CN103193969B - N, N-dimethylaniline-alcohol-based magnesium catalyst, as well as preparation method and application thereof - Google Patents

Abstract

The invention discloses a N,N-dimethylaniline-magnesium alcohol catalyst. The structural formula is shown in the following formula (I), where R ₁ and R ₂ are all selected from the following groups: C1-C4 straight Alkanyl, C5-C6 cycloalkyl, hydrogen, aryl or aryl with substituents, _R1 and _R2 are the same or different, and _R3 is C1-C4 linear alkyl. The invention also discloses its preparation method and application. The preparation method of the catalyst is simple, and the obtained catalyst has various structures, high catalytic activity and high stereoselectivity, and can be used to catalyze the ring-opening polymerization reaction of lactide, and the polymerization reaction process is simple. Using the usual solution polymerization method, it can occur at a relatively low temperature and the conditions are mild. The resulting polymer has high yield, less metal residue, molecular weight from several thousand to 700,000, and wide selectivity.

Description

N, N-dimethylaniline-magnesium alcohol catalyst and its preparation method and application

technical field

The present invention relates to a catalyst for ring-opening polymerization of lactide, in particular to a catalyst for N,N-dimethylaniline-alcohol-based magnesium, its preparation method and its application as a catalyst for ring-opening polymerization of lactide .

Background technique

Due to its excellent biocompatibility and non-toxicity, polylactide has been widely studied in drug controlled release, surgical sutures, fracture internal fixation materials, etc. It is the most widely studied and most widely used degradable biomaterial so far.

At present, the preparation of polylactide usually adopts the method of ring-opening polymerization, that is, lactide is prepared under the action of an initiator system to prepare high-molecular-weight polylactide. Lactide has three stereoisomers of L-lactide, D-lactide and meso-lactide. Therefore, polylactide has a variety of sequence structures, including isotactic, syndiotactic stereotactic, heterogeneous stereotactic and block stereotactic.

Polylactide with different sequence structures can be obtained from different raw materials. The sequence structure of polylactide determines the properties of polylactide to a large extent: atactic and heterogeneous stereoregular polylactide are amorphous polymers, They can be obtained by the polymerization of meso-lactide or racemic-lactide. Isotactic, syndiotactic and block-tactic polylactides are all crystallizable polymers. Among them, isotactic polylactide can be polymerized from pure L-lactide or pure D-lactide, and the melting point of high molecular weight isotactic lactide is about 180 oC. The melting point of the racemic mixture of lactide and poly-D-lactide is about 230 ^o C. Syndiotactic and block stereotactic polylactides have only been synthesized in recent years. They can only be obtained by stereoselective polymerization of lactide, and this polymerization reaction must be carried out with the aid of catalysts with special stereoselectivity. There are many catalysts that have been studied, such as complexes of magnesium, calcium, germanium, tin, aluminum, zinc, iron, titanium, zirconium, lanthanides, etc. These catalysts can inhibit possible transesterification reactions during polymerization and control Polymer stereo configuration and molecular weight. In addition, since polylactide materials are widely used in the field of biomedicine, the catalyst should not only have good catalytic performance, but also be non-toxic and have less residue.

As can be seen from the above description, the catalyst has a significant impact on the formation of syndiotactic and block stereotactic polylactide, and the quality of the catalyst directly affects the quality of the resulting product and the degree of polymerization difficulty. Therefore, it is always important to study catalysts with good catalytic performance. Hotspots in this field.

Magnesium-based catalysts have attracted the attention of scientists due to their relatively high catalytic activity, less metal residues, and non-toxicity. Due to the small ionic radius of magnesium, organic magnesium is easy to dimerize when it reacts with the ligand, which reduces the catalytic activity of the catalyst. The ligand with large steric hindrance is beneficial to protect the central metal magnesium from dimerization inactivation, so the magnesium system The ligands of the catalyst need a large steric hindrance, such as diimine or nitrogen-silicon ligands, so the choice of ligands is one of the key factors affecting the performance of magnesium-based catalysts.

