Amidation of Alcohols with Nitriles Under Solvent-Free Conditions
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Journal of Oleo Science Copyright ©2010 by Japan Oil Chemists’ Society J. Oleo Sci. 59, (11) 607-613 (2010) Amidation of Alcohols with Nitriles under Solvent-free Conditions Using Molecular Iodine as a Catalyst Yoshio Kasashima1* , Atsushi Uzawa1, Kahoko Hashimoto2, Yu Yokoyama3, Takashi Mino3, Masami Sakamoto3 and Tsutomu Fujita3 1 Education Center, Faculty of Engineering, Chiba Institute of Technology (2-1-1shibazono, Narashino-shi, Chiba 275-0023, JAPAN) 2 Department of Life Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology (2-17-1 Tsudanuma, Narashino-shi, Chiba 275-0016, JAPAN) 3 Graduate School of Engineering, Chiba University (1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba 263-8522, JAPAN) Abstract: The reactions of alcohols with nitriles under solvent-free conditions, using molecular iodine as a catalyst, were investigated. The reaction of 1-phenylethanol with propanenitrile produced the amide N-(1- phenylethyl)propanamide, by dehydration and tautomerization, in 71% yield, under the following conditions: temperature=90℃, alcohol:iodine molar ratio=1:0.2, alcohol:nitrile molar ratio=1:5, and reaction time=5 h. The amidation reactivity depended on the stability of the cationic intermediate formed from the alcohol. The reaction of (−)-borneol with benzonitrile produced a racemic amide in 83% yield. Key words: iodine, solvent-free, amidation, borneol 1 INTRODUCTION spectrometer(JASCO, Easton, MD, USA). Gas chromatog- Compounds with amide linkages are important in the raphy/mass spectra(GC-MS)were recorded on a Shimadzu chemical industry. The Ritter reaction, which is the reac- GCMS-QP5050A(Shimadzu, Kyoto, Japan)[column: JW tion of alcohols with nitriles, is one method of producing Scientifi c DB-5ms(30 m×0.25 mm, 0.25 μm fi lm), Agilent, amides1-5). However, the catalysts used in this reaction are Santa Clara, CA, USA]. Optical rotations were measured generally strong acids or heavy-metal compounds, which on a JASCO DIP-370. X-ray measurements were made on a are very expensive and/or toxic. In the present study, io- Bruker axs-SMART APEX II at -100℃. dine was investigated as a catalyst for the reaction of alco- hols with nitriles. Recently, iodine has been investigated as 2.2 Materials a potential efficient catalyst in several organic reactions 1-Phenylethanol(1)was synthesized as follows: because it has low toxicity6-18). In this study, we also inves- Acetophenone(6.02 g, 50 mmol)and ethanol(50 mL) tigated solvent-free conditions, from the viewpoint of were placed in a fl ask and the mixture was stirred. Sodium “green chemistry”. borohydride(3.88 g, 102 mmol)was added and the mixture was stirred at 0℃ for 1 d. After evaporation, diethyl ether (50 mL)and then 6M aqueous HCl were added. The mix- ture was then extracted twice with 100 mL of diethyl ether. 2 EXPERIMENTAL The organic layer was washed with 100 mL of aqueous so- 2.1 General dium hydrocarone solution, dried with anhydrous sodium Melting points were measured on a Shibata micro melt- sulfate, and evaporated. The product was purifi ed by col- ing point apparatus(Shibata, Tokyo, Japan), and were un- umn chromatography with hexane/ethyl acetate(4/1)as the corrected. NMR spectra were obtained using a 400 MHz or eluent. A total of 4.38 g(36.0 mmol; 72% yield)of 1 was 300 MHz FT-NMR spectrometer(JEOL JNM-LA-400, JEOL, obtained. Tokyo, Japan, or Bruker DPX-300, Bruker, Billerica, MA, USA)with Me4Si as the internal standard and CDCl3 as the 2.3 Amidation solvent. IR spectra were recorded on a JASCO FT/IR-230 A typical procedure is as follows: *Correspondence to: Yoshio Kasashima, Education Center, Faculty of Engineering, Chiba Institute of Technology, 2-1-1shibazono, Narashino-shi, Chiba 275-0023, JAPAN E-mail: [email protected] Accepted May 21, 2010 (received for review March 29, 2010) Journal of Oleo Science ISSN 1345-8957 print / ISSN 1347-3352 online http://www.jstage.jst.go.jp/browse/jos/ 607 Y. Kasashima, A. Uzawa1, K. Hashimoto et al. 13 Compound 1(121 mg, 1.0 mmol), propanenitrile(2)(272 m), 7.74(2H, d, J=8.9 Hz); C-NMR(CDCl3)δ: 21.8, 49.1, mg, 5.0 mmol)and iodine(50.0 mg)were place in a reaction 55.4, 113.7, 126.2, 126.8, 127.4, 128.7, 128.7, 143.3, 162.1, tube, and the tube was sealed. The mixture was stirred at 166.0; IR(KBr): 3335, 1628 cm-1; EI-MS m/z(rel intensi- 90℃ for 5 h. Diisopropyl ether(3 mL)was added, and then ty): 255(M+, 27) a 20% aqueous solution of sodium thiosulfate(5 mL)was 2.3.7 N(- 2-Octyl)benzamide(10) 1 added to the reaction mixture to remove the iodine. The White crystals, mp 66-67℃. H-NMR(CDCl3)δ: 0.88(3H, mixture was then extracted three times with 20 mL of di- t, J=6.6 Hz),1.29(3H, t, J=7.0 Hz), 1.22-1.56(10H, m), isopropyl ether. The organic layer was washed with 100 mL 4.12-4.26(1H, m), 5.87(1H, bs), 7.40-7.52(3H, m), 13 of water, dried with anhydrous sodium sulfate, and evapo- 7.74-7.76(2H, m); C-NMR(CDCl3)δ: 14.1, 21.1, 22.6, 26.0, rated. The product was purified by column chromatogra- 29.2, 31.8, 37.1, 45.8, 126.8, 128.5, 131.2, 135.1, 166.8; IR phy with hexane/ethyl acetate(10/1)as the eluent. A total (KBr): 3292, 2923, 2851, 1635 cm-1; EI-MS m/z(rel inten- of 124 mg(0.70 mmol; 71% yield)of N(- 1-phenylethyl)pro- sity): 233(M+, 9) panamide(3)was obtained. The GC-MS purities of all prod- 2.3.8 N-Cyclohexylbenzamide(11) 1 ucts were above 98%. White crystals, mp 137-138℃. H-NMR(CDCl3)δ: The spectroscopic data of the product from 1 is as fol- 1.13-1.30(3H, m), 1.36-1.50(2H, m), 1.62-1.79(3H, m), lows: 2.01-2.06(2H, m), 3.92-4.04(1H, m), 6.02(1H, bs), 13 2.3.1 N(- 1-Phenylethyl)propanamide(3) 7.39-7.51(3H, m), 7.74-7.77(2H, m); C-NMR(CDCl3)δ: 1 White crystals, mp 55-56℃. H-NMR(CDCl3)δ: 1.16(3H, 24.9, 25.5, 33.2, 48.6, 126.8, 128.5, 131.2, 135.1, 166.6; IR t, J=7.6 Hz), 1.49(3H ,d, J=6.9 Hz), 2.21(2H ,q, J=7.6 (KBr): 3318, 3240, 2929, 2851, 1627 cm-1; EI-MS m/z(rel Hz), 5.14(1H, qd, J=6.9, 7.3 Hz), 5.67(1H, bs), 7.24-7.37 intensity): 203(M+, 30) 13 (5H, m); C-NMR(CDCl3)δ: 9.77, 21.7, 29.7, 48.5, 126.1, 2.3.9 N-tert-Butylbenzamide(12) -1 1 127.2, 128.6, 143.3, 172.7; IR(KBr,); 3330, 2972, 1651 cm ; White crystals, mp 135-136℃. H-NMR(CDCl3)δ: 1.48 EI-MS m/z(rel intensity): 177(M+, 46) (9H, s), 5.95(1H, s), 7.39-7.48(3H, m), 7.71-7.73(2H, m); 13 2.3.2 N(- 1-Phenylethyl)acetamide(4) C-NMR(CDCl3)δ: 28.8, 51.6, 126.7, 128.4, 131.0, 135.9, 1 -1 White crystals, mp 70-71℃. H-NMR(CDCl3)δ: 1.49(3H , 166.9; IR(KBr): 3325, 2965, 1636 cm ; EI-MS m/z(rel in- d, J=6.8 Hz), 1.99(3H , s), 5.13(1H, qd, J=6.8, 7.3 Hz), tensity): 177(M+, 18) 13 5.73(1H , bs), 7.24-7.37(5H, m); C-NMR(CDCl3)δ: 21.7, 2.3.10 N-Benzylbenzamide(13) 1 23.4, 48.7, 126.2, 127.4, 128.6, 143.1, 169.0; IR(KBr): 3282, White crystals, mp 92-94℃. H-NMR(CDCl3)δ: 4.65(2H, 1647 cm-1; EI-MS m/z(rel intensity): 163(M+, 41) d, J=5.7 Hz), 6.43(1H, bs), 7.20-7.53(8H, m), 7.78-7.81 13 2.3.3 2-Cyano-N(- 1-phenylethyl)acetamide(5) (2H, m); C-NMR(CDCl3)δ: 44.1, 126.9, 127.6, 127.9, 1 White crystals, mp 100-101℃. H-NMR(CDCl3)δ: 1.53 128.6, 128.8, 131.5, 134.3, 138.1, 167.3; IR(KBr): 3289, (3H, d, J=7.0 Hz), 3.31(2H , s), 5.09(1H, qd, J=7.0, 7.2 3060, 1638 cm-1; EI-MS m/z(rel intensity): 211(M+, 64) 13 Hz), 6.45(1H, bs), 7.26-7.39(5H, m); C-NMR(CDCl3)δ: 2.3.11 (±) -exo-N-Isobornylbenzamide(15) 1 21.4, 25.9, 49.9, 114.7, 126.1, 127.8, 128.9, 141.8, 160.0; IR White crystals, mp 125-126℃. H-NMR(CDCl3)δ: 0.88 (KBr): 3278, 3067, 2975, 2921, 2257, 1648 , cm-1; EI-MS (3H, s), 0.92(3H, s), 1.01(3H, s), 1.19-1.25(1H, m), m/z(rel intensity): 188(M+, 54) 1.33-1.42(1H, m), 1.59-1.82(4H, m), 1.93-2.00(1H, m), 2.3.4 N(- 1-Phenylethyl)benzamide(6) 4.08-4.15(1H, m), 6.08(1H, bs), 7.40-7.49(3H, m), 1 13 White crystals, mp 113-115℃.