3,6-Dimethyl-1,4-dioxane-2,5-dione [DL-Lactide] by Asch

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Reactions (32)

Yield

Substances (1)

Citations (31)

Conditions

References

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Rx-ID: 198000 Find similar reactions

T=250 - 260°C; inactive-lactide;

Pelouze

Justus Liebigs Annalen der Chemie, 1845 , vol. 53, p. 116 Full Text View citing articles Show Details

Gay-Lussac; Pelouze

Justus Liebigs Annalen der Chemie, 1833 , vol. 7, p. 43 Full Text View citing articles Show Details

Engelhardt

Justus Liebigs Annalen der Chemie, 1849 , vol. 70, p. 243 Full Text Show Details

T=200°C; Erhitzen im Vakuum und Destillieren in Gegenwart von Zinkoxyd im Vakuum unter Durchleiten von Kohlendioxyd bei 200-220grad;

Chem. Werke Byk

Patent: DE267826 ; Fortschr. Teerfarbenfabr. Verw. Industriezweige, vol. 11, p. 90 Full Text Show Details

durch Destillation; inactive lactide;

Dietzel; Krug

Chemische Berichte, 1925 , vol. 58, p. 1313 Archiv der Pharmazie (Weinheim, Germany), 1926 , p. 123 Full Text View citing articles Show Details

Hide Details With stannous octoate

T=120 - 250°C; P=10 Torr; 5 - 10 h; Product distribution / selectivity; Hide Experimental Procedure

KAMIKAWA, Masayuki; Matsuo, Toshiaki; Oka, Kenichiro; Okamoto, Naruyasu; Kaziya, Ryuji

Patent: US2008/4469 A1, 2008 ; Location in patent: Page/Page column 5-6 ; Title/Abstract Full Text Show Details

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 120150° 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 0.9percent 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, coloration of polylactic acid obtained by opening ring polymerization of the lactide is 2.5 in terms of value b, and thus the influence of heat decomposition of lactide and oligomer in depolymerization is small.As a comparative example, depolymerization of the same oligomer as in the embodiment shown in FIG. 1 was carried out in batch-wise manner using a conventional tank type reaction vessel. In this experiment, the depolymerization was carried out under the conditions of a depolymerization time of 10 hours, an initial liquid level of 80 cm, and an initial catalyst concentration of 5 kg/m3. As a result, for the resulting lactide, increase of optical isomerization rate in the depolymerization step was 9percent, and coloration of polylactic acid obtained by opening ring polymerization using the lactide was 4.4 in terms of value b. With zinc(II) sulfate heptahydrate; zinc(II) sulfate monohydrate in water

T=75 - 180°C; P=2.25023 Torr; 23 h; Product distribution / selectivity; Hide Experimental Procedure

SOLVAY SA; WAUTIER, Henri

Patent: WO2012/921 A1, 2012 ; Location in patent: Page/Page column 10-11 ; Title/Abstract Full Text Show Details

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 75°C during a bout 6 hours under 3 mbar. After 6 hours, water was collected in B2.B2 was replaced and Bl was heated at 180°C 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: 4percent lactic acid, 5percent dimer and 91percent lactide, which corresponds to a global yield in lactide of 51percent. 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 100°C 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 wtpercent 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 71,7percent ZnS04.H20, 9,78percent 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 55°C 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 180°C during 20 min at atmospheric pressure and then at 180°C 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: 30percent lactic acid, 3percent dimer and 67percent lactide, which corresponds to a global yield in lactide of 22percent. 180 g

Stage #1: in tert-butyl methyl ether; water

T=180°C; P=60.006 Torr; 2.06667 h; Stage #2: With stannous octoate

T=200°C; P=3.75038 Torr; 2.55 h; SolventPressureTime; Hide Experimental Procedure

PURAC BIOCHEM BV; GROOT, Wim Jacob; VAN KRIEKEN, Jan; DEKIC ZIVKOVIC, Tanja; DE HAAN, Andre Banier

Patent: WO2016/128501 A1, 2016 ; Location in patent: Page/Page column 22; 23 ; Title/Abstract Full Text Show Details

4:Example 4 (according to the invention) - MTBE as solvent

A solution of 3505.9 g of 12 wtpercent lactic acid (lactic acid crystals, Purac Corbion) in MTBE (methyl tertiair-butyl ether, Acros) containing 4 wtpercent of water was prepared. This solution was concentrated to approximately 90 wtpercent. 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 . percent of the total of D and L lactide and 0.4 wt . percent mesolactide. Next 0.05 wtpercent 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 wtpercent. The meso-lactide content of the lactide was 1.1 wtpercent. 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.

