CH626315A5 - Process for preparing aliphatic compounds with olefinic double bonds - Google Patents

Description

The present invention accordingly relates to a process for the preparation of compounds of the general formula I.

contains, in which R3 represents a hydrogen atom or a methyl group, and R has the meaning given above, with an isoolefin of the general formula III

30th

Ri-R2 '

R

i

-C = CH-CH2-Xm-CH2-C = CH2

(I)

in the

R, Ri and R2 are each alkyl radicals with 1 to 4 carbon atoms,

35 m has the value 0 or 1,

X represents a linear or branched aliphatic radical with 4 to 8 carbon atoms.

The method according to the invention is defined in claim 1. In particular, either a cyclic olefin 40 of the general formula II

45

yCH = C / \

° H2 7ch2

(II)

in which X has the meaning given above, or a compound of this type which is a disproportionation product of such a cyclic olefin having an unbranched monoolefin having 2 to 4 carbon atoms, with an isoolefin of the general formula III

55

Ri-R2 ~

= c = ch2

(in)

in the R! and R2 have the meanings given above, react in the presence of an olefin disproportionation catalyst.

The cyclic olefin of the general formula II is preferably a cyclic dimer or trimer of isoprene, CH2 = C (CH3) -CH = CH2, or a partially hydrogenated product of such a dimer or trimer. Examples of such compounds are

1,5-dimethylcycloocta-l-ene,

1,4-dimethylcycloocta-1-ene,

1,5-dimethylcyclooct a-1,5-diene,

l, 6-dimethylcycloocta-l, 5-diene, 1,5,9-trimethylcyclododeca-l-ene,

1,6,9-Trimethyl Icyclododeca-1, 2,5,9-Trimethylcyclododeca-l-en, 1,5,9-Trimethylcyclododeca-l, 5,9-triene and 2,5,9-Trimethylcyclododeca-l , 5.9-triene. The cyclic olefin disproportionation products which can be used are conveniently obtained by reacting a cyclic olefin with a / 3-olefin, e.g. 2-butene, in the presence of a disproportionation catalyst, as described in NL-OS 7 412 572. However, it is not necessary that the starting aliphatic olefin be obtained by direct disproportionation of a cyclic olefin, but another conventional route can be followed if desired to obtain the starting aliphatic olefin from different compounds. The isoolefin of the general formula III is preferably isobutene.

It can be seen that in the case of a cyclic monoolefin, such as 1,5-dimethylcycloocta-1-ene, two products are theoretically possible in a disproportionation with, for example, isobutene. These two products are

(CHg ^ CHtCHgJgCH (CH2) 3C = CH2 (A)

CH-, CH-? 3rd

and ch2 = ch (ch2) 2ch (ch2) 3c = c (ch3) 2.

CH3 CH3

It has surprisingly been found that only the first of these two products forms.

If, in a similar way, the disproportionation product of 1,5-dimethylcycloocta-1-ene is reacted with, for example, 2-butene with isobutene, in addition to the two aforementioned products A and B, the following two theoretically possible compounds are obtained:

h2o = ch (ch2) 2o (ch2) 3c = oh2

CKj CH3

and

(oh3) 2o = ch (ch2) 2c (ch2) 3o = c (ch3) 2 (b)

CH3 CH3

Again, Product A is the major product along with - in some cases - a small amount of Compound C. However, Compound C is originally the ethenolysis product of 1,5-dimethylcycloocta-1-ene, and by properly adjusting the reaction conditions can also this compound C can be converted into product A.

An even more complicated scheme of end products is possible if the cyclic olefin of the general formula II contains more than two double bonds, since disproportionation is possible on all or only some of these double bonds. Again, however, the main products fall under the general formula I. Therefore, if the starting compound 1,5-dimethylcycloocta-1,5-diene or its disproportionation

626 315

product with 2-butene, the main product is:

(CH3) 2C = CH- (C »2) 2C = CH (CH2) 2C = CH2 CH3 CHj and as a by-product:

(ch3) 2c = ch-ch2ch2c = ch2

the latter connection being the result of a disproportionation on both double bonds.

The preferred olefin disproportionation catalysts in the process of the present invention are transition metal oxides, such as Re207, which are applied to a suitable support material, such as aluminum oxide. A particularly preferred catalyst consists of 5 to 70 weight percent Re207 on y-alumina, which contains a small amount, e.g. 5 weight percent, of an alkali metal compound, e.g. of potassium.

