DE10003435A1 - Synthesis of macrocyclic monomers - Google Patents

Abstract

A method for the production of a macrocyclic monomer ( for example, ethylene brassylate) comprises the following steps: treatment of a polymer (for example, polyethylene brassylate) with a supercritical fluid, under conditions which bring about a depolymerisation of the polymer to macrocyclic monomers, extraction of the macrocyclic monomer, with the supercritical fluid as extraction agent and separation of the supercritical fluid from the macrocyclic monomer. The extraction can be carried out continuously and/or simultaneous to the treatment of the polymer with the supercritical fluid.

Description

The present invention relates to a method for producing Macrocycles (macrocyclic monomers), which are used in particular in Provision of macrocycles with special organoleptic or sensory Properties can be used.

A large number of natural or synthetic macrocyclic Connections are made due to their excellent sensory properties used in perfume compositions. Examples of such connections and routes their manufacture is described in a review article by Alvin S. Williams, Synthesis 1999, 10, 1707-1723.

A number of different approaches to the synthesis of macrocyclic compounds have already been followed. The following are examples of modern types of industrial synthesis:

• - Ring expansion syntheses (starting from cyciododecanone)
• - Acyloin condensation
• - Alkyl peroxide rearrangements (story)
• - Polymerization-Depolymerization-Syntheses (Carothers)
• - transesterification syntheses (Collaud)

In addition to these types of synthesis, others are known.

The known synthetic methods generally do not allow any costs inexpensive production of macrocyclic monomers. Therefore, so far only comparatively few macrocyclic monomers in commercial use len perfume compositions, namely those in which the manufacturing costs are still in an acceptable relationship to sensory activity; as An example of such a macrocyclic monomer is the cyclic dilactone Called ethylene brassylate. Other macrocyclic monomers, however, are not to any appreciable extent despite good sensory properties used commercially because their production according to the known methods is expensive.

It was therefore the object of the present invention to develop a new Inexpensive process for the production of macrocyclic monomers specify.

This object is achieved according to the invention by specifying a method with the following measures:

• - Treating a polymer with a supercritical fluid under conditions conditions that depolymerize the polymer to macrocyclic Effect monomer
• - Extraction of the macrocyclic monomer with the supercritical fluid as an extractant,
• - Separation of the supercritical fluid from the macrocyclic monomer.

The process according to the invention can generally be applied to polymers apply in the presence of a supercritical fluid, optionally in Presence of a catalyst to form a macrocyclic Monomers are depolymerizable.

It is important for the extraction success that the macrocyclic monomer is more soluble in the supercritical fluid than the educt polymer. The The supercritical fluid becomes skilled in the art according to the requirements of the individual if selected and the process parameters (especially pressure and Temperature) so that the depolymerization and / or the extraction run optimally. If necessary, he leads this in the usual way Preliminary tests by.

The process according to the invention can be grouped into the group of polymers Classification-Depolymerization-Syntheses (Carothers) as they example from the production of macrocyclic C15 lactones (such as Cyclopentadeca nolid) or dilactones (such as ethylene brassylate) are known.  

In contrast to the process designs known to date, the process according to the invention allows depolymerization, cyclization and extraction of the macrocyclic monomer to be carried out by means of a supercritical fluid in a single process step (carried out continuously or discontinuously). The supercritical fluid usually fulfills a double function as

• a) Reaction medium for the depolymerization (and ring closure) reaction such as
• b) extractant for that which forms during the depolymerization macrocyclic monomer.

However, it is only imperative that the supercritical fluid be the radio tion (b) fulfilled.

The term "supercritical fluid" includes compounds, mixtures or elements above their respective critical pressure (p _C ) and their respective critical temperature (T _C ), but below the pressure required for the condensation to the solid. It also includes homogeneous two - or multi-component mixtures, the temperature and pressure of a respective mixture being selected such that the critical temperature and the critical pressure of the mixture or at least one, but possibly also several, substances contained in the mixture are exceeded.

In particular, the following can be used as supercritical fluid or part of one of the homogeneous two-component or multi-component mixtures mentioned:
Carbon dioxide, ethane, propane, butane, isobutane, pentane, hexane, ethene, propene, benzene, toluene, fluoroform, difluoromethane, dimethyl ether, diethyl ether, methanol, ethanol, water, ammonia, ethylenediamine, nitrogen heteracycles, nitrous oxide, sulfur dioxide, sulfur hexafluoride.

