Supplementary Material (ESI) for Organic & Biomolecular Chemistry This journal is (c) The Royal Society of Chemistry 2011 Reduction of hydrazines to amines with aqueous solution of titanium(III) trichloride Yan Zhang, Qiang Tang and Meiming Luo* Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, People’s Republic of China Supporting Information Contents page General information 2 Preparation of hydrazines 2-8 The reduction of hydrazines 8-12 References 13 NMR spectra of hydrazines 14-34 NMR spectra of amine products 35-54 1 Supplementary Material (ESI) for Organic & Biomolecular Chemistry This journal is (c) The Royal Society of Chemistry 2011 General information 1H NMR spectra were recorded on Bruker instruments (600 MHz, or 400 MHz). Chemical shifts are reported in ppm with tetramethylsilane as internal standard. Data are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet), coupling constants (Hz), integration. 13C NMR data were collected on Bruker instruments (150, or 100 MHz) with complete proton decoupling. Chemical shifts are reported in ppm with tetramethylsilane as internal standard. IR spectra were recorded on a Perkin-Elmer FT-IR spectrometer. Elemental analyses were performed on a CARLO ERBA–1106 apparatus. High-resolution mass spectra were obtained on a Bruker Daltoics Bio TOF–Q mass spectrometer (ESI, MALDI-TOF). GC–MS were measured on Agilent Technologies 6890-5973N. Flash column chromatography was performed with silica gel (300–400 mesh). All reactions were carried out under an argon atmosphere. Commercially available materials were used without further purification unless otherwise noted. Preparation of hydrazines Monosubstituted arylhydrazines were prepared from corresponding amines.1 N-Alkyl-N-arylhydrazines were prepared from corresponding monosubstituted arylhydrazines.2 N,N-Diarylhydrazines3 and N,N-dialkylhydrazines4 were prepared from corresponding secondary amines. N-Acyl-N-arylhydrazines were prepared from corresponding N-arylamines.5 General procedure for the preparation of monosubstituted arylhydrazines.1 To the mixture of amine (20 mmol) and conc. HCl (15 mL) cooled in an ice-bath was added an o aqueous solution of NaNO2 (25%, 5.6 g) slowly. After cooling to -20 C, a mixture of SnCl2 (40 mmol) and conc. HCl (10 mL) was added dropwise. After 4 h, the reaction mixture was filtered. The residues were dissolved in aqueous KOH (25%), exacted with ether (3 × 20 mL). The extracts were combined and dried. The volatiles were removed to give corresponding hydrazines. 2-Methoxyphenylhydrazine (3) o 1 White solid. Mp: 101−102 C. H NMR (400 MHz, CDCl3, TMS) δ (ppm): 7.33 (t, J = 7.2 Hz, 1H), 7.21 (dd, J = 7.2 Hz, 1.2 Hz, 1H), 6.97 (t, J = 7.2 Hz, 1H), 6.92 (d, J = 7.2 Hz, 1H), 3.83 (s, 13 3H), 3.78 (s, 1H), 3.18 (s, 2H); C NMR (100 MHz, CDCl3, TMS) δ (ppm): 144.0, 129.2, 122.8, 120.0, 114.8, 110.0, 55.4; MS (ESI, m/z): 138 [M+]. 4-Chlorophenylhydrazine (4) o 1 White solid. Mp: 116−118 C . H NMR (400 MHz, CDCl3, TMS) δ (ppm): 7.03 (d, J = 8.0 Hz, 13 2H), 6.73 (d, J = 8.4 Hz, 2H), 3.66 (s, 1H), 2.27 (s, 2H); C NMR (100 MHz, CDCl3, TMS) δ (ppm): 143.0, 128.0, 124.2, 116.9; MS (ESI, m/z): 142 [M+]. Cyclohexylhydrazine (6) 1 Colorless oil. H NMR (400 MHz, CDCl3, TMS) δ (ppm): 5.01 (s, 2H), 3.92 (s, 1H), 2.55−2.60 (m, 13 2H), 1.58−1.76 (m, 3H), 0.98−1.29 (m, 5H); C NMR (100 MHz, CDCl3, TMS) δ (ppm): 61.1, 32.2, 25.0, 24.5; MS (ESI, m/z): 114 [M+]. 2 General procedure for the preparation of N-alkyl-N-arylhydrazines. 2 Supplementary Material (ESI) for Organic & Biomolecular Chemistry This journal is (c) The Royal Society of Chemistry 2011 An oven-dried flask was charged with sodium amide (0.43 g, 11 mmol), evacuated, backfilled with argon and then THF (50 mL) was added. The reaction mixture was cooled to 0 oC, then arylhydrazines (10 mmol) in THF (50 mL) was added dropwise and the resulting mixture was allowed to warm up to room temperature. The reaction mixture was stirred for 6 h at room temperature and turned brown. Methyl iodide (10 mmol) was added at 0 oC and the reaction mixture was stirred for additional 2 h. Then H2O (20 mL) was