Salen

YELLOW FINE CRYSTALLINE POWDER

c) Synthesis of VO(salen) catalyst; Step 1 : salen; Salicaldehyde (7.307 g, 6.38 ml, 0. 0598 mol) and ethylene diamine (1. 798 g, 2 ml, 0.0299 mol) were combined in absolute EtOH and stirred for 1 hour at room temperature. The resulting precipitate was filtered, washed with EtOH and air dried. Yield: 7.25 g (90percent).General procedure: The Schiff bases used for the synthesis of the catalysts were prepared by the well known reaction between salicylaldehyde and diamine. Slight experimental variations were introduced with respect to literature methods [27] and the resulting procedure was successfully applied to a number of differently substituted aldehydes. (0015) General procedure: Two equivalents of the appropriate salicylaldehyde were dissolved in the minimum volume of boiling methanol (generally, 20 ml) and added dropwise with one equivalent of diamine (either 1, 2-diaminoethane or 1, 2-benzenediamine) in 5 ml methanol. The solution was refluxed until all the aldehyde disappeared (TLC analysis) and then cooled to room temperature, thus causing precipitation of the Schiff base, as a yellow solid. The filtered solid was washed with a small amount of methanol, then with diethyl ether and dried. The following Schiff bases were prepared: (0016) Salophen, [1, 2-bis-(salicylideneamino)benzene]: yield 95.3percent; 5, 5′-ClGeneral procedure: Varying the procedure from the literature, 10 mg catalyst was added to a solution of ethylenediamine (1 mmol, 60 mg) and 2 mmol of benzaldehyde derivative in 10 mL distilled water and refluxed at 80 °C for 2 h. The reaction mixture was poured onto ice, and the resulting precipitate was dissolved in ethyl acetate and the catalyst was separated by filtration. Evaporate off EtOAc to get Schiff bases, which can be further recrystallized using ethanol. (4a) 2, 2’-((1E, 1’E)-(Ethane-1, 2-diylbis(azanylylidene))bis (methanylylidene))diphenol (Yield = 79percent); 1H NMR (400 MHz, CDCl3) δ = 13.19 (s, 2H), 8.35 (s, 2H), 7.30-7.21 (m, 4H), 6.94 (d, J = 8.35 Hz, 2H), 6.8 (t, J = 7.75 Hz, 2H), 3.93 (S, 4H). 13C NMR (100 MHz, CDCl3) 166.52, 161.02, 132.41, 131.50, 118.69, 118.65, 116.97, 59.77. GC-MS m/z: calcd. for C16H16N2O2: 268.1212 and found 268.2494.Catalytic Disproportionation of Hydrogen Peroxide General procedure: The Schiff base (2.27 mmol) dissolved in dichloromethane (10 mL). Reaction mass cooled at 00C and 2-3 drops of conc. KOH solution added. The solution of NaBH4 (2.0 mmol) in methanol added dropwise. Reaction mass stirred for 4-5 h until the yellow colour disappeared. Reaction monitored on TLC. After completion of reaction solvent distilled and cold water (10 mL) added to dissolve residue. pH adjusted to 4-5 by addition of dilute HCl. The white solid filtered, washed with water dried. 2, 2?-[ethane-1, 2-diylbis(azanediyl methylene)]diphenol [RSB01]m.p.: 1180C; Colour: white; MS [M+2]: 273.99; FTIR(KBr cm-1): 3490, 3463, 3363, 3052, 2942, 2852, 2593, 1602, 1479, 1417, 1353, 1268, 1189, 1126, 1074, 960, 815, 757, 626; 1H NMR (300 MHz, DMSO-d6) delta: 2.481 (m, 4H), 3.770 (s, 4H), 5.031 (s, 2H), 6.658-6.686 (m, 4H), 7.01-7.06 (m, 4H), 13.335 (s, 2H); Elemental analysis [C16H20N2O2]: observed (Calculated): C 70.63% (70.56%), H 7.31% (7.40%), N 10.34% (10.29%).Synthesis of A 0.745g (4.647mmol) sample of H2Salen was added to a stirred solution of 1.274g (4.647mmol) of HMeSi(NCS)2 in acetonitrile (20mL). The reaction mixture was stirred for 24h at room temperature producing a pale yellow solid that was dissolved by heating the solution to ca 80C, filtering it off and slowly cooling it to 20C. The pale yellow crystals that formed were filtered off, washed with 20mL of diethyl ether and dried under vacuum (0.1mbar, 2h). Yield: 0.755g (44.0%). Mp: 210C (dec). Anal. Calc. for C18H17N3O2SSi (367.50): C, 58.83; H, 4.66; N, 11.43; S, 8.73. Found: C, 58.83; H, 4.68; N, 11.48; S, 8.77%. 1H NMR (200MHz, C2D4Cl2): delta=0.06 (s, 3H, SiCH3), delta=4.25 (s, 2H, CH2), delta=6.96-7.53 (m, 4H, C6H4 aromatic), delta=8.67 (s, 1H, N=CH). 1H NMR (200MHz, dmso-d6): delta=-0.08 (s, 3H, SiCH3), delta=4.08 (s, 2H, CH2), delta=6.96-7.53 (m, 4H, C6H4 aromatic), delta=8.67 (s, 1H, N=CH). 1H NMR (200MHz, acetone-d6) mixture of two stereoisomers: delta=0.06 and 0.20 (s, SiCH3), delta=4.25 and 4.26 (2H, CH2), delta=6.84-7.53 (m, 4H, C6H4 aromatic), delta=8.55 and 8.78 (s, 1H, N=CH). 1H NMR (200MHz, C2D4Cl2) mixture of two stereoisomers: delta=0.02 and 0.24 (s, SiCH3), delta=3.96 and 4.03 (s, CH2), delta=6.84-7.53 (m, C6H4 aromatic), delta=8.13 and 8.39 (s, 1H, N=CH). 13C NMR (50MHz, dmso-d6): delta=9.55 (SiCH3), delta=51.94 (CH2) delta=119.27, 121.19, 133.78, 137.05 (CH aromatic), delta=165.86 (N=CH), delta=159.98 (Cipso-CH=N), (NCS) not detected. 29Si INEPT NMR (59.6MHz, dmso-d6): delta=-168.75. 29Si CP/MAS NMR (59.6MHz): delta=-177.15. FT-IR: nu(-NCS) 2115cm-1, nu(N=C) 1641cm-1.General procedure: Corresponding metal salt solution (1 mmol) and Schiff base ligand(1 mmol) were dissolved in methanol (10 mL) and reflux for 1 h.Crystals of the metal complexes were obtained by cooling the reactionmixture.General procedure: Corresponding metal salt solution (1 mmol) and Schiff base ligand(1 mmol) were dissolved in methanol (10 mL) and reflux for 1 h.Crystals of the metal complexes were obtained by cooling the reactionmixture.

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