DE1254618B - Process for the catalytic production of hexenes, in particular methyl pentenes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C 07 c

German class: 12 ο -19/01

Number: 1 254 618

File number: E 21808 IV b / 12 ο

Filing date: October 14, 1961

Opening day: November 23, 1967

The invention relates to an improved process for the catalytic production of hexenes, in particular Methyl pentenes, from propylene.

Of the various hexene isomers, the methyl pentenes are particularly valuable. So is for example 2-methylpentene-2 is of value in isoprene production, and 4-methylpentene-1 is a valuable one Monomer.

It is already known to use propylene at higher pressures and temperatures with the aid of a catalyst to dimerize, either from finely divided sodium precipitated on activated carbon or consists of finely divided potassium, optionally precipitated onto potassium carbonate. However, these catalysts are difficult to manufacture because of their sensitivity to air and moisture, to store and handle and experience has shown that only after many hours of reaction time give acceptable yields of the desired dimer products, such as B. 4-methylpentene.

In contrast, the invention provides a process for the catalytic production of hexenes, in particular methyl pentenes, which has the disadvantages of the known, with elemental alkali metal as a catalyst, the process works freely and can also be carried out in this way is that it selectively allows particularly desirable products to be obtained.

The invention accordingly consists of a process for the catalytic production of hexenes, especially methyl pentenes, by dimerizing propylene with the aid of organometallic compounds as a catalyst, optionally in the presence of an inert solvent, its characteristics consists in carrying out the process at a temperature between about 40 and about 225.degree and at a pressure between normal pressure and about 150, preferably up to about 125 atmospheres, carried out in the presence of an organoalkali metal compound as a catalyst.

In this process, the propylene is dimerized such that the reaction product is a mixture of hexene isomers with predominantly methyl pentenes, which in a manner known per se separated from it and won.

The process according to the invention can in principle also be carried out in the absence of diluents for the reaction mixture. Preferably, however, the reaction is allowed to proceed in a neutral, practically anhydrous solvent. The diluents which are preferably suitable for this purpose are paraffinic and aromatic processes for the catalytic production of
Hexenes, especially methyl pentenes

Applicant:

Ethyl Corporation, New York, N.Y. (V. St. A.)

Representative:

Dr. phil. G. Henkel

and Dr. rer. nat. W, -D. Henkel, patent attorneys,

Munich 9, Eduard-Schmid-Str. 2

Named as inventor:

Rex Dewayne Closson, Northville, Mich .;

Waldo Buford Ligett, Pontiac, Mich .;

Alfred Jerome Kolka, Pittsburgh, Pa. (V. St. A.)

Claimed priority:

V. St. v. America October 21, 1960 (63 978)

Hydrocarbons that are liquid under the given reaction conditions. Particularly useful are paraffinic hydrocarbons such as hexane, heptane, octane, nonane, decane, undecane, dodecane, their branched chain isomers and their various mixtures, cycloparaffins, such as. B. Cyclopentane, Cyclohexane, cycloheptane, their ring alkylated derivatives and their various mixtures and non-alkylated aromatic hydrocarbons such as benzene. These hydrocarbons tend to take part in side reactions less easily than other diluents, which only lead to increased Propylene consumption and greater non-uniformity of the reaction mixture would lead.

The catalysts used according to the invention consist of organoalkali metal compounds which consist of an alkali metal atom and a hydrocarbon radical. To the alkali metals include lithium, sodium, potassium, rubidium, and cesium, with those with an atomic weight over 7 to be favoured. Useful catalysts are, for example, aromatic alkali metal compounds, such as B. phenyllithium, phenyl sodium, benzyl sodium, benzyl potassium, naphthyl potassium, alkyl alkali metal compounds, such as B. Ethyllithium, Butyllithium, Propyl Sodium, Ethyl Sodium, Amyl Sodium, Hexyl potassium, butyl cesium and alkenyl alkali metal compounds, such as butenyl sodium,

709 689/494

Propenyl sodium, sodium pentenyls, potassium hexenyls or potassium butenyls. The allyl alkali metal catalysts and in particular allyl sodium and allyl potassium are the most preferred Group. The alkali metal catalysts used according to the invention can according to known Process are produced.

Deposition and isolation of the hexenes formed according to the invention from the reaction product can in a manner known per se, for example by means of distillation processes, by means of chromatographic Methods, solvent extraction methods or other known methods with distillation and fractionation procedures generally being the most convenient. On> 5 In the same way, individual methylpentene isomers can be obtained from the isomer mixture product obtained according to the process isolate.

