CA1158258A

CA1158258A - Polymerizable monomer mixture

Info

Publication number: CA1158258A
Application number: CA000304224A
Authority: CA
Inventors: Lewis B. Young; Warren W. Kaeding
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1977-05-27
Filing date: 1978-05-26
Publication date: 1983-12-06
Also published as: BR7803375A; JPS53147031A; IT7823885A0; IT1096348B; NL7805686A; FR2392047A1; AR223816A1; FR2392047B1; DE2821589A1; JPS626528B2; BE867416A; AU3653678A; IN149596B; DD138201A5; AU522620B2; GB1592130A; MX149020A

Abstract

ABSTRACT OF THE DISCLOSURE
A mixture of isomeric methyl ethenyl benezenes having a particular distribution of isomers is useful for preparing polymers with advantageous properties. The isomeric mixture may be polymerized with other monomers to produce copolymers.

Description

2 ~ ~

POLYMERIZABLF MONOMFR MIXTURE

This invention relates to a polymerizable mixture of isomeric methylethenyl benzenes and to polymers of such mixtures.
Styrene has been used for a long period of time in the manufacture of polymers and polystyrene has attained a large market for many purposes. Alkylated styrenes such as alpha-methylstyrene have also been of interest for certain purposes.
The nuclear alkyl substituted styrenes have also been used in various applications. The monomer which has been prin-cipally used is known as vinyltoluene. This is a mixture whichconsists mainly of meta- and para-methyl styrenes (vinyl toluenes) produced by the catalytic dehydrogenation of a mixture of the corresponding m- and p-ethyltoluenes. The ethyltoluene mixture is itself obtained by the fractional distillation of a mixture of the o-, m~ and p-ethyltoluenes. The ratio of the m- and p-isomers in the monomer mixture is approximately 65:35 (m:p). A
convenient summary of the preparation and properties of the monomer mixture and of polymers produced ~rom it is given in "~tyrene: Its Polymers, Copolymers and Derivatives" Ed. R.~. Boundy, R.F. Boyer, ACS Monograph Series, 1952, Hafner Publishing Company, pages 1232 to 1245.
Vinyltoluene is produced by the dehydrogenation of ethyl-toluene. Since the ethyltoluene starting material itself comprises a mixture of isomers the vinyl toluene product will also comprise an isomer mixture and the isomeric constitution will approximate that of the original ethyltoluene. ~hus, if a different isomeric distribution is desired in the vinyltoluene, the isomer distri-bution of the ethyltoluene must be modified accordingly.
Processes for producing various mixtures of ethyltoluene isomers 30 are know. In these mixtures, the para isomer has generally been present in ~ 3L5~25~

an amount less than 40 weight percent with the meta isomer generally present in a major proportion, together with smaller amounts of the ortho isomer. U.S. Patent 2,763,702 (Amos et al), for examplet describes a mixture of ethyltoluene isomers resulting from ethylation of toluene with ethylene in the presence of a Friedel-Crafts catalyst, such as aluminum chloride, containing isomeric mn-ethyltoluenes in relative proportions of from 8 to 30 percent of the ortho isomer, 40 to 65 percent of the meta isomer and from 20 to 40 percent of the para isomer.
U.S. Patent 2,778,862 (Gorham et al) describes the ethylation of toluene in the presence of an aluminum chloride catalyst to yield an isomeric mixture in which the meta isomer predominates, the para isomer is present to a lesser degree and the ortho isomer is present in still smaller amount. A typical isomer mixture disclosed contains 10 to 20 weight percent of ortho-ethyltoluene, 25 to 30 weight percent oE para-ethyltoluene and 55 to ~0 weight percent of meta-ethylto:Luene. U.S. Patent 2,920,119 (Egbert et al~ refers to a conventional ethyltoluene isomer mixture obtained by ethylation of toluene in the presence of a Friedel-Crafts catalyst. This mixture has a meta isomer content of 72 per~ent, a para isomer content of 20 percent and an ortho isomer content of 8 percent. U.S. Patent

3,720,725 (Olechowski) discloses a product mixture containing about 45 percent of ortho-ethyltoluene, about 38 percent para-ethyltoluene and about 3 percent of meta-ethyltoluene. This mi~ture is obtained by alkylating an aromatic hydrocarbon in the presence of a catalyst comprising a molybdenum halide, an alkylaluminum dihalide and a proton donor.
The presence of substantial quantitites of the ortho isomer in the ethyltoluene is highly undesirable because, cn dehydrogenation, it tends to undergo ring closure with formation of indenes and indanes which adversely effect the ~c,-,~

