| 90% |
With formic acid In ethanol; water at 18 - 23℃; for 65h; Industrial scale; |
N,N’-Bis(2,6-di-iso-propylphenyl)glyoxaldiimine (4)[9]
Glyoxal (199 g of a 40% aqueous solution, 1.37 mol) was added to a solution of 2,6-di-iso-propylaniline (470 g, 2.65 mol) in ethanol (1.25L) followed by 4 drops of formic acid. The mixture was stirred at 18-23 oC for 65 h. The product was collected by filtration, washed with ca. 10 C methanol (2x250 mL), and dried under vacuum at 65 C to give 2 (447.1 g, 90%) as a yellow solid. Mp 107-108 oC; 1H NMR (CDCl3): d 8.10 (s, 2H), 7.12-7.23 (m, 6H), 2.94 (septet, J=6.8 Hz, 4H), 1.21 (d, J=6.8 Hz, 24H). |
| 90% |
In methanol |
|
| 90% |
With acetic acid In methanol; water at 20 - 50℃; for 20h; |
In the air, in a 500ml round bottom flask,2,6-Diisopropylaniline (98.5g, 50mmol, 2.00equiv) and HOAc (0.5mL, 0.009mol, 0.0175equiv) were dissolved in 125mL MeOH,A mixed solution of glyoxal (36.5 g, 40% in water, 0.25 mol, 1.0 equiv) dissolved in 125 mL of MeOH was added to the round bottom flask.The reaction mixture was stirred in an oil bath at 50°C for 15 minutes,Then it was stirred at room temperature for 10 h. The reaction mixture was filtered. The filter cake was washed with MeOH (3×100 mL) and dried to obtain S1 as a yellow solid (84.5 g, yield 90%). |
| 89% |
With acetic acid In methanol at 23 - 50℃; Sealed tube; |
|
| 89.2% |
With formic acid In ethanol for 48h; |
1-4
Combine 2,6 diisopropyl aniline with 40% glyoxal, Formic acid was added to the third organic solvent absolute ethanol to react for 2d, filter, The diazabutadiene is obtained after washing with cold methanol; in, The molar ratio of the 2,6-diisopropylaniline to the glyoxal is 2:1 ; The yield of diazabutadiene is 89.2% |
| 88% |
With toluene-4-sulfonic acid at 20℃; for 0.583333h; |
|
| 88% |
With acetic acid In ethanol at 20℃; for 72h; |
1.1; 1.1; 2.1; 3.1 Step 1, Synthesis of Schiff base glyoxal-bis-(2,6-diisopropylphenyl)imine
In the air, add 2,6-diisopropylaniline (500mmol), glyoxal (250mmol) and acetic acid (50mmol) into the reaction flask,Then add 250 mL of ethanol, and the mixture is reacted at room temperature for three days. After the reaction is complete,The resulting precipitate was filtered and dried under vacuum to obtain Schiff base glyoxal-bis-(2,6-diisopropylphenyl)imine (yellow solid) with a yield of 88%. |
| 86% |
With acetic acid In methanol; water at 50℃; |
|
| 86% |
With acetic acid In methanol; water at 23 - 50℃; |
|
| 85% |
In water; isopropyl alcohol at 20℃; for 24h; Inert atmosphere; Glovebox; |
|
| 84% |
In ethanol for 4h; Schlenk technique; Inert atmosphere; |
|
| 83% |
In propan-1-ol; water at 20 - 70℃; for 2h; Inert atmosphere; Schlenk technique; |
2.1. Procedure for preparation of diimine ligand 6
N,N-(ethane-1,2-diylidene)bis(2,6-diisopropylaniline) (6) was prepared according to the literature method.3 A mixture of 0.96 g of 40% aqueous solution of glyoxal (6.6 mmol), 1.0 ml of n-propanol and 2.5 ml of water was added to a solution of 2.48 g (14 mmol) of 2,6-diisopropylphenylamine in 10 ml of n-propnaol at room temperature. The reaction was carried out at 70 °C for 2 h, and then 10 ml of water was added. The resulting yellow precipitate was collected by filtration, washed with water and dried under pressure. After recrystallized from methanol, N,N'-(ethane-1,2-diylidene)bis(2,6-diisopropylaniline) (6) was obtained in 83% yield as a yellow solid, m.p. 106 - 107 °C. |
| 82% |
In water; isopropyl alcohol at 70℃; for 2h; |
