CN105111418B - The preparation method of stereoregular polylactic acid under a kind of temperate condition - Google Patents
The preparation method of stereoregular polylactic acid under a kind of temperate condition Download PDFInfo
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- CN105111418B CN105111418B CN201510589810.XA CN201510589810A CN105111418B CN 105111418 B CN105111418 B CN 105111418B CN 201510589810 A CN201510589810 A CN 201510589810A CN 105111418 B CN105111418 B CN 105111418B
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Abstract
The present invention relates to the preparation method of a kind of stereoregular polylactic acid, its step is as follows: add in reaction vessel by composite catalyst, rac-lactide, add appropriate solvent to dissolve, gained reactant liquor reacts 20min-4 hour in 0-25 DEG C, reaction adds methanol hydrochloride solution and terminates reaction after terminating, products therefrom methanol washing precipitation obtains stereoregulated polylactic acid.The present invention is catalyzed the ring-opening polymerisation of rac-lactide under the conditions of relatively mild, and monomer conversion is more than 90%；Polylactic acid obtained by preparation in accordance with the present invention has stereoregular structure, and isotaxy content is more than 70%.
Description
Technical field
The present invention relates to technical field of macromolecules, be specifically related to a kind of by rac-lactide polymerization preparation
The method of stereoregular polylactic acid.
Background technology
Polylactic acid is a kind of macromolecule with good biodegradability properties, and raw material sources are in biomass such as Semen Maydiss
Resource, energy-conserving and environment-protective, polyethylene, polrvinyl chloride can be replaced to be applied to agricultural film, packaging material etc.,
" white pollution " problem of solution, it is also possible to be applied to biological medicine aspect, as absorbable surgery hands
Art stitching thread, degradable material implanted and backing material, slow releasing carrier of medication etc., cause people
Broad interest.Having chiral carbon in polylactic acid construction unit, the arrangement of chiral carbon can generate various solid
Isomery, including unformed, Quan Tong, miscellaneous with, equal, the difference of stereochemical structure can directly affect it
Performance.Undefined structure polylactic acid vitrification point is low, for 50-60 DEG C, and poor mechanical property, degradable,
Stereoregular polylactic acid (PLLA or poly-D-lactide) can form crystalline texture, crystallization temperature
High (more than 170 DEG C), mechanical property is good, and degradation cycle is long.And as PLLA and poly-D-
When lactide forms three-dimensional mixture (stereo-complex), crystallization temperature is higher, can reach 220 DEG C.
Document it has been reported various Schiff's base alkyl/metal alkoxides catalyst and can be catalyzed rac-lactide and open
Cyclopolymerization, prepares the polylactic acid of high tacticity, but General reactions temperature is high (more than 70 DEG C), instead
Between Ying Shi long (a few hours), CN104211929A reports outside a kind of organozinc catalyst can be catalyzed
Polylactic acid is prepared in the ring-opening polymerisation of meso-lactide, and this catalyst at room temperature has higher complete same selectivity
With the feature of greater activity, but catalyst is prepared loaded down with trivial details, and the requirement to polymerizing condition is the harshest, it is desirable to
Anhydrous and oxygen-free.
Summary of the invention
The technical problem to be solved is for above-mentioned deficiency present in prior art, it is provided that
A kind of method utilizing rac-lactide to prepare stereoregular polylactic acid in a mild condition, gained founds structure
In regular polylactic acid, isotaxy content is more than 70%.
For solving above-mentioned technical problem, present invention provide the technical scheme that
Thering is provided the preparation method of stereoregular polylactic acid under a kind of temperate condition, its step is as follows: will be multiple
Close catalyst, rac-lactide adds in reaction vessel, adds solvent and dissolves, and gained reactant liquor is in 0
-25 DEG C are reacted 20min-4 hour, and reaction adds hydrochloric acid methanol after terminating and terminates reaction, products therefrom
Stereoregulated polylactic acid is obtained by methanol washing precipitation；
Described composite catalyst is made up of with promoter major catalyst, major catalyst and promoter
Mol ratio is 1:0.5-2, wherein major catalyst be metal salung M (III)-salen (M=Cr, Co) or
Metalloporphyrin M (III)-porphyrin (M=Al, Cr, Co), promoter is double-(dihalotriphenylphosphoranes base)
One in ammonia chloride (PPNCl), dimethyl aminopyridine (DMAP), 2,6-lutidines；
The structural formula of described metal salung M (III)-salen (M=Cr, Co) is:
M=Cr or Co；R1=o-C6H4, 1,2-cyclohexenyl group ,-CH2CH2-or-CH (CH3)CH2-；R2、
R3Separately replace or the substituted aliphatic group of bromine selected from hydrogen, chlorine, bromine, chlorine；X is-Cl ,-Br,
CCl3COO-、CF3COO-, 2,4-dinitrophenol,DNP epoxide, 3,5-dinitrophenol,DNP epoxide, 2,4,6-tri-
One in nitrophenol epoxide；
The structural formula of described metalloporphyrin M (III)-porphyrin (M=Al, Cr, Co) is:
M=Cr or Co or Al, R2、R3、R4Separately replace selected from hydrogen, fluorine, chlorine, bromine, chlorine
Or the substituted aliphatic group of bromine；X is-Cl ,-OCH2CH3、-OCH(CH3)2、-Br、CCl3COO-、
CF3COO-, 2,4-dinitrophenol,DNP epoxide, 3,5-dinitrophenol,DNP epoxide, 2,4,6-trinitrophenol oxygen
One in base；
Described solvent is epoxide or the mixed solvent containing epoxide, described containing epoxy compound
The mixed solvent of thing is the mixture of epoxide and oxolane (THF), or epoxide with
The mixture of dichloromethane, or the mixture of epoxide and toluene, or epoxide and dioxy six
The mixture of ring, in the mixed solvent containing epoxide epoxide account for the volume ratio of mixed solvent >=
10%.
