CA1049570A - Method of separating and recovering alkenylbenzenes and unreacted alkylbenzenes from the alkenylation reaction product - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
In the method wherein an alkenylation reaction product liquid obtained by the alkenylation reaction of an alkylbenzene and a C4-C5 conjugated diene in the presence of alkali metal catalysts and containing unreacted alkylbenzene, alkali metal catalysts and organo-alkali metal compounds is conveyed to a dis-tillation zone at which said alkenylation reaction product liquid is separated by distillation to recover an alkenylbenzene-con-taining fraction and an unreacted alkylbenzene-containing frac-tion, the improvement which comprises adjusting the total of the concentrations of said alkali metal catalysts and organo-alkali metal compounds in said alkenylation reaction product liquid introduced to the distillation zone so as to be 0.09 - 15 milli-gram atoms per kilogram or said product liquid, calculated as alkali metal atoms, and thereafter conducting the distillation of said product liquid under conditions of non-addition of alcohols.

Description

~ID49570 ~hi3 invention relates to a method whereby in separat-ing and recovering alkenylbenzenes and unreacted alkylbenzenes from an alkenglation reaction product the alkenylbenzene-contain-ing fraction and the unreacted alkylbenzene fraction suitable for recycling an~ reuse can be separated an~7 recovered by dis-tillation commercially advantageously in high purity and good yield while checking the formation of objectionable by-products w~ose separation from the ~ntended alkenylbenzenes involve not only difficulty but also complicated separation operations~
The alkenylbenzene obtained by reacting an alkylbenzene with a conjugated diene of 4 - S carbon atoms in the presence o~
~n alkali metal catalyst, e.g., S-(o-tolyl)pentene-(2~ obtained by reacting o-xylene with l,~-butadiene, is a commercially ~valuable compound, since it can be converted to naphthalenedi- ; p lS carboxylic aci~, a very ~aluable starting material for the pre-paration of high polyme s, by effecting t~e latter'~ intra- ;
~.
mol~cular cyclization reaction to convert it to l,~-dimethyl-tetralin followed by dehydrogenation and oxidation~
It i~ known to prepare alkenylbenzenes by reacting alkylbenzenes with C4 - C$ conjugated dlenes in the presence of an alkali metal catalyst (e.g., U.S.~Patent 3,244,758). In car-~
rying out the foregoin~ alkenylat1on reaction~continuously on a commerclal scale, an excess of alky}benzenes is used relative to th~ conjuEated dienes for enhancing-the reaction yield. Hence, , " :
in practicing this alkenylation reaction, it is usually carried out in the following manner. ~he alkenylbenzene-containing fraction consisting predominantly of alkenylbenzene and the un-reacted alkylbenzene-co~tainin~ fraction are recovered by dls~
tillation fro~ the alkenylation reaction product, ~he alkenyl-, ~
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~04957~
benzene-co~taini~g ~raction being further distilled and purified, i~ necessary~ On th~ other hand, the unreacted alkylbenzene- ~
containing fraction is purified, if desired, and then recycled :
.to the alkenylation reaction zone and reusedO
I~ carrying out the distillation of the aforesaid alkenylation reaction product9 for preventing the setting up of .
objectionable-side reactions in this distillation step due to the presence of alkali metal catalysts and organo-alkalimetal compounds that are contained in the reaction product~ an inac- ;
tivation treatment of the catalysts is carried out in the afore~
mentioned U.S. Patent 3,244,7~8 by~adding in advance lsopropyl alcohol to th~ alkenylation reaction product.
In consequence of our researches into the matter of sep~rating and recovering the alkenylbenzene-conta ming fraction and the unreacted alkylbenzene-containing fraction by:carrying out the distillation under conditions o~ the addition of this .
PlCO~Ol~ the following unexpected~fact was discovered-According to our researches, we found that the iso-propyl alcohol added for the purpose of deactiv~ting the catalysts was contained in the recovered unre~cted alkylbenzene and that ~
even though the amount contained was conside~ably small, it would :
.~
- greatly impair the reaction when reused in the alkenylation reac-tion. Thus, lt is necessary to carry out a disadvantageous speration of treating the recovered unreacted alk~lbenzene-con-, taining fraction to eliminate the-isopropyl a].cohol. Further, ot only is it difficult to remove the isopropyl alcohol to an exte~t as would be substantially harmless even though such a disadvantageous op~ration is added, but also the di~advantages ~ .
involved as seen from thn aspects of apparatus, operation and , . . .
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- ~4~57~) cost are ~ceedin~ly great in practicing this ad~ed step on a commercial scale. For example. in the instance of the alkenyla-tion re~ction of o-xylene and 1,~-but~iene in the presence of an alkali metal catalyst, it was found that there was an extreme decline in the yield of the inten~ed 5-(o-tolyl)pentene-(2) even when the isopropyl alcohol was contained in only a small amount of 0.~ ppm in the o-xylene.
Further, in ~ttempting the distillation and separation into an alkenylbenzene-containing fraction and an unreacted alkylbenzene-containing fraction of the alkenylation reaction profluct, which has substantially undergone the deacti~ation treatment of the catalysts with an alcohol such as isopropyl alcohol, by conyeying the reaction product to the distillation zone, it was found that objectionable by-products would form during this distillation? i.e., lt was found that especially in the case where it was attem~ted to convert the r~sulting alkenyl-benzene into alkyltetralin by the;cyclization reaction~ the conversion would not proceed smoot ly and,~in a~dition, there ` was the formatioli of objectionable isomers, which were difficul- `~
tly separated from the intended alkyltetralin. ~hereas the olefinic double bond o~ alkenylbenzene, the principal product, is positioned at 2, the by-products are those isomers ~hose position of the double bon~ differs, for example, when the~
principal product is ~-tolylpentene-(2), the isomers are ~-tolylpentene-tl), ~-tolylpentene-(~) and ~-tolylpentene-(4). ~`~
Of these isomers, that in which the`olefinic double bond is in -~
the l-position, e.gO~ ~-tolylpentene-(l), can be cyclized and conYerted to an alkyltetralin, but in the case of the other iso-mers not only is it not possible to convert them to alkyl-`: :

