DD245193B1 - PROCESS FOR ISOMERIZING 2,4,4-TRIMETHYL-PENT-2-EN - Google Patents

Description

Field of application of the invention

The invention relates to a process гиг isomerization of 2,4,4-Tnmethylpent-2-ene, which is used for alkene reactions in organic synthesis, ζ B for alkenylation of maleic anhydride as a precursor for surfactants

Characteristic of the known technical solutions

It is possible to isomerize alkenes with the aid of catalysts. It is possible to shift the terminal double bond in the 2-position and, conversely, the internal double bond in the 1-position to the setting of the ultimate modynamic equilibrium

Suitable catalysts for the isomerization of alk-1-enes to alk-2-enes are noble metals and compounds (US Pat. No. 3,409,702, 3,752,864, SU Pat. No. 5,238,888, DE-OS 2,729,218), cobalt compounds (US Pat. No. 3,542,896) Zeolites (US Pat. DE-OS 2057813, US-PS 757 507) aluminum-silicon oxide, tungsten and other metal oxides with silicon dioxide (EP-PS 0066485, DD-PS 209801, US-PS 3660516) aluminum alcoholate (US-PS 3240838) and acidic compounds, such as boron phosphate (DE-OS 1935504) and acidic cation exchangers (SU-PS 455083, 644767, DE-OS 3022821) described.

Partly similar catalysts are used for the isomerization of alkenes with internal double bond to alkenes with terminal double bond

DE-OS 3323022 uses for the isomerization of but-2-ene to 1-butene as catalyst a zeolite of the pentasil type, DE-OS 3319171 aluminum (y-alumina), silicon and other metal oxides, US-PS 2921103 chromium Aluminum oxide, DE-AS 1 593292 tungsten oxide on an acidic support, such as silica, US Patent 3527833 a magnesium-chromium-iron oxide defined composition, US-PS 3527834 a zinc-chromium-iron oxide of certain composition and DE-OS 3323021 acidic metal phosphates of alkaline earths , Manganese, iron, chrome, aluminum

Most of the catalysts mentioned become active only at higher temperature. Simultaneously with the isomerization, however, an oligomerization occurs which is accelerated by increasing the temperature. The use of diluents is said to limit the formation of by-products. US Pat. No. 2,921,103 uses steam for this purpose and SU-PS 644767 describes organic solvents. such as ethyl alcohol, tert-amyl alcohol, tert-butanol, tert-butyl methyl ether and acetone

It is known that strongly acidic cation exchange resins in the H ⁺ form, which are used for the oligomization of alkenes, can simultaneously shift terminal double bonds as well (Hydrocarbon Processing 52 [4] 171 [1973J) DE-OS 3022821 used for the isomerization of alkanols). 1-enen having at least 4 carbon atoms to alk-2-enes a nachsulfatisiertes, strongly acidic cation exchange resin based on divinylbenzene crosslinked polystyrene or phenol-formaldehyde resin having a water content of 5 to 60% of its total weight The alkene used is a water content in the range of 0 up to 95% of the water saturation concentration Under these conditions, 2,4,4-t-methylpent-1-ene should also be isomerized to 2,4,4-t-methylpent-2-ene until the equilibrium of the equilibrium is reached

SU-PS 455083 describes a process for the isomerization of specifically 2-methylbutene with a gel-form styrene-divinylbenzene copolymer having sulfo groups crosslinked with thermoplastic material (polypropylene or polyethylene). The balance of 2-methylbut-1-ene 2-Methylbut-2-ene is adjusted under pressure at 70-80 ⁰ C the reaction is coupled with a distillation, so that in the bottom 2-methylbut-2-ene and at the top of the column 2-methylbut-1 -en star equilibrium can be withdrawn

This gel-like styrene-divinylbenzene copolymer is only surface-active and has less accessible active sites, resulting in lower activity.

