Magnesium/lanthanum mixed oxide is an effective heterogeneous catalyst for aldol-type condensation of aldehydes and imines with ethyl diazoacetate (EDA) at room temperature in water to afford corresponding b-hydroxy-a-diazo carbonyl compounds and b-amino-a-diazo carbonyl compounds in good yields. The catalyst is recovered and reused for several cycles with consistent activity.Keywords: b-amino-a-diazo carbonyl compounds; b-hydroxy-a-diazo carbonyl compounds; heterogeneous catalyst; magnesium/lanthanum mixed oxide; water as solvent a-Diazo carbonyl compounds [1] are a potential source of amino alcohols and acids. a-Diazo carbonyl compounds are generally prepared by the azido transfer reaction of carbonyl compounds.[2] Condensation of acyldiazomethane to aldehydes and imines also yields a-diazo carbonyl compounds but requires deprotonation of the acyldiazomethane. This is usually carried out by using strong bases, such as butyllithium, [3] lithium diisopropylamide (LDA), [4] sodium hydride, [5] potassium hydroxide, [6] [7] and quarternary ammonium hydroxide.[8] However, some of the methods require low temperatures and absolutely anhydrous conditions, moreover the use of such strong bases may not be compatible with functional groups in the substrates. Thus, the development of more improved synthetic methods for the preparation of a-diazo carbonyl compounds remains an active research area.In recent years, there has been increasing emphasis on the use and design of environment-friendly solid catalysts to reduce the amount of toxic waste. The use of a solid catalyst allows easy separation of catalyst from the reaction mixture in large-scale production to conform to the concept of green technology. In a recent review, Sheldon [9] emphasized the point that "the best solvent is no solvent and if a solvent (diluent) is needed then water is preferred. Water is nontoxic, non-flammable, abundantly available and inexpensive" therefore, reactions performed in water are safer and cheaper.We herein report the synthesis of b-hydroxy-adiazo carbonyl compounds and b-amino-a-diazo carbonyl compounds by condensation of a wide variety of aldehydes and imines with ethyl diazoacetate using the Mg/La mixed oxide catalyst in water (Scheme 1).To the best of our knowledge, there are no reports on this condensation using a heterogeneous catalyst and water as solvent. The Mg/La mixed oxide catalyst was prepared by the co-precipitation method described earlier.[10] Chemical analysis of the solid gave the composition La 2 O 3 29.5 %, MgO: 30.1 %, K 2 O: 3.4 %, H 2 O: 37 %. The catalyst is well characterized by XRD, DTA coupled with mass spectrometry, FTIR and calorimetry. This mixed oxide is macroporous and shows a surface area of 37.6 m 2 g À1 after calcination at 923 K. Recently, we have efficiently performed transesterifications of diethyl carbonate by alcohols [11] and Michael addition reactions [10] by using this highly Scheme 1.

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N-Arylation of azoles and amines with arylboronic acids was efficiently carried out with heterogeneous copper(I) oxide in methanol at room temperature under base-free conditions. The products N-arylazoles and N-arylamines were isolated in good to excellent yields. A variety of arylboronic acids and amines were converted to the corresponding N-arylazoles and N-arylamines, demonstrating the versatality of the reaction.

The procedure for the classical chemical refining of vegetable oils consists of degumming, alkali neutralization, bleaching, and deodorization. Conventional refining of rice bran oil using alkali gives oil of acceptable quality, but the refining losses are very high. A critical work has been carried out to study the application of membrane technology in the pretreatment of crude rice bran oil. Oils intended for physical refining should have a low phosphorus content, and this is not readily achievable by the conventional acid/ water degumming process. The application of membrane technology for the pretreatment of rice bran oil has been investigated. The process has already been successfully applied to other vegetable oils. Ceramic membranes, which are important from the commercial point of view, were examined for this purpose. The results showed that the membrane-filtered oils met the requirements of physical refining, with a substantial reduction in color. It was observed that most of the waxy material was also rejected. Experiments were carried out to establish the relationship between permeate flux and rejection with membrane pore size, trans-membrane pressure and micellar solute concentration.

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