2 5 ~

properties of resultant polymer produced from the resultant vinyl toluene. The indenes and indanes are difficult to separate - 2a -115~25~

from the vinyl toluene. It has therefore been necessary to remove the ortho isomer from the ethyltoluene ~y expensive distillation techniques prior to dehydrogenation.
It is evident that the availability of ethyltoluene in which the ortho isomer is either absent or present only in trace amount would eliminate the necessity for expensive prior removal of this isomer. Such products have not pre~iously been available but in our U.S. Patent No. 4,143,084, issued March 6~ 1979, and in the corresponding copending Canadian Application No. 304,223, filed May 26, 1978, we have described a process for preparing an ethyltoluene isomer mixture which consists almost entirely of the para isomex. The ortho isomer is either entirely absent or present in extremely small amounts.
Said U.S. Patent No. 4,143,084 and said Canadian application disclose an ethyltoluene isomer mixture comprising at least 90 wt. % of p-ethyltoluene, 1-10 wt. ~ of _-ethyltoluene, and 0Ø1 wt. ~ of o-ethyltoluene.
According to the present invention we provide a polymerizable mixture of isomers of met~yl ethenyl benzene which consists essentially of 1-methyl-2-ethenyl benzene, l-methyl-3-ethenyl benzene and 1-methyl-4-ethenyl benzene in which the isomeric distribution is as follows:
Range - Wt. percent Isomer Broad _eferred l-methyl-2-ethenyl benzene 0-0.1 0 - 0.05 l-methyl-3-ethenyl benzene less than 15 less than 10 l-methyl-4-ethenyl benzene at least 85 at least 90 This polymerizable mixture is the direct product of catalytic dehydrogenation of a mixture of ethyltoluene isomers which comprises at least 90 wt. ~ of p-ethyltoluene, 1-10 wt. % of m-ethyltoluene, and 0-0.1 wt. % of o-ethyltoluene.

~ ~825~

In preferred mixtures the l-methyl-4-ethenyl benzene comprises 97 to 99 weight percent (and preferably 98 to 99 weight percent), the 1-methyl-2-ethenyl benzene 0 to 0.1 weight percent (less than 0.05 weight percent) with the l-methyl-3-ethenyl benzene making up the balance of the ethenyl benzene content (preferably 1 to 3 weight percent).
~owever, the content of the l-methyl-4-ethenyl benzene may be allowed to be as low as 95% without serious effects on the resultant polymers.

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The isoner mixture may contai~ ~mpurities and ad~entitious materials in addition to the methyl ethenyl benzenes. Generally, these other materials will not constitute re than 1 percent by ~relght o~ the total mixture. Ihese other ~ater~?~s derive essen~ially from ~e process used to make ~he meth~l ethenyl benzenes.
A typical isomer mLxture has the following analysis, by weight, determdned by gas chromatography:

. ~_rcent Tbtal ethengl benæenes 99.41 Residue:
Ethyl toluene 0.10 ~sitylenes etc. 0.15 - Non-vinyllc higher boilers ~
0.59 a.59 `
100 .00 ' `'~

E~h~n~l benzenes:-l-ne~hyl-2-ethenyl benzene 0.05 l~et~yI--3-ethe~yl benzene 2.6 1-methyl-4-ethenyl benz~ne 97.4 Ihe mixture o~ the isoneric methyl ethenyl ben2enes may be obtained by the catalytic dehydrogenatlon o~ a mix*uxe of the correspond~ng ethyl toluenes. The deh~droOenation is suitably carried out under the conditions conventionally used ~or the dehydrogen~tion of ethyl benzene to ~orm styrene. lhus, the dehydrcgenation will generally be carried out in the vapor phase at ele~ated temperatures in the presence of' a dehydroOenation catalyst. Ihe pressure may be at~ above or below atmospheric pressure.
Generzlly, for ease of operation~ atmospheric pressure is preferred but a non-reactive diluent may be present to reduce the partial pressure o~ the ~ ~5~258 ethyltoluene so that the dehydrogenation is effectively carried out under reduced pressure to obtain a favorable e~uilibrium. Water in the form of steam is a suitable diluent and will generally be present in a major proportion in the feed. Feed ratios from 1:1 to 5:1 are genrally preferred. Temperatures of 500 to 750C are generally used, preferably from 600 to 650C. Liquid hourly space velocities of about 1.2 (for ethyltoluene) are suitable and preferred. Conversion is usually about 60~ with selectivities of about 94% on the 1-methyl-4-ethenyl benzene isomer. Catalysts are the conventional dehydrogenation type, generally comprising complex oxide mixtures. ~ typical catalyst comprises ferric oxide, potassium carbonate, cerium oxide and molybdenum oxide as follows:

