WO2012055754A2

WO2012055754A2 - Method for the production of 1-methylcyclopentane derivatives

Info

Publication number: WO2012055754A2
Application number: PCT/EP2011/068328
Authority: WO
Inventors: Andreas Lanver; Klaus Ebel; Rainer Klopsch; Werner Bertleff; Richard Dehn; Joaquim Henrique Teles; Helmut Kronemayer; Marcus Georg Schrems
Original assignee: Basf Se
Priority date: 2010-10-25
Filing date: 2011-10-20
Publication date: 2012-05-03
Also published as: WO2012055754A3

Abstract

The invention relates to a method for the production of 1-methylcyclopentene by the thermal reaction of cyclohexanol or cyclohexene or mixtures of both compounds to 1-methylcyclopentene, characterized in that the obtained byproducts 3-methylcyclopentene and 4-methylcyclopentene (double bond isomers of 1-methylcyclopentene) are fed back to the reaction.

Description

description

Process for Preparing 1-Methylcyclopentane Derivatives The present application includes, by way of reference, US Provisional Application 61 / 406,183 filed Oct. 25, 2010.

The present invention relates to a process for the preparation of 1-methylcyclopentene by thermal reaction of cyclohexanol or cyclohexene or mixtures of both

Compounds of 1-methylcyclopentene, which is characterized in that the resulting by-products 3-methylcyclopentene and 4-methylcyclopentene (double bond isomers of 1-methylcyclopentene) are recycled to the reaction.

Likewise, the present application relates to a process for the preparation of cyclopentane derivatives of the following formula I.

C

in which X represents a hydroxyl group, an alkoxy group or a chlorine atom, by thermal reaction of cyclohexanol or cyclohexene to form 1-methylcyclopentene (stage I) and subsequent addition of compounds HX, where X has the above meaning, to the double bond of the 1 - Methylcyclopentene (2nd stage), which is characterized in that the by-products obtained 3-methylcyclopentene and 4-methylcyclopentene from the

Product mixture of the 1st or 2nd stage can be attributed to the implementation of the 1st stage.

Cyclopentane derivatives of the above formula I are of importance as starting materials for chemical syntheses of various compounds. From US Pat. No. 5,498,802 it is known to prepare 1-methyl-1-hydroxycyclopentane in three separate reaction steps, wherein in the first step cyclohexanol is dehydrated to cyclohexene, in the second step cyclohexene is isomerized to 1-methylcyclopentene and in the third step water is added to 1-methylcyclopentene is added in the presence of isopropanol as a solvent. According to Example 1 of US 5,498,802 dissolved in methanol cyclohexanol is dehydrated at 250 ° C on silica to cyclohexene. At complete cyclohexanol conversion, a cyclohexene yield of 97.5% was achieved in the first step.

In the second step, cyclohexene is isomerized at 400 ° C. in the gas phase on silica to give 1-methylcyclopentene. The 1-methylcyclopentene yield was 60.3% (Example 2). In the third step, a mixture of pure 1-methylcyclopentene, isopropanol and water is passed through Amberlyst15 resin at 80 ° C. The 1-methylcyclopentene conversion was 41.9%, the yield of 1-methyl-1-hydroxycyclopentane 22.9% (Example 3). A disadvantage of the process according to US Pat. No. 5,498,802 is the number of reaction steps and the low total yield of 1-methyl-1-hydroxycyclopentane of only 13%, calculated over all partial steps. For the catalytic addition of water to 1-methylcyclopentene to 1-methyl-1 - hydroxycyclopentane pure 1-methylcyclopentene is used. Neftekhimiya (1991), 31 (3), pages 386 to 390 (Item 12) describes the reaction of cyclohexanol in one step to 1-methylcyclopentene. Cyclohexanol is converted at 450 ° C in the gas phase of chlorine-doped alumina to methylcyclopentenes.

US 4,661,639 relates to a process for the preparation of cyclic alcohols by addition of water to cyclic olefins using modified aluminosilicate catalysts.

Compared to the above prior art, it was the object of the present invention to provide a process for the preparation of cyclopentane derivatives of the formula I available, which is continuously feasible, with as few process steps and with the high yields and selectivities of the products in all process stages be achieved. In this context, it was also an object of the invention to provide an improved process for the preparation of 1-methylcyclopentene. 1-methylcyclopentene is required as starting material or intermediate product for the preparation of the cyclopentane derivatives; moreover, 1-methylcyclopentene is also the starting material for other syntheses.