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With 1,4-diazabicyclo[2.2.2]octane; tris(pentafluorophenyl)borate in toluene

T=20°C; 0.0833333 h; GloveboxInert atmosphere; Catalytic behavior; Reagent/catalystSolventTemperature;

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Rx-ID: 41120911 Find similar reactions

Zhu, Jian-Bo; Chen, Eugene Y.-X.

Journal of the American Chemical Society, 2015 , vol. 137, # 39 p. 12506 - 12509 Title/Abstract Full Text View citing articles Show Details

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With calcium diphosphate; nitrogen; water

T=170°C; Kinetics; Reagent/catalystTime; Hide Experimental Procedure

Blanco; Delichere; Millet; Loridant

Catalysis Today, 2014 , vol. 226, p. 185 - 191 Title/Abstract Full Text View citing articles Show Details

2.3 Catalytic testing

General procedure: Dehydration of lactic acid was conducted in a fixed bed reactor (inner diameter 14 mm) operating at atmospheric pressure. A 20 weight percent aqueous solution of lactic acid was fed using 307 HPLC pump (Gilson), vaporized at 170 °C with home-made system and diluted with N2. The vaporization temperature was determined from liquid vapor equilibrium simulated by the ProSim plus software (ProSim S.A.). The feed composition was LA/H2O/N2: 3/66/31. Before addition of the vaporized LA solution, the reactor was heated at the reaction temperature under N2. The contact time was varied from 0.1 to 4.1 s (GHSV from 36,000 to 880 h−1). Condensable molecules were collected in a cold trap at −4 °C and analyzed off-line with a GC-2014 chromatograph (Shimadzu) equipped with AOC-20i auto injector, ZB-WAXplus (30 m, 0.32 mm) column and FID detector, while gas products, mainly CO, CO2 and N2 were analyzed online with the same chromatograph but using sampling valve, Carboxen 1000 column and TCD detector.

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With calcium diphosphate; nitrogen; water

T=380°C; Reagent/catalystTime; Hide Experimental Procedure

Blanco; Delichere; Millet; Loridant

Catalysis Today, 2014 , vol. 226, p. 185 - 191 Title/Abstract Full Text View citing articles Show Details

2.3 Catalytic testing

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73%

With ytterbium(III) triflate in anhydrous xylene

T=180°C; 14 h; Reagent/catalyst; Hide Experimental Procedure

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Rx-ID: 36292631 Find similar reactions

HYUNDAI MOTOR COMPANY; Hong, Chae Hwan; Kim, Si Hwan; Seo, Jiyoun; Han, Do Suck

Patent: US2013/267716 A1, 2013 ; Location in patent: Paragraph 0057-0059 ; Title/Abstract Full Text Show Details

1:Example 1

Example 1 [0057] A 100 mL round-bottom flask, a dean stark, and a cooling pipe were used. The dean stark is disposed at the center for an azeotropic distillation, and the cooling pipe is connected to an upper portion of the dean stark. [0058] To the round-bottom flask, 100 mg (1.1101 mmol) of ammonium lactate and 40 mL of xylene were added to obtain a mixture. Subsequently, 6.88 mg (0.0111 mmol) of ytterbium triplate was added to the mixture as a catalyst. The mixture was stirred. The flask was heated using a heating plate for 14 hours, and then lactate, lactide produced by the catalytic reaction, lactate by the azeotropic distillation, and other by-products were transferred to a separation funnel with the solvent (xylene). The amount of the catalyst, ytterbium triplate (Yb(OTf)3), was about 1 mol percent. [0059] The solvent, lactide, and impurities obtained from the separation funnel were mixed with ethyl acetate and water to separate the impurities. 40 mL of ethyl acetate and 40 mL of water were added thereto based on the total volume of the solvent, lactide, and impurities. The ethyl acetate layer was subjected to an extraction and the extract was transferred to a rotary evaporator. The ethyl acetate and the solvent (xylene) were evaporated to obtain 58.4 mg (0.4052 mmol) of lactide (73percent). 1H NMR (400 MHz, CDCl3) δ 5.03 (q, 2H), δ 1.68 (d, 6H), 13C NMR (100 mHz) δ 167.4, δ 72.5, δ 15.8, mp 97° C.

