DE2821589A1 - POLYMERIZABLE METHYLAETHENYLBENZENE ISOMER MIXTURE - Google Patents

Description

The invention relates to a polymerizable Methylethenylbenzene isomer mixture, which is particularly advantageous suitable for the production of polymers.

Styrene has long been used in the manufacture of polymers; polystyrene has been used in the art many uses. Alkylated styrenes, e.g. alpha-methylstyrene, are also of technical importance.

The ring-alkyl-substituted styrenes have also been used for various purposes. The monomer, which is generally used is known as vinyl toluene. It is a mixture that mainly consists of meta- and para-methylstyrenes (vinyl toluenes) by catalytic dehydrogenation of a mixture of the corresponding m- and p-ethyltoluenes. The ethyl toluene mixture is through obtained fractional distillation of a mixture of o-, m- and p-ethyltoluenes. The ratio of the m and p isomers in the monomer mixture is about 65:35 (m: p). One suitable compilation with regard to the production and properties of the monomer mixture and the polymers produced therefrom in "Styrene: Its Polymers, Copolymers and Derivatives", Ed. R.H.Boundy, R.F.Boyer, ACS Monograph Series, 1952, Hafner Publishing Company, pages 1232-1245.

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Vinyltoluene is made by dehydrating ethyltoluene. Since ethyltoluene as a starting material is a mixture of isomers contains, the vinyltoluene product also consists of a mixture of isomers; the isomer constitution corresponds about that of the original ethyltoluene. So if there is a different isomer distribution in vinyl toluene the isomer distribution of ethyltoluene is / must be modified accordingly.

Processes for the preparation of various ethyltoluene isomer mixtures are known. In these mixtures the para-isomer is generally present in an amount of less than 40% by weight; the meta isomer is generally present in a major proportion along with minor amounts of the ortho isomer. For example, US Pat. No. 2,763,702 describes a mixture of ethyltoluene isomers from the ethylation of toluene with ethylene in the presence of a Friedel-Crafts catalyst such as aluminum chloride, the isomeric monoethyltoluenes in relative proportions of 8 to 3o% of the ortho isomer , 40 to 65% of the meta isomer and 2o to 40% of the para isomer are present. US Pat. No. 2,773,862 describes the ethylation of toluene in the presence of an aluminum chloride catalyst, resulting in an isomer mixture in which the meta isomer predominates, the para isomer to a lesser extent and the ortho isomer in an even smaller amount . A typical mixture of isomers described in this way contains 10 to 20% by weight of ortho-ethyltoluene, 25 to 3o% by weight of para-ethyltoluene and 55 to 60% by weight of meta-ethyltoluene. U.S. Patent No. 2,921,119 relates to a conventional one

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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%, a para isomer content of 20% and an ortho isomer content of 8%. Furthermore, US Pat. No. 3,720,725 describes a product mixture with a content of about 45% ortho-ethyltoluene, about 38% para-ethyltoluene and about 3% meta-ethyltoluene. This mixture is obtained by alkylating an aromatic hydrocarbon in the presence of a catalyst which is a molybdenum halide, comprises an alkyl aluminum dihalide and a proton donor.

The presence of substantial amounts of the ortho isomer in ethyl toluene is highly undesirable because the dehydrogenation has a tendency to ring closure with the formation of indenes and Indanes, which have the properties of the resulting polymer made from the corresponding vinyl toluene, adversely affect. The indenes and indanes are difficult to separate from vinyl toluene. It was therefore necessary that To remove ortho isomers from ethyl toluene by complex distillation techniques before dehydrogenation.

It can therefore be seen that the availability of ethyltoluene, in which the ortho isomer is either absent or only in Trace amounts are present, eliminating the need for laborious prior removal of this isomer. Such products however, have not yet been available; however, a concurrent patent application describes a method for

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Production of an ethyltoluene isomer mixture which consists almost entirely of the para isomer. The ortho isomer is either not contained or is only available in extremely small quantities.