Accordingly, the above-defined methods have been found. In this application, the following seven compounds are designated as follows:

1 cyclohexanol

2 cyclohexene

3 1 -methylcyclopentene

4-methylcyclopentene

5 4- methylcyclopentene

6 1 -methyl-1-hydroxycyclopentane 7: 1-methyl-1-methoxycyclopentane

8: 1-methyl-1-chlorocyclopentane

For the preparation of 1-methylcyclopentene

The following statements relate to the preparation of 1-methylcyclopentene as the end product. Starting compound of the process for the preparation of 1-methylcyclopentene is cyclohexanol or cyclohexene or a mixture of the two.

The reaction is a gas phase reaction. Starting from the cyclohexene is a rearrangement to 1-methylcyclopentene; starting from cyclohexanol in the 1st stage, a dehydration to cyclohexene and then the subsequent rearrangement to 1-methylcyclopentene according to the following schematically illustrated reaction sequence:

This gas phase reaction is known per se.

Cyclohexene as the starting compound can also be obtained by separately pre-dehydration of cyclohexanol or any other method, e.g. by partial hydrogenation of benzene by the Asahi process.

Preferred starting compound is cyclohexanol or a mixture of cyclohexanol and cyclohexene, wherein the molar ratio of cyclohexanol to cyclohexene 1 to 0.1 to 0.1 to 1.

The reaction of cyclohexanol to cyclohexene is generally complete.

The reaction may be batchwise or, preferably, continuous, i. with continuous feed of the starting materials and continuous discharge of the products.

In the process according to the invention, the by-products 3-methylcyclopentene and 4-methylcyclopentene and optionally also unreacted starting compounds are recycled. The term "starting compounds" therefore always includes in the following recycled compounds, eg, recycled by-products and recycled, unreacted starting compounds, as discussed in more detail below.

The reaction is preferably carried out in the gas phase in the presence of acidic catalysts. The gas phase reaction can be carried out in reactors such as stirred reactors or tubular reactors.

The acidic catalysts can be arranged in the reactor as a fixed bed or fluidized bed. A necessary inertization of the catalysts may be carried out with a carrier gas, e.g. Nitrogen or argon.

As solid acid catalysts are e.g. SiO 2, Al 2 O 3, mixtures of SiO 2 and Al 2 O 3, aluminum silicates, ZrO 2, CO 2 or zeolites. As catalysts for the reaction of cyclohexanol or cyclohexene to 1-methylcyclopentene, naturally occurring or synthetically prepared zeolites are also suitable.

The catalyst loading is preferably 0.05 to 3, preferably 0.1 to 2, particularly preferably 0.2 to 1 kg of starting compounds per liter of catalyst per hour.

The residence time is in particular from 1 to 50 seconds, preferably 5 to 15 seconds.

The reaction can be carried out at temperatures of 250 to 500, preferably 300 to 450, particularly preferably from 400 to 450 ° C.

The reaction pressure is not critical. It may, for example, be 0.1 to 10 bar, preferably 1 to 5 bar.

The product mixture obtained in the reaction contains, in addition to the desired product 1-methylcyclopentene, the following compounds: the by-products 3-methylcyclopentene and 4-methylcyclopentene (double bond isomers of 1-methylcyclopentene),

unreacted cyclohexene and

- optionally water (if it was assumed that cyclohexanol).

In general, in the reaction, 1 to 50 parts by weight, especially 2 to 40 parts by weight, often 5 to 30 or 10 to 30 parts by weight of 3-methylcyclopentene per 100 parts by weight of obtained 1-methylcyclopentene. In general, 1 to 50 parts by weight, in particular 1 to 30 parts by weight, frequently 1 to 20 or 2 to 20 parts by weight of 4-methylcyclopentene per 100 parts by weight of 1-methylcyclopentene obtained in the reaction. Preferably, the entire resulting amount of the 3- and 4-methylcyclopentene is recycled to the reaction.

