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Which is the Best way to make Dry DMF?
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+ Drying
+ Solvents
+ Dimethylformamide
+ Organic chemistry
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Judas Matete
Which is the Best way to make Dry DMF?
Hi , First u can distill out DMF using azeotrpoic distillation technique using toluene as the azeotrope so that majority of water will be removed by this technique.and then store it by adding 4A molecular seives which will trap any trace of water if present.So that now you have anhy. DMF.
Hi , First u can distill out DMF using azeotrpoic distillation technique using toluene as the azeotrope so that majority of water will be removed by this technique.and then store it by adding 4A molecular seives which will trap any trace of water if present.So that now you have anhy. DMF.
P2O5 + distillation was recommended by RG-people some time ago, in addition to previous procedures. Such drying lead to removal of basic impurities in one run. 3A molecular sieves are slightly better for drying in place of 4A..If it is applied in column version, 250g of 3A molecular sieves allow to dry 3L of DMF from initial 0.3% H2O to ~70ppm H2O.
P2O5 + distillation was recommended by RG-people some time ago, in addition to previous procedures. Such drying lead to removal of basic impurities in one run. 3A molecular sieves are slightly better for drying in place of 4A..If it is applied in column version, 250g of 3A molecular sieves allow to dry 3L of DMF from initial 0.3% H2O to ~70ppm H2O.
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
Dimethylformamide: Decomposes slowly at room temperature and more rapidly at reflux, releasing dimethylamine and carbon monoxide. This decomposition is catalysed by acidic and basic impurities, and standing DMF for several hours at room temperature with basic drying agents such as calcium hydride or sodium hydroxide leads to noticeable decomposition. Dry DMF can be prepared by drying overnight over barium oxide or 4A molecular sieves, followed by decantation of the drying agent and vacuum distillation (~20 mmHg is a sufficient vacuum to lower the boiling point over DMF to a reasonable value). Dry DMF can be stored over 4A molecular sieves.
Dimethylformamide: Decomposes slowly at room temperature and more rapidly at reflux, releasing dimethylamine and carbon monoxide. This decomposition is catalysed by acidic and basic impurities, and standing DMF for several hours at room temperature with basic drying agents such as calcium hydride or sodium hydroxide leads to noticeable decomposition. Dry DMF can be prepared by drying overnight over barium oxide or 4A molecular sieves, followed by decantation of the drying agent and vacuum distillation (~20 mmHg is a sufficient vacuum to lower the boiling point over DMF to a reasonable value). Dry DMF can be stored over 4A molecular sieves.
Dear friends, DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2. If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF. Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure. Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF. More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colourreaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
Dear friends, DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2. If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF. Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure. Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF. More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colourreaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
Dear friends, DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2. If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF. Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure. Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF. More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colourreaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
Dear friends, DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2. If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF. Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure. Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF. More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colourreaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
I use 4A molecular sieves and cap the flask, let it settle overnight. After use, It is good to store the flask in a non-vacuum desiccator to create a dry atmosphere.
I use 4A molecular sieves and cap the flask, let it settle overnight. After use, It is good to store the flask in a non-vacuum desiccator to create a dry atmosphere.
Hi ,
First u can distill out DMF using azeotrpoic distillation technique using toluene as the azeotrope so that majority of water will be removed by this technique.and then store it by adding 4A molecular seives which will trap any trace of water if present.So that now you have anhy. DMF.
Hi ,
First u can distill out DMF using azeotrpoic distillation technique using toluene as the azeotrope so that majority of water will be removed by this technique.and then store it by adding 4A molecular seives which will trap any trace of water if present.So that now you have anhy. DMF.
More
1
P2O5 + distillation was recommended by RG-people some time ago, in addition to previous procedures. Such drying lead to removal of basic impurities in one run.
3A molecular sieves are slightly better for drying in place of 4A..If it is applied in column version, 250g of 3A molecular sieves allow to dry 3L of DMF from initial 0.3% H2O to ~70ppm H2O.
P2O5 + distillation was recommended by RG-people some time ago, in addition to previous procedures. Such drying lead to removal of basic impurities in one run.
3A molecular sieves are slightly better for drying in place of 4A..If it is applied in column version, 250g of 3A molecular sieves allow to dry 3L of DMF from initial 0.3% H2O to ~70ppm H2O.