Preferably, the mol ratio of described major catalyst and promoter is 1:1.
Preferably, described promoter is dimethyl aminopyridine (PPNCl).
By such scheme, described major catalyst and rac-lactide mol ratio are 1:100-500.
By such scheme, described epoxide is in expoxy propane, oxirane, 7-oxa-bicyclo[4.1.0
One.
By such scheme, described rac-lactide is at described epoxide or containing epoxide
Mass body volume concentrations in mixed solvent is 0.01-0.1g/mL.
By such scheme, conversion ratio >=90% of described rac-lactide.
The present invention also provides for the stereoregular polylactic acid prepared according to said method, and described vertical structure is advised
Whole polylactic acid number-average molecular weight is 2500-10000, and molecular weight distribution is 1.1-1.5, complete with vertical in polylactic acid
Structure content is 70-85%.
The synthesis route of metal salung M (III)-salen (M=Co, Cr) of the present invention is as follows:
I+MX2+O2→M(III)-salen
Its preparation method is:
Prepare metal salung M (III)-salen (M=Cr, Co): substituted salicylic aldehydes is molten with diamine monomer
In ethanol, (molar concentration of substituted salicylic aldehydes is 0.01-0.03M, substituted salicylic aldehydes and diamine monomer
Mol ratio is 2:1), add 2-3 and drip formic acid, in room temperature or back flow reaction 24h, sedimentation filtration must be sunk
Forming sediment, precipitation by water and washing with alcohol, is vacuum dried and prepares salung part, then by molten for salung part successively
In dichloromethane, (molar concentration of salung part is for addition slaine acetic acid Asia cobalt or chromous chloride
0.05-0.1M, salung part is 1:1.5 with the mol ratio of slaine), room temperature the most in a nitrogen atmosphere
Reaction 24h, adds halo slaine or replaces organic acid or fortified phenol (salung part: halo metal
Salt or replace organic acid or fortified phenol=1:1.5 (mol ratio)), react 24h in air atmosphere,
Remove solvent, recycling water or washing with alcohol vacuum drying and obtain metal salung (SalenM, M=Cr, Co)
Catalyst.
The synthesis route of metalloporphyrin M (III)-porphyrin (M=Al, Cr, Co) of the present invention is:
II+MY2+O2→ Metal-porphyrin-Y M=Cr, Co
II+AlEt2Cl→Al-porphyrin-Cl
II+AlMe3→Al-porphyrin-Me
Al-porphyrin-Me+Y-H→Al-porphyrin-Y
Its preparation method is:
Benzaldehyde or substituted benzaldehyde are added (benzaldehyde or substituted benzaldehyde in propanoic acid solvent with pyrroles
Molar concentration be 0.4-0.5M, the mol ratio of pyrroles and benzaldehyde or substituted benzaldehyde is 1:1.2),
Back flow reaction 24h, solution is concentrated into the half of original volume, adds equal-volume by back flow reaction after terminating
The methanol of amount, stands 24h, sucking filtration in 0 DEG C after mixing, is vacuum dried, and column purification prepares porphyrin part,
Then following a or b step is used to obtain catalysis of metalloporphyrin agent:
A. the preparation of metalloporphyrin (PorphyrinM, M=Cr, Co) catalyst: by porphyrin part and chlorine
In the sub-chromium of change or cobalt chloride addition solvent dimethylformamide, (molar concentration of porphyrin part is
0.01-0.02M, chromous chloride or cobalt chloride are 1.5:1 with the mol ratio of porphyrin part), in
150-170 DEG C of reaction, takes a small amount of reactant liquor, utilizes ultraviolet detection after 2 hours, if porphyrin part is the most anti-
Should be complete, add slaine chromous chloride or cobalt chloride, the chromous chloride added or cobalt chloride and porphin
The mol ratio of quinoline part is 1.5:1, until porphyrin part is totally converted, is then cooled to room temperature, adds
Hydrochloric acid, adds a large amount of frozen water, and 0 DEG C settles 24 hours, filters, water or washing with alcohol, vacuum drying,
Through column chromatography for separation, obtain metalloporphyrin (PorphyrinM, M=Cr, Co) catalyst；
B. the preparation of metalloporphyrin (PorphyrinM, M=Al) catalyst: under nitrogen atmosphere, by porphin
Quinoline part is dissolved in dichloromethane solvent (molar concentration is 0.05-0.1M), add diethyl aluminum chloride or
The hexane solution (molar concentration is 1-2M) of trimethyl aluminium, porphyrin part and diethyl aluminum chloride or three
