Synthesis of Aldehydes and Ketones by the

CEJC 2(1) 2004 214{219

Communication

Synthesis of Aldehydes and Ketones by the Dehydrogenation of Alcohols in the Presence of a Raney Nickel/Aluminium Isopropoxide/Alumina Catalyst Ilie Ciocan Tarta1 , Ioan A. Silberg1;2 , Mircea Vlassa2¤ , Ioan Oprean1;2 1

\Raluca Ripan" University, Institute of Chemistry, 30 F^ant^anele Str., RO-3400 Cluj-Napoca, Romania 2 \Babes-Bolyai" University, Department of Chemistry, 11 Arany Janos Str., RO-3400 Cluj-Napoca, Romania

Received 24 June 2003; accepted 13 October 2003 Abstract: The synthesis of aldehydes and ketones by the dehydrogenation of allylic and secondary alcohols using a Raney-Ni-Al(i-OPr)3 -Al2 O3 catalyst without hydrogen acceptors is presented. c Central European Science Journals. All rights reserved. ® Keywords: dehydrogenation, alcohols, heterogeneous catalysis Raney nickel, aluminium isopropoxide, alumina

1

Introduction

¤

The oxidation of alcohols to carbonyl compounds is a fundamental reaction in organic synthesis [1]. A number of transition metal-catalyzed procedures have been developed, such as those using ruthenium [2] or palladium[3]. A Raney-Ni catalyst is used frequently for the dehydrogenation of secondary alcohols to ketones because of the high yields. However, this later method has the disadvantage of requiring either high temperatures[4] or large amounts of hydrogen acceptors (i:e. cyclohexanone), which are required for complete conversion[5]. Sometimes, noncatalytic quantities of Raney-Ni have been used for the dehydrogenation of primary and secondary alcohols [6]. E-mail: [email protected] Unauthenticated Download Date | 3/25/16 6:57 AM

I.C. Tarta et al. / Central European Journal of Chemistry 2(1) 2004 214{219

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Our studies show that the dehydrogenation of the secondary and allylic alcohols can be achieved with a catalytic mixture of Raney-Ni:Al(i-OPr)3 :Al2 O3 :substrate (3:5:5:100 weight) without hydrogen acceptors and at temperatures between 120-170 0 C (see Table 1). The reaction is selective, producing ketones, and the yields obtained are quite impressive. This procedure has industrial signi¯cance, as the reaction could potentially be conducted in a semi-continuous mode.

2

Results and Discussion

The experimental results are shown in Table 1. Secondary saturated alcohols are oxidized to the corresponding ketones in high yields (90-98%; see Table 1: entry 1-4, 7.). Primary and secondary allylic alcohols produce the corresponding saturated carbonyl compounds by redox isomerization (Table 1: entry 6, 7) [7]. Tertiary alcohols (see Table 1: entry 9) and primary alcohols do not react. The dehydrogenation reaction of secondary alcohols to ketones does not occur when either Raney-Ni , Al(i-ORr)3 , or alumina are absent from the catalytic mixture. No reaction is observed if the Raney-Ni is substituted with other Ni(II) salts (i:e. NiCl2 ) or complexes (i:e. Ni(PPh 3 )2 Cl2 ). We also observe that using octene as a hydrogen acceptor has no in°uence on the yield or the reaction time, but if air is bubbled through the reaction mixture, the reaction does not proceed at all. This mechanism is supported by the following observations: a) The formation of complex 3 is possible knowing the tendency of Al compounds to form four-coordinate complexes ( i.e.Meerwein-Pondorf-Verley reaction). b) The transition state is favored by Raney-Ni due to the great a±nity of Ni for hydrogen. c) The elimination of one hydride ion from the alkoxide carbon and one proton from the oxonium ion in the presence of Ni-Raney via a six-atom concerted ring transfer, leads to the formation of the ketone, 4. d) The inductive e®ect (+I) or conjugation e®ects (+E) of the substituents stabilize the carbocation obtained by elimination of hydride ion. This can be explained based on the high reactivity of allylic and secondary alcohols.