The gaseous reaction is condensed. This can e.g. by adding an organic solvent such as toluene (quenching) done. When using cyclohexanol as the starting material, the condensate consists of two liquid phases, one aqueous and one organic. The two phases are separated. The organic phase contains the above product mixture, in particular the desired product 1-methylcyclopentene. The water phase is discharged. The separation of the two liquid phases can be carried out by gravimetric phase separation. As phase separation vessels, for example, conventional standard apparatuses and standard methods are suitable. Alternatively, water can be separated from the condensed reaction product by an azeotropic distillation. The organic phase containing generally unreacted cyclohexene (boiling point 83 ° C), 1-methylcyclopentene (boiling point 76 ° C), and the two isomers 3-methylcyclopentene and 4-methylcyclopentene (boiling points 65-66 ° C), can be worked up by distillation The above boiling points apply to atmospheric pressure; 1-methylcyclopentene can then be separated from this organic phase and used as the end product in the desired manner.

Preferably, the entire residue of the organic phase, which contains 3-methylcyclopentene and 4-methylcyclopentene and cyclohexene, is recycled to the reaction. For the preparation of the cyclopentane derivatives of the formula I.

General

The process for the preparation of cyclopentane derivatives of the formula I is a two-stage process. In a 1st stage, the thermal conversion of cyclohexanol or cyclohexene to 1-methylcyclopentene; in the second stage the addition of compounds HX takes place.

In formula I, X is a hydroxyl group, an alkoxy group, preferably a C1 to C10 alkoxy group or a chlorine atom. In particular, X represents a hydroxyl group or an alkoxy group. Suitable alkoxy groups are in particular alkoxy groups having 1 to 10 C atoms, particularly preferably having 1 to 5 C atoms. X is particularly preferred for an alkoxy group, in particular a C 1 to C 5 alkoxy group, for example a methoxy group, ethoxy group, isopropoxy group, n-propoxy group, n-butoxy group or a pentoxy group. Most preferably, X is a methoxy group. In the first stage of the two-stage process, 1-methylcyclopentene is produced. All statements above on the preparation of 1-methylcyclopentene apply here accordingly, unless otherwise stated below.

In the subsequent reaction in the 2nd stage, the addition of the compounds HX to the double bond of 1-methylcyclopentene takes place.

According to the desired radical X in formula I, HX is water (X = hydroxy group), HCl (X = Cl) or an alcohol corresponding to the abovementioned alkoxy groups. HX is preferably corresponding to water or preferably to a C 1 to C 10, in particular a C 1 to C 5, alcohol. Particularly preferred is methanol.

In the 2nd stage, 1-methylcyclopentene is preferably reacted in the liquid phase in the presence of acidic catalysts with compounds HX to give cyclopentane derivatives of the formula I.

The reaction can be carried out at temperatures of, for example, 20 to 100.degree. C., preferably 50 to 90.degree. C., particularly preferably 40 to 90.degree.

The molar ratio of 1-methylcyclopentene to compounds HX may be e.g. 1 to 10 to 10 to 1. In a preferred embodiment, HX is employed in molar excess; the molar ratio of 1-methylcyclopentene to the compounds HX is then in particular from 1: 1 to 1: 10, more preferably from 1: 2 to 1: 5.

As acidic catalysts, preferred are solid acidic catalysts, e.g. strong acid ion exchangers or zeolites used, as also mentioned in US 5,498,802. The solid acidic catalysts can either be fixed in a reactor or are suspended in the liquid phase.

The catalyst loading may be, for example, 20 to 1, preferably 15 to 3, more preferably 5 to 3 kg of methylcyclopentenes per liter of catalyst per hour.

The residence time may be, for example, 5 minutes to two hours, more preferably 5 minutes to 2 hours, and preferably 10 minutes to 30 minutes. In the case of hydration (HX = H 2 O), the reaction in the second stage is preferably carried out in the presence of a polar organic solvent, for example secondary alcohols such as sec-butanol and isopropanol. The solvent serves as a solubilizer between the water and the non-polar starting material 1-methylcyclopentene.

The reaction effluent from stage 2 contains the desired cyclopentane derivatives of the formula I, unconverted 1-methylcyclopentene, optionally its isomers as by-products and optionally unreacted HX and optionally solvent. If the acidic catalyst was suspended in the reaction mixture, it can be separated by filtration and recycled to synthesis step 2.

The workup of the reaction can be carried out by distillation. For purification and separation of the desired cyclopentane derivative of the formula I, fractional distillations can be carried out.

In the event that X in formula I is a C1 to C10 alkoxy group and in the second stage, the addition of the C1 to C10 alcohol corresponding to the 1-methylcyclopentene, in the second stage in a preferred embodiment, a reactive distillation carried out. In the reactive distillation, the reaction of the starting compounds in the

Carrying out the distillation.

