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Synlett 2006(9): 1374-1378  
DOI: 10.1055/s-2006-939697
LETTER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of β-Amino Alcohols from Aromatic Amines and Alkylene Carbonates Using Na-Y Zeolite Catalyst

Anandkumar B. Shivarkar, Sunil P. Gupte*a, Raghunath V. Chaudhari*b
Homogeneous Catalysis Division, National Chemical Laboratory, Pune-411008, India
Fax: +91(20)25902621; e-Mail: sp.gupte@ncl.res.in; e-Mail: rv.chaudhari@ncl.res.in;
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Publication History

Received 16 January 2006
Publication Date:
22 May 2006 (online)

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Abstract

A simple, efficient, and environmentally benign methodology for the synthesis of β-amino alcohols from aromatic amines and alkylene carbonates in the presence of the highly active and ­reusable solid base catalyst Na-Y zeolite is demonstrated.

Key words

alkylation - amine - amino alcohols - alkylene carbonate - zeolite

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The reaction of p-toluidine ethylene carbonate and triglyme (solvent) using Na-Y catalyst was carried out at 140 °C for 12 h. The product distribution and progress of the reaction were monitored by withdrawing samples. It was observed that even at lower temperature bis-amino alcohol formation was seen after 70% formation of mono-amino alcohol. It shows that bis-amino alcohol formation is also dependant on the concentration of mono-amino alcohol.

