Pasha et al. Int. J. Res. Chem. Environ. Vol.3 Issue 1 January 2013(226-230) 226 International Journal of Research in Chemistry and Environment Vol. 3 Issue 1 January 2013(226-230) ISSN 2248-9649 Research Paper Microwave-assisted direct Synthesis of Nitriles from Aromatic Aldehydes under Solvent-Free Condition Sadeq Hamood Saleh Azzam and * Pasha M. A. Department of Studies in Chemistry, Central College Campus, Palace Road, Bangalore University, Bengaluru–560 001, INDIA (Received 13 th November 2012, Accepted 29 th November 2012) Available online at: www.ijrce.org Abstract: A simple and convenient one-pot protocol for preparing nitriles by treating different aromatic aldehydes with hydroxylamine hydrochloride in the presence of Na 2 CO 3 - a simple, mild, and inexpensive catalyst, without any solvent under microwave irradiation is reported. The significant features of the present protocol are simplicity, high yields, short reaction time, involvement of non-aqueous work-up procedure, environmentally benign nature, using of microwave reactor and no chromatographic purification. Keywords: Aldehydes, Hydroxylamine hydrochloride, Microwave Reactor, Nitriles, Na 2 CO 3 . Introduction Nitriles are very useful starting materials for the synthesis of a variety of biologically important heterocyclic compounds and the direct transformation of aldehydes into the corresponding nitriles is one of the most important reactions in organic transformations [1] . The multipurpose application of nitriles include the preparation of thiozoles [2] , oxazoles [3,4] tetrazoles [5,6] , 1,2 diarylimidazoles [7,8] , 2-oxazolines [9] and benzamidines which possess a broad spectrum of biological activities [10–12] . Further, the conversion of nitriles into ketones, amides, amines, esters and carboxylic acids is also interesting [4] . In addition to this, the nitrile function is found in a number of pharmaceutical products such as HIV protease inhibitors, in 5-lipoxygenase inhibitors, and in many other bioactive molecules [13,14]. Reports on the preparation of nitriles from aldehydes as well as by the dehydration of corresponding aldoximes using reagents such as NaN 3 [15] AlCl 3 [15] , (CH 3 ) 3 SiN 3 [16] , 1-nitropropane [17,18] (NH 4 ) 2 HPO 4 [19] , triazidochlorosilane [20] , S,S-dimethylsulphurdiimide [21] , N,N-dimethylhydrazine [22] and magnesium monoperoxyphthalate hexahydrate [23] , aq. NH 3 and iodine [24] or lead tetraacetate [24] are available in the literature. Dewan, et al. recently reported a one-pot conversion of benzaldehyde into nitriles using Na 2 SO 4 or NaHCO 3 [25] in a domestic microwave oven, but the amount of reagent used is more than 10 times the amount of the reactants. The reported methods thus have both advantages and limitations. Some of the methods require long reaction durations, give low yields of the products and involve use of expensive or commercially unavailable reagents and some reactions are loaded with the reagents. A general method for the synthesis of nitriles is the nucleophilic substitution reaction of alkyl halides with metal cyanides [26] . This method is hazardous because of highly toxic metal cyanides. In the last decade microwave irradiation technique has been utilized as a powerful tool for the various organic transformations [27] . The main benefits of use of microwave irradiation includes significant enhancement of the rate of reactions, improvement in the yields, and selectivity [28] . On the other hand, microwave promoted dehydration of aldoximes into nitriles using reagents such as silica gel [29] , Montmorillonite K-10 [30] or KSF [30] , Red mud (RM) [31] is known. Recently, from our laboratory we have reported a one pot conversion of aldehydes into nitriles by catalytic amount of ZnO [MW/320W, solvent-free] [32] , pyridine [MW/320W, solvent-free] and catalytic ZnCl 2 [MW/160W, solvent-free] under microwave irradiation. Herein, we are reporting another simple, mild, inexpensive, general and eco-friendly one-pot synthesis of nitriles from corresponding aldehydes and NH 2 OH·HCl using ready available and inexpensive Na 2 CO 3 as catalyst without any additional solvent in a microwave reactor as shown in the Scheme 1.