In the present case, in the reactive distillation, the addition of the alcohol to the double bond of 1-methylcyclopentene and the separation by distillation of the product or product mixture thereby obtained. The product or product mixture is due to the difference in boiling point of the resulting cyclopentane derivative of the formula I (vorzugweisel-methyl-1-methoxycyclopentane) to the starting materials as the bottom product. By a reactive distillation high conversions in equilibrium reactions are possible because the forming product is removed immediately.

In a suitable distillation apparatus for continuous operation as shown in Figure 1, the starting materials (here C1 to C10 alcohol, preferably methanol, and 1-methylcyclopentene, and optionally recycled by-products) of the apparatus are supplied gaseous or liquid (stream 1 in Fig.1) , In the column, the reaction takes place to the cyclopentane derivative of the formula I (preferably 1-methyl-1-methoxycyclopentane). The readily volatile starting compounds are condensed at the top of the column and returned to the column (stream 2). The less volatile cyclopentane derivative of the formula I (preferably 1-methyl-1-methoxycyclopentane) and less volatile by-products accumulate in the bottom of the column and can be withdrawn (stream 3). The distillation apparatus may preferably contain conventional internals for promoting the separation by distillation (packing or column bottoms) and the acid catalyst, for example as a fixed bed or fluidized bed (see internals A and B in Fig. 1). The second stage process may be carried out batchwise or continuously; Preferably, the process is carried out continuously in the 2nd stage.

It is therefore preferable in the entire process comprising the 1st and 2nd stage to a continuously carried out process.

For the return

An essential feature of the two-stage process according to the invention for the preparation of cyclopentane derivatives is that 3-methylcyclopentene and 4-methylcyclopentene, and optionally unreacted starting compounds are recycled in the product mixture of the 1st or 2nd stage in the implementation of the 1st stage.

Feedback from 1st stage

In one embodiment, 3-methylcyclopentene and 4-methylcyclopentene and optionally unreacted starting materials, that is cyclohexene, from the

Product mixture of the 1st stage in the implementation of the 1st stage attributed.

In this embodiment, therefore, 1-methylcyclopentene is separated as described above from the product mixture of the 1st stage and fed to the 2nd stage, while 3-methylcyclopentene and 4-methylcyclopentene and preferably also the unreacted cyclohexene are recycled to the reaction of the 1st stage , In particular, as described above in the preparation of 1-methylcyclopentene, the entire organic residue is recycled after separation of the 1-methylcyclopentene.

When cyclohexanol is used as the starting compound alone or in admixture with cyclohexene, the product mixture contains water from the dehydration of cyclohexanol to cyclohexene. Water is obtained as a separate aqueous phase and can be easily separated from the organic phase as described above. The aqueous phase is discarded and not recycled to the 1st stage reaction.

In this embodiment, in addition to the return in the 1st stage, a return can also be carried out in the 2nd stage. In particular, unreacted starting materials of the second stage, that is, 1-methylcyclopentene and unused HX, are attributed to the second stage reaction. Feedback from product mixture 2nd stage

In a second embodiment of the two-stage process, there is no separation and recycling of 3-methylcyclopentene and 4-methylcyclopentene after the 1st stage. Instead, 3-methylcyclopentene and 4-methylcyclopentene are recycled from the second stage product mixture to the first stage reaction.

In this second embodiment, the product mixture of the 1st stage is condensed and the organic phase without separation of the by-products 3-methylcyclopentene and 4-methylcyclopentene and without separation of the unreacted starting compounds (cyclohexene) supplied to the further reaction in the 2nd stage. Insofar as an aqueous phase is obtained in the condensation of the product mixture due to the (use) of cyclohexanol, this is preferably separated and discarded, as far as no water is needed in step 2. However, if an addition of water should take place in stage 2 (HX = H 2 O), the aqueous phase is also fed to the second stage.

The product mixture obtained in the 2nd stage accordingly contains the desired cyclopentane derivative of the formula I

unreacted 1-methylcyclopentene and HX (starting materials for stage 2)

the by-products from stage 1: 3-methylcyclopentene and 4-methylcyclopentene unreacted starting materials from stage 1: cyclohexene

optionally water

In the case of an addition of water (HX = H 2 O), further water is preferably added in the second stage. In addition to the water from the 1st stage, which is used in the 2nd stage, an addition of 1 to 100 mol, in particular 10 to 80 mol of water per 1 mol of 1-methylcyclopentene is preferred.