|
| 79.1% |
With formic acid In ethanol; water at 20℃; for 49h; |
1.1 1) Before preparing the rare earth imidazolium salt, HIPrCl is first prepared and its preparation method is as follows:
53.1 g (300 mmol) of 2,6-diisopropylaniline, 16.95 mL (150 mmol, 40%) of aqueous glyoxal solution, and 150 mL of absolute ethanol were added to a 500 mL eggplant-shaped flask. An aqueous solution of 88 wt% formic acid 0.5-1.5 mol% was added as a catalyst. The reaction solution quickly changed from colorless to yellow, and after 1 h, a large amount of yellow solids were produced. After stirring at room temperature for 48 h, suction filtration gave a yellow solid which was washed 3 times with cold dry methanol to give pure product 44.62 g (79.1% yield). |
| 77% |
In propan-1-ol; water at 20 - 60℃; for 20h; |
|
| 77% |
With formic acid In ethanol; water at 20℃; for 48.5h; |
|
| 76% |
With acetic acid In methanol; water at 20 - 50℃; for 14h; |
|
| 74% |
With formic acid In methanol; water at 0 - 20℃; |
5 Synthesis of ligand having formula (L5)
A solution of 17.73 g (100 mmol) of 2,6-di- sopropylaniline in methanol (50 ml) was added, drop by drop, to a solution of 7.26 g (50 mmol) of glyoxal (40% by weight aqueous solution) in methanol and distilled water (30 ml + 10 ml, respectively), cooled to 0°C and kept under stirring, and, subsequently some drops of formic acid (85% by weight aqueous solution): the reaction mixture obtained was left, under stirring, at ambient temperature, until the formation of a precipitate was noted, which was filtered, washed with methanol, and vacuum dried, at ambient temperature, obtaining 14 g of a yellow powder (yield = 74%) corresponding to the ligand having formula (L5).FT-IR (nujol): 1614 cm"1V(C=N).Molecular weight (MW): 376.59.Elementary analysis [found (calculated) for C26H38N2]: C: 82.88% (82.93%); H: 9.85% (9.64%); N: 7.99% (7.44%).1H-NMR (CDCIs, ppm): 1 ,22 (d, 24H, CH(CH3)2); 2,95 (m, 4H, CH(CH3)2); 7,19 -7,22 (m, 6H C8H3); 8,1 1 (s, 2H, NCH).Figure 6 shows the FT-IR (solid state - UATR) spectrum of the ligand (L5) obtained. Figure 7 shows the1H-NMR spectrum of the ligand (L5) obtained. |
| 72% |
In methanol; water at 20℃; Inert atmosphere; Schlenk technique; |
|
| 70% |
In methanol; water at 20℃; for 3h; |
D; 1
Charging a 1000 mL round bottom flask with methanol (500 mL), 2,6-diisopropylaniline (63.8 mL, 340 mmol), glyoxal (40 wt % soln in water, 19 mL, 170 mmol), and formic acid (1 mL).Stirring the resulting mixture for 3 hours at room temperature.Filtering the yellow precipitate, (3) (Diagram D)Washing precipitate with cold methanol.Drying precipitate in vacuo overnight (70%, 44.2 g, 238 mmol).Charging a 5 L round bottom flask with precipitate (3) (200 g, 532 mmol) and ethyl acetate (2 L).Stirring the resulting mixture until (3) was dissolved.Cooling the solution to 0° C. but this can be carried out at room temperature.Charging a 500 mL Erlenmeyer flask with paraformaldehyde (20.7 g, 690 mmol), HCl (4N in dioxane, 212 mL, 851 mmol).Stirring this solution for 10 minutes, then added.Stirring the resulting mixture for 2 hours at room temperature.Filtering precipitateDissolving precipitate in methanol (200 mL).Adding 15.0 g of sodium bicarbonate.Stirring the solution for 1 hour or until there is no more carbonation.Filtering the solution to remove the solids.Reprecipitating the product with 250 mL of diethyl etherCollecting product by filtrationWashing product with diethyl ether.Drying the product in vacuo to yield IPr.HCl (4) as a white powder (70%, 158.25 g, 371 mmol). 