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~ 9570 tetralins- but also these other isomers react with alkylte-tralins, the other product, an~ form high boiling products, with the consequence that the yield of the intended product declinesr Further~ore, it is extremely difficult to separate and remove thes~ objectionable isomers from the alkenylbenzenes, the intended product of the invention method, because the boil-ing points and chemical properties of these isomers are similar ;
to those of alkenylbenzenesO
~ As a consequence of our researches with the view to overcoming the disadvantages and shortcomings such as abovedescribed, we found khat by not adding the isopropyl alcohol for deactivating the catalysts but by carrying out the distillation while causing the presence in the reaction product. of the c~t~lyst~ the presence of which in the distillation step was hitherto considered to be objectionable, i.e., by positively causing the presence of the catalysts, the unreacted alkali metal catalysts and organo-alkalimetal compounds, in the alkenyla- `
tion reaction product during the distillation step, with the ~proviso that they are present in an amount adjusted to a speciflc range, th~ side reactions by which the aforesaid objectionable isomers are formed could be fully ohecked. Furthermore, it was found not only that th~ shortcoming that the reaction was impaired as a result of recycling and reu5ing the separated and recovered u~reacted alkylbenzene could be overcome, but also that there 2~ was an improvement of the reaction yield rather than its declineO
As shown by the hereinafter presented control experiments, it was found that the foregoing unexpected results could not be achi~ed when the amount of the catalysts deviated from the range indicated above an~ was either too small or too large.
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- , ~04~570 It is therefore an object of thi~ invention to provide a methcd where~y ill separating and recovering the alkenylbenzene and unreacted alkylbenzene from the alkenylation reaction product obtained by cærrying out the alkenylation reaction of an alkyl-benz~ne and a C4 - C5 conjugated diene in the presence of an alkali metal catalyæt9 not only an alkenylbenzene-containing fraction can be obtained in good yield, but also an unreacted alkylbenzene fraction suitable for recycling and reuse can be obtained commercially advantageously whi~e checking the formation of obJectionable by-products whose separation from the intended alkenylbenzene not only is difFicult but involves complicated ~eparation operations as well.
Other objects and adv~ntages of the present invention will become apparent from the~th~ following descriptionO
According to the invention méthod, in carrying out the distillation and separation of the alkenylbenzene-containing ~raction and unreacted alkylbenzene-containing fraction by con~
~eying to a distillation zone an alkenylation reaction product containing an unreacted alkylbenzene,~alkali metal catalysts and organo-alkalimetal compounds, the total of the concentrations of said alkali metal catalysts and organo-alkalimetal compounds ~ ~ -is adjusted so as to be 0.09 - 1~ m~ OE am atoms, and preferably 0.12 - 8 miIligram atoms, per kilogram`of the product, calculated as alkali~metal atoms, and ~he so adjusted reaction product is 2~ distilled under conditions of non-aaditlon of an alcohol such as~
isopropanol to be used for deactivating the catalyst. ~ ~
~ he method of adJusting the total o~ the concentrations~ ~-of the alkalimetal catalysts and organo-alkalim~tal compounds to an amount coming within the range specified above can be :