When using the method according to the invention, it is advantageous t not necessary to use the depolymerization (and ring closure) Reaction and extraction of the macrocyclic monomer from the reaction mixture in separate process steps or equipment. Rather, it is preferred to carry out the process simultaneously, in which the formed reaction product, d. H. the macrocyclic monomer, continuous (a) transferred into the supercritical fluid and (b) with it is removed from the reactor. The ongoing removal of the newly formed macrocyclic monomer from the reaction system forces its con Continuous replication with further depolymerization of the used Polymers. The and from the reaction system are advantageously removed amount of supercritical fluid loaded with the macrocyclic monomer an appropriate amount of fresh or recycled supercritical fluid replaced, preferably continuously.

The supercritical fluid removed from the reaction system becomes usual way of the extract (i.e. the macrocyclic monomer and given if any by-products of the depolymerization) separated, in the Usually through controlled pressure reduction. Other known methods the deposition from supercritical fluids such. B. rapid relaxation (RESS process), changing the temperature or adding an anti-solvent can also be used to separate the macrocyclic monomer will. The macrocyclic monomer can also by adsorption on suitable th solid phases or by absorption in corresponding solvents from Extractants are separated. The extraction and separation can also can be used to fractionate the extract, with additional parts such as Extraction columns with or without packing elements installed in the plants can be. In particular, such modifications can ensure that in addition to the macrocyclic monomer, no or only small amounts of depoly merization by-products (dimers; short-chain, non-cyclic Monomers) are separated from the reaction system. An overview of Process designs are: M. McHugh, V. Krukonis, Supercritical Fluid Extraction, Butterworths, Boston, 1986.

A continuous process is preferred, one discontinuous process design (batch operation) is also possible.

The depolymerization reaction is usually called 2-phase reaction carried out, wherein the polymer and the supercritical fluid in there are separate phases with a common phase boundary; the polymer forms the first (solid or liquid) phase and the supercritical Fluid the second. Depending on the nature of the polymer used, the  used supercritical fluid and the set process parameters (in particular pressure, temperature, quantitative ratio of supercritical fluid: polymer) it is a reaction in the system firmly supercritical or liquid supercritical.

However, the depolymerization reaction can also take place in a reaction system with more than two phases.

Performing the depolymerization reaction in one reaction system with a single phase is possible in exceptional cases, provided that Process parameters are set so that the polymer at the Depoly Merization is completely dissolved in the supercritical fluid. In this In this case, the reaction step and extraction step are preferably carried out simulatively dance. B. in a reactor with an integrated extraction column, or them take place under different conditions, either discontinuously in the same reactor, or semi-continuously in series Containers.

To accelerate the depolymerization (and ring closure) reaction can use the usual catalysts for a given polymer will. With the method according to the invention, the depolymerization of Polyesters can be carried out particularly easily, as a catalyst here, for example, that of Alvin S. Williams in Synthesis 1999, 10, 1707-1723, Scheme 35 use specified catalysts, see the Table 1 below:

Table 1 Depolymerization catalysts

KAl (ethyl digol) ₃

(OCOC ₁₇

H ₃₅

)
Bu ₂

SnO
Bu ₂

SnO + (PhO) ₃

P
Zn (OAc) ₂

2H ₂

O
MgCl ₂

Bu ₂

Sn (OH) OSn (Cl) Bu ₂

Ti (O ⁱ

Pr) ₄

on montmorillonite
Ti (OBu) ₄

PbO
(MeO) ₃

Al

There are other depolymerization catalysts in the literature called, which can also be used. Compare the Table 2 below, in addition to the corresponding references the catalysts specified therein are mentioned.