British Pat. No. 1,475,191 describes the preparation of 2,3-dimethylbut-2-enes specifically from 2,3-dimethylbumines in the presence of a macroporous styrene-divinylbenzene copolymer having sulfo groups, it being understood that various catalysts have 2,3-dimethylbenzenesulfonates -Dimethylbut-2-en can cause different side reactions such as polymerization and structural changes

Object of the invention

The aim of the invention is a process for the preparation of 2,4,4-Tn methyl-pent-1-ene from secondary raw materials

Explanation of the essence of the invention

The object of the invention is to provide a technically simple durchfuhrbares process for the isomerization of 2,4,4-trimethylpent-2-ene to 2,4,4-TnmethylpenM-enzu, in which the target product is produced in high yield and largely suppresses by-product formation becomes

The task loosening process for the isomerization of 2,4,4-Tnmethylpent-2-ene in the presence of a catalyst is then that 2,4,4-Tnmethylpenten at 10 to 100 ⁰ C for 1 to 10 hours with 2-10% anhydrous, macroporous, strongly acidic cation exchanger based on styrene-divinylbenzene copolymer with sulfo groups, based on the 2,4,4-Tnmethylpenten used, brings into contact

With the process according to the invention it is possible to isomerise both technical isomer mixtures with enriched 2,4,4-trimethylpent-2-ene content and pure 2,4,4-trimethylpent-2-ene. Depending on the selected conditions, the isomerization may vary in quantity By-products arise, the majority of which are dimerized 2,4,4-Tnmethylpentene

The reaction rate, the degree of isomerization and the by-product formation are dependent on time, temperature, amount of catalyst and the drying of the catalyst. It is advantageous to choose the reaction temperature as low as possible and the time as short as possible, because temperature increase and time extension lead to the dimerization of 2,4, 4-methylpentene and for the Formation of Other Oligomeric By-Products For reasons of simple process engineering and to suppress these side reactions, the reaction is preferably carried out at room temperature in the range from 20 to 30 ^° C. If a catalyst amount of 10%, based on the starting material, is used , the isomerization is practically completed after 4-8 hours. A mixture of 72 to 82% of 2,4,4-t-methylpent-1-ene and 18 to 28% of 2,4,4-t-methylpent-2-ene is obtained. If the reaction time is increased, the proportion of by-products by oligomerization increases the amount of catalyst again requires an increase in the reaction temperature and / or an extension of the reaction time. In the batchwise procedure, 2,4,4-t-methylpentene is stirred with the catalyst and then separated by filtration. A continuous process can also be easily operated. It is important to ensure that the macroporous, strongly acidic cation exchanger based on styrene-divinylbenzene copolymer with sulfone groups used according to the invention is anhydrous

This cation exchanger is hygroscopic and must be dried before use and optionally kept under a vacuum of moisture. The drying can be either azeotropic with dichloromethane or benzene or by drying at 105 ⁰ C to constant weight in about 20 hours carried out after the isomerization catalyst is instant can be used again if the filtration was carried out with the exclusion of atmospheric moisture. Otherwise, drying is required before reuse. The process according to the invention allows the 2,4,4-t-methylpent-1-ene to be enriched in the isomer mixture up to about 80% without The process can be coupled with organic syntheses which use 2,4,4-trimethylpent-1-ene as the starting component. If, for example, is used for the alkenylation of maleic anhydride with 2,4,4-t-methylpent-1 the commercial mixture of isomers in excess, enriches itself in the recovered alkene mixture 2,4,4-Tnmethyl-pent-2-en, so that a complete utilization of the alkene used and a circulation mode are not possible. The particular advantage of the inventive method is that such otherwise discarded as a waste Isomerengemische enriched with 2,4,4-Tnmethylpent-2-ene content is isomerized in a separate process almost until the setting of the thermodynamic equilibrium. Under the conditions according to the invention, side reactions are suppressed to such an extent that the resulting mixture can be reused for alkenylation without purification

Among other possible applications, it is possible to convert a waste product into a valuable raw material with the inventive method.

Exemplary embodiments example 1

In a sulphonation with Ruhrer, internal thermometer and Kuhler 10 g of a dried by azeotropic distillation with benzene macroporous, strong acid cation exchanger based on a sulfo-containing styrene-divinylbenzene Copolymensats and 100ml of a mixture of 2,4,4-trimethylpent-1-ene and - The mixture is stirred at 25 ° C. for 8 hours. The results are summarized in Table 1. (TMP 2,4,4-t-methylpentene)

Table 1 Reaction time [h] TMP-1-ene / -2 s 0 1.30 2 2.73 4 2.79 8th 3.01

TMP dimers [%]

Example 2

In Example 2, the same experimental conditions as in Example 1 are chosen. As a water tractor for the azeotropic drying of the catalyst dichloromethane is used. Results in Table 2.