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:~049~70 achieved by adjusting the conditions of the alkenylation reac-tion, the amount of the catalyst, and the amounts used of the starting alkylbenzene and conjugated dienc, or by a method of mixing a suitable amount of alkylbenzRne and alkenylbbnzene in the reaction proAuctO The best method is, however, that of con-ducting the reaction product to a catalyst separating zone and 9eparating the product into a catalyst phase consisting pre-dominantly of alkali mctals and a hydrocarbon phase consisting predominantly of alkenylbenzene and unreact~d alkylbenzene. A
p~rt of the alkali metals used as the alkenyletion reaction ca-talyst reacts with the alkylbenzene and alkenylbenzene and become organo-alkalimetal compounds, which are contained in the reaction productD ~hese organo-alkalimetal compounds also act as catalyst~
While a part of these catalysts dissol~e in hydrocarbons, a major proportion do not ~issolve in hydrocarbons and are present in the form of a liquid or solid. Hence, for recovcring the ca-talysts in a reusable state without decomposing and deactivating them~ a procedure consisting of merely separating the catalyst ~; phase from the hydrocarbon phase wlll do. ~or separating the two phases, advantageously usable are such methods as the decantation method consisting of letting the alksnylation re~ction product st~nd still to settle the c~t~lyst by gravity and thereafter separating and recov~ring the catalysts by decsntation, the cen-trifu~al method wherein the settling and separstion are carried out in a centrifuge, and the method of separation by filtration.
However, when considered from thc standpoint of safety and the ~act that the amount Or catalysts to be mixed in the hydrocarbon phase can bR readily controlled so as to come within the afore- ;~
mentioned specifled range, the decantation method is preferably ~ 7 :~ .

1049S~
employed. ~he temperaturè at which the separation of the ca-talyst is carried out is imposed no special restrictions. In general~, a higher temperature in carrying out the separation is preferred from the performance standpoint, but since side reac-tions tend to be set up when the temperature is too high, theseparation is preferably carried out at a temperature ranging ~rom room temperature to about 200C., and more preferably from about 60 to about 180Co - According to the in~ention method, the alkenylation reaction product to be introduced to the distillation zone is one whose concentration of alkali metal catalysts and organo-alkalimetal has been ad justed as hereinabove described to a ~alue of 0009 - 15 milligram atoms, and preferably 0~12 ~ 8 milligram atoms, per kilogram of said;product. ~his reaction l~ product is distilled under conditions of the non-addition of ..
alcohols for deactivating the catalystsq iOe., in the absence of isopropyl alcohol that has been used~in the past for deactivating the catalysts. If the concentration of the alkali metal catalysts and organo-alkalimetal is too small, for exa~ple, as shown in , the hereinafter-given control ~xperiment, i.e., if the reaction is carried out with the addition of isopro~yl alcohol, and the concentration of the alkali metal catal~sts and organo-alkalimetal ~ :
is made to be zero, there is such inconveniences as a decline in the effect of improving the yield of the intended product when the separated and recovered unreactsd alkylbenzene is recycled and reused as the starting material for the alkenylation reaction as well as a decline in the effect of checking the formation of `~
obaectionable isomers during the distillation. Cn the other .~ .
l hand, if the concentration of the alkali metal catalysts and ~ , . . .