1~1t. percent Fe2O3 SS - 61 Ce2O3 4.6 - 5.6 (Ce) MOO2 2.2 - 2.8 The eth~l toluene starting material may be obtained by the process described in our co~pending Canadian Patent ~pplication ~o. 3~4,223, filed May 26, 1978. Upon dehydrogenation, the isomeric distribution of the ehtyl toluene carries through to the dehydrogenated product and therefore, a product high in the para isomer (1 methyl-4-ethenyl benzene) is obtained. The ortho isomer (l-methyl-2-ethenyl benzene) is either absent or present in only trace amounts.
me method disclosed in co-pending Canadian application ~ 3~4,223 essentially invDlves the alkylation of toluene with ethylene in the presence of oertain ~5--115825~
. `

crystalline aluminosil~cate zeolite catalysts. The catalyst has a silica:
alumina ratio of at least 12 and a constraint index within the range of 1 to 1~. The process produces an extremely high proportion of the limethyl-

4-ethyl benzene isomer, with o~ly a mdnor proportion o~ the 1-methyl-3-ethyl benzen`e i omer and negligible am~unts of the limethyl-2-ethyl benzene iso~er. r~he almDst complete absence af the l-~.ethyl-2~et~yl ison~r is highly ad~antageous because, as previously mentioned, this isomer tends to produce undesired by-prcducts during the dehydrogenation step ~indanes and i~d~nes which adversely ~f~ect the properties of the resultant poly~ers and which cannot be easily separated ~rcm the met~yl ethe~yl benzenes).
rDhe mixtuxe of isom~ric methyl et~yl ben2enes m2y be sub~ected to distillation prior to the dehydro~enation step in order to separa~e out various by-products and after the dehydrogenation has been completed, a flurther distilla~ion ~ay be ¢arrled out to separate the methyl ethenyl be~zenes ~rom their sa~urated precur~ors.
Since the prcportion o~ the l-~ethyl-4~ethenyl benzene in the mlx~ure is so hi~h, usually at le ~t 95 by weight, t~e mix~ure can be regarded essentially as the para ~1,4-) lsomer.
Ihe mdxture o~ the mathyl ethenyl benzene isomers may be polymerized by itself to produce polymers or with o~her copolymeriæable m~nomersto produce copolymers. In general, the polymer~zation conditions appropria~e to styrene will also be use~ul with the methyl ethengl ben2ene mixture, whether polymerlzed by i~self or with other monomers. qhus, polymerizatlon may be e~fected under bulk conditions or in solutio~, suspension or emulsion techniques comparable to those used ~or styrene polyme~lza~ion. 1he poly-merization catalysts may be of the ~ree r~dical, anionic or cationic types.
Sultable free radical initiators include di-tertia~y butyl peroxidé, azobis (isobutyronitrile), di-benzoyl peroxide, tertia~y butyl pe~benzoate, di cumyl 1 15~2~

peroxide and potassium persulfate. Cationic initiators are generally of the Lewis acid type, for example, al~num trichloride, boron trifluoride~ boron trifluoride etherate complexes, titanium tetrachloride and the like. Anionic initiators are generally of the organometallic type such as methyl lithium, ethyl lithium, methyl sodium, propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, butyl sodium, lithium naphthalene, phenyl lithium, phenyl sodium, benzyl lithium or cumyl sodium.
The polymers have useful and valuable properties which distinguish them from related materials such as polystyrene.
The following Examples are given to illustrate the in~ention. Example 1 describes a known procedure for producing the ethyl toluene precursor. ~his process produces only a small amount of the para isomer.
Example 1 To 100 ml. of toluene was added 1 gram of aluminum chloride and ethylene at a rate of 40 cc/minute ~t a temperature of 80C. After 2 hours, the composition was that shown in Table 1 below.