Rx-ID: 38674935 Find similar reactions

A: 10% B: 10% E: 20% F: 4%

With sulfuric acid; dihydrogen peroxide in water

T=4 - 20°C; 25.5 h;

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Novikov; Shestak

Russian Chemical Bulletin, 2013 , vol. 62, # 10 p. 2171 - 2190 Izv. Akad. Nauk, Ser. Khim., 2013 , vol. 62, # 10 p. 2171 - 2190,20 Title/Abstract Full Text View citing articles Show Details

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B: 5% C: 16% D: 24%

With dihydrogen peroxide in tert-butyl alcohol

36 h; Reflux;

Novikov; Shestak

Russian Chemical Bulletin, 2013 , vol. 62, # 10 p. 2171 - 2190 Izv. Akad. Nauk, Ser. Khim., 2013 , vol. 62, # 10 p. 2171 - 2190,20 Title/Abstract Full Text View citing articles Show Details

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T=150°C; im Luftstrom; inactive-lactide;

Wislicenus

Justus Liebigs Annalen der Chemie, 1873 , vol. 167, p. 319 Full Text View citing articles Show Details

With zinc sulfate heptahydrate powder; zinc sulfate monohydrate in water

T=45 - 140°C; P=3.0003 Torr; 13 h; Hide Experimental Procedure

SOLVAY SA; WAUTIER, Henri

Patent: WO2012/921 A1, 2012 ; Location in patent: Page/Page column 9-10 ; Title/Abstract Full Text Show Details

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 100°C 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 wtpercent 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 90°C 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 140°C 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: 58percent lactic acid, 12percent dimer and 22percent lactide,- B3: 75percent lactic acid, 8percent dimer and 17percent lactide.The global yield in lactide was 14percent.

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T=170 - 280°C; P=4.50045 Torr; 2.7 h; Hide Experimental Procedure

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Rx-ID: 28603267 Find similar reactions

KTANTON Ltd.

Patent: WO2009/80834 A1, 2009 ; Location in patent: Page/Page column 9-10 ; Title/Abstract Full Text Show Details

Magnesium Lactate Dihydrate (PURAMEX.(R). MG) was dehydrated at atmospheric pressure at 1850C during 4h. 20.2 g of the resulting Anhydrate was thoroughly mixed (mortar) with 22.5 g of 80percent Lactic Acid (PURAC FCC80). The homogeneous and fairly fluid mixture was left to react at HO0C for 2,5 hours, which resulted in complete solidification.20,82 g of that solid were introduced in the boiler of a BUCHI Glass Oven B-585 and heated under atmospheric pressure to 1000C (1 hour), 12O0C (1 hour), 16O0C (40 minutes), and then under 6 mbar at 16O0C (1 hour). Two fractions of condensate were collected in 2 separate vessels in line with the boiler, that in the vessel closest to the boiler being 1,51 g of a transparent oily liquid (Fl) that was analyzed by RMN, while that collected in the last vessel (4,37 g) was assumed to be essentially water and was not analyzed.The condensate collection vessels were replaced by clean ones and distillation under 6mbar went on for 2,7 hours, while the set point of the boiler slowly increased from 17O0C to 28O0C.2,19 g of solids (F2) were collected and analyzed by RMN.The white solid residue in the boiler amounted to 10.09 g (a weight loss of 10,73 g having hence taken place).The analytical results (percent by weight) collected were as follows: Fl : 3percent LD, 7percent dimer of lactic acid (LA), 90percent LA F2: 88percent LD, 5percent LA dimer, 7percent LA <n="11"/>These analytical results could be interpreted as follows: a. - Magnesium Lactoyllactate Dihydrate was produced under atmospheric pressure up to 16O0C by reaction between the Anhydrate and the Water brought in with the Lactic Acid. b. - Decreasing the pressure to 6 mbar at 16O0C resulted in the distillation of free water. c. - Progressively increasing the temperature to 28O0C under vacuum led to the dehydration of the Hydrated Magnesium Lactoyllactate and to the its decomposition in Magnesium Hydroxide and Lactide, the former remaining in the boiler and the latter being condensed in F2 mainly. A

