Liquid acetic acid

Example 55

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br, 100 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and 3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, Corbion Purac Co., Lenexa, Kans.) were first mixed at room temperature and atmospheric conditions in a 100 mL three-necked glass reactor. 0.3 g of liquid acetic acid (5 mmol, 100%; VWR International GmbH, Darmstadt, Germany; catalog #20104.334) was then added to the reaction mixture, thus generating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to acetic acid equal to 1:2:0.1. The reaction mixture was then heated to a reaction temperature of 150° C. under continuous stirring with an overhead stirrer at a speed of 300 rpm. After the reaction mixture reached a constant temperature of 150° C., the system was batchwise refluxed and gaseous by-products were routed to the off-gas or collected in a hydrostatic column. After a reaction time of 168 h, the hot molten salt was allowed to cool down to room temperature and was analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acid yield (AAY) of about 30 mol %.

Example 55

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and 3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, Corbion Purac Co., Lenexa, Kans.) were first mixed at room temperature and atmospheric conditions in a 100 mL three-necked glass reactor. 0.3 g of liquid acetic acid (5 mmol, 100%; VWR International GmbH, Darmstadt, Germany; catalog #20104.334) was then added to the reaction mixture, thus generating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to acetic acid equal to 1:2:0.1. The reaction mixture was then heated to a reaction temperature of 150° C. under continuous stirring with an overhead stirrer at a speed of 300 rpm. After the reaction mixture reached a constant temperature of 150° C., the system was batchwise refluxed and gaseous by-products were routed to the off-gas or collected in a hydrostatic column. After a reaction time of 168 h, the hot molten salt was allowed to cool down to room temperature and was analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acid yield (AAY) of about 30 mol %.

Example 55

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and 3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, Corbion Purac Co., Lenexa, Kans.) were first mixed at room temperature and atmospheric conditions in a 100 mL three-necked glass reactor. 0.3 g of liquid acetic acid (5 mmol, 100%; VWR International GmbH, Darmstadt, Germany; catalog #20104.334) was then added to the reaction mixture, thus generating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to acetic acid equal to 1:2:0.1. The reaction mixture was then heated to a reaction temperature of 150° C. under continuous stirring with an overhead stirrer at a speed of 300 rpm. After the reaction mixture reached a constant temperature of 150° C., the system was batchwise refluxed and gaseous by-products were routed to the off-gas or collected in a hydrostatic column. After a reaction time of 168 h, the hot molten salt was allowed to cool down to room temperature and was analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acid yield (AAY) of about 30 mol %.