According to the invention, a mixture of methylathenylbenzene and isocyanates is used created / which consists essentially of 1-methyl-2-ethenylbenzene, 1-methyl-3-ethenylbenzene and 1-methyl-4-ethenylbenzene where the isomer distribution is as follows:

Range (wt%)

Isomers broadly preferred

1-methyl-2-ethhenylbenzene ο - o, 1 ο - o _r o5

1-methyl-3-ethenylbenzene less than 15 less than 1-methyl-4-ethenylbenzene at least 85 at least 9o

In preferred mixtures this is 1-methyl-4-ethenylbenzene 97 to 99% by weight (preferably 98 to 99% by weight), the 1-methyl-2-ethenylbenzene o to 0.1% by weight (preferably less than 0.05% by weight) and the 1-methyl-3-ethenylbenzene the remainder of the ethenylbenzene content (preferably 1 to 3% by weight). However, the content of 1-methyl-4-ethhenylbenzene can be as low as 95% lie without any disadvantages for a polymer produced therefrom.

The mixture of isomers can contain impurities and by-products in addition to the methylethenylbenzenes. In general these other materials are no more than 1% by weight of the

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Total mixture. These other materials are essentially the result of the manufacturing process used of methylathenylbenzenes.

A typical mixture of isomers corresponds to the following analysis (% by weight, determined by gas chromatography):

Wt%

Total Ethenylbenzenes Ethyl toluene o, 1o 99.41 Rest: Mesitylene etc. o, 15 non-vinyl type,
higher boiling
Products o, 34 o, 59 o, 59 100.00

Ethenylbenzenes:

1-methy1-2-ethenylbenzene o, o5 1-methyl-3-ethenylbenzene 2,6

1-methy1-4-ethenylbenzene 97.4

The mixture of isomeric Methyläthenylbenzenes can by catalytic dehydrogenation of a mixture of the corresponding Ethyltoluenes are obtained. The dehydration becomes more suitable Way carried out under conditions commonly used for the dehydrogenation of ethylbenzene to form styrene will. The dehydrogenation is generally carried out in the vapor phase at elevated temperatures in the presence of a dehydrogenation

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catalyst carried out. The pressure can be at atmospheric pressure, be above or below. In general, atmospheric pressure is preferred for ease of operation. However a non-reactive diluent may also be present to reduce the partial pressure of ethyltoluene so that the Dehydration is effectively carried out under reduced pressure to achieve a favorable equilibrium. water in the form of steam is a suitable diluent; it is generally contained in a larger proportion in the feed material. Feed ratios of 1: 1 to 5: 1 are generally preferred. Temperatures of 50 ° to 75 ° C. are common used, preferably 600 to 65o C. Hourly room air velocities the liquid of about 1.2 (for ethyl toluene) are suitable and preferred. The conversion is usually about 60% with selectivities of about 94% for the 1-methyl-4 = -ethenylbenzene isomer. Catalysts are the customary dehydrogenation catalysts, generally containing complex oxide mixtures. A typical catalyst contains ferric oxide, potassium carbonate, cerium oxide and molybdenum oxide as shown below:

Wt%

Fe ₂ O ₃ 55-61

K ₂ CO ₃ 21-25

Ce ₃ O ₃ 4.6-5.6 (Ce)

MoO _{2 2.2-2.8}

The starting material ethyltoluene can be obtained in accordance with the aforementioned parallel patent application. In the

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Dehydrogenation takes the isomer distribution of ethyltoluene through the dehydrogenated product. Hence becomes a product obtained, which is rich in para isomers (1-methyl-4-ethenylbenzene). The ortho isomer (1-methyl-2-ethenylbenzene) is either absent or only present in trace amounts.

The said parallel patent application relates essentially to the alkylation of toluene with ethylene in the presence of certain crystalline AluminosJLicat zeolite catalysts. The catalyst has a silica / alumina ratio of at least 12 and a constraint index within the range of 1 to 12. In this way, a extremely high proportion of the 1-methyl-4-ethylbenzene isomer with only small proportions of 1-methyl-3-ethylbenzene isomers and insignificant proportions of i-methyl-2-ethylbenzene isomers generated. The almost complete absence of the 1-methyl-2-ethyl isomer is extremely advantageous, as see above - this isomer tends to form undesirable by-products during the dehydrogenation stage (indane and Indenes, which adversely affect the properties of the polymer to be produced, and those from methylethenylbenzenes cannot be easily separated).