The mol ratio of aluminium methyl is 1:1.5, room temperature reaction 24h, and decompression removes dichloromethane, utilizes pentane
Wash 3 times, vacuum drying obtains porphyrin aluminum chloride catalyst PorphyrinAlCl or porphyrin methylates aluminum
PorphyrinAlMe, porphyrin methylate aluminum PorphyrinAlMe dichloromethane solution in add alcohol
Class or replace organic acid or fortified phenol (molar concentration of PorphyrinAlMe is 0.05-0.1M,
PorphyrinAlMe is 1:1.5 with the mol ratio of alcohols or replacement organic acid or fortified phenol), backflow
Reaction 24h, washing with alcohol, vacuum drying obtains other metalloporphyrin aluminum (PorphyrinM, M=Al)
Catalyst.
The beneficial effects of the present invention is: 1, the present invention under the conditions of relatively mild (under air conditions,
0-25 DEG C) catalysis rac-lactide ring-opening polymerisation, reacting 20min-4 hour monomer conversion can
More than 90%；2, the polylactic acid obtained by preparation in accordance with the present invention has stereoregular structure,
Isotactic structure content is more than 70%.
Accompanying drawing explanation
Fig. 1 is the homogeneous uncoupling of the polylactic acid prepared by embodiment 11H NMR spectra (polylactic acid
Construction unit-CH (the CH of PLA3)-CH-part in COO-).
Detailed description of the invention
For making those skilled in the art be more fully understood that technical scheme, the most right
The present invention is described in further detail.
Lactide used by the present invention is rac-lactide.
Embodiment 1
Prepare major catalyst: in a nitrogen atmosphere, by 7.7g benzaldehyde (72.6mmol) and 4.2g
Pyrroles (62.6mmol) is dissolved in 180mL propanoic acid solvent, and back flow reaction 24h, back flow reaction terminates
After solution is concentrated into the half of original volume, add the methanol of equal volume amounts, in 0 DEG C of standing after mixing
24h, sucking filtration, vacuum drying, column purification obtains tetraphenylporphyrin TPPH2.By 1g tetraphenylporphyrin (1.6
Mmol) being dissolved in 20mL dichloromethane solvent, adding 2.4mL concentration is the diethyl aluminum chloride of 1M
Hexane solution (2.4mmol), be stirred at room temperature reaction 24h, removal of solvent under reduced pressure, pentane wash
3 times, taking solvent away, vacuum drying obtains tetraphenylporphyrin aluminum chloride catalyst TPPAlCl, structural formula
As follows:
By above-mentioned TPPAlCl catalyst 23.6mg (0.035mmol), promoter PPNCl 20mg
(0.035mmol), lactide 0.504g, expoxy propane 5mL, dioxane 5mL add respectively
Enter (TPPAlCl catalyst: promoter: lactide=1:1:100 (mol ratio)) in vial,
Room temperature 25 DEG C stirring reaction 1h, adds 10mL hydrochloric acid methanol (mass percentage concentration of HCl is 1%) eventually
Only, removal of solvent under reduced pressure.Polymer washs with a large amount of methanol, and vacuum drying obtains white adipose adoption ester
PLA.Conversion ratio >=90% of rac-lactide, the number-average molecular weight 2,500 of polylactic acid, molecular weight divides
Cloth 1.3, in product, (wherein parameter Pm is to form an isotactic placement to isotaxy content Pm=0.78
Probability, i.e.-RRRRRRR-key or the bonded probability of-SSSSSS-, coordination compound one L-LA of initiation (or
D-LA) after open loop, continuing to aggregate into a probability with identical configuration monomer, Pr represents miscellaneous with vertical
The probability that structure is bonded, i.e. formation RRSSRRSS type connects, and m represents complete with connecting, and r represents miscellaneous same
Connecting, in rac-lactide ring-opening polymerisation resulting polymers, four-tuple also has five kinds of connected modes, point
Not Wei rmr, rmm, mmr, mmm and mrm, they are in homogeneous uncoupling1In H NMR spectra also
There will be five groups of peaks, chemical displacement value is respectively 5.22,5.20,5.17,5.16,5.15ppm；According to
The integral area at each group peak and Markov Equation for Calculating: [mmm]=P2 m+ (1-Pm) Pm/2, [mmr]=
[rmm]=(1-Pm) Pm/2, [rmr]=[(1-Pm)2]/2, [mrm]=[(1-Pm)2+ Pm (1-Pm)]/2 can count
Calculate Pm；Figure one is the homogeneous decoupling of the polylactic acid that the polymerization of this example catalyst rac-lactide obtains
Close1H NMR spectra (construction unit-CH (the CH of polylactic acid PLA3)-CH-part in COO-,
[mmm], [rmm], the distribution of [rmr] see Fig. 1).