3

Conclusions

In conclusion, our studies show that the mixture of Raney-Ni-Al(i-OPr)3 -Al2 O3 is an excellent catalyst for the preparation of ketones and aldehydes from secondary and allylic alcohols in good yields.

4

Experimental

1

H-NMR spectra were recorded on a Gemini 300MHz spectrometer using CDCl 3 as the solvent and TMS (tetramethylsilane) as the Unauthenticated internal standard. IR spectra were recorded Download Date | 3/25/16 6:57 AM

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on a Perkin Elmer 700 spectrophotometer. GC and MS analyses were performed on a Hewlett Packard 5890(GCL)-5872(MSD) using a HP-5MS 30m x 0.25 ¹m capillary. The reactions were carried out under a nitrogen atmosphere. Aluminium oxide granules, about 1-5 mm, were obtained from Merck. All alcohols were obtained commercially. General oxidation procedure To a degassed alcohol (0.1 mol), 3%( weight mass) of freshly prepared Raney-Ni [8], 5% (w/w) of Al(i-OPr)3 , and 5%(w/w) of Al2 O3 were added. This mixture was magnetically stirred under nitrogen and heated for 6-50 hrs (see Table 1). The catalyst was removed by ¯ltration under an inert atmosphere and washed with petroleum ether. Subsequently, the ¯ltrate was puri¯ed by fractional distillation in vacuo, yielding 52-95% of the pure carbonyl compounds (see Table 1). The catalyst removed by ¯ltration (a mixture of Ni and alumina) was reused. The mass, 1 H, and IR spectra of the products corresponded with those reported in literature.

References [1] (a) G. Cainelli, G. Cardilo: Chromium Oxidation in Organic Chemistry, SpringerVerlag, Berlin, 1984. (b) R.C. Larock: Comprehensive Organic Transformations, VCH Publishers Inc., New-York, 1989, pp. 604{614. [2] (a) C. Bilgrein, S. Davis, R.S. Drago : \The selective oxidation of primary alcohols to aldehydes by O2 employing a trinuclear ruthenium carboxylate catalyst", J.Am.Chem.Soc., Vol. 109,(1987), pp. 3786{3787. (b) G.Z. Wang, J.E. BÄackvall: \Ruthenium-catalyzed oxidation of alcohols by acetone", J. Chem. Soc.Commun., Vol. 4, (1992), pp. 337{339. (c) J.E. BÄackvall, U. Andreasson: \Ruthenium-catalyzed isomerization of allylic alcohols to saturated ketones", Tetrahedron Lett., Vol. 34, (1993), pp. 5459{5462. [3] (a) K.P. Peterson, R.C. Larock: \Palladium-catalyzed oxidation of primary and secondary allylic and benzilic alcohols", J. Org. Chem., Vol. 63, (1998), pp. 3185{ 3189. (b) Y. Shivo, A.H.I. Arisha: \Regioselective catalytic dehydrogenation of aldehydes and ketones", J.Org.Chem., Vol. 63, (1998), pp. 5640{5642. (c) J.H. Kim, R.J. Kulawiec: \Synthesis of 2-phenyl-2-cycloalkenones via palladium catalyzed tandem epoxide isomerization-intramolecular aldol condensation", Tetrahedron Lett., Vol. 39, (1998), pp. 3107{3110. (d) N.S. Wilson, B.A. Keay: \A desilylation and one-pot desilylationoxidation of aliphatic tert- butyldimethylsilyl ethers using catalytic quantities of PdCl2 (CH 3 CN)2 ", J.Org.Chem., Vol. 61, (1996), pp. 2918{2919. (e) K. Kaneda, M. Fujii, K. Morioka: \Highly selective oxidation of allylic alcohols to ®,¯-unsaturated aldehydes using Pd cluster catalyst in the presence of molecular oxygen", J.Org.Chem., Vol. 61, (1996), pp. 4502{4503. (f) S.A. Mohand, F.Henin, J.Muzart: \Palladium(II)-mediated oxidation of alcohols using 1,2-dichloroethane as Pd(0) reoxidant", Tetrahedron Lett., Vol. 36, (1995), pp. 2473{2476. [4] (a) M.R. Sander, D.J. Trecker: \Raney nickel catalyzed decarboxylation of formate esters", J.Org. Chem., Vol. 38, (1973), pp. 3954{3956. Unauthenticated Download Date | 3/25/16 6:57 AM