From the product mixture of the second stage, the desired 1-Methylcyclopentanderivat be separated by fractional distillation as high boilers of the above compounds and, if necessary, again purified by distillation. Preferably, unreacted HX, in particular water and alkanols, are separated from the product mixture of the second stage and are not recycled to the first stage.

There then remain as organic residue from the 2nd stage: unreacted 1-methylcyclopentene (starting materials for stage 2)

the by-products from stage 1: 3-methylcyclopentene and 4-methylcyclopentene unreacted starting materials from stage 1: cyclohexene These compounds are then recycled in this embodiment in the implementation of the 1st stage. The process according to the invention for the preparation of 1-methylcyclopentene and the two-step process according to the invention for the preparation of cyclopentane derivatives are particularly suitable for a continuous process implementation. The yield of 1-methylcyclopentene or of the desired cyclopentane derivative is high. The recycling of 3-methylcyclopentene, 4-methylcyclopentene and cyclohexene does not lead to an increased formation of by-products.

In particular, it should be noted that the isomers 3-methylcyclopentene and 4-methylcyclopentene rearrange to the desired compound 1-methylcyclopentene in the first stage and increase the yield.

Furthermore, it should be noted that a presence of the isomers 3-methylcyclopentene and 4-methylcyclopentene in the second stage is not detrimental and no or hardly any new by-products are observed by an addition of HX to these isomers or to cyclohexene.

The following embodiments of stage 1 (examples 1 to 3) and stage 2

(Examples 6 to 14) show that the reactions take place with high selectivity. Example 5 shows the recycling of the unwanted by-products upon recycling

3-methylcyclopentene and 4-methylcyclopentene to the desired 1-methylcyclopentene. Example 14 shows that the presence of 3-methylcyclopentene, 4-methylcyclopentene and cyclohexene in the second stage does not lead to new by-products.

Examples

The following compounds are named in the examples with the chemical name given below or simply with the corresponding number.

1: cyclohexanol

2: cyclohexene

3: 1 methylcyclopentene

4: 3-methylcyclopentene

5: 4-methylcyclopentene

6: 1 -methyl-1-hydroxycyclopentane

7: 1 -Methyl-1-methoxycyclopentane

Abbreviations used: GC-FI%: gas chromatography area% A) Gas phase reaction of cyclohexanol to 1-methylcyclopentene

Examples 1 -3 A glass reactor (inside diameter 27mm, height 500mm) with electric heating and

Temperature measurement was filled with a catalyst amount of about 300ml. The educt (1) was fed continuously in trickle mode. In the bottom of the glass reactor was condensed in a 1 L flask with attached condenser with toluene as the quench liquid. Nitrogen was used as the carrier gas. From the biphasic mixture, the aqueous phase was separated in a separating funnel. The organic phase was analyzed by GC.

[a] Toluene removed

Example 4

In a 120 cm high column with 3x3 mm mesh rings (about 60 theoretical stages), a mixture consisting of the compounds 2, 3, 4 and 5 was fractionally distilled fractionally at atmospheric pressure. The head temperature was constant at the transition from compound 3 to 72 ° C.

This example shows the distillative removability of the compound 3 from the product mixture obtained in the 1st stage. Example 5

The same experimental setup as in Examples 1-3 was used (catalyst:

S1O2 + 20% H3PO4). The starting material used was the following mixture: compounds 3 (11 GC-FI%), 4 (56 GC-FI%), 5 (24 GC-FI%). At a temperature of 400 ° C, a

Carrier gas flow (N2) of 3 l / h and a catalyst loading of 146 g / kg / h, the following mixture was obtained after condensation in toluene: Compounds 3 (63 GC-FI%),

4 (12 GC-FI%), 5 (5 GC-FI%).

The experiment demonstrates that compounds 4 and 5 can be isomerized again into the desired product 3. In a recycling of these isomers, therefore, the yield is increased accordingly.

B) Hydration of 1-methylcyclopentene

Examples 6-9

In a continuously operated glass reactor (internal diameter 25 mm, height 200 mm) an ion exchanger (Amberlyst type) was charged as a catalyst. In trickle mode, the mixture consisting of 1-methylcyclopentene, isopropanol (iPrOH) and water was fed from a storage tank via a membrane pump at a constant internal volume.

