Name: 95-96-5|3,6-Dimethyl-1,4-dioxane-2,5-dione|95%
Brand: Ambeed
SKU: A267054
Price: 6.0 USD
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Rating: 96 (25 reviews)

1
[ 849585-22-4 ]
[ 95-96-5 ]

Yield	Reaction Conditions	Operation in experiment
95.8%	With poly(dioctylstannane); at 150 - 200℃; under 0.1 - 760 Torr; for 4h;Inert atmosphere; Dean-Stark;	Example 1: [0043] A 500 ml 4-neck round bottom flask reactor equipped with mechanical stirrer, condenser and nitrogen inlet and Dean-stack trap was prepared, and 270 g of lactic acid (Lacticacid, Aldrich) having a concentration of 85 wt% was added to the above-mentioned four-necked flask, and the mixture was purged at 150 C. for 10 minutes under nitrogen gas while stirring. [0044] The internal temperature of the four-necked flask was increased from 10 C / min to 170 C / min, and then gradually reduced from 760 torr to 20 torr at 30 torr and (Temperature 1) and 65% of lactic acid was maintained for 1 hour until excreted water was discharged. At this time, if the decompression was accelerated quickly, the lactic acid in the reactor could be transferred to the dean-stack trap. Therefore, it was confirmed that the lactic acid was transferred to the dean-stack trap while maintaining the decompression rate. [0045] Thereafter, the internal temperature of the four-necked flask was raised to 180 C, and 0.03 parts by weight of 100 parts by weight of lactide using the catalyst Sn (Oct) 2 was added and after slowly raising the temperature to 200 C at 5 C per minute then the pressure was gradually reduced to 10 Torr per minute, and the reaction was continued until the pressure became 0.1 torr and maintained for 3 hours (temperature rise 2). [0046] The lactide obtained in a receiver cooled to 90 C was purified by distilled water at 25 C for 5 minutes and analyzed by GC and 1 H-NMR
95.1%	With stannous octoate; at 180 - 200℃; under 1 Torr; for 3h;Inert atmosphere; Dean-Stark; Industrial scale;	A 500 ml 4-neck round bottom flask reactor equipped with a mechanical stirrer, a condenser and a nitrogen inlet (N2 inlet) and a dean-stack trap was prepared. To the four-necked flask, 85 wt% 270 g of lactic acid (Aldrich) was added and the mixture was purged at 150 DEG C under nitrogen gas for 10 minutes with stirring.The internal temperature of the four-necked flask was increased from 10 C / min to 170 C / min and then from 760 torr to 20 torr at 30 torr(Temperature elevation 1) and reacted while maintaining the reaction time of 1 hour at 65% of lactic acid. At this time, if the decompression was accelerated rapidly, the lactic acid in the reactor could be transferred to the dean-stack trap. Therefore, it was confirmed that the lactic acid was transferred to the dean-stack trap while maintaining the decompression rate.Thereafter, the internal temperature of the four-necked flask was raised to 180 C. and then 0.03 parts by weight of 100 parts by weight of lactide using the catalyst Sn (Oct) 2 was slowly added to the flask at 200 C., The reaction was gradually reduced to 0.1 torr and maintained for 3 hours (temperature rise 2).Thereafter, the resultant product obtained in a receiver cooled to 90 C was introduced into a dropping membrane reactor and cooled to 30 C. After the time required for sufficient crystal growth, the lactide crystals were identified and then precipitated at least five times do. After confirming that the lactide was grown in the shape of a white needle, it was filtered, and then dried under reduced pressure at 40 C for 3 hours and analyzed by GC.
92.26%		FIG. 2 shows a process flow chart of the process for the catalytic synthesis lactide from lactic acid of the present invention. As shown in FIG. 2, lactic acid and a catalyst are firstly added to a round-bottom flask (250 ml), and the lactic acid and the catalyst are uniformly mixed by means of a magnetic stirrer under the conditions of 60-80 C. and 60 kPa, and reacted for 2 hours to remove free water therefrom. Then, the heating temperature is gradually adjusted to 120-150 C., and the reactants are subjected to a polymerization reaction for 3 hours under 10 kPa conditions to obtain an oligomer. Finally, depolymerization is performed at 170 C. for a period of time (about 20-30 minutes), the temperature is then increased and the pressure reduced gradually, and under the conditions of 1-3 kPa and 170-220 C., lactide is continuously distilled out until no more product is formed.

