Synlett 2012(5): 706-710  
DOI: 10.1055/s-0031-1290595
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Base-Catalyzed Direct Transformation of Benzylamines into Benzyl Alcohols

Yutaka Kanbara*, Takafumi Abe, Norio Fushimi, Taketo Ikeno
Niigata Research Laboratory, Mitsubishi Gas Chemical Company, Inc., 182, Shinwari, Tayuhama, Niigata 950-3112, Japan
Fax: +81(25)2584800; e-Mail: yutaka-kanbara@mgc.co.jp;
Further Information

Publication History

Received 13 November 2011
Publication Date:
28 February 2012 (online)

Abstract

Benzylamines were directly transformed into benzyl alcohols in superheated aqueous methanol in the presence of a base catalyst. This process is simple and will provide an alternative industrial route to benzyl alcohols such as xylene glycols.

    References and Notes

  • 1a Ringk W. Theimer ET. In Kirk-Othmer Encyclopedia of Chemical Technology   3rd ed., Vol. 3:  Grayson M. John Wiley & Sons; New York: 1978.  p.796 
  • 1b Brühne F. Wright E. In Ullmann’s Encyclopedia of Industrial Chemistry   5th ed., Vol. A4:  Gerhartz W. VCH; Weinheim: 1985.  p.6 
  • 2a Bungs JA. inventors; U. S. Patent  2967854. 
  • 2b Nishimura AA. Polymer  1967,  8:  446 
  • 2c Laguerre A. Pilard J.-F. Couvercelle J.-P. Bunel C. Kebir N. Campistron I. e-Polymers  2006,  no. 048:  1 
  • 2d Ho T. Wynne KJ. Nissan RA. Macromolecules  1993,  26:  7029 
  • 3a Adkins H. Org. React. (N. Y.)  1954,  8:  1 
  • 3b Onda Y, Kosuge F, and Tsunoda M. inventors; U. S. Patent  4990690. 
  • 3c Toba M. Tanaka S. Niwa S. Mizukami F. Koppany Z. Appl. Catal., A  1999,  189:  243 
  • 4a Weissermel K. Arpe H.-J. Industrial Organic Chemistry   3rd ed.:  VCH; Weinheim: 1997.  p.400 
  • 4b Wittcoff HA. Reuben BG. Plotkin JS. Industrial Organic Chemicals   2nd ed.:  Wiley-Interscience; New Jersey: 2004.  p.327 
  • 4c Saunders JH. In Kirk-Othmer Encyclopedia of Chemical Technology   3rd ed., Vol. 18:  Grayson M. John Wiley & Sons; New York: 1982.  p.400 
  • 4d Kohan MI. In Ullmann’s Encyclopedia of Industrial Chemistry   5th ed., Vol. A21:  Elvers B. Hawkins S. Schulz G. VCH; Weinheim: 1992.  p.180 
  • 5a Clarke HT. Hartman WW. Org. Synth., Coll. Vol. I  1932,  455 
  • 5b Boswell DE. Brennan JA. Landis PS. Tetrahedron Lett.  1970,  60:  5265 
  • 6a Baumgarten RJ. J. Chem. Educ.  1966,  43:  398 
  • 6b Kirmse W. Angew. Chem. Int. Ed. Engl.  1976,  15:  251 
  • 6c Naik R. Pasha MA. Synth. Commun.  2005,  35:  2823 
  • 6d Moss RA. Chem. Eng. News  1971,  49:  28 
  • 7 Brasen WR. Hauser CR. Org. Synth., Coll. Vol. IV  1963,  582 
  • 8a Curtis VA. Kuntson FJ. Baugarten RJ. Tetrahedron Lett.  1981,  22:  199 
  • 8b Müller P. Thi MPN. Helv. Chim. Acta  1980,  63:  2168 
  • 8c Kato Y. Yen DH. Fukudome Y. Hata T. Urabe H. Org. Lett.  2010,  12:  4137 
  • 8d Katritzky AR. Tetrahedron  1980,  36:  679 
  • 9a Siskin M. Katritzky AR. Chem. Rev.  2001,  101:  825 
  • 9b Katritzky AR. Nichols DA. Siskin M. Murugan R. Balasubramanian M. Chem. Rev.  2001,  101:  837 
  • 9c Katritzky AR. Lapucha AR. Siskin M. Energy Fuels  1990,  4:  555 
  • 9d Katritzky AR. Nichols DA. Shipkova PA. Siskin M. ACH - Models Chem.  1998,  135:  553 
  • 10a Deka DC. Indian J. Chem. Technol.  1995,  2:  197 
  • 10b Nandi DK. Palit SK. Deka DC. J. Chem. Technol. Biotechnol.  1987,  38:  243 
  • 10c Deka DC. Nandi DK. Palit SK. J. Chem. Technol. Biotechnol.  1988,  41:  95 
  • 11a