The mixture of isomeric Methyläthylbenzenes can be subjected to a distillation before the dehydrogenation, so that the various by-products are separated; after the end of the dehydrogenation, a further distillation can be carried out, thus the Methyläthenylbenzenes from the saturated precursors

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- 1ο -

be separated.

Since the proportion of 1-methyl-4-ethenylbenzene in the mixture is so is high, usually at least 95% by weight, the mixture can be viewed as being essentially the para (1,4) isomer.

The mixture of methylethenylbenzene isomers can be polymerized as such, with polymers being produced, or it can be polymerized together with other copolymerizable monomers to form copolymers. In general, the polymerization conditions that are suitable for styrene also apply to the methylethenylbenzene mixture to be used, i.e. both for the polymerization of this mixture as such and for the polymerization together with other monomers. Thus, the polymerization can be carried out in bulk or in solution, suspension or emulsion according to the techniques are carried out, which are suitable for styrene polymerization. The polymerization catalysts can be free radical catalysts, be anionic or cationic catalysts. Suitable free radical initiators are, for example, ditertiary ones Butyl peroxide, azobis isobutyronitrile, dibenzoyl peroxide, tertiary butyl perbenzoate, dicumyl peroxide and potassium persulfate. Cationic initiators are generally those of the Lewis acid type, for example aluminum trichloride, boron trifluoride, Boron trifluoride etherate complexes, titanium tetrachloride, etc. Anionic Initiators are generally organometallic compounds, e.g. methyl lithium, ethyl lithium, methyl sodium, propyl lithium, n-butyllithium, sec-butyllithium, tert-butyllithium, butyl-

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sodium, lithium naphthalene, phenyllithium, sodium lithium or cumyl sodium.

The polymers produced in this way have very useful and valuable properties in contrast to related materials, such as polystyrene.

The invention is illustrated in more detail below with the aid of a few examples. Example 1 explains a known process for the preparation of the ethyltoluene precursor. Only a small amount of the para isomer is produced by this process.

example 1

To 100 ml of toluene, 1 g of aluminum chloride and ethylene at a rate of 40 cm / min was added at a temperature of 80 ⁰ C. After 2 hours the composition was as shown in Table I:

Table I. Weight percent component 0.20 benzene 71.90 toluene 0.17 Ethylbenzene Xylene 0.15 P. 0.06 m 0.04 O Ethyl toluene 6.43 P. 14.37 m 3.24 O 1.45 higher 1.99 other

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The p / m / o ethyltoluene ratio was 27/60/13.

Example 2 Catalyst Preparation

A 5.3 g sample of the hydrogen form of ZSM-5 having a crystallite size of about 2 μπι was steam treated at 515 ⁰ C for 2 h and at a feed rate of 8.8 cm of liquid water per hour. The temperature was then raised to 640 ⁰ C. Toluene was then fed at a rate of 180 ml / hour for about 4 hours and 15 minutes. The temperature was then lowered to 550 ⁰ C, the catalyst is flushed with nitrogen and then cooled to afford a kokshaltiges product.

Toluene alkylation

Toluene was alkylated with ethylene in the presence of the above catalyst. The reaction conditions were a temperature of 300 ⁰ C, a weight hourly space moderate flow rate of 7.4, a molar feed ratio of toluene / ethylene of 5 and an operating time of 1 hour. The toluene conversion achieved was 4.1 percent by weight, that for ethylene was 24.1 percent by weight. It was found that the ethyltoluene isomer mixture contained 93.15 percent by weight of the p-isomer and 6.85 percent by weight of the m-isomer.

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Ethyltoluene dehydration

The ethyltoluene isomer mixture was via a complex Oxide dehydrogenation catalyst at a temperature of 62o ° to 64o ° C and atmospheric pressure. Water was used as a diluent in a water / ethyltoluene weight ratio of 3: present. The hourly space velocity of the Liquid was 1.2. The conversion was about 60% per pass; the selectivity for the para isomer was 94%.