83.3%	With dealuminated zeolite H-beta; In water; toluene;Reflux; Large scale;Catalytic behavior;	An aqueous solution of lactic acid (50 weight%) was at least partially converted into the lactide of formula (II) according to the present invention) in toluene. (0286) In first step a mixture was prepared by filling (0287) - 10 g of toluene, (0288) - 0.5 g of the respective zeolitic material, and (0289) - 1.67 g of an aqueous solution of lactic acid (50 weight-%) (0290) into a 25 ml. three-necked round bottom flask operates with removal of the water at reflux temperature and with condenser and phase-separator for continuous toluene recirculation. (0291) In a second step the mixture inside the glass reactor was heated to reflux temperature while stirring. The reaction temperature was maintained for 3 hours (see Table 1 , below) while continuing stirring the reaction mixture inside the heated glass reactor.
	stannous octoate; at 120 - 250℃; under 10 Torr; for 5 - 10h;Product distribution / selectivity;	EXAMPLES; Next, an example of the present invention will be explained referring to FIG. 4. The construction of this example is similar to that illustrated in FIG. 1, but in this example, oligomer is returned to a concentrated lactic acid buffer tank 5. Polylactic acid was produced using the apparatus for producing polylactic acid having a construction as shown in FIG. 4.In lactic acid concentration device 3, water contained in lactic acid is evaporated by heating. The heating is carried out at 120-150 C. under passing of nitrogen gas. In the lactic acid concentration reaction, water and lactic acid are produced as gases. These gases enter into distillation column 18, and lactic acid is removed from the gases and refluxed to the lactic acid concentration device 3.The concentrated lactic acid produced in the lactic acid concentration device 3 is sent to lactic acid polycondensation device 7 through concentrated lactic acid buffer tank 5. In the lactic acid polycondensation device 7, polycondensation reaction of lactic acid is allowed to proceed, and water produced is evaporated. The reaction is carried out at a temperature of 120-250 C. under a reduced pressure of 10 torr or lower. In the lactic acid polycondensation reaction, there are produced water, lactic acid, lactic acid oligomer of low molecular weight and lactide produced by the decomposition of the oligomer as gases. They transfer from the lactic acid polycondensation device 7 to vacuum pump 23. These gases enter into distillation column 21, and lactic acid, lactic acid oligomer of low molecular weight and lactide are removed from the gases and refluxed to the lactic acid polycondensation device 7.The lactic acid oligomer produced in the lactic acid polycondensation device 7 is sent to depolymerization device 11. In the depolymerization device 11, depolymerization reaction of lactic acid oligomer is allowed to proceed. The reaction is carried out at a temperature of 120-250 C. under a reduced pressure of 10 torr or lower by contacting the lactic acid oligomer with a depolymerization catalyst such as antimony trioxide or tin octylate. The gaseous lactide produced by this reaction is fed to lower distillation column 12.In the lower distillation column 12, impurities such as oligomer contained in lactide is liquefied by cooling the gaseous lactide and the gaseous lactide is sent to upper distillation column 13. In the liquid containing oligomer separated from lactide, in many cases, the molecular weight of the oligomer becomes lower due to the depolymerization reaction. In order to improve the yield of lactide, it is preferred to condense again the oligomer of low molecular weight to increase the molecular weight, and, therefore, the liquid containing the oligomer of low molecular weight separated from lactide is refluxed to the concentrated lactic acid buffer tank 5.The gaseous lactide is cooled and condensed in the upper distillation column 13 and then fed to lactide purification device 15. The gas containing a large amount of water vapor separated from lactide enters into cooling device 24, where lactic acid, lactic acid oligomer of low molecular weight and lactide are removed from the gas and refluxed to the upper distillation column 13.The vapor which is not condensed in the cooling device 24 enters into impurity cooler 25 and is condensed and liquefied here. The liquefied impurities are usually abandoned. The gas which is not condensed in the impurity cooler 25 is discharged out of the system through a vacuum pump 26.The lactide discharged from lactide purification device 15 is transferred to opening ring polymerization device 17. In the opening ring polymerization device 17, the opening ring polymerization reaction of lactide proceeds. The reaction is carried out at a temperature of 120-250 C. under a reduced pressure of 10 torr or lower by contacting the lactide with an opening ring polymerization catalyst such as antimony trioxide or tin octylate and a polymerization initiator such as 1-dodecanol. When the concentration of the polymerization initiator is 700 ppm, the weight-average molecular weight of polylactic acid is about 200000.Crude lactide was produced by the apparatus of this example. The oligomer used in this experiment had an average molecular weight of 630. The retention time of oligomer in the depolymerization device 11 was 5 hours, thickness of the liquid film was 5 cm, and increase of optical isomerization rate in the depolymerization step was 0.9% in the case of the concentration of the catalyst (tin 2-ethylhexanoate) being 0.7 kg/m3. Here, the retention time of the oligomer is defined to be a ratio of a feed flow rate of molten oligomer and a retention amount of molten oligomer in the oligomer depolymerization device 11 when the feed flow rate of the molten oligomer and the flow rate of vapor condensate discharged from the depolymerization reactor are equal, and when the thickness of liquid film is stabilized. Furthermore, color...