Contents of the invention

The present invention provides a kind of, N,N-dimethylaniline-alcohol magnesium catalyst, this catalyst is suitable for lactide ring-opening polymerization reaction, can obtain polymer rapidly at lower temperature, has high catalytic activity, can catalyze Internal and internal racemic lactide with good stereoselectivity. the

The invention also provides a preparation method of the catalyst, which is simple in operation and convenient for implementation.

The invention also provides the application of the catalyst in lactide polymerization, which is especially suitable for catalyzing the ring-opening polymerization of L-lactide, D-lactide, racemic lactide and meso-lactide.

The present invention uses a class of N, N-dimethylaniline-alcohols with large steric hindrance as ligands to synthesize N, N-dimethylaniline-alcohol-based magnesium catalysts. During the ring-opening polymerization of ester, the polymerization reaction can occur at room temperature or even lower temperature, the reaction is fast and the yield is high; when polymerizing racemic lactide, polylactide with heterogeneous stereoregular structure can be obtained. Esters, works very well.

Technical scheme of the present invention is as follows:

A N, N-dimethylaniline-alcohol-based magnesium catalyst is characterized in that: the structural formula is shown in the following formula (I), wherein R ₁ and R ₂ are all selected from the following groups: C1-C4 straight Alkanyl, C5-C6 cycloalkyl, hydrogen, phenyl or aryl with substituents; R ₃ is C1-C4 straight-chain alkyl; wherein, R ₁ and R ₂ can be the same or different .

In the above catalyst, the aryl substituent is selected from C1-C4 alkyl, C1-C4 alkoxy or halogen, and the number of substituents is 1-2. Preferably: the aryl group with substituents is o-fluorophenyl, o-bromophenyl, o-methylphenyl, p-methylphenyl or p-methoxyphenyl.

Among the above catalysts, R ₁ and R ₂ are preferably selected from the following groups: hydrogen, methyl, ethyl, cyclopentyl, cyclohexyl, phenyl, o-fluorophenyl, o-bromophenyl, o-methyl Phenyl, p-methylphenyl or p-methoxyphenyl, R1 and R2 are the same or different.

The present invention also provides N, the preparation method of N-dimethylaniline-alcohol base magnesium catalyst, it is characterized in that comprising the following steps:

(1) Preparation of the ligand: Dissolve N, N-dimethylaniline in dry ether, add n-butyllithium in an equimolar amount to N, N-dimethylaniline, and then ) add tetramethylethylenediamine, react at room temperature for 12 hours, and then add an aldehyde or ketone substituted with aryl or alkyl in an equimolar amount to N, N-dimethylaniline, react at room temperature for 12 hours, and then add The aqueous solution of ammonium chloride stops the reaction, separates the liquid, and collects the organic phase. The organic phase is dried over anhydrous sodium sulfate, and the solvent is spin-dried to obtain the crude product. The crude product is recrystallized with hexane to obtain the N, N-dimethylaniline-alcohol ligand. The structural formula is shown in formula (II), wherein, R ₁ , R ₂ are C1-C4 linear alkyl, C5-C6 cycloalkyl, hydrogen, phenyl or aryl with substituents, R1, R2 is the same or different, and R1 and R2 are introduced by aryl-substituted aldehydes or ketones; or alkyl-substituted aldehydes or ketones;

(2) Preparation of catalyst: Add N, N-dimethylaniline-alcohol ligand into the organic solvent, then add dialkylmagnesium in an equimolar amount to the ligand at -10-0°C, and use The reaction solution naturally rises to room temperature, and then reacts the reaction solution at 20-110°C for 1-12 hours. After the reaction, the solvent is evaporated to obtain a crude product, and the crude product is recrystallized to obtain N, N-dimethylanilino-alcohol Magnesium catalyst.

The reaction formula is as follows:

In the above catalyst preparation method, the reaction is carried out under the protection of an inert gas.