1H NMR (CDCl3, 400 MHz) δ 10.1 (s, 1H), 8.15 (s, 2H), 7.57 (t, 2H, J=7.8 Hz), 7.35 (d, 4H, J=8.4 Hz), 2.43(m, 4H), 1.28 (m, 24H) 13C NMR (CDCl3, 400 MHz) δ 145, 132.1, 129.9, 126.8, 124.7, 29.1, 24.7, 23.7. Synthesis of 1,3-Bis(2,6-diisopropylphenyl)imidazolium chloride (IPr.HCl, 4)A 1000 mL round bottom flask was charged with methanol (500 mL), 2,6-diisopropylaniline (63.8 mL, 340 mmol), glyoxal (40 wt % soln in water, 19 mL, 170 mmol), and formic acid (1 mL). The resulting mixture was allowed to stir for 3 hours at room temperature. The yellow precipitate (3) was filtered, washed with cold methanol and dried in vacuo overnight (70%, 44.2 g, 238 mmol). A 5 L round bottom flask was charged with 3 (200 g, 532 mmol) and ethyl acetate (2 L) and the resulting mixture was stirred until 3 was dissolved. The solution was cooled to 0° C. A 500 mL Erlenmeyer flask was charged with paraformaldehyde (20.7 g, 690 mmol), HCl (4N in dioxane, 212 mL, 851 mmol). This solution was stirred for 10 minutes, then added. The resulting mixture was then stirred for 2 hours at room temperature. The precipitate was filtered, dissolved in methanol (200 mL) and 15.0 g of sodium bicarbonate was added. The solution was stirred for 1 hour or until there was no more carbonation. The solution was filtered to remove the solids and the product was reprecipitated with 250 mL of diethyl ether, collected by filtration, washed with diethyl ether and dried in vacuo to yield IPr.HCl (4) as a white powder (70%, 158.25 g, 371 mmol). 1H NMR (CDCl3, 400 MHz) δ 10.1 (s, 1H), 8.15 (s, 2H), 7.57 (t, 2H, J=7.8 Hz), 7.35 (d, 4H, J=8.4 Hz), 2.43(m, 4H), 1.28 (m, 24H) 13C NMR (CDCl3, 400 MHz) δ 145, 132.1, 129.9, 126.8, 124.7, 29.1, 24.7, 23.7. |
| 70% |
In methanol; water at 20℃; for 3h; |
1; D
Synthesizing of l,3-Bis(2,6-dsopropylphenyl)imidazolium chloride (IPr HCl, 4) by:; Charging a 1000 mL round bottom flask with methanol (500 mL), 2,6- diisopropylaniline (63.8 mL, 340 mmol), glyoxal (40wt % soln in water, 19 mL, 170 mmol), and formic acid (ImL).Stirring the resulting mixture for 3 hours at room temperature. Filtering the yellow precipitate, (3) (Diagram D)Washing precipitate with cold methanol.Drying precipitate in vacuo overnight (70%, 44.2 g, 238 mmol).Charging a 5 L round bottom flask with precipitate (3) (200 g, 532 mmol) and ethyl acetate (2 L). Stirring the resulting mixture until (3) was dissolved.Cooling the solution to 0° C but this can be carried out at room temperature.Charging a 500 mL Erlenmeyer flask with paraformaldehyde (20.7 g, 690 mmol), HCl (4N in dioxane, 212 mL, 851 mmol).Stirring this solution for 10 minutes, then added. Stirring the resulting mixture for 2 hours at room temperature.Filtering precipitateDissolving precipitate in methanol (20OmL).Adding 15.Og of sodium bicarbonate.Stirring the solution for 1 hour or until there is no more carbonation. Filtering the solution to remove the solids.Reprecipitating the product with 250 mL of diethyl etherCollecting product by filtrationWashing product with diethyl ether.Drying the product in vacuo to yield IPrHCl (4) as a white powder (70%, 158.25g, 371 mmol). 