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Rx-ID: 28972480 Find similar reactions

Stage #1: T=110°C; P=760.051 Torr; 1.5 h; Stage #2: With phosphoric acid in water

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KTANTON Ltd.

Patent: US2009/318713 A1, 2009 ; Location in patent: Page/Page column 4-5 ; Title/Abstract Full Text Show Details

The purpose of this example is to demonstrate that the distillation allows the acid to be effectively separated from the diester.In order to do this, the procedure below was followed:13.9 g of CaLa pentahydrate and 10.5 g of lactic acid (LA, 88percent) were mixed in a Petri dish. The mixture was partially dehydrated under atmospheric pressure at 110° C. over 90 min. The solid obtained, which weighed 19.3 g, was finely milled and 18.8 g of powder was recovered, with which 12.2 g of phosphoric acid (85percent aqueous solution) were mixed in a mortar.The resulting paste was extruded using a syringe to form a sort of rod (spaghetti) weighing 26.9 g that was dried in a Petri dish for 3.5 h under atmospheric pressure at 110° C. The solid, dried and coarsely milled to particles of 2 to 5 mm then weighed 23.4 g.2 g of a previous batch (produced under identical conditions) were added thereto and a BUeCHI type distillation device (as described previously) was loaded with the 25.4 g of solid thus obtained.The device was put under vacuum (5 to 10 mbar) and the setpoint temperature was changed as indicated in FIG. 2 (which in fact represents, on the y-axis, this temperature -100° C.).At regular intervals, the rotation of the device and the heating were stopped in order to be able to recover sublimate (strictly speaking, at the start of the operation it is a condensate), that was weighed and kept airtight before the analysis. FIG. 2 also gives on the y-axis, the change in the product of the accumulated sublimate mass (m. cum., in g) times 10, over time.The composition of the consecutive sublimate fractions was analysed by NMR (dissolution in acetone).The result of these analyses appears in the appended table and in FIG. 3 (where the x-axis gives the accumulated weight of sublimate and the y-axis the weight fraction of each constituent).It can be seen therein that the 9 g recovered in total contain 8.08 g of lactate groups whereas 10.18 g thereof were introduced at the start. The lactate recovery rate is therefore 79percent.By mixing all the fractions a crude lactide containing 39percent by weight of lactide would be obtained.This figure clearly shows that, at the start of the separation, it is mainly lactic acid that is recovered at the condenser, whilst the lactoyl-lactic acid and the lactide only appear later. It is advantageous to note that the last three samples recovered contain around 90percent lactide, which suggests that the subsequent purification described above will be easy. A

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Rx-ID: 28972481 Find similar reactions

Stage #1: in water

P=760.051 Torr; 1 h; Boiling; Stage #2: With phosphoric acid in water

T=20°C; Product distribution / selectivity; Hide Experimental Procedure

KTANTON Ltd.

Patent: US2009/318713 A1, 2009 ; Location in patent: Page/Page column 6 ; Title/Abstract Full Text Show Details

The purpose of this example is to demonstrate that it is possible to add a reaction by-product from a previous batch (here, lactic acid) to the mixture.In order to do this, the procedure below was followed:A 250 ml vessel was charged with 55 g of calcium lactate pentahydrate, 42.1 g of 88percent lactic acid and 25 g of water. After boiling, whilst stirring, for one hour at atmospheric pressure, the slurry obtained was transferred into a mortar and 50.2 g of 85percent phosphoric acid were added thereto. After mixing, the pasty mixture was extruded as a spaghetti that was left to age at ambient temperature for a few days, until becoming a solid that was coarsely milled into granules having an average diameter of 2 to 5 mm.To prevent these granules from agglomerating during the separation in the mini-sublimer, added to the charge was a small amount of desiccant (5 g of anhydrous monocalcium phosphate powder, obtained by milling the residue of a previous batch) for a charge of 25 g of granules.FIG. 6 shows that, under a pressure of 5 to 10 mbar, the separation can be carried out at a relatively low temperature. But in this case (FIG. 7), the lactide concentration of the sublimate only becomes high at the end of the separation.In FIG. 7, the concentrations obtained by analysis of the NMR signals by the two routes described in the previous example are given.The weight contents of the mixture of all the sublimate fractions would be:L1A: 0.747LD2: 0.170L2A: 0.082LD3: 0.001 A