added to remove superfluous sodium amide. To the resulting mixture was extracted with CH2Cl2 three times. The extracts were dried over MgSO4. After removal of the solvent, the residue was purified by column chromatography on silica. N-Methyl-N-(2-naphthyl)hydrazine (11) o 1 White solid. Mp: 50−52 C; H NMR (400 MHz, CDCl3, TMS) δ (ppm): 7.68−7.73 (m, 3H), 7.44 (dd, J = 9.2 Hz, 2.4 Hz, 1H), 7.39 (t, J = 7.2 Hz, 1H), 7.26 (t, J = 8.0 Hz, 1H), 7.18 (d, J = 1.6 Hz, 13 1H), 3.89 (brs, 2H), 3.22 (s, 3H); C NMR (100 MHz, CDCl3, TMS) δ (ppm): 150.6, 134.7, 128.7, 128.0, 127.6, 126.7, 126.4, 123.2, 117.4, 107.3, 44.8; IR (KBr, ν, cm-1): 3333.8, 3052.6, 2862.5, 1629.1, 1506.3, 1102.6, 834.4, 746.4; MS (ESI, m/z): 172 [M+]. N-Heptyl-N-(2-naphthyl)hydrazine (12) 1 Colorless oil. H NMR (400 MHz, CDCl3, TMS) δ (ppm): 7.66−7.71 (m, 3H), 7.38 (t, J = 7.2 Hz, 1H), 7.33 (dd, J = 9.2 Hz, 2.4 Hz, 1H), 7.24 (t, J = 7.6 Hz, 1H), 7.19 (d, J = 2.4 Hz, 1H), 3.72 (brs, 2H), 3.48 (t, J = 7.2 Hz, 2H), 1.66−1.70 (m, 2H), 1.28−1.38 (m, 8H), 0.89 (t, J = 6.8 Hz, 3H); 13C NMR (100 MHz, CDCl3, TMS) δ (ppm): 149.8, 135.0, 128.8, 127.8, 127.7, 126.7, 126.4, 122.7, 117.1, 106.9, 56.0, 32.1, 29.5, 27.3, 26.1, 22.9, 14.4; IR (film, ν, cm-1): 3337.6, 3054.9, 2925.9, 2854.7, 1628.9, 1467.4, 830.7, 744.2; MS (ESI, m/z): 256 [M+]. 3 General procedure for the preparation of N,N-diarylhydrazines. To a mixture of CH2Cl2 and Et2O (250 mL, 4:1 v/v), was added TiCl4 (6.6 mL, 0.06 mol) slowly with stirring to give a yellow complex. Mg powder (1.5 g, 0.06 mol) was added under argon. The mixture was stirred for 2.5 h at room temperature to give a black solution. Then an ethereal solution of N-nitrosodiarylamine (0.015 mol) was added to the solution at room temperature with stirring. After 30 min, the reaction was quenched with dil. HCl and the mixture was stirred for 1 h. The resulting solution was made alkaline by addition of NaOH and extracted with Et2O to give N,N-diarylhydrazine. General procedure for the preparation of N,N-dialkylhydrazines.4 N-Nitrosodialkylamine (10 mmol) were dissolved in EtOH (10 mL) under argon. Then aqueous solution of titanium trichloride (40 mmol) was added and the mixture was stirred for 1 h at room temperature. The mixture was basified to pH > 10 by adding aqueous NaOH (20%) dropwise under ice-bath extracted with CH2Cl2 repeatedly. The extracts were combined and dried, and the volatiles were removed. The residue was purified by column chromatography on silica to obtain N,N-dialkylhydrazines . N-Acetyl-N-phenylhydrazine (14)5,6 A mixture of acetaldehyde phenylhydrazone (4.0 g), pyridine (2.4 g), and ether (30 mL) was 3 Supplementary Material (ESI) for Organic & Biomolecular Chemistry This journal is (c) The Royal Society of Chemistry 2011 stirred and maintained at -88 oC and acetyl chloride (2.4 g) was added dropwise over 25 min. After stirring for an additional 4 h at room temperature, a white needle of acetaldehyde N'-acetylphenylhydrazone were obtained. A mixture of acetaldehyde N'-acetylphenylhydrazone (3.58 g), ethanol (5 mL) and ether (5 mL) were cooled under ice-bath and nearly saturated with gaseous hydrogen chloride. The addition of ether (15 ml) caused the precipitation of crystalline solids which were filtered, washed with ether, and dried under reduced pressure to give N-acetyl-N-phenylhydrazine hydrochloride (17). Mp: 186−189 oC dec.. N,N-Dicyclohexylhydrazine (15)3 o 1 White solid. Mp: 163−165 C. H NMR (400 MHz, CDCl3, TMS) δ (ppm): 4.86−4.91 (m, 1H), 13 3.69−3.74 (m, 1H), 1.58−1.93 (m, 13H), 1.10−1.47 (m, 9H); C NMR (100 MHz, CDCl3, TMS) δ (ppm): 58.4, 52.1, 34.3, 29.3, 26.0, 25.4, 25.3, 25.2; MS (ESI, m/z): 196 [M]+. Piperidin-1-amine (17)4 o 1 Colorless liquid. Bp: 145−147 C. H NMR (400 MHz, CDCl3, TMS) δ (ppm): 3.42 (s, 2H), 2.35 13 (s, 4H), 1.54−1.59 (m, 4H), 1.43−1.45 (m, 2H); C NMR (100 MHz, CDCl3, TMS) δ (ppm):62.5, 26.2, 24.8; MS (ESI, m/z): 196 [M]+. Procedure for the preparation of other types of substituted hydrazines. N,N′-Diphenylhydrazine (18)7 Hydrazine hydrate (100 mL) was added to a solution of azobenzene (3.64 g, 0.02 mol) in ethanol (500 mL).