Ecofriendly solvent

The cyclization procedure of imines 56 was developed by using microwave heating in such high boiling solvents as yV-methylpyrrolidin-2-one at 150 °C, or even an ecofriendly solvent-free process in the presence of graphite at the same temperature <2003SC3795>. Yields are moderate (45-52%). 

Ethyl-lactate is a novel ecofriendly solvent with potential applications in supercritical fluid technology, as a co-solvent of earbon dioxide, in high pressiue chemical reactions, supercritical extraction processes and/or anti-solvent precipitation processes. In view of this, knowledge of the phase behavior of (ethyl lactate + CO2) binary is essential for the modeling and design of sueh proeesses. 

Finally, it should be stated that ethyl lactate is a novel ecofriendly solvent for potential applications in supercritical fluid technology, as a cosolvent of carbon dioxide. Ethyl lactate can be readily dissolved in CO2 in the amounts usually employed for supercritical extraction processes (15-20 wt% or lower). Additionally, at the typical temperatures employed (35-70°C) the ethyl lactate -1- CO2 system presents homogeneous (single) phase at relative low pressures. 

The ecofriendly solvent-free reactions of o-aminothiophenol and aromatic or aliphatic P-keto esters with microwave irradiation produced 2-substituted benzothia-zoles in excellent yields. The formation of the 2-substituted benzothiazoles probably involves the nucleophilic addition of the thiol group to the keto group of the P-keto ester followed by elimination of ethyl acetate from the resulting adduct. Then it undergoes an intramolecular addition of the o-amino group to the carbonyl group to give an adduct, from which water is eliminated to afford the 2- substituted benzothiazoles (Kamila et al., 2005). 

An ecofriendly solvent-free Fries rearrangement with acyl/alkyl migration has been observed by Selvakumar et al. (2007). Rearrangement of N-acylaniline in presence of AlClj adsorbed on neutral alumina under microwave irradiation afforded exclusively the p-rearranged product. Reactions were completed within 3-5 min and the yield varies between 86-96%. 

Solvent-free processing, 24 170-171 Solvent-free protocol, ecofriendly advantages of, 76 585 Solvent Green 3, 5, 28... 

Ecofriendly Fast Batch Synthesis of Dioxolanes, Dithiolanes, and Oxathio-lanes Without Solvent Under Microwave Irradiation (Perio et al., 1998)... 

Another method involves microwave irradiation. It has been described for the synthesis of 1,3-dialkylimidazolium tetrachloroaluminates [40]. This method precludes the use of volatile organic solvents and is faster, more efficient and also ecofriendly, affording high yields of the desired products. 

The electrochemical reduction of unsaturated organic compounds to paraffins is usually undertaken in nonaqueous solutions. However, the use of ultrasound allows voltammetry to be performed in a more ecofriendly manner by using a sonoemulsion of the substrate in water, so eliminating the need for the nonaqueous solvent. For example, voltammograms for the reduction of diethylmaleate, diethylfumarate, and diethylacetylene dicarboxylate in the form of microscopic droplets generated by applying power... 

Indulkar, U.U., Kale, S.R., Gawande, M.B. and Jayaram, R.V. 2012. Ecofriendly and facile nano ZnO catalyzed solvent-free enamination of 1, 3-dicarbonyls. Tetrahedron Lett. 53 ... 

Sellami et al. (2012) in a solvent free system using a Rhizopusoryzae lipase immobilized onto CaCOs to produce a suitable fat for margarine formulation. This ecofriendly approaeh used low value bioresources like palm stearin and palm olein to obtain a healthier product. The triacylglycerol (TG) profile showed a decrease in the amoimts of saturated TG and increased the lower melting point TG ratio, especially triolein (000). 

Use safer solvents and auxiliaries Reduce the use of solvents that cause pollution. If necessary, use solvents that are benign to the enviromnent. In this context, supercritical CO2 (SCCO2) and ionic liquids show remarkable potential as ecofriendly substitutes for solvents that are toxic to the environment. 

An efficient and ecofriendly microwave irradiated solvent-free benzoylation method was developed by Al-Masum et al. (2011). 50 mol% AICI3 was used as a Lewis aeid catalyst at 130 °C for C-benzoylation and the reaction was completed in 10 min. The isolated yield was between 71-100%. N-benzoylation was also eondueted in a catalyst-free environment at 130 °C in 10 min but the yield was between 80-100%. 

Bhuiyan et al. (2012) reported that arylidene-malononitrile can be prepared by Knoevenagel condensation reaction of malononitrile with corresponding aromatic aldehydes in presence of ammonium acetate (NH OAc), using microwave irradiation under solvent-free condition. The reaction proceeds in a clean manner with shorter reaction time, mild reaction condition, ecofriendly and with excellent yields as compared to conventional methods. A variety of functional groups such as nitro, chloro, amino and ether survived under the reaction conditions. 

Microwave-assisted synthesis of nano-sized cadmium oxide as a new and highly efficient catalyst for solvent-free acylation of amines and alcohols was developed (Mazaheriehrani et al., 2010). The biological synthesis of silver nanoparticles is not only a cost-effective and ecofriendly method but also time consuming. A rapid method of silver nanoparticle synthesis using E. coli culture supernatant along with microwave irradiation has been proposed (Mahanty etal., 2013). 

Meshram et al. (1999b) also observed the deprotection of a variety of tetrahy-dropyranyl ethers (THP), acetonides and acetals into their parent compounds using clayan under microwave irradiation. The ecofriendly nature of the reagent and solvent-free conditions are the important features of the procedure. 

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