The process of the invention is expediently carried out at temperatures from -20 to 200 ° C., preferably from 20 to 80 ° C., and at pressures from 1 to 100 bar. The process can also be carried out in a liquid diluent, e.g., an alkane of 5 to 14 carbon atoms, such as heptane.

The process according to the invention is of particular interest for the preparation of the compounds 2,6-dimethyl-hepta-1,5-diene and 2,6,10-trimethylundeca-1,9-diene. The latter connection is new. This compound is a valuable chemical intermediate, e.g. in the manufacture of phyton.

The examples illustrate the invention.

example 1

A y-aluminum oxide (Ketjen CK 300) serves as the catalyst, which is first impregnated with an aqueous potassium carbonate solution, then dried at 120 ° C. and finally treated with a solution of rhenium heptoxide. After drying for 3 hours at 120 ° C., the catalyst is calcined at 500 ° C. for 3 hours. The catalyst produced in this way contains 14 percent by weight Re207 and 1.3 percent by weight potassium ions. Before using the catalyst, it is activated by heating for 3 hours in a pure nitrogen stream at 500 ° C.

10 g of the catalyst are mixed with 20 ml of a mixture of 85% 1,5-dimethylcycloocta-1-ene and 15% 1,4-dimethyl-cycloocta-1-ene and with 80 ml of isobutene and 20 ml of n-heptane. The mixture is stirred under nitrogen at 70 ° C for 25 hours and then examined by means of gas-liquid chromatography. It is found that 11.7% of the starting compounds have been converted to a mixture of 95% 2,6,10-trimethylundeca-1,9-diene and 5% 2,7,10-trimethylundeca-1,9-diene.

The 2,6,10-trimethylundeca-1,9-diene has a boiling point of 118 ° C at 20 torr and has an NMR spectrum in deuterochloroform with the following absorptions: ó = 5.17 ppm, triplet (fine structure), IH (J = 7 Hz); <5 = 1.8-2.2 ppm, multiplets, 4H;

ó = 1.72 ppm, multiple, 6 H;

ó = 1.63 ppm, singlet (fine structure), 3H;

ó = 0.88 ppm, doublet, 3H (J = 5.5 Hz);

<5 = 1.0-1.8 ppm, multiplets, 7H.

3rd

5

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626 315

4th

Example 2

Using the same catalyst as in Example 1, 1,5-dimethylcycloocta-1-ene is converted into 3,7-dimethyldodeca-2,10-diene by disproportionation with 2-butene. 11.4 g of this compound are mixed with 50 g of isobutene, 10 g of the catalyst mentioned in Example 1 and 30 ml of n-heptane. The mixture is stirred under nitrogen at 25 ° C for 16 hours. Analysis of the product obtained indicates that 100% conversion of the starting compound to a mixture of mainly 2,6,10-trimethylundeca-1,9-diene and 2,6-dimethyldeca-1,9-diene in a ratio of approximately 7 : 3 took place.

Example 3

"20 g of 2,6-dimethyldeca-l, 9-diene, 10 g of the catalyst mentioned in Example 1, 80 ml of liquid isobutene and 20 ml of n-heptane are stirred for 18 hours at 50 ° C. The analysis of the end product indicates that 70% of the starting compound had been converted and that 2,6,10-trimethylunde-ca-1,9-diene was obtained with a selectivity of 90%.

Example 4

By means of a controlled disproportionation of 1,5-dimethylcycloocta-1,5-diene with 2-butene, 3,7-dimethyldo-deca-2,6,10-triene is produced. 20 ml of this compound, 10 g of the Re207 catalyst mentioned in Example 1, 80 ml of liquid isobutene and 30 ml of n-heptane are stirred together at 25 ° C. for 16 hours. A practically 100% conversion of the starting compound is found. The product consists mainly of a mixture of 2,6-dimethylhepta-l, 5-diene and 2,6,10-trimethylundeca-1,5,9-triene in a weight ratio of approximately 21: 9. The latter compound provides an NMR spectrum in deuterochloroform with the following absorptions: ô = 5.17 ppm, multiplet, 2H;

ò = 4.73 ppm, multiplet, 2H;

ô = 2.07 ppm, multiplet, 8H;

ô = 1.72 ppm, multiplet, 9H;

ò = 1.62 ppm, singlet (fine structure), 3H.