Table 1 Component Benzene 0.20 Toluene 71.90 Ethylbenzene 0.17 Xylene Para 0.15 Meta 0.06 ortho o Ethyl Toluene Para 6.43 Meta 14.37 Ortho 3.24 Higher 1.45 Other 1.99 The para/meta/ortho ethyltoluene ratio was 27/60/13.

~ -7-1 15~258 ExamDle 2 A 5.3 ~r~m sample of the hydrogen form o~ ZSM-5 having a crystalllte ~iæe o~ abou~ 2 micro~s was steamed a~ 515C. ~or a period of 2 hours and a feed ra~e of 8.8 cc of liquld wa~er per hour. Ihe temperature was then raised to 640~C. Toluene was then ~ed at a rate of 180 ml per hour ~or a period of 4 hours and 15 minutes~ The tempera~ure w2s then reduced to 550C., the catalyst flushed with nltrogen and then cooled to yield a cohe-cont ~ product.
AIkylat~on o~ toluene Toluene was aIkylated wlth ethylene in the pre~ence of the above catalyst. qhe.condl~ions o~ reactlon included a temperature of 300C.
a welght hourly space veloclty of 7.4, a molar feed ratio o~ toluene to ethylene of 5 and a st~eam time of one hour. qhe convers~on of toluRne obtai~ed was 4.1 wel$ht percent and of ethylene 24.1 weight percent. Ihe ethyltoluene .~soner ~ ture was found to conkain 93,15 weight percent o~ pa~a is~mer and 6.85 weight percent o~ the meta isomer~
~g~ ~
~he ethyl to~uene isomer mlx~ure was passed o~er a complex oxide zo dehydrogenation ca~alyst at a temperature o~ 620 - 640C and at atmospheric p~es~ure. Water was present as a d~luent in aswater:ethyl toluene weight ratio o~ 3:1~ qhe llquid hourly space velocity was 1.2. Convexsion ~s about 60% per pass and the selectivity 94% ~or the para~isomer.
Ihe catalyst us~d ~as~irdler ~-64-CI~ ch had the ~ollowing con~osition~
Wt. percent Ce20~ 4.6 - 5.5 MOO2 2.2 - 2.8 , ~r~ * Trademark A~_ , _ _ _ _ __ . _ .__ _ .___, ._ __ .__ _. . _. _.. ~ _, .__ _ ,_ _~._ . __ ._ _ .. _ _ _ .. . . .. . .... _ . ~ .. _ .. _ . . .

1 ~15~258 Dhe isomeric distribu~ion of the dehydrogenated product was the same as that ~or the ethyl toluene charge (93.15:6.85; para:meta;
ortho substanti~ly absent).

~
HZSM-5 having a cryst~llite size of 0.02 to 0.05 microns was mi~ed with 35 weight percent alumlna blnder and extruded to produce a 1.5 mm. cylln~rical particle. A ten gram sample of this extrudate was soaked overnight at room temperaturé in a solution of 8 grams of 85%
phosphoric acid in 10 ml of water. Ihe resulting product was filtered, - dried at 120C. for about 2 hours and calcined at 500C. for approxlmately an additional 2 hours. Ten gra~s of ~he phosphoxus impregnated extru~ate was then soaked at rocm temperature overnight in a solution of 25 ~rams o~ nagnesiun acetate tetrahydrate in 20 ml of water~ It was then filtered, dried at 120C. ~or about 2 hours and then placed in a ~ur~ace at 500CC.
~or approximately 2 hcurs. ~he resulting product contained 4.18 weight percent phosphorus and 7.41 weight percent m~gnesium.
~t~n ~ olo~
loluene was alkylated with ethylene ln the presence of the above catalyst. qhe conditions of reaction ar.d analytical results are summarized in qable 2 belo~.

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Dehydrogenation of ethyltoluene The ethyltoluene product was dehydrogenated using the conditions specified in ExamPle 2 following an initial distilla-tion step to remove any toluene starting material. The dehydro-genated product was also distilled to remove unreacted ethyltoluene.
The isomer distribution of the dehydrogenated producttortho, meta, para) was equivalent to that of the ethyltoluene ~
starting material in each case.
Example 4 Preparation of polymer from mixture of methyl-ethenyl benzene isomers.
The mixture of methyl ethenyl benzene isomers used had the following composition (weight percent):
Methyl ethenyl benzenes 99.43 ~thyltoluene 0.53 Xylenes, cumenes, mesitylenes 0.01 High boiling materials 0.03 Methyl ethenyl benzenes:
l-methyl-2-ethenyl benzene -(1) 1-methyl-3-ethenyl benzene 97.0 - 1 methyl-4-ethenyl benzene 3.0 Note: (1) Less than 0.05%
The mixture (120 g.) was dissolved in 46.75 g toluene and 0.168 g. azobis (isobutyronitrile) and poured into a dry ~ 25 bottle which was then closed by a coupling/ball valve assembly~
;~ Dry nitrogen was then bubbled through the mixture in the bottle for 10 minutes by means of a needle inserted through the septum and the open ball valve. The nitrogen exited through a short needle piercing the septum on top of the ball valve. The two needles were then removed, the ball valve closed and the bottle placed ,7,~",,r,~