In the above catalyst preparation method, the dialkylmagnesium molecular formula is (R ₃ ) ₂ Mg, and R3 is a C1-C4 linear alkyl group, such as dimethylmagnesium, diethylmagnesium, dipropylmagnesium, dibutylmagnesium base magnesium. Dialkylmagnesium and ligand are added in equimolar proportions.

In the catalyst preparation method above, the organic solvent is C5-C10 saturated alkane, C5-C10 aromatic hydrocarbon or C5-C10 halogenated alkane, and the organic solvent is preferably hexane, toluene, methylene chloride or chloroform. The organic solvent provides an organic environment for the reaction, and its dosage is generally 5 to 40 times the total mass of the reaction raw materials.

In the above catalyst preparation method, the solvent used for recrystallization is preferably hexane.

The present invention also provides the application of the above-mentioned N,N-dimethylaniline-alcohol magnesium catalyst, which can be used as a catalyst for the ring-opening polymerization of lactide, and the lactide can be L-lactide, D- One or both of lactide, racemic lactide, and meso lactide. the

The N,N-dimethylaniline-alcohol magnesium compound is used as a catalyst to carry out the ring-opening polymerization of lactide, the reaction rate is very fast, the obtained product has high molecular weight, high stereoselectivity and less metal residue. In particular, it can catalyze the polymerization of meso or racemic lactide to obtain stereoregular polymers (see Figure 4).

In the above application, the ring-opening polymerization of lactide specifically includes the following steps: mixing N,N-dimethylaniline-magnesium alcohol catalyst, organic solvent, alcohol co-catalyst and lactide (monomer), Under the protection of no oxygen and inert gas, the polymerization ring-opening reaction is carried out, and the reactants are processed after the reaction to obtain polylactide.

In the above ring-opening polymerization reaction, the organic solvent used in the reaction is toluene, dichloromethane or tetrahydrofuran, preferably tetrahydrofuran.

In the above-mentioned ring-opening polymerization reaction, the alcohol co-catalyst is benzyl alcohol or isopropanol.

In the above ring-opening polymerization reaction, the molar ratio of cyclic lactone to N, N-dimethylaniline-magnesium alcohol catalyst is 30-2000:1, and the alcohol co-catalyst and N, N-dimethylaniline-magnesium alcohol The molar ratio of the catalyst is 1-4:1.

In the above ring-opening polymerization reaction, the polymerization reaction temperature is -20-110°C, preferably 0-70°C, most preferably about 20-30°C. The catalyst of the invention has high catalytic activity, wide adaptable temperature range, fast reaction at room temperature and good effect.

According to the molecular weight of the obtained polymer, the reaction time can be 0.1-600 minutes, and generally a polymer product with a molecular weight of less than 700,000 can be obtained within 0.1-30 minutes.

In the above ring-opening polymerization reaction, ethanol is added after the reaction to precipitate polylactide, and the precipitate is washed and vacuum-dried at room temperature to obtain polylactide.

In the above ring-opening polymerization reaction, N,N-dimethylaniline-magnesium alcoholate is used as a catalyst to initiate the polymerization of lactide, thereby obtaining a series of polylactides. The molecular weight Mn of the polylactide finally obtained in the present invention is between 1,000 and 700,000, and polymers with different molecular weights can be obtained by adjusting the reaction conditions (the ratio of the lactide monomer to the catalyst and the co-catalyst, etc.).

The preparation method of the catalyst of the invention is simple, the structure of the obtained catalyst is various, the catalyst activity is high, and the stereoselectivity is high, and the catalyst can be used for catalyzing the ring-opening polymerization reaction of lactide. Due to the high activity of the catalytic system, good stereoselectivity and fast reaction rate, it can catalyze the occurrence of polymerization reaction at a relatively low temperature, the conditions are mild, and the obtained product has high molecular weight, high yield and less metal residue. The magnesium-based catalyst with the highest activity so far can convert 1000 molar equivalents of lactide monomer by 98% within 0.3 minutes. In addition, the polymerization process is simple, and the usual solution polymerization method can be used. Through the control of the polymerization reaction conditions, the molecular weight of the polymer can be adjusted from several thousand to 700,000, and the selectivity is wide.