    After our patent application,¹¹b another patent application¹¹c was published. It was reported that when benzylamine and an equivalent amount of glycolic acid were heated in supercritical methanol, the amide was probably generated in situ, and then it was converted into benzyl alcohol with good yield.

  • 11b Kanbara Y, Abe T, and Fushimi N. inventors; Jpn. Patent Appl.  288352. 
  • 11c Kamimura A, Kaiso K, and Sugimoto T. inventors; PCT Int. Appl. WO  016409. 
12

We examined the reaction of MXG and methylamine as a representative of the reverse reaction, that is, transformation of benzyl alcohols into benzylamines. So far, MXDA was not obtained.

13

In order to check metal leaching from the stainless-steel autoclave, ICP analysis of the reaction solution was performed [reaction conditions: MXDA/MeOH/H2O/NaOH = 1:110:70:1.4 (molar ratio), 240 ˚C, 2 h]. The concentrations of Fe, Cr, Ni, and Mo were 0.018, 0.058, 0.0, and 3.0 ppm, respectively. The reaction also conducted in a glass vessel when it was carried out in 1-undecanol under reflux at atmospheric pressure. Therefore, it was considered that metal leaching from the reaction vessel was minute and its effect was marginal.

14

MXDA, mono-alcohol, MXG, MeOH, and methylamine were only observed, and no other byproducts or inter-mediates were detected in the time-course GC analysis of the reaction.

15

Reactions under N2 and H2 (initial pressure: 1 MPa) were investigated and compared with those at 1 atm N2. Even under H2 pressure, the reaction smoothly proceeded and no differences were observed. Combined with the fact that no byproducts or intermediates were detected, it was thus not considered probable that the reaction proceeded via imine or aldehyde intermediates.

16

From the fact that the yields of N-methyl and N,N-dimethyl benzylamine were very low, it was apparent that N-methylation by methanol did not occur during the reaction

17

Preparation of m -xylene glycol (MXG); Typical Procedure (Table 1)
To a 30-mL autoclave was added MXDA (0.30 g, 2.2 mmol), catalyst (0.1 g), and MeOH (7.4 g), and then the inner gas was replaced by N2. The mixture was heated at 240 ˚C for 2 h, and then cooled in an ice-water bath. The yield was determined by GC analysis using tridecane as internal standard. The crude products were purified by Kugelrohr distillation.
Spectral data of MXG (Table  [³] , entry7): ¹H NMR (500 MHz, CD3OD): δ = 4.60 (s, 4 H), 7.24-7.34 (m, 4 H). ¹³C NMR (126 MHz, CD3OD): δ = 65.2, 126.6, 126.9, 129.4, 142.8.

18

Preparation of benzyl alcohol derivatives (Table 4): To a 30-mL autoclave was added benzylamine derivative (4.4 mmol for entry 9, 11, and 12, and 2.2 mmol for the others), powdered NaOH (0.1 g, 2.5 mmol), MeOH (7.4 g), and H2O (2.9 g), then the inner gas was replaced by N2. The mixture was heated at 240 ˚C for 2 h, and then cooled in an ice-water bath. The reaction mixture was neutralized with 1 M HCl (2.5 mL, 2.5 mmol). GC yield was determined by GC analysis using tetradecane (entry 4) and tridecane (for the others) as internal standard. For entry 1, the solutions were dried over Na2SO4, concentrated, and purified by silica-gel column chromatography (hexane-EtOAc, 75:25 v/v). The other products were purified by Kugelrohr distillation.
Spectral data of benzyl alcohol (Table  [4] , entry1): ¹H NMR (500 MHz, CD3OD): δ = 4.59 (s, 2 H), 7.23-7.33 (m, 5 H). ¹³C NMR (126 MHz, CD3OD): δ = 65.2, 126.6, 126.9, 129.4, 142.8. All other products were characterized by comparison of GC retention time with chemical reagents purchased from commercial suppliers.