It became a Girdler G-64-C catalyst with the following Composition used:

Wt%

Fe ₂ O ₃ 55-61

K ₂ CO ₃ 21-25

Ce ₂ O ₃ 4.6-5.6

MoO _{2 2.2-2.8}

The isomer distribution of the dehydrogenated product corresponded to that of the ethyl toluene feed (93.15: 6.85; para: meta; essentially without the ortho component).

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Example 3
Catalyst manufacture

HZSM-5 with a crystallite size of 0.02 to 0/05 μm was mixed with 35 percent by weight of aluminum oxide binder and extruded to give cylindrical particles of 1.5 mm. A 10 g sample of this extrudate was soaked overnight at room temperature in a solution of 8 g of 85% phosphoric acid in 10 ml of water. The product obtained was filtered, ^{dried at 120 °} C. for 2 hours and ^{calcined at 500 °} C. for about a further 2 hours. 10 g of the phosphorus-impregnated extrudate were soaked in a solution of 25 g of magnesium acetate tetrahydrate in 20 ml of water at room temperature overnight. It was then filtered, ^{dried at 120 °} C. for about 2 h and then placed in an oven at 500 ^° C. for about 2 h. The product obtained contained 4.18 percent by weight of phosphorus and 7.41 percent by weight of magnesium.

Toluene alkylation

Toluene was alkylated with ethylene in the presence of the above catalyst. The reaction conditions and the analysis results are summarized in Table II below.

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QO O CO 00

CD

cn OO - «a

1 2 Table II 4th 5 6th 7th approach 300 350 3 350 400 400 450 Temp., ⁰ C 7.4 7.4 350 3.9 3.9 3.9 3.9 w.stdl.RStr.spw. 3.9 Feed molar ratio 5.1 5.1 2.5 2.5 2.5 2.5 Toluene / ethylene 1 2 2.5 4th 5 6th 7th Operating time, h 2.4 7.1 3 9.2 8.0 20.1 13.2 Conversion) toluene 1/6 29.3 8.2 55.1 12.7 59.9 2.1 Wt .-%) ethylene 17.2 Ethyl toluene 100 100 98.6 98.04 98.96 98.84 P. - - 99.2 1.4 1.88 1.04 1.16 m - - 0.8 - 0.08 0.04 _ O -

Catalyst calcines between runs 3 and 4 and runs 5 and 6.

οι
t

ro oo ho

cn oo co

Ethyltoluene dehydration

The ethyl toluene product was prepared using the conditions of Example 2 following the original distillation step to remove any starting toluene material present dehydrated. The dehydrated product was also distilled / to remove unreacted ethyltoluene.

The isomer distribution of the dehydrated product (ortho, meta, para) corresponded in each case to that of the ethyltoluene starting material.

Example 4

Preparation of a polymer from the mixture of methylethenylbenzene isomers

The mixture of methylethenylbenzene isomers used had

the following composition (% by weight):

Methylethenylbenzene 99.43 Ethyl toluene o.53

Xylenes, cumene, mesitylene. o, o1 high-boiling materials o, o3

Methylethenylbenzenes:

1-Methy1-2-ethenylbenzene - (D

1-methyl-3-ethenylbenzene 97, ο
1-methyl-4-ethenylbenzene 3, ο

Note: (1) means less than 0.05%.

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The mixture (120 g) was dissolved in 46.75 g of toluene and 0.168 g Azobis-isobutyronitrile dissolved and poured into a dry jar that had a connecting ball valve assembly was locked. Dry nitrogen was then passed through the mixture in the vessel for 10 minutes with the aid of a needle passed through the vessel wall was inserted and the open ball valve initiated. The nitrogen flowed in through a short needle the wall on the upper part of the ball valve. The two needles were then removed; the ball valve was closed; the jar was placed in an oil bath at 60 ° C for 96 hours and at 90 ° C for 24 hours.