	With zinc(II) sulfate heptahydrate; zinc(II) sulfate monohydrate; In water; at 75 - 180℃; under 2.25023 Torr; for 23h;Product distribution / selectivity;	Example 3Example 2 was reproduced but 22.6 g of the solid were introduced into Bl which was connected with B2 and placed in a ventilated oven at 75C during a bout 6 hours under 3 mbar. After 6 hours, water was collected in B2.B2 was replaced and Bl was heated at 180C during 17 hours at 3 mbar.1.0 g of matter was collected into B2. 1 H-NMR analysis of the content of B2 showed the following composition: 4% lactic acid, 5% dimer and 91% lactide, which corresponds to a global yield in lactide of 51%. Example 29.1 g of water (0.5 mol) were added to 28.8 g of ZnS04.7H20 (0.1 mol) and the mixture was heated to 100C to solubilize the ZnS04.7H20. A clear solution was obtained and it was allowed to cool to room temperature. The solution remained clear.10.9 g of lactic acid as a 90 wt% solution in water (i.e. 9.78 g / 0.1 mol lactic acid and 1.09 g / 0.06 mol H20) were added to the ZnS04.7H20 solution, then 53.7 g of ZnS04.H20 (0.3 mol) were added while mixing, to produce a paste which rapidly solidifies when mixing is stopped. The mixture was kept in a dessicator. At the time of using the mixture, it was weighted again and it was noted that 1.9 g of water had evaporated. The composition at the time of the experiment was 71,7% ZnS04.H20, 9,78% lactic acid and 18,53 H20.22.5 g of the solid were introduced into Bl which was connected with B2 and placed in a ventilated oven at 55C during about 24 hours under 3 mbar. After 24 hours, 3.93 g of water were collected in B2.B2 was replaced and Bl was heated at 180C during 20 min at atmospheric pressure and then at 180C during 3 hours at 3 mbar. 0.57 g of matter were collected into B2. 1 H-NMR analysis of the content of B2 showed the following composition: 30% lactic acid, 3% dimer and 67% lactide, which corresponds to a global yield in lactide of 22%.
180 g		A solution of 3505.9 g of 12 wt% lactic acid (lactic acid crystals, Purac Corbion) in MTBE (methyl tertiair-butyl ether, Acros) containing 4 wt% of water was prepared. This solution was concentrated to approximately 90 wt%. at 80-90 C at reduced pressure in a rotavap (3040.3 water and MTBE condensed) . After the concentration there was 434.9 g of concentrated lactic acid solution. The solution was transferred to a round-bottom flask with a mechanical stirrer and was heated in 101 minutes to the set point 180 C . At 180 C slowly vacuum was applied down to 80 mbar in 23 minutes, while water and MTBE were further evaporating. At 80 mbar some lactide present at equilibrium in the prepolymer started to evaporate, and crystallise in the condenser, and prepolyemrisation was stopped. In total 110 g of water and MTBE was evaporated. It was estimated that a pre-polymer with an average degree of polymerization of 7-8 was made. The prepolymer comprised 4.7 wt . % of the total of D and L lactide and 0.4 wt . % mesolactide. Next 0.05 wt% of tin 2-ethylhexanoate (catalyst) was added. The prepolymer (316 g) was heated to 200 C, and the vacuum reduced slowly to 5 mbar . In 153 minutes 180 g of lactide was distilled off, faster than the reference. The lactide had a content of D+L lactide of 77 wt%. The meso-lactide content of the lactide was 1.1 wt%. Figure 2 shows the weight of lactide produced from prepolymer over time for the systems of Example 1 (reference aqueous based system) and Example 4 (MTBE based system according to the invention) . From Figure 2 it can be seen that the system according to the invention shows a higher reaction rate than the comparative system. This can be used in the configuration of a total process and in equipment design to reduce costs.
		(1) dehydration of D, L-lactic acid. Measuring 100mLD, L-lactic acid raw materials containing 100g lactic acid into the three-necked flask,Installation of electric stirring system, condensation system, constant temperature heating system, vacuum system. Decompression 13. 3KPa gradually heated to 80 C, the condensation system using cold water cooling, the temperature maintained at 50 C, free water about 2h or so, to no water droplets drop to stop heating. (2) polymerized into lactic acid oligomer.Mass ratio of a certain amount of catalyst, under reduced pressure (13.3KPa) under re slowly warmed to 140 , the condensing system uses chilled water temperature was maintained at 140 , de-bound water of about 1h about to drop out of the water fraction of ignorance stop heating. (3) allowed to stand for 10 minutes after addition of the catalyst, water was added with stirring and heated to 90 C kept by cooling again after 3-5 hours. (4) oligomer depolymerization into the ring.Replace the receiver means, rapid heating resumed, when the pressure was reduced to 190 to 1KPa, slowly warming continued, the reaction temperature is controlled at 200 ~ 210 , until no distillate was up about 1.5h.Distilled lactide vapor condensed rapidly wall, pale yellow liquid lactide gradually crystallized. (5) Extraction and Separation: The resulting solution was allowed to stand for 10 minutes, after adding the extraction agent and the extract solution was obtained, acquired.As a preferred option, the product by suction filtration to give solid crude product.The crude lactide pale yellow, recrystallized from ethyl acetate three times.After drying in vacuo to give a transparent layered crystal.
	With stannous octoate; at 150 - 180℃; for 4h;Inert atmosphere; Dean-Stark;	A 500 ml 4-neck round bottom flask reactor equipped with a mechanical stirrer, a condenser and a nitrogen inlet (N2 inlet) and a dean-stack trap was prepared and to the four-necked flask, 85 wt. % Lactic acid (Lacticacid, Aldrich), and the mixture was purged at 150 DEG C under nitrogen gas for 10 minutes with stirring.The internal temperature of the four-necked flask was raised to 170 C. at a rate of 10 C. per minute, and then the reaction was progressed at a reduced pressure of 30 torr per minute from 760 torr to 20 torr (temperature rise 1) Keep for 1 hour untilRespectively.At this time, if the decompression was accelerated quickly, the lactic acid in the reactor could be transferred to the dean-stack trap. Therefore, it was confirmed that the lactic acid was transferred to the dean-stack trap while maintaining the decompression rate.Thereafter, the internal temperature of the four-necked flask was raised to 180 C. and then 0.03 parts by weight of 100 parts by weight of lactide using the catalyst Sn (Oct) 2 was added. The temperature was gradually raised to 200 C. at 5 C. per minute The pressure was gradually reduced to 10 torr / min, and the reaction was continued until the pressure became 0.1 torr.The lactide obtained in a receiver cooled to 90 C was purified with distilled water and analyzed using GC and H1 -NMR.

