
  • the material entering the flash chamber will normally be at about the boiling point of o-xylene. Accordingly any heat supplied via means 41 will result in some o-xylene vaporization. On the other hand heat does not need to be the means by which o-xylene is separated in flash chamber 20.
  • the chamber could be maintained under vacuum so that as soon as reaction product entered it would vaporize in part.
  • heater 12 will depend, inter alia, upon the temperature of the o-xylene in line 19.
  • a condenser may be employed in line 19 to condense the flash chamber vapors, depending on how flash chamber 20 is operated. This will also affect heater 12 input.
  • the amount of o-xylene separated in flash chamber 20 will be at least 20 percent by weight of the total recycled o-xylene, i.e., line 11 plus line 19 oxylene. Preferably the amount is at least 30 percent, more preferably at least 40 percent.
  • the unvaporized material is withdrawn through line 42 and sent to fractional distillation tower 43.
  • the unreacted o-xylene is removed overhead via line 44, cooled in condenser 45 and passes to recycle tank 46.
  • the recovered oxylene is recycled for reuse through line 11.
  • the relatively pure mono-adduct bottoms from tower 43 pass through line 47 to a second distillation column 48 from which the desired mono-adduct product is recovered via overhead line 49.
  • the higher adduct material, obtained in minor proportion as bottoms through line 50, is composed principally of di-adduct with lesser amounts of tri-adduct and higher material.
  • 167 parts of o-xylene per unit time are fed to the system (line 10).
  • Fresh o-xylene at this rate admixes with 1,500 parts of recycled o-xylene from line 11 and most of the mixture passes through heater 12, where the temperature is raised to 145C, and then to reactor tank 21.
  • About 6 parts of the 167 parts of oxylene are diverted through line 13 and heated to l1l5C in tank 14 and are mixed in tank 14 with 0.7 parts sodium and 0.3 parts potassium. After an average residence time of about one hour in tank 14, the resulting catalyst dispersion flows through line 17 to reactor 21. 100 parts butadiene (line 31) is added to the reactor.
  • the latter preferably is provided with cooling means to prevent the temperature from rising above; l45-150C as the reaction occurs and also preferably is of a size such that the total residence time in the tank is 2-3 hours.
  • the slurry leaving reactor 21 through line 37 (1,770 parts excluding catalyst) passes through settler 38 whereby the alkali metal components are separated from the bulk of the hydrocarbon phase.
  • the hydrocarbon phase (1,767 parts) is sent directly to distillation column 43 (bypassing flash chamber in which 1,500 parts of o-xylene are recovered for recycling.
  • the bottoms from column 43 are distilled in column 48 to yield an overhead product containing 245 parts mono-adduct.
  • Analogous results can be obtained in the alkenylation of other alkylbenzenes by conjugated diolefins by the procedure of the invention.
  • Other particularly useful alkenylations are the reaction of toluene with butadiene to given phenylpentene and the reaction of other xylenes with butadiene to yield other tolylpentenes, via m-tolylpentene-Z from m-xylene or p-tolylpentene-Z from p-xylene.
  • reaction mass containing the mono-adduct alkadiene-alkylbenzene addition product
  • reaction mass is fractionated in a distillation column to separate a relatively pure mono-adduct and alkylbenzene, the latter being employed as said recycle
  • reaction mass a reaction mass to a flash chamber to separate a portion of the alkylbenzene therein;

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US411563A 1973-10-31 1973-10-31 Process for alkenylation of alkylbenzenes Expired - Lifetime US3865889A (en)

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CA211,062A CA1034961A (en) 1973-10-31 1974-10-09 Process for alkenylation of alkylbenzenes
JP49124040A JPS6014004B2 (ja) 1973-10-31 1974-10-29 アルキルベンゼン類のアルケニル化法

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3954895A (en) * 1975-05-27 1976-05-04 Teijin Limited Method of separating and recovering alkenylbenzenes and unreacted alkylbenzenes from the alkenylation reaction product
US3954896A (en) * 1974-07-02 1976-05-04 Teijin Limited Process for preparing monoalkenylbenzenes
US4714778A (en) * 1986-03-07 1987-12-22 Air Products And Chemicals, Inc. Alkenylated toluenediamines for use in preparing polyurethane/urea systems
US4845291A (en) * 1986-12-24 1989-07-04 Air Products And Chemicals, Inc. Cycloalkenyl aryldiamines
US4990717A (en) * 1989-11-16 1991-02-05 Amoco Corporation Monoalkenylation of alkylbenzenes in a fixed catalyst bed
US5072045A (en) * 1986-03-07 1991-12-10 Air Products And Chemicals, Inc. Process for the catalytic alkenylation of arylamines with conjugated dienes

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766288A (en) * 1971-03-29 1973-10-16 Teijin Ltd Process for preparation of alkenylbenzene

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3437705A (en) * 1967-03-02 1969-04-08 Universal Oil Prod Co Process for aromatic alkylation and olefinic oligomerization

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766288A (en) * 1971-03-29 1973-10-16 Teijin Ltd Process for preparation of alkenylbenzene

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3954896A (en) * 1974-07-02 1976-05-04 Teijin Limited Process for preparing monoalkenylbenzenes
US3954895A (en) * 1975-05-27 1976-05-04 Teijin Limited Method of separating and recovering alkenylbenzenes and unreacted alkylbenzenes from the alkenylation reaction product
US4714778A (en) * 1986-03-07 1987-12-22 Air Products And Chemicals, Inc. Alkenylated toluenediamines for use in preparing polyurethane/urea systems
EP0235825A3 (en) * 1986-03-07 1990-03-14 Air Products And Chemicals, Inc. Alkenylated toluenediamines for use in preparing polyurethane/urea systems
US5072045A (en) * 1986-03-07 1991-12-10 Air Products And Chemicals, Inc. Process for the catalytic alkenylation of arylamines with conjugated dienes
US4845291A (en) * 1986-12-24 1989-07-04 Air Products And Chemicals, Inc. Cycloalkenyl aryldiamines
US4990717A (en) * 1989-11-16 1991-02-05 Amoco Corporation Monoalkenylation of alkylbenzenes in a fixed catalyst bed

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JPS5071633A (enrdf_load_stackoverflow) 1975-06-13
CA1034961A (en) 1978-07-18

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