The product mixture was analyzed by GC. The yields and conversions were calculated from GC% by weight results.

AusSelek¬

Use T Residence Umsat;

Eg iPrOH H ₂ 0 Catalyst prey (3) [° C] time (3)

(6) (6)

[Weight%] [weight%] [weight%] [min] [%] [%] [%]

6 8 53 39 Amberlyst 36 70 22 57 24 42

7 8 53 39 Amberlyst 15 55 36 61 30 49

8 4 55 41 Amberlyst 15 55 1 1 43 28 65

9 4 55 41 Amberlyst 15 55 48 59 39 66 C) Etherification of 1-methylcyclopentene with methanol Example 10

Preparation of 1-methoxy-1-methyl-cyclopentane (molar ratio olefin: methanol

3 7

1-Methylcyclopentene (99.2 g, 1.21 mol) and methanol (75.0 g, 2.34 mol) were placed in a 3-necked flask under nitrogen. A Soxhiet attachment with an extraction tube filled with 15.0 g Amberlyst 15 was placed on the flask and the mixture was heated to reflux (oil bath: 85 ° C). After a total of 67 hours, the oil bath was removed and the reaction cooled. A GC sample was taken showing a conversion of about 94%.

Composition of the product mixture:

MeOH: 19.7%

3 (1-methylcyclopentene): 4.6%

7 (ether): 72.5%

By using a soxhlet, the following effect is achieved when the temperature is set at 85 ° C. The two reactants methylcyclopentene and methanol then boil and condense on the reflux condenser. Then, the condensed mixture enters the reaction zone with the ion exchanger and reacts to the product 1-methoxy-1-methylcyclopentane. Since the boiling point is above 85 ° C, the product can be enriched in the sump to near full conversion.)

Example 1 1

Preparation of 1-methoxy-1-methyl-cyclopentane (olefin: MeOH = 1 / 5.2) Procedure analogous to Example 10, wherein

99.0 g (1.20 mol) of 1-methyl-cyclopentene,

200.0 g (6.24 mol) of methanol and

27.1 g of Amberlyst 15 were used. The reaction time was 18.5 h.

A GC sample showed a conversion of 96%. Composition of the product mixture:

MeOH: 35.5%

3 (1-methylcyclopentene): 2.7%

7 (ether): 60.1%

Example 12

Preparation of 1-methoxy-1-methyl-cyclopentane (olefin: MeOH = 1 / 5.1, short reaction time)

Procedure analogous to Example 1 1 where

100.0 g (1.22 mol) of 1-methyl-cyclopentene,

200.0 g (6.24 mol) of methanol and

27.1 g of Amberlyst 15 were used. The reaction time was 4.6 h.

A GC sample showed a conversion of 96%.

Composition of the product mixture:

MeOH: 33.7%

3 (1-methylcyclopentene): 2.3%

7 (ether): 61, 7%

In this example it is shown that even with reasonable residence times a good

Sales / yield is achieved.

Example 13

Preparation of 1-methoxy-1-methyl-cyclopentane (without Soxhlet)

1-Methylcyclopentene (50.0 g, 0.61 mol), methanol (200.0 g, 6.24 mol) and 25.0 g of Amberlyst 15 were placed in a 3-necked flask under nitrogen. The mixture was heated to 50 ° C. After 6 h, a GC sample was taken which showed a conversion of about 50%. After 24 h, another GC sample was taken which showed a conversion of about 67%. Neither a longer reaction time nor the addition of 5.0 g Amberlyst 15 led to a further implementation. Example 14

Preparation of 1-methoxy-1-methyl-cyclopentane starting from a mixture containing components 2, 3, 4 and 5

The experiment was carried out analogously to Example 12 with Amberlyst 15 as a catalyst. The following educt mixture was used:

MeOH (31 GC-FI%), 2 (14 GC-FI%), 3 (38 GC-FI%), 4 (10 GC-FI%), 5 (4 GC-FI%).

After a reaction time of 19h at 48 ° C the following mixture was obtained: MeOH (28 GC-FI%), 2 (14 GC-FI%), 3 (15 GC-FI%), 4 (10 GC-FI%) , 5 (4 GC-FI%), 7 (25 GC-FI%). The example shows that only compound 3 reacts to the product 7. Compounds 2, 4 and 5 do not react according to GC analysis and can be recycled to the gas phase reaction (see Examples 1-3).