Reference： [1]Patent: KR101679032,2016,B1 .Location in patent: Paragraph 0042-0045
[2]Patent: KR2017/36494,2017,A .Location in patent: Paragraph 0043-0047; 0071
[3]Patent: US2019/47976,2019,A1 .Location in patent: Paragraph 0028-0040
[4]Patent: WO2018/167143,2018,A1 .Location in patent: Page/Page column 32-33
[5]Justus Liebigs Annalen der Chemie,1845,vol. 53,p. 116
[6]Chemische Berichte,1925,vol. 58,p. 1313
Archiv der Pharmazie (Weinheim, Germany),1926,p. 123
[7]Patent: US2008/4469,2008,A1 .Location in patent: Page/Page column 5-6
[8]Patent: WO2012/921,2012,A1 .Location in patent: Page/Page column 10-11
[9]Patent: WO2016/128501,2016,A1 .Location in patent: Page/Page column 22; 23
[10]Patent: CN105461679,2016,A .Location in patent: Paragraph 0015-0021
[11]Patent: KR101679031,2016,B1 .Location in patent: Paragraph 0041-0052
[12]Patent: DE267826,
Fortschr. Teerfarbenfabr. Verw. Industriezweige,vol. 11,p. 90

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[ 849585-22-4 ]
[ 617-57-2 ]
[ 95-96-5 ]