Embodiment 2
Prepare major catalyst: in a nitrogen atmosphere, by 9.87g P-methoxybenzal-dehyde (72.6mmol)
It is dissolved in 180mL propanoic acid solvent with 4.2g pyrroles (62.6mmol), back flow reaction 24h, backflow
Solution is concentrated into the half of original volume by reaction after terminating, add the methanol of equal volume amounts, after mixing in
0 DEG C stands 24h, sucking filtration, and vacuum drying, column purification obtains four (methoxyphenyl) porphyrin.Nitrogen
Under atmosphere, gained four (methoxyphenyl) porphyrin 1g (1.36mmol) is dissolved in 20mL dichloromethane
Alkane solvents, adds the hexane solution 1mL (2mmol) of the trimethyl aluminium that concentration is 2M, is stirred at room temperature
24h, removal of solvent under reduced pressure, add 50mL pentane and wash 3 times, remove solvent, add 20mL
Dichloromethane dissolves, and adds 2,4-DNP 0.37g (72.6mmol), and reflux 24h, subtracts
Pressure takes solvent, washing with alcohol 3 times away, takes solvent away, and vacuum drying obtains porphyrin aluminum
PorphyrinAl(O(C6H3(NO2)2) catalyst, structural formula is as follows:
By above-mentioned PorphyrinAl (O (C6H3(NO2)2) catalyst 26.6mg (0.035mmol), help
Catalyst DMAP 8.54mg (0.07mmol), oxirane 50mL and lactide 2.52g are respectively
Add (PorphyrinAl (O (C in vial6H3(NO2)2) catalyst: promoter: lactide
=1:2:500 (mol ratio)), room temperature 25 DEG C stirring reaction 4h, add 50mL hydrochloric acid methanol (HCl
Mass percentage concentration be 1%) terminate, removal of solvent under reduced pressure.Polymer washs with a large amount of methanol, vacuum
It is dried and obtains white adipose adoption ester PLA.Polymerization yield is more than 90%, the number-average molecular weight of polylactic acid
1,0000, molecular weight distribution 1.5, (Pm computational methods are shown in embodiment 1 to product Pm=0.7, [mmm's]
Being distributed similar with Fig. 1, figure is slightly).
Embodiment 3
Prepare major catalyst: in a nitrogen atmosphere, by 14.23g pentafluorobenzaldehyde (72.6mmol)
It is dissolved in 180mL propanoic acid solvent with 4.2g pyrroles (62.6mmol), back flow reaction 24h, backflow
Solution is concentrated into the half of original volume by reaction after terminating, add the methanol of equal volume amounts, after mixing in
0 DEG C stands 24h, sucking filtration, column purification, and vacuum drying obtains four (pentafluorophenyl group) porphyrin.By gained
Four (pentafluorophenyl group) porphyrin ligand 1 g (1.03mmol) is dissolved in 100mL DMF solvent, adds 0.189
The anhydrous chromous chloride of g (1.54mmol), 150-170 DEG C of back flow reaction 2 hours, ultraviolet detection four (five
Fluorophenyl) whether porphyrin react complete, if it did not, add chromous chloride 0.189g (1.54mmol),
Till ultraviolet detection is without four (pentafluorophenyl group) porphyrin, it is cooled to room temperature, adds 50mL hydrochloric acid,
Adding 300mL frozen water, 0 DEG C settles 24 hours, washs by massive laundering after filtration, is dried, and utilizes
Alumina column chromatography is isolated and purified obtains porphyrin chromium PorphyrinCrCl catalyst, and structural formula is as follows:
By above-mentioned PorphyrinCrCl catalyst 37.6mg (0.035mmol), promoter 2,6-
Lutidines 3.75mg (0.035mmol), expoxy propane 5mL, lactide 0.504g, molten
Agent dioxane 45mL be separately added in vial (PorphyrinCrCl catalyst: promoter:
Lactide=1:1:100 (mol ratio)), room temperature 25 DEG C stirring reaction 4h, add 20mL hydrochloric acid first
Alcohol (mass percentage concentration of HCl is 1%) terminates, removal of solvent under reduced pressure.Polymer washs with a large amount of methanol,
Vacuum drying obtains white adipose adoption ester PLA.Polymerization yield is more than 90%, the equal molecule of number of polylactic acid
Amount 5,500, molecular weight distribution 1.4, (Pm computational methods are shown in embodiment 1 to product Pm=0.8, [mmm]
Distribution similar with Fig. 1, figure is slightly).