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With phosphoric acid in water

T=50°C; Hide Experimental Procedure

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KTANTON Ltd.

Patent: US2009/318713 A1, 2009 ; Location in patent: Page/Page column 5-6 ; Title/Abstract Full Text Show Details

The purpose of this example is to demonstrate that the starting reactants do not necessarily have to be anhydrous.In order to do this, the procedure below was followed:28.1 g of calcium lactate pentahydrate were dissolved in 100 g of water in a 250 ml container, with stirring at 60° C., then 12.8 g of 85percent phosphoric acid were added. After 80 minutes of evaporation, a partly crystallized mass remained, which was transferred into a mortar and mixed with 12.5 g of 85percent phosphoric acid. It was possible to recover 49.4 g of paste, the consistency of which permitted extrusion using a syringe, the diameter of the tip of which was 5.2 mm.46.9 g of the rod thus produced were raised in an oven to 50° C. for 18 hours, which reduced the weight to 36.7 g. After coarse milling, 33.7 g of the granules obtained were loaded into the evaporator of the BUeCHI B-585 Kugelrohr minisublimer. Accumulated Weight weight L1A LD L2A L1A LD L2A Lactate Fraction No. g G x x x g g g ex-L1A ex-LD ex-L2A 1 0.7 0.7 0.9 0.03 0.07 0.63 0.021 0.049 0.504004 0.021 0.043556 2 2.2 2.9 0.76 0.11 0.13 1.672 0.242 0.286 1.33761 0.242 0.254223 3 1.9 4.8 0.58 0.25 0.16 1.102 0.475 0.304 0.881606 0.475 0.270223 4 1.7 6.5 0.48 0.4 0.13 0.816 0.68 0.221 0.652805 0.68 0.196445 5 0.8 7.3 0.24 0.67 0.09 0.192 0.536 0.072 0.153601 0.536 0.064 6 0.5 7.8 0.11 0.83 0.05 0.055 0.415 0.025 0.044 0.415 0.022222 7 0.4 8.2 0.05 0.89 0.06 0.02 0.356 0.024 0.016 0.356 0.021333 8 0.3 8.5 0.03 0.88 0.09 0.009 0.264 0.027 0.0072 0.264 0.024 9 0.6 9.1 0.02 0.92 0.06 0.012 0.552 0.036 0.0096 0.552 0.032 Sum 4.508 3.541 1.044 3.606426 3.541 0.928004 x = weight fraction L1A = lactic acid LD = cyclic dilactide L2A = lactoyl-lactateThe device was put under vacuum (5 to 10 mbar) and the setpoint temperature was gradually increased as indicated in FIG. 4 (which in fact represents, on the y-axis, this temperature -100° C.).At regular intervals, the rotation of the device and the heating were stopped in order to be able to recover sublimate (strictly speaking, at the start of the operation it is a condensate), that was weighed and kept airtight before the analysis. FIG. 4 also gives on the y-axis, the change in the product of the accumulated sublimate mass (m. cum., in g) times 10, over time.The NMR analysis made it possible to measure the concentrations of the various constituents, either by considering the protons included in the CH3 group, or by considering the protons bonded to a carbon bearing an alcohol group or an ester group. The averages of these concentrations (x or mass fraction) are given in FIG. 5 for each sample.It can be seen therein that, at the start of the distillation, mostly lactic acid (L1A) is released, then lactoyl lactic acid (L2A) and lactide (or dilactide, LD2), and that it is only at the end of the separation that the lactide becomes dominant in the sublimate. Therefore, if all the sublimate fractions were mixed together, a mixture would be obtained for which the weight contents would be:L1A: 0.631LD2: 0.225L2A: 0.144 A

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With ACP; phosphoric acid in water

T=80 - 180°C; P=3.0003 - 760.051 Torr; Hide Experimental Procedure

KTANTON Ltd.