Description of drawings

Fig. 1 is that R1 is an ethyl group, and R2 is a crystal structure diagram of a ligand of a phenyl group;

Fig. 2 is that R1 is ethyl, R2 is phenyl, and R3 is the crystal structure diagram of the N, N-dimethylaniline-alcohol base magnesium catalyst of n-butyl;

Fig. 3 is that R1 is hydrogen, R2 is phenyl, and R3 is the crystal structure diagram of the N, N-dimethylaniline-alcohol base magnesium catalyst of n-butyl;

Figure 4 is the homonuclear decoupling 1H spectrum of methine in polylactide (obtained by catalyzing racemic lactide with a catalyst in which R1, R2 is phenyl, and R3 is n-butyl), Pr = 79%.

Detailed ways

The present invention is further described below through specific examples, but the present invention is not limited thereto, and the specific protection scope is shown in the claims.

Preparation of N,N-dimethylaniline-alcohol ligands

Example 1

Dissolve N, N-dimethylaniline (5.0 g, 41.3 mmol) in dry diethyl ether, slowly add n-butyllithium (41.3 mL, 41.3 mmol) of double the molar amount, and at low temperature (below 0 °C ), add TMEDA (5mL), react at room temperature for 12 hours, slowly add double molar amount of acetophenone, react at room temperature for 12 hours, add ammonium chloride aqueous solution to stop the reaction, separate the layers, collect the organic phase, and dry over anhydrous sodium sulfate , and the solvent was spin-dried to obtain a crude product, which was recrystallized from hexane to obtain ligand (II) (8.1 g, 81%) of R _{1 and} R ₂ , one of which was phenyl and the other was methyl.

Example 2

The ligand was prepared by the method of Example 1, and N, N-dimethylaniline (5.0 g, 41.3 mmol) was used as the raw material. The difference was that acetophenone was changed to propiophenone, and the obtained ligand was R _1, R ₂ One of them is phenyl and the other is ethyl. Ligand (8.2 g, 78%) was obtained.

Example 3

The ligand was prepared by the method of Example 1, and N, N-dimethylaniline (5.0 g, 41.3 mmol) was used as the raw material. The difference was that acetophenone was changed to benzaldehyde, and the obtained ligand was R _{1 ,} R ₂ One of them is phenyl and the other is ethyl. The ligand was obtained (8.5 g, 91 %).

Example 4

The ligand was prepared by the method of Example 1, and N, N-dimethylaniline (5.0 g, 41.3 mmol) was used as the raw material. The difference was that acetophenone was changed to acetone, and the obtained ligand was R _1, R ₂ Both are methyl. Ligand (4.0 g, 54%) was obtained.

The preparation of other ligands can be prepared by changing the raw materials according to the above method.

Preparation of N,N-dimethylaniline-alcohol magnesium catalyst

N, N-dimethylaniline-alcohol-based magnesium catalyst is a complex formed by the reaction of ligand N, N-dimethylaniline-alcohol ligand and dialkylmagnesium. The structural formula of the ligand is as follows: formula (II) , the catalyst obtained by different ligands is exemplified below, the preferred ligand is R _1, R ₂ is phenyl or cyclohexyl; R _1, one of R ₂ is phenyl, cyclohexyl, o-fluorophenyl , o-bromophenyl, o-methylphenyl, p-methylphenyl or p-methoxyphenyl another ligand is hydrogen, methyl, ethyl, phenyl, cyclohexyl.

Example 5

The structural formula of the ligand used is the above formula (II), wherein R _{1 and} R ₂ are phenyl, and the reaction process is as follows: under a nitrogen atmosphere, dissolve 1.20 g of the ligand in 30 mL of toluene, and add an equimolar amount of Dimethylmagnesium was slowly raised to room temperature, heated to 80°C for 5 hours, the solvent was removed, and the crude product was recrystallized with hexane to obtain 1.2 g of pure product with a yield of 93%. The structural formula is as follows.