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~ 049S7~3 .
organo-alkalimetal exceeds 15 milligram atoms per kilogram, this also is inconvenient9 as shown in the hreinafter~given control experiment 9 in that not only is there an increase in the amount of the by-products due to the addition reaction of the alkylbenzene, alkenylbenzene and by-products during the dis-tillatio~9 but also the liquid becomes viscous, with the con-sequence that extreme di~ficulty is exp~rienced in carrying out the distillation operation.
~he distillation can be carried out at either normal atmospheric superatmospheric or r~duced pressureO The use o~ -a column top pressure of above about 50 mm Hg absO is preferred, si~ce the use of such a pressure serves to fully bring about the m~nifestation of the effects of improving the alkenyIation reac-tion yield when reusing the recovered unreacted alkylbenzene in ~
15~ the alkenylation reactionO For example, in carr~ing out the distillation it is best to use a column top pressure ranging - ~ ~rom 50 mm Hg abs. to I400 mm Hg abs., and preferably 100 mm Hg abs. to 1000 mm Hg abs. As r~rds the distillation temperature, ~ the distillation temperature of the unreacted alkylbenzene can be suitably chosen in accordance with the pressure used.
The distillation may be carried out either batchWise or continuously. ~he distillation apparatus may also be those which are known such, for example, as the tray or packed columnO
, , The unreacted alkylbenzene that has been separated by the distillation can be recycled and reused in the aforementioned alkenylation step In carrying out the distillation, the separation of the alkenylbenzene-containing fractlon and unreacted alkyl-- benzene-containing fraction can be carried out by any o~ the , ~
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~al4957(~ . -various optional modes of operation. For instance, in one mode the alkenylation reaction pro~uct can be separated into an u~-rescted alkylbenzene-containing fraction and an alkenylbenzene--containing fraction containing a reaction by-product fraction, ~ollowing which the latter alkenylbenzene-containing fraction can be distilled further to separate same into an alkenylbenzene-containing fraction and a by-product fractionO Again, there isj for example, a mode which comprises separating the alkenylation ~ FeaCtion product into a fraction consisting of a mixture of an ;
unreacted alkylbenzene-containing fraction and an alkenylbenzene- ~ -containing fraction not containing any reaction by-products and a by-product fraction, and thereafter separating the former ~-~
~ractional mixture into an unreacted alkylbenzene-conta;n;ng - -~raction and an alkenylbenzene-containing fraction.
15 ~ In practicing the invention method, there can be employed, for example, the following modes of operation.
- ~ (1) In the m~thod o~ preparing alkenylbenzenes consis~ing , . .
of the steps of A~ reacting an alkylbenzene with a con~ugated diene of ~20 4 - 5 csrbon atoms in the presence of alkali metal catalysts, Bo separating the alkenylation reaction product obtained in the foregoing Step A into a catalyst phase consisting pre-dominantly of the~alkali metal and a hydrocarbon phase consisting predominantly of an alkenylbenzene and unreacted alkylbenzene, C, distilling the hydrocarbon phase separated in the ~oregoing Step B and separating same into an unreacted alkyl- - -benzene-containing fraction and an alkenylbenzene-containing ~raction, and :
D. recycling to Step A the unreacted alkylbenzene-con-~, ,~ _ 10- .
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taining fraction separated in the foregoing ~tep C; a method ~ : ch~racterized b~ adjusting the concentration of the alkali metal catalysts and organo-alkalimetal compounds contained in the hydrocarbon phase distilled in the goregoing Step C to 0.09 - :
15 milligram atoms, calculated as alkali m~tal9 per kilogram of the hydrocarbon phase.
(2) In the method of preparing alkenylbenzenes consisting of the steps of Ao reacting an alkylbenzene with a conjugated diene of :
4 - 5 carbon atoms in the presence of alkali metal catalysts, . B. separating the al~enylation r~action product obtained ; in the foregoing Step A into a catalyst phase consisting pre-dominantly of the alkali m~tals and a hydrocarbon phase consis-ting predominantly of an alkenylbenzene and unreacted alkyl-benzene, CO distilling the hydrocarbon phase separated in the ~ .
foregoing ~tep B and separating same into an unreacted alkyl- :
benzene-containi~g fraction and an alkenylbenzene-containing fraction consisting predominantly of an alkenylbenzene and reac- ~ :
tion by-products, ~ . .
C'. distilling the alkenylbenzene-containing fraction consisting predom~nan~ly of alkenylbenzene and reaction by-pro-duc~s that has been separated in the aforesaid Step C, and ~:~
separating same into an alkenylbenzene-con~taining fraction re~
move of by products and a reaction by-product fraction, and Do recycling to Step A the unreacted alk~lbenzene-contain- ~ ~
ing fraction separated in the aforesaid Step C; a method charac- ~:
terized by ad~usting the concentration of the alkali metal ca-talysts and organo-alkalimetal compounds contained in the , ~ :

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~049570 hydrocarbon phase used as the distillation starting material in -tha forego m g Step C ~nd the alkenylbenzene-containing fraction consisting predominantly of alkenylbenzene and reaction by-products used in as the distillation starting material in the foregoing Step C' to 0.09 - 15 milligram atoms, calculated as alkali metal, per kilogram of the distillation starting material.
'rhe process for the preparation of the alkenylation reaction product, which is obtained by reacting an alkylbenzelle with a C4 - C5 conjugated diene in the presence of alkali metal catalysts, and to which the invention method finds appllcation, is known. As the starting alkylbenzenes, mention can be made of the compounds of the following formula having at least one methyl or ethyl group substituted on the benzene ring.

R2,~R

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wherein Rl is either methyl or ethyl,~ and R2, R3 and R4 are each either hydrogen or an alkyl group of 1 - ~ carbon atoms, which may be the same or differentO
Examples of the pr~ferred alkylbenzenes include toluene, xylene, ethylbenzene, trimethylbenzene and te~ramethylbenzene, of which especially used are o-xylene, m~xylene and p-xylene, as well as the mixtures of two or more of these compounds.
On the other hand, the conjugated dienes are those of 4 - 5 cnrbon atoms, usable being such compounds as I,3-butadiene and isoprene~
2S As c~talysts for the alkenylation reaction, there can , - 12 ~
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~ 4957al be named the alkall metals such, ~or exa~ple9 as metallic sodium and metallic potassiumL ~hese alkali metals may be used either singly or m combinations of two or more thereof. While the amount in which the catalyst is used is imposed no special res-trictions, it is preferably used in the proportions indicatedbelow, since by using the cat~lyst in such proportions it becomes possible for it to demonstrate great activity even though the amount in which it is used is small. That is, the catalyst com-ponents are preferably used on the basis of 100 parts by weight I0 of the al~ylbenzene present in the reaction system in the follow-ing proportlons: ~
(1) 0.0005 - 0.005 parts by weight of metallic potassium and less than 0.1 part by weight of metallic sodium, or (2) -5 ~ 0.08~ part by wei~ht of metallic potassiu ~nd Y part by weight as expressed by the following expression of metallic sodium:
, ~
2 z ~ O ~ 0 5 wherein Z represents the weight of the metallic potassium per 100 parts by weight o~ the alkylbenzene present in the reaction system. Still more pr~ferred i9 the use of the catalyst com~
ponents in the proportions of 0.0005 - 0.005 part by weight of metallic potassium and Y part by weight as expressed by the fol-lowing expression of metallic sodium:
, ;~ -5 ~ Y < 0.59 Z ~ 0-025 -i 25 wherein Z is as ~bove defined. W~.en making conjoint use of me-. .
' ` tallic potassium and metallic sodium, they may be added separately ;~; to the reaction system, but preferred is their use in the form of : ' i~ - 13 -' ~ .