Patent: US2009/318713 A1, 2009 ; Location in patent: Page/Page column 4 ; Title/Abstract Full Text Show Details

In this example, the following reaction has in fact been carried out:MgLa2+2H3PO4.H2O+Ca(H2PO4)2-->Mg(H2PO4)2.2H2O+LD+Ca(H2PO4)2.2H2O In order to do this, the procedure below was followed:Magnesium lactate dihydrate (bought from PURAC under the trade name PURAMEX.(R). MG) was dried by static heating at atmospheric pressure at 130° C. for 7 hours. The dehydrated salt was then kept in a desiccator.20.2 g of this anhydrous Mg lactate were mixed with 17 g of (Ca(H2PO4)2 (previously dehydrated at 110° C. under atmospheric pressure over 12 h in an oven). 23.2 g of 85percent technical grade phosphoric acid were then gradually poured over the powder, while mixing in a mortar. In this step the phosphoric acid released lactic acid. The paste obtained was white and very thick.This paste was put in an oven for 12 h at 80° C. under atmospheric pressure. The hard solid obtained was milled into grains that were introduced into a distillation flask. The latter was heated in an oil bath at 180° C. and under 4 mbar for 5 h.Crystals were obtained on the walls of the glassware. 2.7 g of these crystals were recovered. NMR (nuclear magnetic resonance) analyses were carried out on these crystals (see FIG. 1) and revealed that 2.7 g of 85percent pure lactide had been extracted, the 15percent impurity being 7.3percent lactic acid and 8.4percent open dimer. Therefore a yield by mass of the order of 20percent was obtained.Here is the protocol used for the NMR analyses: 20 mg of the sample were withdrawn; it was put into solution in acetone; the insolubles of the solution were dispersed using ultrasounds; the solution was filtered in order to remove the insolubles therefrom before analysing it by the NMR technique. A

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With water; Amberlyst-15 ion exchange resin

7.06667 h; Heating / reflux; Product distribution / selectivity; Hide Experimental Procedure

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Board of Trustees of Michigan State University

Patent: US2006/14977 A1, 2006 ; Location in patent: Page/Page column 11 ; Title/Abstract Full Text Show Details

41:

EXAMPLE 41; Hydrolysis Experiment of Oligomers and Oligomer Esters Hydrolysis experiment was performed with 37 g of residue, collected by completely removing ethyl lactate by vacuum distillation, and 37 g of water (to maintain the concentration of final solution in a range of 50 wt percent). This residue contains monomer, dimer, and trimer lactic acid along with dimer and trimer ethyl esters. A reaction was performed in batch reactive distillation apparatus to remove the ethanol as it was formed during the hydrolysis reaction. A schematic of the reaction set-up is provided in FIG. 6. Reaction was catalyzed by AMBERLYST-15 ion exchange resin at a loading of 3 wt percent of total weight of reaction mass. Reaction mixture was first allowed to reflux for 2 minutes before adding the catalyst and after adding the catalyst, periodic samples were collected to follow the concentration profile of reactants and products. The reaction proceeded with hydrolysis of the ethyl ester of dimer lactoyllactic acid and trimer lactoyllactoyl lactic acid yielding ethanol. The reaction was allowed to proceed for 7 h and sample was analyzed for final concentration of lactic acid and dimer. All dimer and trimer esters were consumed along with all trimer acid. Lactic acid and dimer acid were determined by direct titration with NaOH and back titration of excess NaOH by sulfuric acid. Lactic was estimated to be 52 wt percent while dimer was estimated around 6 wt percent of the solution. Water was estimated by gas chromatograph to be 41 wt percent. These compositions are consistent with the equilibrium concentrations of monomer and dimer as reported in literature at this concentration level of lactic acid. An efficiency of 95percent was obtained in apparatus in FIG. 6. A

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With stannous oxide

T=215°C; P=16.5017 Torr; Product distribution / selectivity; Hide Experimental Procedure

HYCAIL B.V.