Elemental analysis results: C 77.41; H 6.83; N 4.18%. the

Example 6

The structural formula of the ligand used is the above formula (II), wherein R _{1 and} R ₂ are cyclohexyl. The reaction process is as follows: under nitrogen atmosphere, dissolve 0.90 g of the ligand in 7 mL of toluene, and add an equimolar amount of Diethylmagnesium was slowly raised to room temperature, heated to 110°C for 1 hour, the solvent was removed, and the crude product was recrystallized with hexane to obtain 0.91 g of pure product with a yield of 89%. The structural formula is as follows.

Elemental analysis results: C 75.16; H 10.19; N 3.73%.

Example 7

The structural formula of the ligand used is the above formula (II), wherein R ₁ is phenyl and R ₂ is methyl. The reaction process is as follows: under nitrogen atmosphere, dissolve 0.80 g of ligand in 10 mL of chloroform, add at 0°C, etc. The molar amount of dipropylmagnesium was slowly raised to room temperature, heated to 40°C for 12 hours, the solvent was removed, and the crude product was recrystallized with hexane to obtain 0.60 g of pure product with a yield of 91%. The structural formula is as follows.

Elemental analysis results: C 78.16; H 8.57; N 4.54%.

Example 8

The structural formula of the ligand used is the above formula (II), wherein R ₁ is phenyl, R ₂ is ethyl, and the reaction process is as follows: under nitrogen atmosphere, dissolve 1.0 g of ligand in 30 mL of dichloromethane and add at 0°C Equimolar amount of dibutylmagnesium was slowly raised to 20°C, reacted for 8 hours, and the solvent was removed. The crude product was recrystallized with hexane to obtain 1.10 g of pure product with a yield of 87%. The structural formula is as follows.

Elemental analysis results: C 75.25; H 8.78; N 4.31%.

Example 9

The structural formula of the ligand used is the above formula (II), wherein R ₁ is phenyl and R ₂ is hydrogen. The reaction process is as follows: under nitrogen atmosphere, dissolve 0.51 g of ligand in 15 mL of chloroform, and add equimolar Measure dibutylmagnesium, slowly rise to room temperature, heat to 50 ^o C to react for 3 hours, remove the solvent, and recrystallize the crude product with hexane to obtain 0.60 g of pure product with a yield of 85%. The structural formula is as follows.

Elemental analysis results: C 74.12; H 8.23; N 4.61%.

Example 10

The structural formula of the ligand used is the above formula (II), wherein R ₁ is o-fluorophenyl, R ₂ is hydrogen, and the reaction process is as follows: under a nitrogen atmosphere, dissolve 0.73 g of the ligand in 25 mL of hexane, at 0°C Add an equimolar amount of dibutylmagnesium, slowly rise to room temperature, heat to 50 ^o C for 12 hours, concentrate the solvent, precipitate crystals, and recrystallize the crude product with hexane to obtain 0.86 g of pure product with a yield of 89%. The structural formula is as follows .

Elemental analysis results: C 70.17; H 7.49; N 4.41%.

Example 11

The structural formula of the ligand used is the above formula (II), wherein R ₁ is o-chlorophenyl, R ₂ is hydrogen, and the reaction process is as follows: under a nitrogen atmosphere, dissolve 0.56 g of the ligand in 20 mL of toluene, and add The equivalent molar amount of dibutylmagnesium was slowly raised to room temperature, heated to 90 ^o C for 1 hour to concentrate the solvent, and the crude product was recrystallized with hexane to obtain 0.66 g of pure product with a yield of 90%. The structural formula is as follows.

Elemental analysis results: C 66.77; H 7.11; N 4.14%.

Example 12

The structural formula of the ligand used is the above formula (II), wherein R ₁ is o-bromophenyl, R ₂ is hydrogen, and the reaction process is as follows: under a nitrogen atmosphere, dissolve 1.10 g of the ligand in 25 mL of toluene, at -5 °C Add an equivalent amount of diethylmagnesium, slowly rise to room temperature, heat to 80 ^o C for 3 hours, remove the solvent, and recrystallize the crude product with hexane. 1.22 g of pure product was obtained with a yield of 88%. The structural formula is as follows.