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an alloy of the two metals.
- Th~ foregoing alkali metal catfllysts ca~ also be used supported on such carrier materials as, for example, sodium chloride, potas~ium chloride, calcium oxide, sodium sulfate, carbon c~nd iron.
~ he aforesaid alkenylation reaction can be carrie~ o~t at a temperature of preferably about 80 to about 200C., more preferably about 100 to about 190C., and especially preferably about 110 to about 180C. The aforementioned conjugated dienes are used relative to the alkylbenzenes in a molar ratio of pre-farably 0.001 0.4 mole, more preferably 0.01 - 003 mole, and e~pecially preferably 0.05 - 0.2 ~ole per mole of the alkylbenzenes.
~he reaction time used is preferably about 0~05 hour to about 1 hours, more preferably about 0.2 hour to about 8 hours, and especially preferably about 0.3 hour to about 4 hours~
The reaction may bc carried out by the batch method in which the alkylbenzene9 con~ugated diene c~nd catalyst are charged to a rePction zone followed by carrying out the reaction, or the semi-bstch m~thod in which the alkylbenzene and catalysts are first charged to a reaction zone, a~ter which the reaction is , - . -carried out while introducing the conaugated disne, or the con-tinuous method in which the reaction is carried out while in-troducing the alkylbenzene, conjugated diene and catalyst con~
tinuously to the reaction zone. Of these methods, preferred is either the semi-batch or continuous method. Particularly to be preferred is the continuous reaction method wherein a plurality of r~action zones ara provided, in which zones the alkali metal catalysts are ~aused to be present, the alkylbenzene or a rsaction mixture contaInI~g the alkylbenzene-being passed through these . . ~.

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, ~ 09~9570 plurality of reaction zones, while introducing the conjugated diene to at least two of such reaction zones~ In this case a part or whole of the alkylbenzene may be fed to the reaction zo~e~
after mixing with the conjugated dieneO If the conjugated diene and alkylbenzene are fed to the reaction zones after mixing them, this serves to prevent the conjugated diene from adhering to the vicinity of the inlet port as a result of its polymerization.
The concentration of the alkali metal c~atalysts and organo-alkalimetal compounds in the alkenylationreaction product, as used herein, i9 a value that has been quantitated and calcula-ted in accordance with the following method of quantitation~
antitation of alXali metals A hydrogen generating apparatus charged with 100 pa~s by weight of the specimen alkenylation reaction product liquid f room temperature is placed in a thermostated water tank of , 25C., after which 10 parts by weight of methanol is added to the afore~aid liquid9 a~d the volume of~the hydrogen gas generated . ~ . i5 measured. The amount of hydrogen gas contained dissolved in th~ liquid is also quantitatively analyzed by means of gas chroma-~20 tography. ~he two amounts are then added to obtain a value (x).
-~ - 0~ the other hand, the amount of hydrogen gas (y) contained dis-solved in 100 parts by weight of the specimen alkenylation reac-tion product liquid before addition of methanol is also quantitated .
by means of gas chromatography, after which the r.umber of milli-gram atoms of alkali metal is calculated by subtracting the value (y) from the foregoing value (x)0 - ~uantitation of the organic alkali me~al compounds A liquid mixture of "tr1tium-marked water" and tetra-hydrofuran lg added to the specimen alke~ylation reaotion product : , .
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` ~49570 liquid, a~ter which the resulting liquid mixture is reacted with an organic metal compound. ~he amount of ~-organic compound is the~ quantitated, using a liquid scintillation counter adjusted in ad~ance by the internal standard methodO -~he following examples, along with control experiments, will be give~ for more fully illustrating several modes of prac-ticing the method of this invention.
13xamPle 1 Five stirrer-equipped reaction tanks, each of 20-liter capacity (effective liquid holding capacity of 12 liters)~ were disposed in series~ using overflow pipings to connect the several tanks~ ~hus~ the reaction tanks were adapted to operate con-tinuously? the liquid from the first tank flowing into the seco~
taDk via an overflow pipe1 and flowing in similar manner succes-sively through the third~ fourth and fifth tanks, from which last tank the reaction product liquid is withdrawn. ~he hereinafter- ~-~- described recovered o-xylene and dehydrated fresh o-xylene in an~
amount corresponding to that consumed in the reaction were fed to the ~irst tank at a rate of 19 kg per hour. While adjusting the internal temperatures of the several~tanks at 140C. and the ~ speed of the stirrers a~ ~OO rpm, an alloy of metallic sodium -~
; a~d metallic potassium of 1:1 weight~ratio was fed to the first --tank at a rate of 10 grams per hour.` After 4 hours had passed ~rom the time the feed of the o-xylene and the catalyst was ini- `
tiated, 0.25 kg per tank of dehydrated 1,3-butadiene was introduced to the several tanks continuously (at a rate of 1025 kg per hour for a total of the five tanks), and-t~e reaction of o-xylene and .
butadiene was carried out.
~he àlkenylation reaction product liquid overflowing _ 16 -, ~ : : .