1H NMR (CDCl3, 400 MHz) δ 10.1 (s, IH), 8.15 (s, 2H), 7.57 (t,2H, J = 7.8 Hz), 7.35 (d, 4H, J = 8.4 Hz), 2.43(m, 4H), 1.28 (m, 24H) 13C NMR (CDCl3, 400 MHz) δ 145, 132.1, 129.9, 126.8, 124.7, 29.1, 24.7, 23.7.; Synthesis of l,3-Bis(2,6-diisopropyIphenyl)imidazolium chloride (IPrηCl, 4); A l 000 mL round bottom flask was charged with methanol (500 mL), 2,6- diisopropylamline (63.8 mL, 340 mmol), glyoxal (40wt % soln in water, 19 mL, 170 mmol), and formic acid (ImL). The resulting mixture was allowed to stir for 3 hours at room temperature. The yellow precipitate (3) was filtered, washed with cold methanol and dried in vacuo overnight (70%, 44.2 g, 238 mmol). A 5 L round bottom flask was charged with 3 (200 g, 532 mmol) and ethyl acetate (2 L) and the resulting mixture was stirred until 3 was dissolved. The solution was cooled to 0° C. A 500 mL Erlenmeyer flask was charged with paraformaldehyde (20.7 g, 690 mmol), HCl (4N in dioxane, 212 mL, 851 mmol). This solution was stirred for 10 minutes, then added. The resulting mixture was then stirred for 2 hours at room temperature. The precipitate was filtered, dissolved in methanol (20OmL) and 15.Og of sodium bicarbonate was added. The solution was stirred for 1 hour or until there was no more carbonation. The solution was filtered to remove the solids and the product was reprecipitated with 250 mL of diethyl ether, collected by filtration, washed with diethyl ether and dried in vacuo to yield IPrHCl (4) as a white powder (70%, 158.25g, 371 mmol). 1H NMR (CDCl3, 400 MHz) δ 10.1 (s, IH), 8.15 (s, 2H), 7.57 (t, 2H, J = 7.8 Hz), 7.35 (d, 4H, J = 8.4 Hz), 2.43(m, 4H), 1.28 (m, 24H) 13C NMR (CDCl3, 400 MHz) δ 145, 132.1, 129.9, 126.8, 124.7, 29.1, 24.7, 23.7. |
| 70% |
In propan-1-ol; water Inert atmosphere; Schlenk technique; |
4.2. Synthesis of ligands (R-DAB)
General procedure: The α-diimine ligands (Mes-N=CH-CH=N-Mes) (1a) and(Dipp-N=CH-CH=N-Dipp) (1b) were synthesized using a modificationof the preparation described by Arduengo [32], involving treatment of the respective solution of amine (28 mmol, 2.15equivalents) in n-propanol with glyoxal 40% (13 mmol, 1 equivalent)in n-propanol (50% in water). The ligand (Dipp*-N=CH-CH=N-Dipp*) (1c) was prepared as described by Mark[33]. All these α-diimines were yielded as yellow powders. |
| 67% |
With formic acid In methanol; water at 20℃; for 16h; |
1.2. General preparation of starting diimines 4a-e
General procedure: In a round-bottom flask equipped with a magnetic stirring bar, glyoxal or 2, 3-butanedione (1 mmol), aniline (2 mmol), methanol (0.6 M) for 4a-c,e or iPrOH/H2O (2/1) (0.6 M) for 4d and 98% formic acid (few drops) were added. The mixture was stirred at room temperature for 4a-d or at 50 C for 4e for 16 hours. The precipitated yellow product was filtered under vacuum, rinsed with cold methanol and dried under reduced pressure to give a yellow powder (Yields: 67-99%). |
| 64% |
With formic acid In methanol; water at 0 - 20℃; for 72h; |
|
| 64% |
With formic acid In methanol; water at 0 - 20℃; for 72h; |
|
| 64% |
With formic acid In methanol; water at 20℃; for 24h; |
|
| 61% |
In ethanol; water for 12h; Inert atmosphere; Reflux; Cooling with ice; |
4.2.2. Synthesis and characterization of 3c and 3d