Table 2

Cahill, J., Jr .; Rodenberg, H.G. US Patent 4709058, 1986, National Destillers and Chemical Corp .; Chem. Abstr., 1988, 108, 222302 Metal or mixed metal compound of a metal from groups IIa, IIIa, IVa, IVb, Va, VIb, VIIb and VIII; Oxide, hydroxide, halide or carboxylates of aluminum, magnesium, titanium, manganese, iron, cobalt or lead; Aluminum, alkali metal or magnesium compound Nisso Petrochemical Industries Co. JP Patent 57122078, 1981, Nisso Petrochemical Industries Co .; Chem. Abstr., 1983, 98, 17178 Dibutyltin oxide Andreev, V. M .; Polyakova, S.G .; Bazhulina, V. I .; Gorbunkova, V. P .; Khochenko, I. I .; Khrustova, Z. S .; Ermachenkova, L.A. SU Patent 1077893, 1981, All-Union Scientific-Research Institute of Synthetic and Natural Perfumes; Chem. Abstr., 1986, 104, 68894. Tin catalyst Elsasser, A.F., Jr. WO Patent 9215573, 1991, Henkel Corp .; Chem. Abstr., 1993, 118, 125297 Potassium aluminum catalyst Kitamura, S .; Tobita, T .; Kanazawa, M .; Shiozaki, M. DE Patent 3225431, 1982, Nisso Petrochemical Industries Co., Ltd .; Chem. Abstr., 1984, 100, 209893 - lead compounds, such as lead nitrate, lead borate, - dialkyltin oxides, - complex catalysts - inorganic lead compounds (lead carbonate, lead sulfate) - titanium alkoxides - aluminum alkoxides - aluminum compounds DE 198 08 844 A1 (Huls AG) DE 198 08 846 A1 (Huls AG) commonly used transesterification catalysts; Sulfuric acid, phosphoric acid, sulfonic acids; Alkali metal or alcoholate; one or more magnesium, manganese, cadmium, iron, cobalt, tin, zinc, lead, aluminum, titanium compounds DE 198 08 845 A1 (Hüls AG) Trivalent iron complex compound

The person skilled in the art will find further information via the specified references Information on the specified catalysts and their use.

The invention is explained in more detail below on the basis of the synthesis of ethylene brassy by depolymerizing polyethylene brassylate in the presence of supercritical carbon dioxide; First, however, apparatuses I-IV that can be used for this purpose are described with reference to the attached FIGS. 1-4.

The apparatuses I-IV are very general for the production of macro Cyclic monomers suitable according to the inventive method, wherein Modifications to adapt to the individual case are possible. Same Reference symbols in different figures relate to components of the apparatus with at least essentially the same function. They represent:

Fig. 1 Schematic representation of the apparatus I according to the following Example 3,

Fig. 2 shows a schematic representation of the apparatus II according to the following Example 4,

Fig. 3 Schematic representation of the apparatus III according to the following Example 5,

Fig. 4 Schematic representation of the apparatus IV.

For apparatus I, see FIG. 1

The apparatus I used in the following example 3 and shown in FIG. 1 comprises a fresh gas storage container 1 , a compressor 2 for compressing the fresh gas, a reactor 3 (with thermostat 6 ) for carrying out depolymerization reactions, and a heated valve 4 for decompressing one supercritical extractant and a separator 5 (e.g. comprising a glass jar for collecting the extract).

To carry out the process according to the invention, the polymer sat or the polymer-catalyst mixture is introduced into the reactor 3 and heated to the desired reaction or extraction temperature. From the storage container 1 , the fresh gas compressed by the compressor 2 (extractant, eg carbon dioxide) is passed through the polymer (mixture) via an immersion tube. The extractant is taken off from the top of the reactor and expanded via a heated valve 4 , the macrocyclic monomer including any by-products collecting in the separator 5 . The gaseous extractant emerging from the separator 5 can be returned to the fresh gas.

For apparatus II, see FIG. 2

The apparatus II used in the following example 4 and shown in FIG. 2 comprises, in addition to the apparatus components already known from apparatus I, a separately heated extraction column 7 which is placed on the reactor 3 and which is assigned a control unit 8 .

To carry out the process according to the invention, the polymer or the polymer-catalyst mixture is introduced into the reactor 3 and heated to the desired reaction or extraction temperature. From the storage container 1 , the fresh gas (extractant) compressed by means of the compressor 2 is passed through the polymer material via an immersion tube. The extractant is removed overhead from the extraction column 7 placed on the reactor 3 and expanded via the heated valve 4 , the macrocyclic monomer including any by-products collecting in the separator 5 . The extractant gaseous from the separator 5 can be fed back to the fresh gas.

For apparatus III, see FIG. 3

The apparatus III used in the following example 5 and shown in FIG. 3 comprises, in addition to the apparatus components already known from apparatus I, a heat exchanger 9 which is connected upstream of the reactor 3 and to which a control unit 10 is assigned.

To carry out the process according to the invention, the polymer or the polymer-catalyst mixture is introduced into the reactor 3 and heated to the desired reaction or extraction temperature. From the storage container 1 , the fresh gas (extracting agent) compressed by the compressor 2 and heated by the heat exchanger 9 (with control unit 10 ) is passed through the polymer material from below. The Ex traction agent is removed from the top of 3 and expanded via the heated valve 4 , the macrocyclic monomer including any by-products collected in the separator 5 . The extractant gaseous from the separator 5 can be fed back to the fresh gas (see, for example, apparatus IV).