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~ 049570 .
from the fifth tank was introduced to a cylindrical baf~led decanter of inside diameter 300 mm ~nd length ~80 mm having nine baffles and of total capacity 40 liters, and tho inside tempera-ture of the decanter was adjusted to 140C. ~he alkenylation reaction product liqw d phase containing alkylbenzenes, alkali metal catalysts and alkali metal compounds was then withdrawn continuously from the upper part of the decanter at a rate of 20.~ kg per hour, while the catalyst phase containing predominan-tly the alkali metal c~talyst~ was withdrawn from the bottom part of the dacanter at a rate of 15 grams per each time at 10-minute i~tervals. ~he so obtained alkenylatlon reaction product liquid pha~e was fed continuously to the 14th plate from the bottom of an 18-plate valve tray distillation column of column di~meter o~
6 inches. The distillation column was operated under the condi-1~ tio~s of an operating pressure at the top of the column of 600 - mm Hg abs., a pressure at the bottom of the column of 650 mm Eg abs. and a reflux ratio of 1.0 to obtain continuously at a rate 0~ 16.68 k6 per ~our a fraction containing 99.9 wt. % of unreact~d o xylene, while an alkenylbenzene-containing fraction consisting predominantly of alkenylbenzenes was withdrawn from the bottom of the column at a rate of ~.52 kg per hour. ~he alkenylbenzene-containing fraction obtained by distlllation was then fed con-tinuously to a column having a column diameter of 4 inches packed with Raschig rings to a height of 4 meters, where it was distilled further and separated into 5-(o-tolyl)pentenes and by-products.
~he distill~tion column was operated~at a column top pressure of 500 mm Hg abs., a column bottom pressure of 5~0 mm Hg abs, and a re~lux ratio of 2.0 to continuously Qbtain from the column top 5-(o-tolyl~pentene-(1) and 5-(o-tolyl)pentene-(2) of 99~8 wt. %

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~49570 purity at a rate o~ 3.06 kg per hour and from the column bottom by-products at a rate of 0.4'~ kg per hour. ~his operation was .. . .
c~rried out continuously for 20 days. Samplings were taken from each step once daily and analyzedO ~rom the so obtained results were calculated the concentrations and yields as 20-day average values. ~hese results are summarized below.
tl) When a part of the alkenylation reaction liquid over-flowing from the fifth tank was sampled, and the concentration o~ 5-(o-tolyl)pentene-(1) and 5-(o-tolyl)pentene-(2) was quan-~
1~ titatively analyzed by the gas chromatography method, it was15.3%, and the reaction yield of ~-(o-tolyl)pentene-(l) and 5-(o-tolyl)pentene-(2) based on the 1,3-butadiene ~ed, was 84.~/oO
(2) When the metallic potassiwm and metallic sodium con-tained in the hydrocarbon liquid phase obtained from the catalyst`
separator were quantitatively analyzed by the horeinbefore - ~ ~-described method of measurement from the amount of hydrogen gen-~, . .
erated, their amounts were 2.3 milllgram atoms/kgO On~the otherha~d, when the organic alkali metal compounds were quantitatively~
analyzed by the hereinbefore-described method and the organic .
20 sodium compounds ana organic potassium compounds were calculated ~-~~; as sodium and potassium, the amount was 0.99 mil~igram atom/kg.
(3? ~he recovery rate of the unreacted o-xylene recovered at the first distillation column was 99.7~ based on the amount ~ fed thereto of the alkenylation reaction product liquid phase, while the proportion Or o-xylene converted to high boiling pro-ducts or was not recovered at the distillation column was 0.27% . .
o~ the alkenyl~tion reaction pro~uct liquid phase fed thereto.
(4) On analysis of the intended product obtained from the column top of the second diatillation column7 it was found to be - 18 - ~
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: ~ , . ~ ~ : , , 6.7 wt. % 5 (o tolyl)pentene-(1)9 93~1 wto % 5-(0-tOlyl)peneten-(2)9 OoO wto % t-(o-tolyl)pentene-(3) and 0.2 wt. % 5-(o-tolyl) p~ntene-(4)0 0~ these alkenylbenzenes, the purity of the com-ponents that could be converted to 1,5-dimethyltetralin by the cyclization reaction was 99.8/~. On analysis of the by-pro~ucts from the column bottom, it was found that the proportion of the 5-~o-tolyl)pentene-(2) that waS isomerized or converted to high boiling components was l.C% of the 5-(o-tolyl)pentene-(2) fed to the distillation column.
10It is thus seen from the foregoing results that it was possible by Operating continuously for 20 days to obtain 5-(o-tol~l)pentene-(l) and 5-(o-tolyl)pentene-(2) from the addition reaction of o-xylene and 1,3-butadiene at a stabilized yield of 82/~ based on the 1,3-butadiene ed and 87% based on the o-xylene fed.
xamples ? - 4 and C~ntrol 1 ~ he experiment was carried out exactly as in Example 1 and under identical conditions, except that the composition of th~ catalyst used in the alkenylation reaction and the catalyst -~
fed to the reaction was varied. ~he results obtained are shown in Table lo .