It has been found according to the invention that the organosodium catalysts are not only general effective dimerization catalysts, but also selective for certain methylpentene isomers to lead. If mainly 4-methylpentene-2 and 2-methylpentene-2 are to be produced, an organosodium catalyst is preferably used. On the other hand, when 4-methylpentene-1 is to be prepared and obtained as the main hexene isomer, it is expedient to use it an organopotassium catalyst. In general, the organopotassium, -rubidium- and cesium catalysts have higher hexene product yields than the other organoalkali metal catalysts.

The process according to the invention can be carried out in batch operation or semicontinuously or entirely continuously carry out. In large-scale operations, the process is preferably carried out continuously, which is what after Various processes can be done by using the propylene with or without a neutral carrier or Diluents in liquid or vapor form or as a liquid-vapor mixture mixed by a solid bed of either pure or neutral carrier material Catalyst can pass. The reaction product can be distilled in a continuous borrowed fractionation column are cleaned. Instead, the liquid or liquid-vapor reaction can be used can also be carried out in the presence of a suspended catalyst, which depends on the speed the liquid reaction components and products are dragged along. In the vapor phase conversion The technique of the liquefied catalyst bed can be used. This and other continuous modes of implementation of the invention can be either single throughput or work with circulation of reaction components and products. Both in the continuous as well as in batch operation, the reaction components can be mixed with neutral gases, e.g. B. Propane, ethane, methane, nitrogen, helium or neon.

How much catalyst is to be used depends somewhat on the way in which the process is carried out. So For example, somewhat smaller amounts of catalyst can be used at higher pressures, than is advantageous at lower pressures. In general, the amount of catalyst used should - based on the weight unit applied propylene - be about 0.01 to about 10%. Generally spoken, the propylene catalyst molar ratio is to achieve the maximum, Improvements characteristic of the invention between about 2: 1 and about 500: 1.

For reasons of particularly high economic efficiency, the preferred starting material is a propane-propylene gas mixture subjected to the dimerization process according to the invention, since gas mixtures of this type are largely used in petroleum refining To be available.

The method according to the invention is now to be illustrated even more clearly with the aid of the following examples will.

example 1
a) Preparation of the catalyst

^{A 500 cm 3} articulated flask equipped with a high-speed stirrer, dropping funnel, thermometer, condenser and nitrogen inlet and outlet was flushed through with a slow stream of nitrogen, at the same time dried in the flame and, after cooling, with 5.75 g (0.25 mol) Sodium metal and 150 ecm of dry toluene charged. The toluene was then heated to reflux temperature and the high speed stirring switched on. After a fine sodium dispersion had formed, the heating mantle was removed and stirring interrupted as soon as the toluene suspension had reached just 99 ^0C. The reaction mass was then allowed to cool to 35 ° C. and then about 10 drops totaling 14.1 g (0.125 mol) of chlorobenzene were added, as a result of which heat developed and a color change from gray to black occurred. The remaining chlorobenzene was then added within half an hour under a nitrogen atmosphere, a dry ice-acetone cooling was necessary to maintain the temperature of the reaction mixture between 35 and 40 ⁰ C. After the addition was complete, the reaction mixture was refluxed for 1 hour and solvent was distilled off in an amount of 35 ecm.

b) method of the invention

The dark brown reaction mass containing phenyl sodium was cooled and transferred under nitrogen to a 250 cm ³ pressure vessel which had previously been flushed with nitrogen. 32 g of liquid propylene were then introduced into the pressure vessel and the reaction mass was increased to 179 ^° C. (corresponding to 29.2 kg / cm ² pressure). A pressure drop was observed at this point, whereupon the temperature was held between 179 and 204 ^° C. for 2 hours. This gave a total pressure drop of 0.7 kg / cm ² at 3O ⁰ C. The reaction mixture was added ³ of ethanol and then hydrolyzed first with 25 cm to 250 cm ³ of water and the aqueous layer after separation of the organic layer once with 25 cm ³ of toluene extracted. The two organic layers were combined, dried over magnesium sulfate and fractionated by an approximately 1 m high coil-filled column, 5.8 cm ³ of a boiling from 53.8 to 75 ⁰ C fraction were separated from the primary mixed hexenes. This hexene fraction, which weighed 4.0 g, represented a yield of 12.5% based on the propylene introduced. Its splitting by means of vapor phase chromatography showed that

it consists of 2% 4-methyl-1-pentene, 18% 4-methyl-2-pentene, 16% 2-methyl-1-pentene and 65% 2-methyl-2-pentene duration.