Elemental analysis results: C 59.14; H 6.37; N 3.57%.

Example 13

The structural formula of the ligand used is the above formula (II), wherein R ₁ is o-bromophenyl, R ₂ is hydrogen, and the reaction process is as follows: under a nitrogen atmosphere, dissolve 1.10 g of the ligand in 25 mL of toluene, at -5 °C Add an equivalent amount of dibutylmagnesium, slowly rise to room temperature, heat to 80 ^o C for 3 hours, remove the solvent, and recrystallize the crude product with hexane. 1.20 g of pure product was obtained with a yield of 87%. The structural formula is as follows.

Elemental analysis results: C 56.87; H 5.69; N 3.97%.

Catalyst application

Example 14

The reaction was carried out under the protection of anhydrous, oxygen-free and inert gas. Firstly, 40 μmol R was sequentially added to the ampoule which was washed and baked with high-purity nitrogen. _R1 was o-bromophenyl, _R2 was hydrogen, and _R3 was ethyl catalyst, 60 mL of toluene, 40 μmol of benzyl alcohol, and 40 mmol of L-lactide, and then placed in an oil bath at 70 ^o C, reacted for 0.5 hours and then added a small amount of water to terminate the reaction, precipitated with ethanol, and washed several times. Vacuum drying at room temperature yielded 5.53 g with a molecular weight of 487,000 and a yield of 96%.

Example 15

All operations were carried out under the protection of anhydrous, oxygen and inert gas. First, add 10 μmol R _{1 ,} R ₂ is phenyl, R ₃ is propyl catalyst, 20 mL tetrahydrofuran, 10 μmol isopropanol, and 20 mmol L-lactide was then placed in an oil bath at 60 ^o C to react for 0.3 hours. After the reaction, a small amount of water was added to terminate the reaction, precipitated with ethanol, washed several times, and vacuum-dried at room temperature to obtain 2.74 grams with a molecular weight of 701,000. The yield 95%.

Example 16

All operations were carried out under the protection of anhydrous, oxygen and inert gas. First, add 40 μmol R1 _{, R2} is phenyl, _R3 is butyl catalyst, 30 mL dichloromethane, 80 μmol isopropanol, and 12 mmol of D-lactide was reacted at 20 ^o C for 2 minutes, and then a small amount of water was added to terminate the reaction. It was precipitated with ethanol, washed several times, and dried in vacuum at room temperature to obtain 1.60 g, with a molecular weight of 56,000 and a yield of 93%.

Example 17

All operations were carried out under the protection of anhydrous, oxygen and inert gas. First, add 400 μmol R _{1 ,} R ₂ is phenyl, R ₃ is butyl catalyst, 40 mL tetrahydrofuran, 600 μmol benzyl alcohol, and 40 mmol Racemic lactide was reacted at 0 ^o C for 1 minute, then a small amount of water was added to terminate the reaction, precipitated with ethanol, washed several times, and vacuum-dried at room temperature to obtain 5.53 g, molecular weight 27,000, Pr = 0.70, yield 96%.

Example 18

All operations were carried out under the protection of anhydrous, oxygen and inert gas. First, add 60 μmol R1 _{, R2} is phenyl, _R3 is methyl catalyst, 60 mL tetrahydrofuran, 60 μmol benzyl alcohol, and 100 mmol Racemic lactide, react at -20 ^o C for 10 minutes, add a small amount of water to terminate the reaction, precipitate with ethanol, wash several times, and vacuum dry at room temperature to obtain 13.55 g, molecular weight 573,000, Pr = 0.79, yield 94% .