General procedure: Into a 500 mL round-bottomed flask was placed 60.0 mmol(10.63 g) 2,6-diisopropylaniline (or 60.0 mmol 2,4,6-trimethylaniline) in 130 mL ethanol. Then, the solution of Glyoxal(4.35 g, 40 wt % in H2O, 30.0 mmol) was added slowly to the flaskwhich was placed in ice bath beforehand. The colour of solutionchanged to golden-yellow. It was then refluxed for 12 h beforecooling down to room temperature. The volume of the solutionwasthen reduced to 100 mL under vacuum. Subsequently, the solutionwas filtered through frit at 0°C. The collected product was washedwith ethanol/H2O mixed solution at 0°C. A golden-yellow solid 3c(6.89 g, 18.31 mmol, 61%) or 3d (6.87 g, 23.51 mmol, 47%) wasobtained after all solvent was removed by vacuum.‡ Selected spectroscopic data for 3c, 1H NMR (CDCl3, δ/ppm): 1.22(d, JH-H 7.1 Hz, 24H, CH(CH3)2), 2.96 (m, JH-H 6.7 Hz, 4H,CH(CH3)2), 7.20 (m, 6H, overlapping C6H3), 8.12 (s, 2H, NCH); 13C NMR (CDCl3, δ/ppm): 163.0 (N-C), 147.9 (ipso-CMes), 136.6 (o-CMes),125.0 (m-CMes), 123.1 (p-CMes), 27.9 (iPr CH), 23.3 (iPr CH3). |
| 53% |
With formic acid In methanol at 20℃; for 3h; |
|
| 20% |
In propan-1-ol; water at 70℃; for 2h; |
|
| 20% |
In propan-1-ol; water at 70℃; for 2h; |
|
| 18.6% |
With formic acid In methanol; water at 20℃; for 15h; |
|
|
With formic acid In methanol; water at 20℃; for 3h; |
|
|
In water; acetone |
|
|
With formic acid In methanol; water for 48h; |
|
|
With triethylamine In propan-1-ol; water at 70℃; for 16h; Inert atmosphere; |
|
|
With formic acid In methanol; water at 20℃; for 1h; |
|
|
In ethanol; water at 20℃; |
|
|
In ethanol at 20℃; for 12h; |
4.3.1.1. Preparation of N,N'-(ethane-1,2-diylidene)bis(2,4,6-trimethylaniline)
General procedure: In a flask, 2,4,6-trimethylaniline (6.075 g, 45 mmol) and 40% glyoxylaldehyde (3.250 g, 22.5 mmol) were added to ethyl alcohol (100 ml), the mixture was stirred at room temperature for 12 h and then yellow solid was separated out, the insoluble material was filtered and the filtrate was washed with cold ethyl alcohol, after dried in vacuum, gave 4.7 g yellow solid of imine in 71% yield. |
|
In propan-1-ol; water at 70℃; for 1h; |
1
2,6-Diisopropylaniline (15 g, 84.7 mmol) was dissolved in 67 ml of 1-propanol and 15 in of water, after which glyoxal (40% aqueous solution, 5.6 g, 38.5 mmol) was added thereto. The reaction was carried out at 70° C. for 1 hour, the temperature was lowered to room temperature, and then the reaction product was filtered. The remaining solid was dissolved in methylene chloride, added with anhydrous magnesium sulfate and then filtered, after which the filtered solution was decompressed to a vacuum thus removing the solvent. The compound (5.048 g, 12.73 mmol) thus obtained and para-formaldehyde (0.458 g, 15.27 mmol) were dissolved in 83 ml of toluene and stirred at 100° C. for 2 hours. Thereafter, the temperature was lowered to 40° C., and hydrochloric acid (4 N, d=1.05 g/ml dioxane solution, 4.01 g, 15.27 mmol) was added thereto and thus the resulting precipitate was filtered. The solid compound thus obtained was dissolved in methylene chloride and dried over anhydrous magnesium sulfate, and the filtered solution was decompressed to a vacuum, thus removing the solvent. The compound (1.753 g, 4.124 mmol) thus obtained and potassium tert-butoxide (0.508 g, 4.537 mmol) were dissolved in 24 ml of THF and allowed to react with stirring for 4 hours. The solvent was removed using vacuum decompression, after which the product was dissolved in toluene and filtered using celite. The filtered solution was decompressed to a vacuum thus removing the solvent. The compound (1.335 g, 3.435 mmol) thus obtained and palladium allyl chloride (0.629 g, 3.435 mmol) were dissolved in 8 in of THF and stirred for 4 hours. The reaction solution was passed through silica gel and filtered, after which the solution was decompressed to a vacuum thus removing the solvent, giving the title compound of Formula 10 in which R1═R4=2,6-diisopropylphenyl; R2═R3═H; X1=allyl; X2═Cl. |