Example 2
a) Preparation of the catalyst

To obtain amyl sodium, a 500 cm ³ three-necked kinked flask was used which was equipped with a thermometer, dropping funnel, reflux condenser, nitrogen inlet and high-speed stirrer and which had previously been flame-dried together with the equipment in a stream of nitrogen. The flask was charged with 125 cm ^{3 of} dry n-octane and 5.75 g (0.25 mol) of sodium metal and the solvent was heated to 125 ° C., ie the reflux temperature. The stirrer was now switched on and the heating mantle was removed after a few minutes of vigorous stirring. Once the temperature had dropped to 99 ° C, the stirrer was stopped and then turned back on slow speed after the temperature had dropped to 30 ⁰ C. At this point, were placed freshly distilled amyl chloride in the dropping funnel and it entered a few drops into the sodium suspension 15.25 cm ³ (0.125 mol). A Färb darkening showed onset of the reaction, and the Reaktiönsmischung was then cooled to -20 ⁰ C and kept at this temperature during the slow, requiring about 30 minutes, dropwise addition of the remaining Amylchlorids. The black slurry was then allowed to ^{warm to 0 °} C. and held at this temperature for 45 minutes.

b) method of the invention

The mixture was then transferred to a 250 cm ³ pressure vessel under nitrogen. The vessel was then closed, charged with 60 g (1.42 mol) of propylene and, after a slow initial decrease in the original pressure from 22.8 kg / cm ² to 7.0 kg / cm 2, slowly increased to 148 ^° C. (105 kg / ^{cm 2).} cm ² ) heated. At this point there was a sharp drop in pressure and the temperature increased to 164 ° C. within 5 minutes as a result of a strongly exothermic reaction. The reaction mixture was held at this temperature for 1 hour and then allowed to cool overnight. There was a pressure drop of 2.25 kg / cm ² at room temperature.

After venting and emptying the pressure vessel, the black reaction mixture formed was first mixed with alcohol and then with water hydrolyzed. The aqueous phase was separated from the organic phase and three times with n-octane extracted. The combined organic phases were dried over magnesium sulfate and thoroughly an approximately 1 m long spiral-filled column distilled, whereby the following five fractions were isolated:

1.3 cm ³ boiling range.

2. 1 cm ³ boiling range.

3. 3.9-cm ³ boiling range

4. 1 cm ³ boiling range.

5. 90 cm ³ boiling range.

38 to 39 ⁰ C

39 to 51 ⁰ C
53 to 7O ⁰ C.
70 to 124 ° C

124 to 126 ⁰ C

The analysis of these fractions by means of vapor phase chromatography gave the following results:

fraction Pents Ethanol 4-Me-1-pentene 4-Me-2-pentene 2-Me-1-pentene 2-Me-2-pentene n-octane ¹ Vo "/ (I ° / n % % % ¹ Vn 1 98 *) - - - 2 53 3.2, 21.5 22.1 0.1 0.1 - 3 17.2 9.1 12.3 30.4 7.0 23.0 - 4th - 50.0 5.1 5.1 14.7 10.1 - 5 - - - - - - 100

*) All values are mole percent.

Based on the propylene input, the yield of methyl pentenes was 2.42 g or 4.03%. the Isomer distribution was as follows:

1. 20.0% 4-methyl-1-pentene

2. 40.5% 4-methyl-2-pentene

3. 10.8% 2-methyl-1-pentene and

4. 29.0% 2-methyl-2-pentene

Example 3
a) Preparation of the catalyst

In a 1-1 flask equipped with a reflux condenser, thermometer, nitrogen inlet tube, dropping funnel and paddle stirrer were placed 500 cm ^{3 of} toluene and 34.5 g of sodium. The mixture was heated until the sodium melted and then subjected to high-speed agitation (about 10,000 rpm). The sodium dispersion formed in this way was cooled to room temperature and 67.5 g of chlorobenzene were added in dropwise portions. The reaction started almost immediately; the temperature increased to 40 ⁰ C and was then kept in an ice bath during the lstündigen duration of the reaction between sodium and the dom chlorobenzene piston by periodic cooling.

b) method of the invention

Subsequently, the phenyl sodium contents of the flask containing together with 200 cm ³ of toluene in · entered a nitrogen-flushed out 2-1-pressure vessel is then closed, heated to 120 ⁰ C and filled with propylene up to a pressure of 28.1 kg / cm ² wurClo. ^{The reaction mixture was then heated to a maximum of 188 °} C. for a reaction time of about 2% hours and the pressure vessel was refilled twice with further propylene up to a maximum pressure of 49.2 kg / cm ^{2 during this time.} The pressure vessel was then allowed to cool to room temperature, opened and flushed with nitrogen. The reaction mixture was then first mixed with 50 cm ^{3 of} ethanol and then with 200 cm ^{3 of} water, taken out of the pressure vessel, filtered and poured off and

subsequent azeotropic distillation divided into aqueous and organic phases.

