JPS6239157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing macrocyclic ethylenedioate, and more particularly, to an industrially significantly improved method for producing highly purified macrocyclic ethylenedioate in a high yield by a simple method. Regarding the manufacturing method.

Macrocyclic ethylenedioate, represented by ethylene brasylate, generally has a jacquard-like aroma and is a compound useful as a musk fragrance. As is well known, this compound is produced by reacting the corresponding aliphatic dicarboxylic acid or its lower alkyl ester with ethylene glycol or aliphatic dicarboxylic acid and ethylene oxide to form a linear polyester, and then subjecting this polyester to thermal depolymerization and ring closure. This thermal depolymerization and ring closure reaction is usually carried out under heating and reduced pressure in the presence of a catalyst.

That is, the general production method found in the prior art uses dicarboxylic acid or its lower alkyl ester and ethylene glycol, or dicarboxylic acid and ethylene oxide, and if necessary, in the presence of a polycondensation catalyst, which can be exemplified by an antimony compound. 200
Polycondensation is performed at a temperature of ~300°C under a pressure of 0.1 to 20 mmHg to produce a linear polyester, and then a depolymerization catalyst is added and depolymerization is performed under a pressure of 0.1 to 20 mmHg to close the ring to produce cyclic ethylene. A method has been adopted in which cyclic ethylene dioate is obtained by collecting dioate by distillation and rectifying this fraction. Here, lead compounds (JP-A No. 48-26790) and organotin compounds (JP-A No. 52-1989) are used as depolymerization catalysts.
No. 51385) Aluminum compounds (JP-A-1983-
115390) Composites of lead compounds and metal alkoxides (Japanese Patent Application Laid-Open No. 53-84986) have been proposed, but when these previously disclosed catalysts are used, the desired depolymerization and ring-closing reaction cannot be carried out simultaneously. Polycondensation of the linear polyester in the reaction system and intermolecular cross-linking reaction occur, resulting in a significant increase in the viscosity of the residue, making stirring extremely difficult and significantly impairing heat transfer, resulting in a decrease in yield. changes due to uneven heating, generation of cracked gas, and the gradient of distilled cyclic ethylenedioate.
There were various drawbacks such as poor quality such as color.

As a method to solve the drawback that the viscosity of the residue becomes high due to depolymerization, an example of adding an inert solvent with a high boiling point during depolymerization (Japanese Patent Application Laid-Open No. 53-56681)
The solvents used in this method are liquid paraffin and solid paraffin, and as is well known, these solvents do not dissolve the linear polyester mentioned above, but have a high viscosity. of the polymer is dispersed in a medium of relatively low viscosity; therefore, in some cases, the polymer may aggregate into large particles, and the use of a large amount of medium significantly reduces the efficiency of reactor utilization. I do things. Alternatively, the distilled cyclic ethylenedioate and the solvent dissolve in each other, requiring a complicated operation for separation. Alternatively, a method of depolymerization in the presence of polyoxyalkylene glycols and their derivatives, high-boiling monohydric alcohols, monohydric fatty acids and their derivatives (Japanese Unexamined Patent Application Publication No. 1987-1999)
No. 120581) has been proposed, but in this method, the ether bonds of the added polyoxyalkylene glycol decompose to produce various decomposition products, and decomposition gas is generated significantly, leading to a decrease in the degree of vacuum. Deteriorates the quality of cyclic ethylenedioate. Another disadvantage is that a gradient of monohydric alcohol, monohydric fatty acid, and their derivatives may be mixed into the distilled cyclic ethylenedioate, adversely affecting the aroma of the fragrance.

In order to solve these problems all at once, the present inventors conducted various studies on depolymerization reaction methods, and found that ethylene glycol or/and depolymerization with a low degree of polycondensation was added to the depolymerization reaction system before the viscosity increased. The present invention was achieved by discovering an extremely simple method of adding the same type of oligoester as that used in .
That is, _the present _invention provides aliphatic dicarboxylic acids or The ester and ethylene glycol or aliphatic dicarboxylic acid and ethylene oxide are polycondensed to form a linear polyester, which is thermally depolymerized to form the following general formula: (In the formula, l represents a positive integer of 6 to 14.) In producing the cyclic ethylenedioate represented by the formula, ethylene glycol or/and linear average This is a method for producing cyclic ethylenedioate characterized by adding an oligoester of the same type as that to be subjected to depolymerization having an average molecular weight of dimer or more up to 20-mer. Here, the average molecular weight is determined by measuring the dehydrated weight, the weight of lower alcohol removed, or the weight of ethylene glycol removed during oligoester production, or by measuring the hydroxyl value of the oligoester.