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(d) E.J. Badiu: \Catalytic dehydrogenation I. Catalytic conversion of alcohols into aldehyde, para±ns and ole¯ns", J. Am. Chem. Soc., Vol. 45, (1943), pp. 1809{1813. [5] (b) M. Botta, F. De Angeles, R. Nicoletti: \A new, facile N-alkylation of amines and alcohols", Synthesis, (1977), pp. 722{723. (c) E.C. Kleidere, E.C. Korn¯eld: \Raney nickel as an organic oxidation-reduction catalyst", J. Org. Chem., Vol. 13, (1946), pp. 455{458. (d)S.B. Mahato, S.K. Banerjce, R.N. Chakravarti: \Reaction in high boiling solvent II. E®ect of Raney nickel on triterpenoids", Tetrahedron, Vol. 27, (1971), pp. 177{ 186. (e) J. Forsek: \Conversion of the allylic and homoallylic steroidal alcohols to the corresponding saturated ketones by means of the activated Ra/Ni", Tetrahedron Lett., Vol. 21, (1980), pp. 1071{1074. (f) F.C. Changm: \Potential bile acid metabolites II. 3,7,12-Trisubstituted 5-¯cholanic acids", J. Org. Chem., Vol. 44, (1979), pp. 4567{4572. [6] M.E. Kraft, W.I. Crooks, B. Zorc, S.E. Milczanowski: \Reaction of Raney nickel with alcohols\, J. Org. Chem., Vol. 53, (1988), pp. 3158{3163. [7] B. M. Trost: \On investigation reactions for atom economy", Acc. Chem. Res., Vol. 35, (2002), pp. 695{705. [8] H. Becker, W. Berger, G. Domschke, E. Franghanel, J. Faust, M., Fischer, F. Gentz, K. Gewald, R. Gluch, R. Mayer, K. MÄ uller, D. Pavel, H. Schmidt, K. Scholbergf, K. ScÄ uhwetlick, E. Seiler, G. Zeeppenfeld: Organicum, Editura Stiinti¯ca si Enciclopedica, Bucuresti, 1982, pp. 707.

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Ph-CH(OH)-Ph

CH3 (CH2 )7 -C(OH) (CH3 )-CH3

8

9

CH3 (CH2 )7 -C (OH) (CH)3 -CH3

Ph-C(O)-Ph

CH3 -(CH2 )5 -CH=O

CH3 -CH2 -CH2 -C(O)-CH3

C8 H17 -CH(O)-C3

C4 H9 -C(O)-C2 H5

C4 H9 -C(O)-CH3

Reaction product

Table 1 Carbonyl compounds prepared in the presence of a Raney-Ni-Al(i-OPr)3 /Al2 O3 catalyst.

160/50

170/6

170/14

C4 H9 -CH=CH-CH2 -OH

120/30

7

CH3 -CH=CH-CH(OH)-CH3

4

170/16

170/19

C8 H17 -CH(OH)-CH3

3

150/40

6

C4 H9 -CH(OH)-C2 H5

2

137/30

170/19

C4 H9 -CH(OH)-CH3

1

/Reaction time (h)

Temperature (0 C)

5

Alcohol

Entry

0

52

92

54

80

90

94

98

98

Yields (%)

218 I.C. Tarta et al. / Central European Journal of Chemistry 2(1) 2004 214{219


Scheme 1. Dehydrogenation mechanism of alcohols in the presence of Raney-Ni-Al(-OPr)3 /Al2 O3 catalyst.


219