The organic product was then subjected to rectification in a spiral-filled column. This gave approximately 40 cm ^{3 of} a product boiling between 49 and 54 ° C (uncorrected), which corresponds to 4-methylpentene-1 with the corrected boiling point 53.9 ° C. Moreover were recovered cm ³ of a 66 to 68 ⁰ C boiling product about 20, corresponding to the 2-methylpentene-2 with the corrected boiling point of 67.3 ⁰ C.

Comparative experiment

(using free alkali metal as a catalyst)

^{A dispersion of 5.0 g (0.125 mol) of potassium in 100 cm 3 of} n-octane was prepared in the same way as before a sodium dispersion in n-octane was formed, but the temperature at which the rapid stirring was stopped was used 64 ⁰ C was lowered. The dispersion was enclosed in a 250 cm ³ pressure vessel and this was pressurized with 51 g (1.21 mol) of propylene (18.1 kg / cm ² at 25 ° C.). After 20 minutes of stirring, the system was heated slowly to a maximum of 213 ° C (72.4 kg / cm ²⁾ and the temperature maintained at about 200 ⁰ C for 6 hours. During this time there was no noticeable drop in pressure. However, the final pressure at room temperature was 1.05 kg / cm ² below the initial equilibrium pressure. Work-up was carried out in the same way as in Example 2, except that isopropyl alcohol was used to hydrolyze the reaction mixture. The distillation gave the following four fractions:

1. 9.5 cm ³ boiling range ... 50 to 55 ⁰ C

2.2, l-cm ³ boiling range ... 55 to 72 ⁰ C

3. 12 cm ³ boiling range ... 78 to 83 ° C

4. 150 cm ³ boiling range ... 123 to l27 ° C

An analysis of the fractions by means of vapor phase chromatography gave the following results:

fraction 4-Me-1-pentene 4-Me-2-pentene 2-Me-1-pentene 2-Me-2-pentene Isopropyl alcohol n-octane ¹ Vo % % ¹ Vo ¹ Vo 1 66.5 *) 17.8 7.1 8.3 2 31.0 17.7 9.4 14.9 23 - 3 - - - - 100 - 4th - - - - - 100

*) All values are mole percent.

In fraction 2, trace amounts of 2-hexene and / or 3-hexene were found.

The total yield of methyl pentenes was 7.36 g or - based on propylene input - 14.6% with the following isomer distribution:

1. 63.5% 4-Me-1-pentene

2. 19.0% 4-Me-2-pentene

3. 10.0% 2-Me-2-pentene

4. 2-Me-1-pentene,

5. Traces of n-hexenes

Example 4
a) Preparation of the catalyst

First, a dispersion of 9.9 g (0.25 mol) of potassium in n-octane and from it and 15.1 cm ³ (0.125 mol) of amyl chloride was prepared by the method described in Example 2 for amyl sodium amyl potassium. A very dark blue, insoluble solid with a relatively large particle size resulted.

45

b) method of the invention

A slurry of this catalyst in n-octane was sealed in a 250 cm ³ -Druckgefäß. After adding 41 g (0.98 mol) of propylene (18.1 kg / cm ² at 26 ° C.), the reaction mixture was stirred for 20 minutes. The pressure vessel was slowly increased to 185 ° C. (48.9 kg / cm ² ) The temperature rose to 204 ^° C., and the pressure drop per minute was initially 0.35 kg / cm ² and then slowed down after one hour to 0.07 kg / cm ² , whereupon with stirring and heating were stopped, and the total pressure drop was 17.4 kg / cm ² at 185 ° C.

The reaction mixture was worked up exactly as in the previous comparative experiment and gave the following distillation products:

1. 25.4 cm ³ boiling range

2. 3.5 cm ³ boiling range

3. 10.7 cm ³ boiling range

4. 180 cm ³ boiling range.

