Green procedure

In the malachite green procedure, 10 ml of the sample solution containing up to 0.7 xg phosphorus as orthophosphate was transferred into a 25 ml test tube. To this solution was added 1 ml each of 4.5 M sulfuric acid and the reagent solution. The solution was shaken with 5 ml of a 1 3 v/v mixture of toluene and 4-methylpentan-2-one for 5 min. After phase separation, the absorbance of the organic phase was measured at 630 nm against a reagent blank in 1 cm cells. 

Dong F, Jun L, Xinli Z, Zhiwen Y, Zuliang L (2007) One-pot green procedure for Biginelli reaction catalyzed by novel task-specific room-temperature ionic liquids. J Mol Catal A Chem 274 208-211... 

A recent literature report described a green procedure for the condensation of arylacetonitriles with cyclic ketones using phase-transfer catalysis. This process was applied to the synthesis of venlafaxine, which was realized in overall 30% yield in two steps from commercially available 14. The condensation step was run in aqueous sodium hydroxide in the presence of tetrabutylammonium sulfate, to provide quantitative yield of intermediate 15. Hydrogenation in a formalin-methanol mixture provided the final product venlafaxine (1) in 30% overall yield. This protocol did not necessitate intermediate purification steps, making it attractive from the commercial standpoint. 

Shaterian and co-workers [180] have described an efficient and expeditious route towards the synthesis of l-amidoalkyl-2-naphthols 127 via a three-component reaction of an aryl aldehyde, 2-naphthol and acetamide in the presence of Fe(HS04)3 using a domestic microwave oven. The reaction of 2-naphthol with an aromatic aldehyde in the presence of an acid catalyst gives an o-quinone methide that is subsequently reacted with acetamide to give the desired product 127. This solvent-free microwave-assisted green procedure offers the advantages of short... 

This mechanism is the same as that of 19-27 the products differ only because tertiary amine oxides cannot be further oxidized. The mechanism with other peroxyacids is probably the same. A green procedure for oxidation of tertiary amines has been developed, using a Mg-Al complex with aq. hydrogen peroxide. ... 

It is still in the early days for green analytical chemistry education. Analytical chemists have made significant innovations in greening procedures, giving analytical chemists more choices of greener methods, which are slowly... 

It is clear from the above that there is a long way before photochemistry acquires an important role in industrial chemistry. However, there are in fact some peculiar characteristics in these reactions that makes them indeed green , or at least suitable candidates for green procedures. Therefore, it may be expected that as far as concern about the environmental aspects of chemical synthesis grows, application of photochemistry will take a more important role. 

Green Procedures for the Synthesis of Useful Molecules Avoiding Hazardous Solvents and Toxic Catalysts... 

Approaches to Soil Remediation with Green Procedures... 

The recyclability of some of these solid supports makes these processes truly eco-friendly green procedures. Previous cartography of the oven using a cobalt chloride aqueous solution to determine the best location for placement of vessels (high electric field density) enables accurate and reproducible MW experiments [30]. 

The different routes are as shown in Scheme 10.70 [134]. A variety of starting compounds was used and yields of isolated products ranged from 60 to 86% for irradiation times of 5 to 15 min. This green procedure avoiding solvents constitutes by far a better and more practical alternative to existing methods. 

Solvent-drop grinding is a novel, efiScient and green procedure for polymorphic control [15,16]. It involves grinding a known polymorph of a compound with a very small amount of solvent added in order to effect a polymorphic transformation. Variation of the solvent may lead to different polymorphic outcomes. For example, polymorphic Form I of anthranilic acid (Figure 1, 2), ground in the presence of heptane, transforms to Form II, which in turn converts to Form III whai ground in tiie presence of chloroform [15]. 

Both ( )- and (Z)-allyl dithiocarbamates have been stereoselectively prepared in high yields from acetates of MBH adduets in catalyst-free one-pot three-component coupling reactions of carbon disulfide and amine in water under a mild and green procedure (Scheme 3.152). The reaction pathway involves the nucleophilic displacement (-S n2 ) of MBH acetates by dithio-carbamate anions. The utility of these allyl dithiocarbamates has been demonstrated in the synthesis of 3,5-dibenzyl-l,3-thiazines derivatives 344 and 345 (Scheme 3.153). ... 

The synthesis of carbocycles via a two-component cascade reaction in an asymmetric fashion has attracted much attention from the chemical community. Due to his importance in natural products, the synthesis of cyclopropanes, cyclopentanes, and cyclohexanes has been one of the common goals for organocatalytic methodologies. The high stereoselectivity achieved, green procedures, and soft conditions make this organocatalytic approximation one of the most attractive ones to build complex cyclic scaffolds. 

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