According to the method of the present invention, it is possible to prevent the residual polymer from becoming highly viscous, and therefore, there is no crosslinking reaction due to uneven heating, generation of cracked gas, generation of by-products, and reduction in the activity of the depolymerization catalyst. High purity cyclic ethylenedioate can be obtained in high yield. In addition, if oligoester is used for addition, it is possible to virtually eliminate the reduction of residual polymer, so depolymerization can be carried out continuously for a long time, and the utilization efficiency of the depolymerization reactor can be significantly increased. The present invention also has excellent ripple effects, such as when depolymerization is completed at the stage and the residual polymer can be dissolved and discharged very easily by adding a compound such as ethylene glycol if necessary. It is something.

Although the mechanism of effect in the method of the present invention is not clear in detail, it is believed that the addition of ethylene glycol or/and oligoester causes low polymerization disproportionation of the residual polymer, resulting in lower viscosity and easier stirring and heat transfer. At the same time, as previously thought,
This is thought to be because ring-closing depolymerization does not necessarily require a sufficiently high molecular weight polyester, and even oligomers with a much lower degree of polycondensation can undergo ring-closing depolymerization very easily. In particular, when ethylene glycol is used, it is believed that the produced cyclic ethylenedioate is accompanied by the ethylene glycol having a low boiling point and can be easily distilled out. In this case, even low molecular weight esters such as linear duplexes are not distilled out under depolymerization conditions.

In the present invention, the aliphatic dicarboxylic acids and esters thereof used as raw materials include suberic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, brassylic acid, dodecane-1.
12-dicarboxylic acid, tridecane-1,13-dicarboxylic acid, thapsic acid and their methyl, ethyl, n-propyl, isopropyl, n-butyl,
Isobutyl, secondary butyl or tertiary butyl ester. Moreover, all conventionally known depolymerization catalysts can be used as the depolymerization catalyst. For example, lead compounds such as lead nitrate and lead borate, dialkyl tin oxide, lead carbonate,
Examples include composite catalysts of inorganic lead compounds such as lead sulfate and alkali (alkaline earth, aluminum) alkoxides, aluminum alkoxides, aluminum compounds having carbonate groups, titanium alkoxides, and the like. The amount of these depolymerization catalysts used is usually 0.1 to 10 wt% based on the dicarboxylic acid used as a raw material.

The ethylene glycol to be added may be one that is normally obtained industrially, and is preferably the same type as that used for the polyester that is the raw material for depolymerization. Further, the oligoester may be obtained by a polycondensation process of ethylene glycol and dicarboxylic acid or a lower ester thereof, or ethylene oxide and dicarboxylic acid, which will be described later, and has an average molecular weight equal to or higher than that of an average dimer, and Since the addition has the effect of lowering the viscosity, a compound having a molecular weight equal to or less than an average 20-mer is used. The degree of polycondensation is easily determined by the amount of dehydration (amount of lower alcohol removed) or the amount of ethylene glycol removed during polycondensation, or by the hydroxyl value of the oligoester.

In the method of carrying out the present invention, 1 to 2 moles of ethylene glycol (or ethylene oxide) are used per mole of dicarboxylic acid or its ester, and polycondensation is carried out under heating by dehydration or dealcoholization and deethylene glycol to obtain a linear polyester. Although the linear polyesterification normally proceeds without a catalyst, a polycondensation catalyst such as antimony trioxide may be used to accelerate the reaction.

The polycondensation is finally carried out, as is well known, at a temperature of 200 DEG to 250 DEG C. under a pressure of 1 to 760 mm Hg. The degree of polycondensation is determined by the polycondensation conditions, but any degree of polycondensation may be used as long as it is dimer or higher and the purpose of the present invention can be sufficiently achieved.