|
In ethanol |
|
|
With formic acid In ethanol; water at 20℃; |
|
|
In methanol for 2h; Reflux; |
2.2. Synthesis of the ligands
General procedure: The only difference between the synthesis of the iminopyridineL1 relative to the diazabutenes L2-L4 is the molar ratio of the reactants,which for the former is 1:1 while for the latter 1:2. The reactionswere carried out in methanol without exclusion of oxygen orwater. In a typical reaction, a solution of the desired aldehyde (10mmol in 50 mL solvent) was dropwise added to the analogousamount of amine dissolved in the minimum amount of methanol.Although the formation of a colored product was evident from thebeginning the reaction was carried out under reflux for about 2 h.After cooling to room temperature, filtration and subsequent washing with small amounts of methanol and finally with diethyletherresulted in the isolation of the ligands in pure form and inyields around 90%. The compounds have orange color and presentsubstantial solubility in methanol, dichloromethane and acetonitrile.Their spectroscopic data were confirmed relative to alreadypublished results [16-19]. |
|
In ethanol at 20℃; for 48h; Inert atmosphere; |
|
|
With acetic acid; zinc(II) chloride at 120℃; for 5h; Inert atmosphere; |
Procedure for the Synthesis of α-Diimine Compound A4.
General procedure: 2,4,6-trimethylaniline (2.70g, 20 mmol), acenaphthenequinone (1.82 g, 10 mmol), anhydrous ZnCl2 (3.14 g, 23 mmol) and acetic acid (40 mL) were added into a flask under N2 atmosphere and the mixture was allowed to heat at 120 oC for 5 h. Upon completion of the reaction, the reaction mixture was cooled to room temperature. The resulting solid was collected by filtration, washed by acetic acid, dried by oven and redissolved in 100 mL CH2Cl2. Potassium oxalate (4.60 g, 25 mmol) in 20 mL H2O was added into the CH2Cl2 solution, and the resulting mixture was allowed to stir at RT for 24 h. Upon completion of the reaction, the reaction mixture was filtered to remove white solid and the filtrate was stewed and layered. The organic layer was then dried over anhydrous sodium sulfate, filtered, concentrated under vacuum and recrystallized from CH2Cl2/hexane. The titled compound was obtained as brownish red solids in 58% yield. A4: 1H NMR (400 MHz, CDCl3) δ 7.89 (d, J = 8.3 Hz, Ar-H, 2H), 7.40 (t, J = 7.7 Hz, Ar-H, 2H), 6.97 (s, Ar-H, 4H), 6.77 (d, J = 7.2 Hz, Ar-H, 2H), 2.38 (s, 6H), 2.09 (s, 12H).13C NMR (101 MHz, CDCl3) δ 160.04 (s), 145.74 (s), 139.51 (s), 131.79 (s), 129.97 (s), 128.68 (s), 127.82 (d, J = 16.3 Hz), 127.20 (s), 123.57 (s), 121.46 (s), 19.92 (s), 16.70 (s). |
| 76 % |
In ethanol; water at 20℃; |
|
| 90 % |
With acetic acid In ethanol; water |
|
| 90 % |
With acetic acid In methanol at 23 - 50℃; |
3 Revised procedure: N,N′-1,4-bis(2,6-diisopropylphenyI)-1,4-diazabutadiene (S1)
In air, to a solution of 2,6-diisopropylaniline (10 mL, 53.0 mmol, 2.00 equiv) and HOAc (0.2 mL, 3.5 mmol, 0.066 equiv) in 15 mL of Me0H at 50° C. in a flask was added a solution of glyoxal (3.0 mL, 26.5 mmol, 1.0 equiv) in 15 mL of Me0H. The reaction mixture was stirred at 50° C. for 15 min and then stirred at 23° C. for 10 h. The reaction mixture was filtered. The filter cake was washed with Me0H (3×15 mL) and dried in vacuo at 75 mbarmito afford 8.9 g of compound S1 as a yellow solid (90% yield). |
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