Embodiment 4
Prepare major catalyst: method as described in embodiment 3 prepares four (pentafluorophenyl group) porphyrin part.
Gained four (pentafluorophenyl group) porphyrin ligand 1 g (1.03mmol) is dissolved in 100mL DMF solvent,
Add the anhydrous cobalt chloride of 0.19g (1.54mmol), 150-170 DEG C of back flow reaction 2 hours, purple
Whether outer detection four (pentafluorophenyl group) porphyrin reacts complete, if it did not, add cobalt chloride 0.19g
(1.54mmol), till ultraviolet detection is without four (pentafluorophenyl group) porphyrin, it is cooled to room temperature,
Adding 50mL hydrochloric acid, add 300mL frozen water, 0 DEG C settles 24 hours, uses a large amount of water after filtration
Washing, is dried, utilizes silica gel column chromatography separating purification to obtain Cobalt Porphyrin PorphyrinCoCl catalyst,
Structural formula is as follows:
By above-mentioned PorphyrinCoCl catalyst 37.3mg (0.035mmol), promoter PPNCl
40mg (0.07mmol), oxirane 10mL, lactide 0.504g (3.5mmol) are respectively
In addition vial (PorphyrinCoCl catalyst: promoter: lactide=1:2:100 (mole
Than)), room temperature 25 DEG C stirring reaction 4h, add the 10mL hydrochloric acid methanol (mass percentage concentration of HCl
It is 1%) terminate, removal of solvent under reduced pressure.Polymer washs with a large amount of methanol, and vacuum drying obtains white fat
Fat adoption ester PLA.Polymerization yield is more than 90%, and the number-average molecular weight 4,500 of polylactic acid, molecular weight divides
Cloth 1.3, product Pm=0.8 (Pm computational methods are shown in embodiment 1, and the distribution of [mmm] is similar with Fig. 1,
Figure is slightly).
Embodiment 5
Prepare major catalyst: in a nitrogen atmosphere, by 13.43g p-bromobenzaldehyde (72.6mmol)
It is dissolved in 180mL propanoic acid solvent with 4.2g pyrroles (62.6mmol), back flow reaction 24h, backflow
Solution is concentrated into the half of original volume by reaction after terminating, add the methanol of equal volume amounts, after mixing in
0 DEG C stands 24h, sucking filtration, and vacuum drying obtains four (p-bromophenyl) porphyrin.Under nitrogen atmosphere, will
Gained four (p-bromophenyl) porphyrin 1g (1.07mmol) is dissolved in 20mL dichloromethane solvent, adds
Concentration is the hexane solution 0.8mL (1.6mmol) of the trimethyl aluminium of 2M, and reaction 24h is stirred at room temperature,
Removal of solvent under reduced pressure, adds 50mL pentane and washs 3 times, remove solvent, add 20mL dichloromethane
Dissolving, add trichloroacetic acid 0.26g (1.6mmol), reflux 24h, and solvent, second are taken in decompression away
Alcohol washs 3 times, removes solvent, and vacuum drying obtains porphyrin aluminum PorphyrinAl (OOCCCl3) catalyst,
Structural formula is as follows:
By above-mentioned PorphyrinAl (OOCCCl3) catalyst 39mg (0.035mmol), promoter
PPNCl 20mg (0.035mmol), lactide 0.504g (3.5mmol), 7-oxa-bicyclo[4.1.0 2
ML, dichloromethane 18mL are separately added in vial (PorphyrinAl (OOCCCl3) catalyst: help
Catalyst: lactide=1:1:100 (mol ratio)), room temperature 25 DEG C stirring reaction 4h, add 10mL
Hydrochloric acid methanol (mass percentage concentration of HCl is 1%) terminates, removal of solvent under reduced pressure.The a large amount of first of polymer
Alcohol washs, and vacuum drying obtains white adipose adoption ester PLA.Polymerization yield is more than 90%, polylactic acid
Number-average molecular weight 7,500, molecular weight distribution 1.2, product Pm=0.85 (Pm computational methods are shown in embodiment 1,
The distribution of [mmm] is similar with Fig. 1, and figure is slightly).