Example 19

All operations were carried out under the protection of anhydrous, oxygen and inert gas. First, add 40 μmol of catalysts in which R ₁ is phenyl, R ₂ is hydrogen, and R ₃ is ethyl, 40 mL of dichloromethane, and 120 μmol of isopropanol into the ampoule after washing with high-purity nitrogen gas. , and 30 mmol of racemic lactide, then reacted at 20°C for 10 minutes, then added a small amount of water to terminate the reaction, precipitated with ethanol, washed several times, and dried in vacuum at room temperature to obtain 4.11 grams, molecular weight 486,000, Pr = 0.57, The yield is 95%.

Example 20

All operations were carried out under the protection of anhydrous, oxygen and inert gas. First, 80 μmol _R1 is phenyl, _R2 is hydrogen, _R3 is ethyl catalyst, 20 mL toluene, 80 μmol benzyl alcohol, and 20 mmol of D-lactide, then heated to 110 ^o C for 2 minutes, then added a small amount of water to terminate the reaction, precipitated with ethanol, washed several times, and dried in vacuum at room temperature to obtain 2.82 grams, with a molecular weight of 121,000 and a yield of 98%. .

Example 21

All operations were carried out under the protection of anhydrous, oxygen and inert gas. Firstly, add 30 μmol R ₁ is o-fluorophenyl, R ₂ is hydrogen, R ₃ is butyl catalyst, 10 mL tetrahydrofuran, 90 μmol benzyl alcohol, and 10 mmol of meso-lactide, reacted at 50 ^o C for 10 minutes, added a small amount of water at the end of the reaction to terminate the reaction, precipitated with ethanol, washed several times, and dried in vacuum at room temperature to obtain 1.38 g, molecular weight 23,000, yield 99%.

Example 22

All operations were carried out under the protection of anhydrous, oxygen and inert gas. Firstly, add 30 μmol R ₁ is o-fluorophenyl, R ₂ is hydrogen, R ₃ is butyl catalyst, 10 mL toluene, 30 μmol isopropanol in the ampoule after washing with high-purity nitrogen gas , and 9 mmol of D-lactide, reacted at 110 ^o C for 5 minutes, added a small amount of water to terminate the reaction, precipitated with ethanol, washed several times, and dried in vacuum at room temperature to obtain 1.27 grams, with a molecular weight of 6,000 and a yield of 98%. .

Example 23

All operations were carried out under the protection of anhydrous, oxygen and inert gas. Firstly, add 40 μmol R ₁ is o-chlorophenyl, R ₂ is hydrogen, R ₃ is propyl group, 60 mL toluene, 120 μmol benzyl alcohol, And 40 mmol of L-lactide, reacted at 110 ^o C for 10 minutes, at the end of the reaction, a small amount of water was added to terminate the reaction, precipitated with ethanol, washed several times, and vacuum-dried at room temperature to obtain 5.42 g with a molecular weight of 266,000 and a yield of 94%.

Example 24

All operations were carried out under the protection of anhydrous, oxygen and inert gas. First, add 10 μmol R1 _{, R2} is phenyl, _R3 is n-butyl catalyst, 20 mL tetrahydrofuran, 10 μmol benzyl alcohol, and 10 mmol L-lactide was then placed in an oil bath at 60 ^o C to react for 0.4 minutes. After the reaction, a small amount of water was added to terminate the reaction, precipitated with ethanol, washed several times, and vacuum-dried at room temperature to obtain 14.12 grams with a molecular weight of 672,000. The yield 98%.

comparative example

The method of the present invention is used to catalyze the polymerization of racemic lactide. The difference is that the catalyst used is the catalyst reported in CN201010022624.5, and 10,000 equivalents of lactide are polymerized within 5 minutes. The yield is 86%, and the obtained polylactide is free. Regular polylactide.

Claims (11)

1. a DMA-ol base Mg catalyst, is characterized in that: shown in the following formula I of structural formula, and R in formula ₁, R ₂all from following radicals, select: the straight chained alkyl of C1-C4, the cycloalkyl of C5-C6, hydrogen base, phenyl or with substituent aryl, R ₁with R ₂identical or not identical, R ₃for the straight chained alkyl of C1-C4;

。

2. DMA-ol base Mg catalyst according to claim 1, is characterized in that: the substituting group of aryl is selected from the alkoxy or halogen of the alkyl of C1-C4, C1-C4, and substituent number is 1-2.