Example 5

50 ml of a mixture of l, 5-dimethylcycloocta-l, 5-diene and l, 6-dimethylcycloocta-l, 5-diene in a ratio of 83:17, furthermore 10 g of catalyst, 50 g of isobutene and 30 ml of n-

Heptane is stirred for 20 hours at 20 ° C under nitrogen. The conversion is about 40%. The main product, namely 70% 2,6,10-trimethylundeca-1,5,9-triene, is obtained by disproportionation on one of the double-bin fertilizers of the starting compound. A smaller amount, namely about 9%, of the complete disproportionation product is 2,6-dimethylhepta-1,5-diene.

Example 6

15 g of a mixture of trimethylcyclododeca-l, 5,9-triene (with a content of 85% of the 1,5,9-trimethyl isomer), 10 g of catalyst, 50 g of isobutene and 50 ml of n -Heptane are stirred for 16 hours at 20 ° C under nitrogen. The conversion is approximately 60%. An olefin mixture is obtained. The main product, namely 50% of the mixture, is 2,6-dimethylhepta-1,5-diene.

Example 7

A mixture of the Trime-20 thylcyclododeca-1,5,9-triene also used in Example 6 is first reacted with 2-butene. Due to the conditions used, the main product is either:

(A) 3-Methylocta-2,6-diene by disproportionation on all three double bonds and 25 (B) 3,7, ll-trimethylhexadeca-2,6,10,14-tetra by disproportionation on only one double bond.

(1) When 3 g of the compound (A) is reacted with isobutene as in the manner described in Example 6, 100% conversion takes place, and 2,6-dimethyl

30 thylhepta-l, 5-diene with a selectivity of over 90%.

(2) If 3 g of compound (B) are reacted with isobutene as described in Example 6, a 100% conversion and a complex mixture of olefins are again obtained. The main ingredient, namely 80%

35 of the total mixture, is again 2,6-dimethylhepta-1,5-diene.

Example 8

18.5 g of the 3-Me-40 thylocta-2,6-diene prepared by disproportionation of a dimethylcy-cloocta-l, 5-diene mixture with 2-butene, 10 g of catalyst and 50 g of isobutene are 5 hours at 20 ° C stirred together. An 85 percent conversion is obtained and the end product consists of 61% 2,6-dimethylhepta-l, 5-diene, 16% 2,6-dimethylhepta-2,6-diene and 12% 2-methylhexa-l, 5-diene .

s

Claims (6)

626 315 2nd PATENT CLAIMS 1. Process for the preparation of aliphatic compounds of general formula I having olefinic double bonds R r *> C = CH-CH2-Xm-CH2-C = CH2 (I) in the R, R] and R2 are each alkyl radicals with 1 to 4 carbon atoms, m has the value 0 or 1, X denotes a straight-line or branched aliphatic radical having 4 to 8 carbon atoms in the main chain, characterized in that either a cyclic olefin which has at least one divalent chain of the formula in its ring R -CH2-CH = C-CH2- (Ha) contains, or an aliphatic olefin having an end group of the formula R3-CH = CH-CH2- and an end group of the formula R R, -CH = C-CH2 (IIb) (Hey) Ri-R, ' C = CH2 (III) in which R: and R2 have the meanings given above, can be reacted in the presence of an olefin disproportionation catalyst, at least the double bonds shown in the formulas IIa, IIb, Ile and III being opened and the rest Ri-R2 ' = C = of the isoolefin of the formula III binds to the radical -CH2CH = of the divalent chain of the formula IIa or the end group of the formula IIb mentioned, and the radical = CH2 of the isoolefin of the formula III binds to the radical = C (R) -CH2— binds said divalent chain or said end group of formula Ile. 2. The method according to claim 1, characterized in that the cyclic olefin used is a cyclic dimer or trimere of isoprene or a partially hydrogenated product of such a dimer or trimer. 3. The method according to claim 1, characterized in that one uses an aliphatic olefin in which R3 is a methyl group. 4. The method according to any one of claims 1, 2 or 3, characterized in that isobutene is used as the isoolefin of the general formula III. 5. The method according to any one of claims 1 to 4, characterized in that Re207 is used as olefin disproportionation catalyst on an aluminum oxide support material. 6. The method according to any one of claims 1 to 5, characterized in that one carries out the reaction at 20 to 80 ° C. NL-OS 7 412 572 describes a process for the preparation of acyclic a, w-dienes, where a cyclic olefin of the general formula in which R is an alkyl radical and A is a divalent aliphatic radical, first with a / 3- Olefin, such as 2-butene, and then reacted with ethylene and thereby a product of the general formula R -C = ch2 • CH = CH0 20 d. receives. It has now been found that it is possible to produce related compounds which have only one terminal double bond.