Embodiment 6
Prepare major catalyst: in a nitrogen atmosphere, by 7.7g benzaldehyde (72.6mmol) and 4.2g
Pyrroles (62.6mmol) is dissolved in 180mL propanoic acid solvent, and back flow reaction 24h, back flow reaction terminates
After solution is concentrated into the half of original volume, add the methanol of equal volume amounts, in 0 DEG C of standing after mixing
24h, sucking filtration, vacuum drying, column purification obtains tetraphenylporphyrin TPPH2.By 1g tetraphenylporphyrin (1.6
Mmol) it is dissolved in 20mL dichloromethane solvent, adds the trimethyl aluminium that 1.2mL concentration is 2M oneself
Alkane solution (2.4mmol), is stirred at room temperature reaction 24h, removal of solvent under reduced pressure, pentane washing 3
Secondary, take solvent away, add 20mL dichloromethane, add ethanol 0.11g, back flow reaction 24h, take out
Walking solvent, washing with alcohol 3 times, vacuum drying obtains porphyrin aluminum PorphyrinAl (OEt) catalyst, knot
Structure formula is as follows:
By above-mentioned PorphyrinAl (OEt) catalyst 23.9mg (0.035mmol), promoter
PPNCl 10mg (0.0175mmol), lactide 0.504g (3.5mmol), expoxy propane 15
ML, toluene 5mL be separately added in vial (PorphyrinAl (OEt) catalyst: promoter:
Lactide=1:0.5:100 (mol ratio)), room temperature 25 DEG C stirring reaction 2h, add 20mL hydrochloric acid
Methanol (mass percentage concentration of HCl is 1%) terminates, removal of solvent under reduced pressure.Polymer is washed with a large amount of methanol
Washing, vacuum drying obtains white adipose adoption ester PLA.Polymerization yield is more than 90%, and the number of polylactic acid is equal
Molecular weight 8,500, molecular weight distribution 1.1, (Pm computational methods are shown in embodiment 1 to product Pm=0.8, [mmm]
Distribution similar with Fig. 1, figure is slightly).
Embodiment 7
Prepare major catalyst: 2g 3,5-dimethyl salicylide (13.3mmol) is dissolved in 50mL
In ethanol, it is added dropwise to 0.44mL 1，2-diaminoethane (6.65mmol), adds 2-3 and drip formic acid, room
Temperature reaction 24h, 0 DEG C of sedimentation 24h, filter, wash with water the most successively 3 times, washing with alcohol 3 times,
Vacuum drying preparation 3,5-dimethyl salicyloyl contracting ethylenediamine (Salen part), take 1g 3,5-diformazan
Base salicyloyl contracting ethylene diamine ligand (3mmol) is dissolved in 30mL dichloromethane solvent, adds 0.57g
Anhydrous chromous chloride (4.5mmol), is stirred at room temperature reaction 24h the most in a nitrogen atmosphere, adds 1.03
G 2，4，6-trinitrophenol (4.5mmol), blowing air, it is stirred at room temperature 24 hours, takes solvent away,
Adding the washing of 100mL water, filter, wash 3 times, washing with alcohol 3 times, vacuum drying obtains salung
Chromium SalenCr (OC6H2(NO2)3) catalyst, structural formula is as follows:
By above-mentioned SalenCr (OC6H2(NO2)3) catalyst 21mg (0.035mmol), promoter
PPNCl20mg (0.035mmol), oxirane 10mL and lactide 0.504g (3.5mmol),
Solvent THF 10mL is separately added in vial (SalenCr (OC6H2(NO2)3) catalyst: promoter:
Lactide=1:1:100 (mol ratio)), room temperature 25 DEG C stirring reaction 2h, add 10mL hydrochloric acid first
Alcohol (mass percentage concentration of HCl is 1%) terminates, removal of solvent under reduced pressure.Polymer washs with a large amount of methanol,
Vacuum drying obtains white adipose adoption ester PLA.Polymerization yield is more than 90%, the equal molecule of number of polylactic acid
Amount 5,500, molecular weight distribution 1.3, (Pm computational methods are shown in embodiment 1 to product Pm=0.8, [mmm]
Distribution similar with Fig. 1, figure is slightly).