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Typical Procedure The reaction was conducted in a 50-mL round-bottom flask under a nitrogen atmosphere. Aniline (0.0107 mol), cyclic carbonate (0.013 mol), triglyme (0.0155 mol), and Na-Y zeolite (0.250 g, activated at 500 °C for 6 h) were added. The reaction mixture was stirred at 160 °C for 0.5 h. After cooling to r.t., the reaction mixture was filtered to separate the catalyst and the reaction mass (filtrate) was quantitatively analyzed by GC. Then H2O (15-20 mL) was added and extracted with Et2O (3 × 20 mL). The combined organic layer was dried over Na2SO4, filtered, and concentrated. The residue was purified by flash chromatography (4 g RediSep column normal phase silica, hexane-EtOAc). Liquid chromatography was performed using CombiFlash Companion, supplied by Teledyne ISCO, USA. N-Phenylethanolamine was thus isolated in pure form in 94% yield. After completion of the reaction, the reaction mixture was filtered (sartorius-393 grade filter paper) to separate the catalyst, which was washed with acetone to remove organic impurities. Then the catalyst was calcined at 500 °C for 6 h in air. This catalyst was re-used affording 3a in 100% yield. The catalyst was recycled five times retaining up to 99% of its original activity and selectivity.
N -Phenylethanolamine ( 3a) 24
IR (film): 3392 (OH, NH), 2943 (CH), 1602 (Ar-C=C), 1506 (Ar-C=C), 1323 (Ar-CN), 1058, 752 cm-1. 1H NMR (200 MHz, CDCl3): δ = 2.86 (br s, 2 H, NH, OH), 3.27 (t, J = 5.4 Hz, 2 H, NCH2), 3.80 (t, J = 5.4 Hz, 2 H, OCH2), 6.63-6.77 (m, 3 H, Ar-CH), 7.14-7.22 (m, 2 H, Ar-CH). 13C NMR (50 MHz, CDCl3): δ = 45.99 (NCH2), 60.97 (OCH2), 113.20 (Ar-CH), 117.84 (Ar-CH), 129.21 (Ar-CH), 148.00 (Ar-C). GC-MS (EI, 70 eV): m/z (%) = 137 (23) [M]+, 106 (100) [C6H5NH=CH2]+, 91 (2), 77 (23), 65 (3), 51 (8).
N -Phenyldiethanolamine ( 4a) IR (film): 3382 (OH, NH), 2952 (CH), 1598 (Ar-C=C), 1504 (Ar-C=C), 1355 (Ar-CN), 1062, 750 cm-1. 1H NMR (200 MHz, CDCl3): δ = 3.49 (t, J = 4.9 Hz, 4 H, NCH2), 3.75 (t, J = 4.9 Hz, 4 H, OCH2), 6.63-6.75 (m, 3 H, Ar), 7.17-7.25 (m, 2 H, Ar). 13C NMR (50 MHz, CDCl3): δ = 55.21 (NCH2), 60.48 (OCH2), 112.41 (Ar-CH), 116.75 (Ar-CH), 129.20 (Ar-CH), 147.62 (Ar-C). GC-MS (EI, 70 eV): m/z (%) = 181 (16) [M]+, 150 (100) [C6H5N(C2H4OH)=CH2]+, 106 (56), 91 (7), 77 (16), 65 (1), 52 (4), 45 (7).
2-[Methyl(phenyl)amino]ethanol ( 7) IR (film): 3344 (OH, NH), 2906 (CH), 1596 (Ar-C=C), 1505 (Ar-C=C), 1340 (Ar-CN), 1056, 746 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.74 (br s, 1 H, OH), 2.96 (s, 3 H, NCH3), 3.47 (t, J = 5.6 Hz, 2 H, NCH2), 3.81 (t, J = 5.6 Hz, 2 H, OCH2), 6.72-6.83 (m, 3 H, Ar), 7.21-7.29 (m, 2 H, Ar). 13C NMR (100 MHz, CDCl3): δ = 38.68 (NCH3), 55.32 (NCH2), 59.90 (OCH2), 112.93 (Ar-CH), 117.07 (Ar-CH), 129.11 (Ar-CH), 149.94 (Ar-C). GC-MS (EI, 70 eV): m/z (%) = 151 (17) [M]+, 120 (100) [C6H5N(CH3)=CH2]+, 105(11), 91 (5), 77 (15), 65(1), 51 (5).
2-Phenylamino-1-phenylethanol ( 10b) IR (CHCl3): 3610 (OH), 3433 (NH), 2927 (CH), 1604 (Ar-C=C), 1505 (Ar-C=C), 1316 (Ar-CN), 1060, 790 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.61 (br s, 2 H, NH, OH), 3.32 (dd, J = 8.5, 13.1 Hz, 1 H, NCH2), 3.48 (dd, J = 4.0, 13.1 Hz, 1 H, NCH2), 4.96 (dd, J = 4.0, 8.5 Hz, 1 H, OCH), 6.68 (d, J = 7.6 Hz, 2 H, Ar), 6.76 (t, J = 7.3 Hz, 1 H, Ar), 7.20 (t, J = 7.5 Hz, 2 H, Ar), 7.30-7.42 (m, 5 H, Ar). GC-MS (EI, 70 eV): m/z (%) = 213 (8) [M]+, 194 (13), 182 (10), 165 (2), 106 (100) [C6H5NH=CH2]+, 91 (7), 77 (33), 65 (3), 51 (9).
2-Phenylamino-2-phenylethanol ( 11b) 3,25
IR (film): 3396 (OH, NH), 2927 (CH), 1602 (Ar-C=C), 1504 (Ar-C=C), 1317 (Ar-CN), 1066, 750 cm-1. 1H NMR (200 MHz, CDCl3): δ = 2.71 (br s, 2 H, NH, OH), 3.76 (dd, J = 7.0, 11.1 Hz, 1 H, OCH2), 3.96 (dd, J = 4.2, 11.1 Hz,
1 H, OCH2), 4.50 (dd, J = 4.2, 7.0 Hz, 1 H, NCH) 6.55 (d, J = 7.5 Hz, 2 H, Ar), 6.88 (t, J = 7.3 Hz, 1 H, Ar), 7.11 (t, J = 7.4 Hz, 2 H, Ar), 7.30-7.36 (m, 5 H, Ar). 13C NMR (50 MHz, CDCl3): δ = 59.83 (NCH), 67.33 (OCH2), 113.82 (Ar-CH), 117.86 (Ar-CH), 126.70 (Ar-CH), 127.58 (Ar-CH), 128.80 (Ar-CH), 129.13 (Ar-CH), 140.10 (Ar-C), 147.20 (Ar-C). GC-MS (EI, 70 eV): m/z (%) = 213 (7) [M]+, 182 (100) [C6H5NH=CHPh]+, 104 (17), 91 (4), 77 (23), 65 (2), 51(5). 3-(Phenylamino)propan-1-ol ( 12) IR (film): 3381 (OH, NH), 2935 (CH), 1602 (Ar-C=C), 1506 (Ar-C=C), 1321 (Ar-CN), 1064, 752 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.87 (quin, J = 5.9, 6.4 Hz, 2 H, CH2), 2.79 (br s, 2 H, NH, OH), 3.27 (t, J = 6.4 Hz, 2 H, NCH2), 3.80 (t, J = 5.9 Hz, 2 H, OCH2), 6.62-6.76 (m, 3 H, Ar), 7.14-7.22 (m, 2 H, Ar). 13C NMR (50 MHz, CDCl3): δ = 31.85 (CH2), 41.89 (NCH2), 61.55 (OCH2), 113.10 (Ar-CH), 117.63 (Ar-CH), 129.22 (Ar-CH), 148.28 (Ar-C). GC-MS (EI, 70 eV): m/z (%) = 151 (27) [M]+, 132 (1), 118 (2), 106 (100) [C6H5NH=CH2]+, 93 (5), 77 (15), 65 (4), 51 (4).