More
VOTE
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
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VOTE
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
Dimethylformamide (DMF) can be dried with type 4A molecular sieves (effective pore size: 4 Angstrom), with silica gel, or with (anhydrous) desiccant powders (K2CO3, CaSO4, BaO, Al2O3). Too large amounts of water can be removed by azeotropic distillation with benzene (10% v/v), what can be achieved at atmospheric pressure by 69―80 ºC. DMF stays at the distillation flask and can be further dried with the previously mentioned desiccants.
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The Best way to make Dry DMF by vacuum distillation.
The Best way to make Dry DMF by vacuum distillation.
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Dimethylformamide: Decomposes slowly at room temperature and more rapidly at reflux, releasing dimethylamine and carbon monoxide. This decomposition is catalysed by acidic and basic impurities, and standing DMF for several hours at room temperature with basic drying agents such as calcium hydride or sodium hydroxide leads to noticeable decomposition. Dry DMF can be prepared by drying overnight over barium oxide or 4A molecular sieves, followed by decantation of the drying agent and vacuum distillation (~20 mmHg is a sufficient vacuum to lower the boiling point over DMF to a reasonable value). Dry DMF can be stored over 4A molecular sieves.
From: chem.libretexts.org/Demos%2C_Techniques%2C_and_Experiments/General_Lab_Techniques
Regards
Dimethylformamide: Decomposes slowly at room temperature and more rapidly at reflux, releasing dimethylamine and carbon monoxide. This decomposition is catalysed by acidic and basic impurities, and standing DMF for several hours at room temperature with basic drying agents such as calcium hydride or sodium hydroxide leads to noticeable decomposition. Dry DMF can be prepared by drying overnight over barium oxide or 4A molecular sieves, followed by decantation of the drying agent and vacuum distillation (~20 mmHg is a sufficient vacuum to lower the boiling point over DMF to a reasonable value). Dry DMF can be stored over 4A molecular sieves.
From: chem.libretexts.org/Demos%2C_Techniques%2C_and_Experiments/General_Lab_Techniques
Regards
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Dear friends,
DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2.
If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF.
Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure.
Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF.
More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colour reaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
Dear friends,
DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2.
If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF.
Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure.
Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF.
More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colour reaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
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You can use molecular sieves.
You can use molecular sieves.
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Does it matter which size of melcular sieves we use? We only have 3A while in most recipes 4A is recommended.
Does it matter which size of melcular sieves we use? We only have 3A while in most recipes 4A is recommended.
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Dear friends,
DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2.
If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF.
Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure.
Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF.
More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colour reaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
Dear friends,
DMF decomposes slightly at its normal boiling point to give small amounts of dimethylamine and carbon monoxide. The decomposition is catalysed by acidic or basic materials, so that even at room temperature DMF is appreciably decomposed if allowed to stand for several hours with solid KOH, NaOH or CaH2.
If these reagents are used as dehydrating agents, therefore, they should not be refluxed with the DMF.
Use of CaSO4, MgSO4, silica gel or Linde type 4A molecular sieves is preferable, followed by distillation under reduced pressure.
Larger amounts of water can be removed by azeotropic distillation with *benzene (10% v/v, previously dried over CaH2), at atmospheric pressure: water and *benzene distil below 80o. The liquid remaining in the distillation flask is further dried by adding MgSO4 (previously ignited overnight at 300-400o) to give 25g/L. After shaking for one day, a further quantity of MgSO4 is added, and the DMF is distillied at 15-20mm pressure through a 3-ft vacuum-jacketed column packed with steel helices. However, MgSO4 is an inefficient drying agent, leaving about 0.01M water in the final DMF.
More efficient drying (to around 0.001-0.007M water) is achieved by standing with powdered BaO, followed by decanting before distillation, then with alumina powder (50g/L, previously heated overnight to 500-600o), and distilling from more of the alumina, or by refluxing at 120-140o for 24hours with triphenylchlorosilane (5-10g/L), then distilling at ca 5mm pressure [Thomas & Rochow J Am Chem Soc 79 1843 1957]. Free amine in DMF can be detected by the colour reaction with 1-fluoro-2,4-dinitrobenzene. It has also been purified by drying overnight over KOH pellets and then distilling from BaO through a 10 cm Vigreux column (p 11) [Jasiewicz et al. Exp Cell Res 100 213 1976
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I use molecular sieves.
I use molecular sieves.
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I use 4A molecular sieves and cap the flask, let it settle overnight. After use, It is good to store the flask in a non-vacuum desiccator to create a dry atmosphere.
Best,
Mansour
I use 4A molecular sieves and cap the flask, let it settle overnight. After use, It is good to store the flask in a non-vacuum desiccator to create a dry atmosphere.
Best,
Mansour
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