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Example Example Example Control Experiment 2 3 _ 4 _ 1 Alkenylation reaction Catalyst co~position: Na/E
(wt. ratio) 1 2 10 5 Amount of catalyst fed (g/hr) 3 30 100 200 Reaction yield of 5-(o-tolyl) p~ntene (1) and -(2) based on 193-butadiene fed (,b) 85 84 84 81 C~talyst separation Concentration of alkali metal `
atoms in the alkenylation reaction product submitted to distillation Concentration of the metallic `' sodium and metallic potassium in the hydrocarbon liquid phase (mg atoms/kg) 0.26 2.9 *.5 7.0 Concentration of the organo-sodium and potassium compounds in the hydrocarbon liquid ~
phase (mg atoms/kg) 0.20 1.9 2.4 15.1 .
Distillation Recovery of o-~ylene (%~ 99-8 9908 99~7 98~2 Concentration of products (wt. %) , .
5-(o-tolyl)pentene-(1) 4-8 ~7.5 7.6 8.7 , 5-(o-tol~l)pentene-(2)95.1 920291.988.3 5-(o-tolyl~pentene-(3)0.0 ~ 0.00.1 0.6 5-(o-tolyl)pentene-(4)0.1 0.3 0.4 2.4 ~ ~; . ....
Conversion of 5-(o-tolyl)pen-tene-(2) to other co~lponents (O 0.6 1.5 2.6 7.9 ~otal yield of 5-(o-tolyl) pentene-~l) and 5-(o-tolyl) pentene-(2). (%~
Based on 1,3-butadiene fed 84 82 81 72 B~sed on o-xylene fed 90 87 86 71 - 20 ~
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~ he alkenylAtion reaction was operated under exactly the same conditions as in Ex~mple 1. The alkenylation reaction . .
product liquid overflowing from the fifth tank was fed continu-ou~ly to a tank h~vin~ an inside capacity of 12 liters, and a cloar liquid (hydroc~rbon liquid phase) was withdrawn from the top of the tank at a rate of 20.2 kg per hour, w'nile the catalyst phase used in the reaction was withdrawn from the bottom of the ta~k at a rate of 75 grams per each time at hourly intervals.
0 Tn this case the a~erage residence time of the liquid in the tan~
was 30 minutesO ~he so obtained~hydrocarbon liquid phase was ' distilled by the same method of distillation as in Example 1 to separate unreacted o-xylene, ~-(o-tolyl)pentenes and reaction by-products. The u~reacted o-xylene was recycled to the alkenyla-tion reaction as in Example I and reused in the reaction. The ' opera~ion was,continued for ? days in this manner. The results ;~-obtained are shown in ~able 2 presented ln the same form as that ' ~n the case of Example 1.