For apparatus IV, see FIG. 4

The apparatus IV shown in FIG. 4 comprises, in addition to apparatus components already known from 7 apparatus I, a device for leading the extraction agent back into the reactor. This device comprises a condenser 12 (with Kryomat 13 ) for liquefying the gas escaping at the separator 5 , a pump 14 connected downstream of the condenser 12 and a gasifier 15 connected downstream (with thermostat 16 ), which is connected to the line from compressor 2 via a valve Reactor 3 is connected.

In addition, a removal valve 11 is assigned to the separator 5 .

To carry out the process according to the invention, the polymer or the polymer-catalyst mixture is introduced into the reactor 3 and heated to the desired reaction or extraction temperature. The apparatus is filled with fresh gas from the storage container 1 , which is compressed to the desired operating pressure with the aid of the compressor 2 . The extractant is circulated in the apparatus with the aid of components 12-15 , the macrocyclic monomer including any by-products collecting in the separator 5 , which can be removed via the valve 11 . Possibly. Losses of extractant are continuously replaced by fresh gas from the storage container 1 .

example 1 Production of a be essentially from polyethylene brassylate standing polymer

100 g (0.55 mol) of cyclododecanone, 177 g (1.51 mol) of Diethyl carbonate and 46 g (0.85 mol) of sodium methylate and 4 h heated under reflux (about 130 ° C). After cooling to room temperature a solution of 100 g of sulfuric acid conc. slowly in 750 g of water dripped. The aqueous phase was separated off and mixed with 200 ml of hexane ex trahed. The combined organic phases were washed with 250 ml of water washed. Then was first hexane (at normal pressure), then excess diethyl carbonate (at reduced pressure, approx. 35 mbar) distilled off.

The crude mixture obtained in this way (approx. 175 g, which according to gas chromatogram 88% by weight Brassyl acid diethyl ester and / or methyl ester contained) was with 50 g of ethylene glycol, 260 mg of sodium methylate and 20 ml of methanol are added. It was first heated at about 190 ° C for 1 h; about 33 g went one Methanol / ethanol mixture over. Then was under reduced pressure (see above) and heated to 190 ° C until no excess ethylene glycol more passed over.

In this way, 170 g of an essentially made of polyethylene brassylate existing polymer obtained when cooling to room temperature became firm.  

Example 2 Determination of the proportion of ethylene brassylate in the polymer from example 1

2.4 g of the polymer from Example 1 were with just as much Ethyl ester displaces everything in the warmth. Then was neutral filtered with ethyl acetate through an alumina column. The Solvent was removed, the residue was taken up in diethyl ether and filtered. After the solvent had been stripped off again, 160 mg were obtained a residue, which according to gas chromatogram from 9.8 area percent Ethylene brassylate existed. This corresponds to approximately 0.65% of the used Total mass of polymer.

The process parameters chosen in the examples below (Pressure, temperature, flow rate) can the specialist according to the The requirements of the individual case vary:

Example 3 Preliminary test for the extraction of ethylene brassylate from a Mixture with the polymer according to Example 1

30 g of the polymer from Example 1 and 30 g of ethylene brassylate (purity according to GC 95%) were stirred in a glass flask at 100 ° C. for 5 hours. The mixture was placed in reactor 3, preheated to 80 ° C., of a plant in accordance with apparatus I (see above), and the inlet tube with a lid was placed on it. The jacket temperature of the reactor 3 was increased to 100 ° C. Then carbon dioxide was passed through the apparatus I at a pressure of 200 bar and expanded at a flow rate of 500 l / h via the heated valve 4 , the extract being collected in a glass vessel (separator) 5 . In this way, 18.2 g of extract were separated in 300 minutes. According to GC analysis, the extract contained 92.1 area percent ethylene brassylate.

Example 4 Obtaining ethylene brassylate by depolymerization / extraction tion of the polymer from Example 1

1.6 g of aluminum stearate and 0.6 g of sodium stearate were added to 52.4 g of polymer according to Example 1 and this mixture was stirred in a glass flask at 100 ° C. for 48 hours. The mixture was then placed in reactor 3, preheated to 80 ° C., in a plant in accordance with apparatus II (see above), and the inlet tube with a lid was placed on it. The jacket temperature of the reactor 3 was set to 300 ° C and the jacket temperature of the extraction column 7 to 150 ° C. Then carbon dioxide was passed through the apparatus II at a pressure of 200 bar and expanded at a flow rate of 500 l / h via the heated valve 4 , the extract being collected in a glass vessel (separator) 5 .