Yield	Reaction Conditions	Operation in experiment
	With zinc(II) sulfate heptahydrate; zinc(II) sulfate monohydrate; In water; at 45 - 140℃; under 3.0003 Torr; for 13h;	9.0 g of water (0.5 mol) were added to 28.8 g of ZnS04.7H20 (0.1 mol) and the mixture was heated to 100C to solubilize the ZnS04.7H20. A clear solution was obtained and it was allowed to cool to room temperature. The solution remained clear.1 1.2 g of lactic acid as an 80 wt% solution in water (i.e. 9.0 g / 0.1 mol lactic acid and 2.24 g / 0.12 mol H20) were added to the ZnS04.7H20 solution, then 53,7 g of ZnS04.H20 (0.3 mol) were added while mixing, to produce a paste which rapidly solidifies when mixing is stopped.The solid was introduced into flask Bl which was connected with B2 and placed in a ventilated oven at 45 C during about 6 hours under 4 mbar. After 6 hours, 20.9 g of water were collected in B2. 9.56 g of the mixture present in Bl were kept into Bl which was connected with vessels B2 and B3 and heated at 90C during 4 hours at 4 mbar. 0.25 g of matter (mainly water) were collected into B3, which was replaced.Bl was then heated at 140C during 3 hours at 4 mbar. 0.42 g of a jellified product were collected in B2 and 0.14 g of a solid product were collected in B3. -NMR analysis of the content of B2 and B3 showed the following composition:- B2: 58% lactic acid, 12% dimer and 22% lactide,- B3: 75% lactic acid, 8% dimer and 17% lactide.The global yield in lactide was 14%.

Reference： [1]Justus Liebigs Annalen der Chemie,1873,vol. 167,p. 319
[2]Patent: WO2012/921,2012,A1 .Location in patent: Page/Page column 9-10

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[ 7664-41-7 ]
[ 95-96-5 ]
[ 598-81-2 ]

Reference： [1]Annales de Chimie (Cachan, France),1861,vol. <3> 63,p. 108

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[ 502-97-6 ]
[ 95-96-5 ]
bulk copolymer of lactide and glycolide [ No CAS ]

Reference： [1]European Journal of Inorganic Chemistry,2002,p. 1948 - 1951

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[ 502-97-6 ]
[ 95-96-5 ]
epoxy terminated poly(ethylene glycol) [ No CAS ]
poly(lactic acid-co-glycolic acid)-g-poly(ethylene glycol), Mn = 6000, PDI = 1.7, composition: DDLA 1.21/GA 0.37/EG 1.0, number of PEG graft per PLGA backbone: 3 [ No CAS ]

Reference： [1]Journal of Physical Chemistry B,2003,vol. 107,p. 10032 - 10039

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[ 502-97-6 ]
[ 95-96-5 ]
epoxy terminated poly(ethylene glycol) [ No CAS ]
poly(lactic acid-co-glycolic acid)-g-poly(ethylene glycol), Mn = 7800, PDI = 1.4, composition: DDLA 1.20/GA 0.38/EG 1.0, number of PEG graft per PLGA backbone: 4 [ No CAS ]

Reference： [1]Journal of Physical Chemistry B,2003,vol. 107,p. 10032 - 10039

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[ 502-97-6 ]
[ 95-96-5 ]
epoxy terminated poly(ethylene glycol) [ No CAS ]
poly(lactic acid-co-glycolic acid)-g-poly(ethylene glycol), Mn = 9300, PDI = 1.5, composition: DDLA 1.14/GA 0.36/EG 1.0, number of PEG graft per PLGA backbone: 5 [ No CAS ]

Reference： [1]Journal of Physical Chemistry B,2003,vol. 107,p. 10032 - 10039

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[ 502-97-6 ]
[ 95-96-5 ]
epoxy terminated poly(ethylene glycol) [ No CAS ]
poly(lactic acid-co-glycolic acid)-g-poly(ethylene glycol), Mn = 10000, PDI = 2.0, composition: DDLA 0.78/GA 0.25/EG 1.0, number of PEG graft per PLGA backbone: 4 [ No CAS ]

Reference： [1]Journal of Physical Chemistry B,2003,vol. 107,p. 10032 - 10039

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[ 502-97-6 ]
[ 77-85-0 ]
[ 95-96-5 ]
poly(lactide-co-glycolide), star-shaped, three-armed, hydroxy-terminated, M_n 980 g/mol; monomer(s): dilactide; glycolide; 1,1,1-tris(hydroxymethyl)ethane [ No CAS ]