3. DMA-ol base Mg catalyst according to claim 1, is characterized in that: be adjacent fluorophenyl, o-bromophenyl, o-methyl-phenyl-, p-methylphenyl or p-methoxyphenyl with substituent aryl.

4. DMA-ol base Mg catalyst according to claim 1, is characterized in that: R ₁, R ₂all from following radicals, select: hydrogen base, methyl, ethyl, cyclopentyl, cyclohexyl, phenyl, adjacent fluorophenyl, o-bromophenyl, o-methyl-phenyl-, p-methylphenyl or p-methoxyphenyl, R ₁with R ₂identical or different.

5. a preparation method for the DMA-ol base Mg catalyst described in claim 1,2,3 or 4, is characterized in that comprising the following steps:

(1) preparation of part: by N, accelerine is dissolved in dry ether, add and N, the n-Butyl Lithium of accelerine equimolar amount, then add at low temperatures Tetramethyl Ethylene Diamine, room temperature reaction 12 hours, after reaction, add again and N, the aldehydes or ketones of accelerine equimolar amount, room temperature reaction 12 hours, after reaction, add the aqueous solution stopped reaction of ammonium chloride, separatory, collect organic phase, organic phase is through anhydrous sodium sulfate drying, be spin-dried for solvent and obtain crude product, crude product obtains N with hexane recrystallization, accelerine-ol part, structural formula is as shown in formula II, wherein, R ₁, R ₂for the cycloalkyl of the straight chained alkyl of C1-C4, C5-C6, hydrogen base, phenyl or with substituent aryl,

(2) preparation of catalyzer: by N, accelerine-ol part adds in organic solvent, then at-10～0 DEG C, add the dialkyl magnesium with part equimolar amount, after adding, make reaction solution naturally rise to room temperature, then reaction solution is reacted 1～12 hour at 20～110 DEG C, after having reacted, boil off solvent and obtain thick product, thick product recrystallization obtains DMA base-ol base Mg catalyst;

。

6. preparation method according to claim 5, is characterized in that: reaction is carried out under protection of inert gas; Described dialkyl magnesium molecular formula is (R ₃) ₂mg; Described organic solvent is saturated alkane, the halogenated alkane of C5～C10 or the aromatic hydrocarbon of C5～C10 of C5～C10; Described recrystallization reagent is hexane.

7. preparation method according to claim 5, is characterized in that: described organic solvent is hexane, toluene, methylene dichloride or chloroform.

8. the N described in a claim 1,2,3 or 4, the application of accelerine-ol base Mg catalyst, it is characterized in that: as the catalyzer of rac-Lactide ring-opening polymerization, described rac-Lactide is one or both in levorotatory lactide, dextrorotation rac-Lactide, rac-lactide, Study of Meso-Lactide.

9. application according to claim 8; it is characterized in that; rac-Lactide ring-opening polymerization comprises the following steps: by N; accelerine-ol base Mg catalyst, organic solvent, alcohol promotor and rac-Lactide mix; under anhydrous and oxygen-free and protection of inert gas, carry out polymerization ring-opening reaction, after reaction, reactant is processed to obtain to polylactide.

10. application according to claim 9, is characterized in that: polyreaction organic solvent used is toluene, methylene dichloride or tetrahydrofuran (THF), and alcohol promotor is benzylalcohol or Virahol; Rac-Lactide and DMA-ol base Mg catalyst mol ratio are 30～2000:1, and the mol ratio of alcohol promotor and DMA-ol base Mg catalyst is 1～4:1; Polymeric reaction temperature is-20～110 DEG C, and the time is 0.1-600 minute.

11. application according to claim 10, is characterized in that: polymeric reaction temperature is 0～70 DEG C, and the reaction times is 0.1-30 minute.