The depolymerization ring-closing reaction is effective by continuously distilling the cyclic ethylenedioate produced from the polyester containing the depolymerization catalyst under a pressure of 0.1 to 5 mmHg and a temperature of 230 to 300°C out of the reaction system. It can be done accurately. Since the viscosity of the residue increases as cyclic ethylenedioate is distilled off, ethylene glycol or/and the aforementioned oligoester are added at any stage. These compounds may be added intermittently as the viscosity increases, or more rationally, they may be added continuously. In either case, ethylene glycol is distilled out together with cyclic ethylenedioate, but it is most common when only ethylene glycol is added, followed by oligoester.
It decreases depending on the degree of polycondensation. The two distilled compounds separate into two layers, so they can be easily separated.
Ethylene glycol can be recycled. When adding only ethylene glycol,
As the cyclic ethylenedioate is distilled off, the residual polymer gradually decreases, so either the depolymerization can be stopped and the raw material polyester is charged again, or the depolymerization can be restarted after starting from polycondensation.

Furthermore, when oligoester is added, the amount of residual polymer in the system can be kept constant, so the depolymerization reaction can be carried out continuously for an extremely long time, but the side reactions that occur are very small. The depolymerization may be stopped and discharged at a point where the quality of the residual polymer deteriorates or maintenance of the reaction equipment is required. In addition, the depolymerization catalyst is added to the polyester at the time of initial preparation, and the added glycol or oligoester may be used without any addition, or a part of the catalyst may be added to the prepared polyester.
Even if a part of the catalyst is added to the added glycol or oligoester, the effects of the present invention are the same.

By rectifying the product fraction thus distilled as necessary, it is possible to obtain cyclic ethylenedioate with high purity and a pleasant aroma.

Thus, according to the method of the present invention, depolymerization can be carried out continuously for a long time under virtually any viscosity, and high yields and high purity can be obtained using simple stirring equipment with low power. Cyclic ethylenedioate can be obtained.

The effects of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 100 g of methyl brassylate and 51 g of ethylene glycol were placed in a reactor equipped with a stirrer equipped with distillation equipment and a torque meter, and heated under normal pressure at 180 to 230°C for 3 hours with stirring to remove methanol. Ethylene glycol was distilled out at 130-200° C. under a pressure of ˜10 mmHg to produce polyethylene brassylate. Next, 0.2 g of dibutyltin oxide was added, the degree of vacuum was set to 0.5 mmHg, and the temperature was gradually raised. From 245°C, a depolymerization and ring closure reaction occurred, and cyclic ethylene brasileate began to be distilled out. When about 10g was distilled out after 30 minutes, the torque was
When it reached 3.5Kg・cm (rotation speed 100rpm), we started adding ethylene glycol. Since the distilled cyclic ethylene brasylate and ethylene glycol were separated into two layers, the ethylene glycol in the lower layer was added by circulation. This operation was carried out at an internal temperature of 260 to 270°C for 8 hours. The amount of ethylene glycol added in circulation during this period was 60g, and the stirring torque was 1.0 to 1.5Kg・cm.
(rotation speed 100 rpm). Further, the yield of cyclic ethylene brasylate was 93 g, and the purity was 98.0%.

Comparative Example 1 Polycondensation and depolymerization were carried out in the same manner as in Example 1, except that ethylene glycol was not added. After 1 hour, 16 g was distilled out, and the torque was over 6 Kg cm (rotation speed 100 rpm). Stirring was stopped.
Thereafter, depolymerization was carried out at an internal temperature of 260 to 270° C. for 8 hours without stirring, and 45.3 g of cyclic ethylene furacylate was obtained.

Example 2 Production of oligomer for addition 2.2 mol of ethylene glycol per 1 mol of dodecanedioic acid was placed in a reactor equipped with distillation equipment and a stirrer, heated to 150-210°C for 2 hours to dehydrate, and then heated to 210-230°C. The mixture was heated for 1 hour to perform an ethylene glycol removal reaction and produce an oligomer. The average molecular weight of this oligomer was determined to be approximately 500 by removing ethylene glycol and measuring the hydroxyl value.

Depolymerization 50g of the above oligomer and stannous laurate
0.25g was placed in a reactor equipped with distillation equipment, a stirrer attached to a torque meter, and an inlet tube for oligoester addition, and gradually heated under a pressure of 0.5mmHg. At first, only a small amount of ethylene glycol was distilled out, and then the temperature reached 240°C. Depolymerization occurred and cyclic ethylene dodecanedioate was distilled out. 7.5g after about 1 hour
When distilled, the torque is 3.5Kg・cm (rotation speed
100 rpm), the addition of oligomer was started. The torque gradually decreased to 2~2.5Kg・cm. Oligomer at 260-270℃ for 25 hours
665g added cyclic ethylene dodecanedioate 664
I got g. The torque at that time is 2.5Kg・cm (rotation speed
100rpm).