Example 15

7

A mixture consisting of the compounds 3 and 7 was fractionally distilled at a pressure between 1 bar and 100 mbar. The apparatus used was a 1 liter flask with a 20 cm column with 3 mm V2A Raschig rings.

Connections pressure

Sample [in GC-FI%] Boiling point bar g 3 7 [° C]

Insert 431.0 20.4 73.9

Fr.1 40.7 96.0 0.9 22-35 1 -0.1

Fr.2 34.3 79.2 19.3 35-61 1 -0.1

Fr.3 23.0 33.7 65.9 47-70 1 -0.1

Fr.4 10.4 8.5 91.2 70-71 0.1

Fr.5 71.6 1.2 98.6 72 0.1

Fr.6 183.6 0.0 99.6 72 0.1

Fr.7 27.6 0.0 99.5 72 0.1

Swamp 24.1

The experiment shows the distillative separation of 3 and 7.

Claims

claims

A process for the preparation of 1-methylcyclopentene by thermal reaction of cyclohexanol or cyclohexene or mixtures of both compounds to 1-methylcyclopentene, characterized in that the by-products obtained 3-methylcyclopentene and 4-methylcyclopentene (double bond isomers of 1-methylcyclopentene) in the Be attributed to implementation.

A method according to claim 1, characterized in that additionally not

reacted cyclohexene is recycled to the reaction.

A method according to claim 1 or 2, characterized in that it is carried out continuously.

Process for the preparation of cyclopentane derivatives of formula I below

C

in which X represents a hydroxyl group, an alkoxy group or a chlorine atom, by thermal reaction of cyclohexanol or cyclohexene to form 1-methylcyclopentene (1. stage) and subsequent addition of compounds HX, where X has the above meaning, to the double bond of the 1 - Methylcyclopentene (2nd stage), characterized in that the resulting by-products 3-methylcyclopentene and 4-methylcyclopentene are recycled from the product mixture of the 1st or 2nd stage in the implementation of the 1st stage.

A method according to claim 4, characterized in that X in formula I is a hydroxyl group or a C1 to C10 alkoxy group and HX is H ₂ 0 or a C1 to C10 alkanol.

A process according to any one of claims 4 or 5, characterized in that X in formula I is a C1 to C10 alkoxy group and in the second stage the C1 - to C10 alcohol is added to the 1-methylcyclopentene by a reactive distillation ,

Method according to one of claims 4 to 6, characterized in that the method is carried out continuously.

1 . Illustration

8. The method according to any one of claims 4 to 7, characterized in that the by-products obtained 3-methylcyclopentene and 4-methylcyclopentene from the product mixture of the 1st Stage in the implementation of 1. Be recycled stage. 9. The method according to claim 8, characterized in that from the product mixture of the 1. Step 1 -Methylcyclopenten and optionally water are separated and 3-methylcyclopentene and 4-methylcyclopentene and unreacted cyclohexene in the implementation of the 1 .Stufe be recycled.

Process according to one of Claims 8 or 9, characterized in that unreacted 1-methylcyclopentene and HX are recycled from the second stage product mixture to the second stage reaction.

Method according to one of claims 4 to 7, characterized in that after the 1st stage no separation and recycling of 3-methylcyclopentene and 4-methylcyclopentene takes place, and

3-methylcyclopentene and 4-methylcyclopentene from the product mixture of the 2nd stage in the implementation of the 1st Be recycled stage

A method according to claim 1 1, characterized in that product mixture of the second stage in addition to the desired cyclopentane derivative of the formula I contains the following compounds: unreacted 1-methylcyclopentene

the by-products 3-methylcyclopentene and 4-methylcyclopentene

unreacted cyclohexene

optionally water

A method according to claim 1 1 or 12, characterized in that in the case of X after the implementation of the 1. Stage no separation of water takes place.

Process according to one of Claims 1 1 to 13, characterized in that, in the case of X = OH, after the first stage, 1 to 100 mol of water per 1 mol of 1-methylcyclopentene are added.

Process according to one of Claims 1 1 to 14, characterized in that the desired cyclopentane derivative and optionally water are removed from the product mixture of the second stage and 3-methylcyclopentene and 4-methylcyclopentene and unreacted cyclohexene and 1-methylcyclopentene are reacted in the reaction of Step back.