45 to 55 ⁰ C

55 to 75 ⁰ C

75 to 125 ° C

125 to 127 ⁰ C

Analysis of this Pentane Fractions by means of vapor phase chromatography gave the following results: 4-Me-1-pentene 4-Me-2-pentene 2-Me-1-pentene 2-Me-2-pentene n-octane FYn kt ion "/ ■> Isopropyl alcohol ¹ Vo % 'Vo ° / o ¹ Vo 16.7 *) ¹ Vl) 57.5 18.7 4.0 3.3 - Γ 17.9 - 27.6 22.3 9.2 16.4 - 2 - - U 1.2 0.8 1.0 - 3 - 95 - - - 100 4th

*) All values are mole percent.

Traces of 2-hexene and / or 3-hexene were discovered in fraction 2.

The total yield of methyl pentenes in this case was 17.0 g or - based on the introduction of propylene related - 41.6% with the following isomer distribution:

1. 63.5% 4-Me-1-pentene

2. 19.0% 4-Me-2-pentene

3. 7.6% 2-Me-1-pentene and

4. 10% 2-Me-1-pentene

It should be noted that in Example 4 using an organoalkali metal catalyst, viz Amylpotassium introduced into the reaction system, the yield of hexene in one reaction time of 1.5 hours was 41.5%, while in the above comparative experiment, in the one with free Alkali metal, namely potassium, was worked, the hexene yield with the four times longer reaction time of 6 hours was only 14.6%.

Example 5 below shows that using a dry organoalkali metal compound as a catalyst, the dimerization reaction can be carried out at fairly high pressure.

Example 5
a) Preparation of the catalyst

According to the method described in Example 2, a deep blue suspension of amylpotassium in 50 cm ^{3 of} dry n-heptane was prepared from 0.125 mol of potassium and 0.0625 mol of amyl chloride. This mixture was placed in a 2000-atm Rüttelautoklav and the hexane in the course of 4 hours, removed by the pressure vessel at 50 ⁰ C and 20 mm vacuum was maintained.

b) method of the invention

Thereafter, 79 g of propylene were injected into the vessel, heating this in l _^3/4 hours at 150 ⁰ C, whereafter the internal pressure 141 kg / cm ^2, and held for a further l ^x / 4 hours at 150-160 ⁰ C. After cooling overnight, the pressure vessel was slowly vented over a period of 4 hours using a receiver cooled with dry ice. The contents of the vessel were hydrolyzed with isopropanol with evolution of gas. After completion of the hydrolysis, the liquid was combined with the collected pressure vessel exhaust vapor in a distillation flask cooled with dry ice under nitrogen and passed through a 30 cm long spiral-filled glass tube.

column distilled. At first propylene evaporated and was lost, and then became the following two liquid fractions collected:

1. 12.7 g boiling range 48 to 7O ⁰ C

2. 29.6 g boiling range 73 to 81 ^° C

Analysis by vapor phase chromatography showed fraction 1 to be 84.7% by weight, corresponding to 79.7 mole percent methylpentene in addition to some propylene and isopropanol contained, while Fraction 2 to 1.1 mol percent of 4-methyl-1-pentene and was 98% isopropanol and some propylene. The total yield of methyl pentenes was 11.0 g. The isomer distribution was as follows:

75.6% 4-methyl-1-pentene

15.1% 4-methyl-2-pentene

6.9% 2-methyl-1-pentene and

2.3% 2-methyl-2-pentene

Claims (4)

Patent claims: 1. A process for the catalytic production of hexenes, in particular methyl pentenes, by dimerizing propylene with the aid of organometallic compounds as a catalyst, optionally in the presence of an inert solvent, characterized in that the process is carried out at a temperature between about 40 and about 225 ^° C. carried out at a pressure between normal pressure and about 150, preferably up to about 125 atmospheres, in the presence of an organoalkali metal compound as a catalyst. 2. The method according to claim 1, characterized in that one is used as the inert solvent paraffinic or aromatic hydrocarbons used under the given reaction conditions are liquid. 3. The method according to claim 1 or 2, characterized in that for the purpose of production of 4-methylpentene-2 and 2-methylpentene-2 used an organosodium catalyst. 4. The method according to claim 1 or 2, characterized in that for the purpose of production of 4-methylpentene-1 uses an organopotassium catalyst. Considered publications:
British Patent No. 824,917;
U.S. Patent No. 2,881,23A. 709 689/494 11. 67 © Bundesdruckerei Berlin