1.78 g of extract were separated in this way within 9 hours. The According to the gas chromatogram, the extract contained 48.5 area percent ethylene brassy lat. This corresponds to approx. 1.7% of the total mass of polymer used.

Example 5 Obtaining ethylene brassylate by depolymerization / extraction tion of the polymer from Example 1 after thermal pre treatment Thermal pretreatment

To 70.1 g of a consisting essentially of polyethylene brassylate The polymers according to Example 1 were 1.6 g of aluminum sterate and 0.6 g Given sodium sterate and this mixture for 20 hours at 220 ° C in one Glass flask stirred.

This pretreatment was used for homogenization, but did not lead to an appreciable formation of ethylene brassylate, as in Example 2 was proven. See also Example 6 below.

Reaction / extraction

The mixture present after the pretreatment was placed in the reactor 3, preheated to 80 ° C., of a plant in accordance with apparatus III (see above), the cover put on and the jacket temperature of the reactor 3 increased to 350 ° C. Then, carbon dioxide, preheated to 260 ° C., was passed through apparatus III at a pressure of 200 bar and expanded at a flow rate of 500 l / h via heated valve 4 , the extract being collected in a glass vessel (separator) 5 .

13.1 g of extract were separated in this way within 26 hours. The According to the gas chromatogram, the extract consisted of 45 area percent ethylene brassylate. This corresponds to the amount of polymer used a yield of about 8.3%.

Example 6 Obtaining ethylene brassylate by depolymerization / extraction of the polymer from Example 1 after prior cleaning of the polymer by extraction with CO ₂ Extractive cleaning of the polymer

70.0 g of a polymer essentially consisting of polyethylene brassylate according to Example 1 were placed in a reactor of a plant according to apparatus III, the lid was put on and the jacket temperature of the reactor 3 was raised to 230 ° C. Then carbon dioxide preheated to 240 ° C. was passed through the apparatus at a pressure of 200 bar and expanded at a flow rate of 500 l / h via a heated valve 4 , the extract being collected in a glass vessel. 1.92 g of extract were separated off within 12.5 hours, which according to GC analysis contained 17.7 area percent ethylene brassylate and the rest of its composition largely corresponded to the low-molecular-weight impurities in the polymer.

Reaction / extraction

After cooling to 30 ° C. and releasing the pressure, the reactor 3 was opened and 1.6 g of aluminum stearate and 0.6 g of sodium stearate were added to the purified polymer with heating to 80 ° C. while stirring. After the lid was put on, the jacket temperature of the reactor was increased to 330 ° C. Then carbon dioxide preheated to 240 ° C. was passed through the apparatus at a pressure of 200 bar and expanded at a flow rate of 500 l / h via the heated valve 4 , the extract being collected in a glass vessel. Within 22 hours, 6.94 g of extract were separated which, according to GC analysis, contained 68.7 area percent of ethylene brassylate. This corresponds to approx. 6.8% of the total mass of polymer sat.

Claims (7)

1. A process for the preparation of a macrocyclic monomer, comprising the following measures:

• Treating a polymer with a supercritical fluid under conditions that cause the polymer to depolymerize to the macrocyclic monomer,
• Extraction of the macrocyclic monomer with the supercritical fluid as the extraction agent,
• - Separation of the supercritical fluid from the macrocyclic monomer.

2. The method according to claim 1, characterized in that the extraction continuously and / or simultaneously for the treatment of the polymer with the supercritical fluid is carried out. 3. The method according to any one of the preceding claims, characterized records that the depolymerization in a system of two or more Phases is carried out, the polymer and the supercritical Fluid in separate phases with a common phase boundary. 4. The method according to any one of the preceding claims, characterized records that the depolymerization in the presence of a catalyst he follows. 5. The method according to any one of the preceding claims, characterized records that the polymer is a polyester which forms a Lactons depolymerized. 6. The method according to claim 5, characterized in that the polymer Polyethylene brassylate is that which forms ethylene brassylate depolymerized.   7. The method according to any one of claims 5 or 6, characterized in that that carbon dioxide is used as the supercritical fluid.