The polymerized mixture was removed from the jar and dissolved in more toluene at 90 ° C. The volume of the final Solution was about 400 ml. The polymer was then made by pouring the solution into about 100 to 1500 ml of methanol precipitated in a 4 liter mixing vessel (Waring Blendor), the agitation speed on the comminution of the polymer was discontinued. The liquid was decanted; the polymer was washed once with methanol in the mixing vessel. The solid polymer was filtered off and dried in a vacuum oven at 100 ° C. under vacuum for 48 hours.

The properties of the polymer were as follows:

Molecular weight (M -viscous average) 269 χ 1o

(M -No avg.) 158 χ 1o ~ ³ η

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111 1 119 oo 8 98 2, 1, 6o65 3 2o 331 4th 338 7th ο, ο 4, 89 41,

Vicat ( ⁰ C) dimensional stability ( ⁰ C) melt index (Cond G)

Density (g / cm ³ ) Breaking strength (psi) Elongation (%) Tensile modulus:

Rheovibron (psi χ 1o ~) Instron (psi χ Io)

Impact Strength (ft / lb-in) Opacity Permeability (%) Pentane absorption

Examples 4A, 4B and 4C

Polymers prepared in the same manner as in Example 4 of similar Monomer mixtures containing different proportions of the p-isomers (1-methyl-4-ethenylbenzene), had the following properties:

Example 1A 1B 1C

p-isomer content (%) 89.3 95.5 99.7

Molecular weight

(M _v χ 1o " ³ 271 278

(M _n χ 1o ~ ³ - 168

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T _G ( ⁰ C)

Vicat ( ⁰ C) Dimensional stability ( ⁰ C) Melt index (Cond G) Density (g / cm ³ ) Breaking strength (psi) Elongation (%) Tensile modulus:

Rheovibron (psi χ Ιο ") Instron (psi χ 1o ~)

Impact Strength (ft / lb-in) Opacity Permeability (%) Pentane absorption

1o6 Ho 4th 113 1o8 114 oil 118 93 I08 1o4 3, o 2, 2.3 1, o14 1, 1, oo8 60I0 533o 517o 1.4 8th 13th 3 363 325 2 355 3o9 3o1 7th 332 o, 28 0, 0 o, 21 5, o 4, 5.2 88.3 88 88.7 4o, o 4o, 4o, o

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Claims (4)

Dr. D.Thomsen PATE NTANWALTS OFFICE 0 Telephone (039) 530211 O D O 1 C O Q 01 530212 ZO Z ΙϋΟ3 W. Weinkauff τ ^ 2ϊΐ £ Ξ} Telex 524303 xpert d PATENTANWÄLTE Munich: Frankfurt / M .: Dr. rer. nat. D. Thomsen Dipl.-Ing. W. Weinkauff (Fuchshohl 71) Dresdner Bank AQ, Munich, Account 5574237 8000 Munich 2 Kalser-Ludwlg-Platz6 May 17, 1978 Mobil Oil Corporation New York, N.Y., U.S.A. Polymerisable methylene-benzene-isomer-based patent claims 1. Polymerizable methylethenylbenzene isomer mixture, consisting essentially of l-methyl-3-ethenylbenzene, at least 85% by weight of the mixture of 1-methyl-4-ethenylbenzene and ο bis 0.1% by weight of 1-methyl-2-ethenylbenzene. 2. Mixture according to claim 1, wherein the isomers are in the following Parts by weight are present: 809849/0687 ORIGINAL INSPECTED 1-methyl-2-ethenylbenzene ο to ο, 1% 1-methyl-3-ethenylbenzene 1 to 1o% i-methyl-4-ethenylbenzene 90 to 99%. 3. Mixture according to claim 2, wherein the isomers are present in the following proportions by weight: 1-methyl-2-ethhenylbenzene ο to o, o5% 1-methyl-3-ethenylbenzene 1 to 5% 1-methyl-4-ethhenylbenzene 95 to 99%. 4. Mixture according to claim 3, wherein the isomers are present in the following proportions by weight: 1-methyl-2-ethhenylbenzene ο to Ο, ο5% 1-methyl-3-ethenylbenzene 1 to 3% 1-methyl-4-ethenylbenzene 9 7 to 99%. 809849/0687