Embodiment 8
Prepare major catalyst: be dissolved in by the 2g 3-tert-butyl group-5-chloromethyl salicylaldehyde (8.8mmol)
In 50mL ethanol, it is added dropwise to 0.38mL 1,2-propane diamine (4.4mmol), adds 2-3 and drip formic acid,
Room temperature reaction 24h, 0 DEG C of sedimentation 24h, filter, wash with water the most successively 3 times, washing with alcohol 3 times,
The vacuum drying preparation 3-tert-butyl group-5-chloromethyl salicyloyl contracting propane diamine (Salen part), takes 1g 3-
The tert-butyl group-5-chloromethyl salicyloyl contracting propane diamine part (2mmol) is dissolved in 30mL dichloromethane solvent,
Add the anhydrous chromous chloride of 0.375g (3mmol), first 24h is stirred at room temperature in a nitrogen atmosphere, adds
Enter 0.3mL trifluoroacetic acid (3mmol), blowing air, be stirred at room temperature 24 hours, take solvent away, add
Entering the washing of 100mL water, filter, wash 3 times, ethanol is washed 3 times, and vacuum drying obtains salung chromium
SalenCr(OOCCF3) catalyst, structural formula is as follows:
By above-mentioned SalenCr (OOCCF3) catalyst 23mg (0.035mmol), double-(triphenyl
Phosphoranyl) ammonium chloride PPNCl 40mg (0.07mmol), oxirane 10mL, lactide 0.504
G (3.5mmol) is separately added in vial (SalenCr (OOCCF3) catalyst: promoter: third
Lactide=1:2:100 (mol ratio)), room temperature 0 DEG C stirring reaction 4h, add 10mL hydrochloric acid methanol
(mass percentage concentration of HCl is 1%) terminates, removal of solvent under reduced pressure.Polymer washs with a large amount of methanol,
Vacuum drying obtains white adipose adoption ester PLA.Polymerization yield is more than 90%, the equal molecule of number of polylactic acid
Amount 5,500, molecular weight distribution 1.3, (Pm computational methods are shown in embodiment 1 to product Pm=0.8, [mmm]
Distribution similar with Fig. 1, figure is slightly).
Embodiment 9
Prepare major catalyst: the 2g 3-tert-butyl group-5-bromosalicylaldehyde (7.8mmol) is dissolved in 50mL
In ethanol, add 0.425g o-phenylenediamine (3.9mmol), add 2-3 and drip formic acid, back flow reaction
24h, 0 DEG C of sedimentation 24h, filter, wash with water the most successively 3 times, washing with alcohol 3 times, and vacuum is done
The dry preparation 3-tert-butyl group-5-bromine salicyloyl contracting o-phenylenediamine (Salen part), takes the 1g 3-tert-butyl group
-5-bromine salicyloyl contracting o-phenylenediamine part (1.7mmol) is dissolved in 30mL dichloromethane solvent, adds
0.637g tetra-is hydrated acetic acid Asia cobalt, and 24h is first stirred at room temperature in a nitrogen atmosphere, adds 0.468g 2,4-
Dinitrophenol,DNP, blowing air, it is stirred at room temperature 24 hours, takes solvent away, add the washing of 100mL water,
Filtering, wash 3 times, washing with alcohol 3 times, vacuum drying obtains salung cobalt SalenCo (OC6H3(NO2)2)
Catalyst, structural formula is as follows:
By above-mentioned SalenCo (OC6H3(NO2)2) catalyst 29mg (0.035mmol), promoter
2,6-lutidines 7.58mg (0.07mmol), oxirane 10mL, lactide 0.504g
(3.5mmol) (SalenCo (OC it is separately added in vial6H3(NO2)2) catalyst: promoter:
Lactide=1:2:100 (mol ratio)), room temperature 25 DEG C stirring reaction 4h, add 10mL hydrochloric acid first
Alcohol (mass percentage concentration of HCl is 1%) terminates, removal of solvent under reduced pressure.Polymer washs with a large amount of methanol,
Vacuum drying obtains white adipose adoption ester PLA.Polymerization yield is more than 90%, the equal molecule of number of polylactic acid
Amount 4,500, molecular weight distribution 1.3, (Pm computational methods are shown in embodiment 1 to product Pm=0.8, [mmm]
Distribution similar with Fig. 1, figure is slightly).