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Alkenylation re~ction Alkenylation reaction yi~ld of S-(o-tolyl)pen,-tene-(l) and 5-(o-tolyl)pentene-(2) based on ~ butadiene fed (,~) 82 Conce~tration of alkali metal atoms in the alkenylation reaction product submitted to distillation Concentration of the metallic sodium and metallic ~otassium in the hydroc~rbon liquid phase ~mg atoms/kg) 6.3 Concentration of the organo-sodium and potassium compounds in the hydrocarbon liquid phase ,' (mg ~toms/kg) ~ 12.1 ~ - , Distillation ' Reco~ery of o-xylene (//7) ^ 98.9 Concentration of products~(wt. /0) ' ; ~ :
5-(o-tolyl)pentene~ ' 8~6 5-(o-tolyl~pentene-(2) ~ ' 88.8 "'' ~-(o-tolyl3pentene-(3) ~ 0.5 '- -,~-(o-tolyl)pentene-(4) ' ~- 2.1 Conversion of 5-(o-tolyl)pentene-(2) to other components (%) ~ 7.5 Total yield of 5-(o-tolyl~pe~tene-(1) and ~-(o-tolyl)pentene-(2) (%) Based on 1,3-butadiene fed - , 72, Based on o-xylene fed ' ?5 , - , iControl 3 ~ ' ' ~ he alkenylation rea~,tion was carried out under exactly the same conditions as in Example 1. The alkenylation reaction liquid overflowing from the fifth tank was continuously fed to , . . .
` ' a stirrer-equipped reaetion tank of 20-liter inside c~pacity.
On the other h~nd, isopropyl alcohol was fed to this tank at a : ~, 22_ .

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lOa~95 170 rate of 150 grams per hour 9 and the metallic sodium, mctallic potassium, and organo-sodium and potassium compounds were reac-ted with the isopropyl alcohol. ~he so obtained liquid was distilled by the same distillation procedures as used in ~xample 1 to separate same into o-xylene and isopropyl alcohol, 5-(o-tolyl)pentenes and reaction by-products. The o-xylene And isopropyl alcohol fraction was then continuously fed to a dis-tillation column of 4-inch diameter packea to a height of 4 meters with Raschig rings to separate the fraction-into o-xylene and isopropyl alcohoi. ~he disti~lation column was operated at normal atomospheric pressure and a reflux ratio of 3O0, and the o-xylene fraction obtained from tha column bottom was recycled to the alken~lation re~ction step and reused. ~he concentratiDn of isopropyl alcohol in the recycled o-xylene was below the identification limit (0.2 ppm). ~he operation was conducted in this manner for 7 days. ~he results obtained are sho~n in-~able .~

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3l(~495~70 ~able 3 k~nylation reaction Alkenyl~tion reaction yield of 5-(o-tolyl) pentene-(l) and 5-(o-tolyl)pentene-(2) based on 1 3-butadiene fed (/~ 76 Concentration of alkali metal ~toms in the alkenylation r~action product submitted to distillation Concentration of the metallic sodium and metallic potassium in the hydrocarbon Iiquid phase i :.
(mg atoms/kg) ~ 0 .
Concentration of the organo-sodium and p`otassium :~
compounds in the hydroccæbon liquid phase .~t ,'. '~.
(m~ atoms/kg) 0 Distill~tion Recovery of o-xylene (/~ . 98.7 : Concentration of products (wt. /) . : . i`r. -5-(o-tolyl~pentene-(1) ~ . 8.7 ~-5-(o-tolyl~pentene-(2~ 88.0 ~ .
- S-(o-tolyl)pen-tene-(3) ~ - 0j8 5-(o-tolyl)pentene-(4~ 2.5 .~ Conversion of 5-(o-tolyl)pentene-(2)~to other ~ components () ` -~5.5 -~ .
; Total ~ield of 5-(o-tolyl)pen$ene~
: ~nd 5-(o-tolyl)pentene (2) ~%? ~-Based on 1 3-butadiene fed 71 :~
Based on o-xylene fed ~ ~ 68 J-i i ' ,; . , ' ' ' ' ' , ~.~ ':
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Claims (4)

WE CLAIM:

1. In the method wherein an alkenylation reaction product liquid obtained by the alkenylation reaction of an alkylbenzene and a C4 - C5 conjugated diene in the presence of alkali metal catalysts and containing unreacted alkylbenzene, alkali metal catalysts and organo-alkalimetal compounds is conveyed to a dis-tillation zone at which said alkenylation reaction product liquid is separated by distillation to recover an alkenylbenzene-con-taining fraction and an unreacted alkylbenzene-containing frac-tion, the improvement which comprises adjusting the total of the concentrations of said alkali metal catalysts and organo-alkali-metal compounds in said alkenylation reaction product liquid introduced to the distillation zone so as to be 0.09 - 15 milli-gram atoms per kilogram of said product liquid, calculated as alkalimetal atoms, and thereafter conducting the distillation of said product liquid under conditions of non-addition of alcohols.

2. The method of claim 1 wherein said total of the con-centrations of said alkalimetal catalysts and organo-alkalimetal compounds is, calculated as alkalimetal atoms, 0.12 - 8 milli-gram atoms per kilogram of said product liquid.

3. The method of claim 1 wherein the adjustment of the to-tal of the concentrations of said alkali metal catalysts and organo-alkalimetal compounds is carried out by conducting said alkenylation reaction product liquid to a catalyst separating zone and separating from said product liquid a phase consisting predominantly of the catalysts.

4. The method of claim 1 wherein said unreacted alkyl-benzene separated and recovered by distillation is recycled to said alkenylation reaction and reused.