- ~15~2~

in an oil bath at 60C for 96 hours and at Y0C for 24 hours.
The polymerized mixture was removed from the bottle by dissolving it in additional toluene at 90C. ~he volume of the final solution was about 400 ml. The polymer was then precipitated by pouring the solution into about 1000 1500 ml methanol in a 4 liter blender "(Waring Blendor)"*, adjusting the stirring speed to shred the polymer. The liquid was decanted and the polymer washed once with methanol in the blender. The solid polymer was filtered off and dried in a vacuum oven at 100C under vacuum for 48 hours.
The properties of the polymer were as follows:
Molecular wt (Mv-viscos. ~ve) 269 x 10 3 (Mn-number Ave) 158 x 10 3 TG, C 111 15 Vicat, C 119 Deflection temp. C Y8 Melt Index (Cond G~ 2.1 Density g/cc 1.008 Break strength, psi 6065 20 Elongation, % 3 Tensile Modulus:
Rheovibron, psi x 10 3 331 Instron, psi x 10 3 338 Impact strength, ft/lb-in 0.20 25 Haze 4.4 Transmittance, % 8Y.7 Pentane uptake 41.0 * Trademark I .......... , .. . . .... ., . .. . . ., ... ,,.. ~. ~ .

: 115~25~

, Exa~ples 4A, 4B~ 4C
Polymers prepared in th~ sa~e way as in Example 4 ~rom similar m~no~er mix~ures containing different proportions of the p-isomer (l-methyl-4-etheny1 be~zene) had the following properties:

Example lA lB lC
p isomer content, % 89.3 95.5 99.7 M~lec~llar wt (Mv x 10 3) 2n 278 269 (Mn x 10-3) - 168 177 TG, C 106 llO 113 ~cat, C . 108 114 I18 Deflectlon temp. C 93 108 104 ~ ~elt Index, (Cond G) 3.0 2.4 2 3 : Density g/cc 1.014 1.011 1.008 Break streng~h, psi 6010 5330 5170 Elong~tion, % 1.4 8 3 Tbn~lle Modulu$
Rheov1br2n, p~i x 10 3 363 325 355 Ins~ron, psi x 10 3 30g 301 332 pact Strenæth, ft/lb~in 0.28 0.13 0.21 Haze 5.0 4.2 5.2 Transmi~tance, % 88.3 88.7 88.7 : Pentane uptake 40.0 40.0 40.0

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A polymerizable mixture of isomers of methyl ethyl benzene, consisting essentially of 1-methyl-3-ethenyl benzene, 1-methyl-4-ethenyl benzene and 1-methyl-2-ethenyl benzene, said isomers being present in the mixture in the following proportions by weight:
1-methyl-2-ethenyl benzene 0 to 0.1%
1-methyl-3-ethenyl benzene 1 to 10%
l-methyl-4-ethenyl benzene 90 to 99%
said polymerizable mixture being the direct product of catalytic dehydrogenation of a mixture of ethyltoluene isomers which comprises at least 90 wt. % of p-ethyltoluene, 1-10 wt. %
of methyltoluene, and 0-0.1 wt. % of o-ethyltoluene.

2. The mixture of claim 1 in which the isomers are present in the mixture in the following proportions by weight:
1-methyl-2-ethenyl benzene 0 to 0.05%
1-methyl-3-ethenyl benzene 1 to 5%
1-methyl-4 ethenyl benzene 95% to 99%

3. The mixture of claim 2 in which the isomers are present in the following proportions by weight:
1-methyl-2-ethenyl benzene 0 to 0.05%
1-methyl-3-ethenyl benzene 1 to 3%
1-methyl-4-ethenyl benzene 97% to 99%.