Table 2 Reaction time [h] TMP-1-ene / -2 s 0 1.30 2 1.91 4 2.52 8th 3.03

TMP dimers [%]

0.5 0.91.1

Example 3

In Example 3, the same experimental conditions as in Example 1 are chosen. The catalyst is dried for 24 hours at 105 ° C in a heating cabinet. The result of the experiment is found (Table 3):

Table 3 Reaction time [hl TMP-1-ene / -2 s 0 1.30 2 2.96 4 3.19 8th 4.39

TMP dimers [%]

<1

Example 4

In Example 4, the same experimental conditions as in Example 3 are chosen. The amount of catalyst used is reduced to 5 g. The reaction time is extended to 48 hours. Results in Table 4.

Table 4 Reaction time [h] TMP-1-ene / -2 s 0 1.24 4 1.42 8th 1.81 24 2.36 32 3.22 48 3.84

TMP dimers [%]

<0.5 <0.5 <0.5

Example 5

In Example 5, the same experimental conditions as in Example 4 are chosen. The reaction temperature is 50 ⁰ C and the reaction time 8 hours. The results are summarized in Table 5.

Table 5 Reaction time [h] TMP-1-ene / -2 s 0 1.24 0.5 2.42 1 3.15 2 3.86 4 4.19 6 4.86 8th 4.79

TMP dimers [%]

0.2 1.2 1.9 2.6

Example 6

In Example 6, the same experimental conditions as in Example 4 are chosen. The reaction temperature amounts to 95 ⁰ C. Results in Table 6 below.

TMP dimers [%]

12.8 18.4 26.0 40.1 44.4 47.1

Example 7

In Example 7, the same experimental conditions as in Example 3 are chosen. However, pure 2,4,4-trimethylpent-2-ene is used. After 8 stems, the ratio of TMP-1-en / -2-en4.01, the TMP dimer content is <1.

Table 6 Reaction time [h] TMP-1-ene / -2 s 0 1.24 0.5 3.46 1 4.68 2 4.22 4 5.28 6 9.94 8th 8.08

Example 8

In Example 8, the same experimental conditions as in Example 4 are chosen. The amount of catalyst used is reduced to 2 g. Results in Table 7.

Example 7

TMP dimers [%]

Reaction time [h] TMP-1-ene / -2 s 0 1.24 4 1.26 8th 1.32 24 1.42 32 1.47 48 1.70

<0.5

Comparative Example 1 according to GB-PS 1475191

10 g mak-roporoses, sulfonated styrene-divinylbenzene copolymer are dried at 105 ⁰ C to constant weight. After cooling, the catalyst is added to 100 ml of 94% 2,4,4-trimethylpent-1-ene and stirred at 27 ° C. After 1,2,4 and 10 hours, samples are taken. The concentration of 2,4,4-trimethylpent-1-ene remains unchanged.

Comparative Example 2 according to GB-PS 1 457191

100 ml of 94% pure 2,4,4-trimethylpent-1-ene are stirred with 10 g of undried, macroporous, sulfo-containing styrene-divinylbenzene copolymer at 27 ° C. The samples taken after 1, 2, 4 and 10 hours did not differ in their composition from the 2,4,4-trimethylpent-1-ene employed.

Claims (3)

1. A process for the isomerization of 2,4,4-Tnmethylpent-2-ene in the presence of a macroporous strongly acidic cation exchange resin based on styrene-divinylbenzene copolymers with sulfo groups, at temperatures of 10-100 ° C, characterized in that , 4,4-Tnmethylpent-2-ene 1-10 hours with 2-10% anhydrous cation exchanger, based on the 2,4,4-Tnmethylpenten used in contact. 2. A process for the isomerization of 2,4,4-Tnmethylpent-2-ene to item 1, characterized in that for the isomerization as 2,4,4-Tnmethylpenten pure 2,4,4-Tnmethylpent-2-ene or a Isomer mixture with enriched 2,4,4-Tnmethylpent-2-en-content used. 3. A process for the isomerization of 2,4,4-Tnmethylpent-2-ene according to item 1, characterized in that a suspension of an isomer mixture enriched with 2,4,4-Tnmethylpent-2-ene content and 10 % of anhydrous cation exchanger for 4 to 8 hours and then separating the catalyst.