Embodiment 10
Prepare major catalyst: 2g 3,5-di-tert-butyl salicylaldehyde (8.5mmol) is dissolved in 50mL
In ethanol, add 0.52mL 1,2-cyclohexanediamine (4.25mmol), add 2-3 and drip formic acid, room
Temperature stirring 24h, 0 DEG C of sedimentation 24h, filter, wash with water the most successively 3 times, washing with alcohol 3 times,
Vacuum drying preparation 3,5-di-t-butyl salicyloyl contracting cyclohexanediamine (Salen part), take 1g (1.8
Mmol) 3,5-di-t-butyl salicyloyl contracting cyclohexanediamine part is dissolved in 30mL dichloromethane solvent, adds
The anhydrous chromous chloride of 0.34g (2.7mmol), is stirred at room temperature reaction 24h the most in a nitrogen atmosphere,
Add 0.11g LiCl, blowing air, be stirred at room temperature 24 hours, take solvent away, add 100mL washing
Washing, filter, ethanol is washed 3 times, and vacuum drying obtains salung chromium SalenCrCl catalyst, and structural formula is such as
Under:
By above-mentioned SalenCrCl catalyst 22.7mg (0.036mmol), promoter PPNCl 20
Mg (0.036mmol), lactide 0.518g, expoxy propane 10mL are separately added in vial
(SalenCrCl catalyst: promoter: lactide=1:1:100 (mol ratio)), 25 DEG C of stirrings
Reaction 20min, adds 10mL hydrochloric acid methanol (mass percentage concentration of HCl is 1%) and terminates, and decompression removes
Remove solvent.Polymer washs with a large amount of methanol, and vacuum drying obtains white adipose adoption ester PLA.Polymerization
Yield be more than 90%, the number-average molecular weight 4,500 of polylactic acid, molecular weight distribution 1.2, product Pm=0.75
(Pm computational methods are shown in embodiment 1, and the distribution of [mmm] is similar with Fig. 1, and figure is slightly).
The explanation of above example is only intended to help to understand method and the core concept thereof of the present invention.Should
When pointing out, for those skilled in the art, in the premise without departing from the principle of the invention
Under, it is also possible to the present invention is carried out some improvement and modification, and these improve and modification also falls into present invention power
In the protection domain that profit requires.
Claims (6)
1. the preparation method of stereoregular polylactic acid under a temperate condition, it is characterised in that step is as follows:
Composite catalyst, rac-lactide are added in reaction vessel, adds solvent and dissolve, gained reactant liquor
Reacting 20min-4 hour in 0-25 DEG C, reaction adds hydrochloric acid methanol after terminating and terminates reaction, and gained produces
Thing methanol washing precipitation obtains stereoregulated polylactic acid；
Described composite catalyst is made up of with promoter major catalyst, major catalyst and promoter
Mol ratio is 1:0.5-2, and wherein major catalyst is metal salung M (III)-salen, wherein M=Cr, Co,
Or metalloporphyrin M (III)-porphyrin, wherein M=Al, Cr, Co, promoter is double-(triphen
Base phosphoranyl) ammonia chloride, dimethyl aminopyridine, one in 2,6-lutidines；
The structural formula of described metal salung M (III)-salen is:
M=Cr or Co；R1=o-C6H4, 1,2-cyclohexenyl group ,-CH2CH2-or-CH (CH3)CH2-；R2、
R3Separately replace or the substituted aliphatic group of bromine selected from hydrogen, chlorine, bromine, chlorine；X is-Cl ,-Br,
CCl3COO-、CF3COO-, 2,4-dinitrophenol,DNP epoxide, 3,5-dinitrophenol,DNP epoxide, 2,4,6-tri-
One in nitrophenol epoxide；
The structural formula of described metalloporphyrin M (III)-porphyrin is:
M=Cr or Co or Al, R2、R3、R4Separately replace selected from hydrogen, fluorine, chlorine, bromine, chlorine
Or the substituted aliphatic group of bromine；X is-Cl ,-OCH2CH3、-OCH(CH3)2、-Br、CCl3COO-、
CF3COO-, 2,4-dinitrophenol,DNP epoxide, 3,5-dinitrophenol,DNP epoxide, 2,4,6-trinitrophenol oxygen
One in base；
Described solvent is epoxide or the mixed solvent containing epoxide, described containing epoxy compound
The mixed solvent of thing is the mixture of epoxide and oxolane, or epoxide and dichloromethane
Mixture, or the mixture of epoxide and toluene, or the mixing of epoxide and dioxane
Thing, in the mixed solvent containing epoxide, epoxide accounts for volume ratio >=10% of mixed solvent.
The preparation method of stereoregular polylactic acid the most according to claim 1, it is characterised in that institute
Stating major catalyst with rac-lactide mol ratio is 1:100-500.
The preparation method of stereoregular polylactic acid the most according to claim 1, it is characterised in that institute
Stating epoxide is the one in expoxy propane, oxirane, 7-oxa-bicyclo[4.1.0.
The preparation method of stereoregular polylactic acid the most according to claim 1, it is characterised in that institute
State rac-lactide mass body in described epoxide or the mixed solvent containing epoxide
Volume concentrations is 0.01-0.1g/mL.
The preparation method of stereoregular polylactic acid the most according to claim 1, it is characterised in that institute
State conversion ratio >=90% of rac-lactide.
6. the stereoregular polylactic acid prepared according to the arbitrary described method of claim 1-5,
It is characterized in that, described stereoregular polylactic acid number-average molecular weight is 2500-10000, and molecular weight distribution is
1.1-1.5, in polylactic acid, isotaxy content is 70-85%.
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