Comparative Example 2 Depolymerization was carried out in the same manner as in Example 2, except that no oligomer was added. After about 1.5 hours, about 10 g of cyclic ethylene dodecanedioate was distilled out, and the torque was over 6 kg cm, so stirring was stopped. It became difficult and the depolymerization was stopped.

Example 3 Production of oligomer for addition 2.2 mol of ethylene glycol per 1 mol of dodecanedioic acid was placed in a reactor equipped with distillation equipment and a stirrer, heated to 150 to 210°C for 2 hours to dehydrate, and then
The mixture was heated at 210 to 230°C for 1 hour to perform an ethylene glycol removal reaction to produce an oligomer. The average molecular weight of this oligomer was determined to be approximately 1000 by measuring the amount of ethylene glycol removed and the hydroxyl value.

Depolymerization 50 g of the aforementioned oligomer, 0.1 g of dibutyltin oxide, and 0.1 g of stannous laurate were placed in a reactor equipped with distillation equipment, a stirrer equipped with a torque meter, and an inlet tube for adding the oligoester.
When heated gradually under a pressure of 0.5 mmHg, only a small amount of ethylene glycol was distilled out, and then depolymerization occurred at 240°C and cyclic ethylene dodecanedioate was distilled out. About 1 hour later, when 7.3 g was distilled out, the torque reached 3.5 Kg·cm (rotation speed: 100 rpm), so addition of the aforementioned oligomer was started. 600g of oligomer was added in accordance with the distillation rate under the conditions of 260-270℃ for 20 hours, and cyclic ethylenedioate was
Obtained 590g. During this period, the torque is 2.0 to 2.8Kg・cm
(rotation speed 100 rpm).

Example 4 Production of oligomer for addition An oligomer was produced in the same manner as in Example 2 from sebacic acid and ethylene glycol using the same reactor as in Example 2. The molecular weight of this oligomer was determined to be approximately 500 by measuring the amount of ethylene glycol removed and the hydroxyl value.

Depolymerization 50g of the above oligomer and stannous laurate
Example 2: 0.2 g and 0.2 g of dibutyltin oxide
The mixture was placed in a reactor in the same manner as in Example 2, and depolymerized in the same manner as in Example 2. Distillation of cyclic ethylene sebacate began at 240° C., and about 10 g was distilled out after about 1 hour, when the torque reached 4 kg·cm, so the addition of the oligomer was started. 550 g of oligomer was added in accordance with the distillation rate under conditions of 260 to 275°C to obtain 541 g of cyclic ethylene sebacate. During this time, the torque is 1.5 to 2.0
Kg・cm (rotation speed 100 rpm).

Comparative Example 3 Depolymerization was carried out in the same manner as in Example 4, except that no oligomer was added. When 12 g of cyclic ethylene sebacate was distilled out after about 1.5 hours, the torque was reduced.
Since the weight exceeded 5.5Kg・cm, stirring became difficult.
Depolymerization was stopped.

Claims (1)

[Claims] 1 General formula ROOC (CH ₂ ) _l COOR (where l is 6 to
is a positive integer of 14, and R represents either a hydrogen atom or a lower alkyl group. ) A linear polyester is obtained by polycondensing an aliphatic dicarboxylic acid or its ester represented by ethylene glycol or an aliphatic dicarboxylic acid and ethylene oxide, and the polyester is thermally depolymerized to obtain the general formula (In the formula, l represents a positive integer of 6 to 14.) In producing cyclic ethylene dioleate, at any stage of depolymerization, ethylene glycol or/and on average 2 or more A method for producing cyclic ethylenedioate, which comprises adding an oligoester of the same type as that to be subjected to depolymerization having an average molecular weight corresponding to up to a 20-mer. 2. The production method according to claim 1, wherein ethylene glycol is added at any stage of depolymerization. 3. The manufacturing method according to claim 1, which comprises adding at any stage of the depolymerization an oligoester of the same type as that to be subjected to depolymerization and having an average molecular weight corresponding to an average of dimers to 20-mers. .