Green synthesis reactions

Additional reactions which need to be highlighted are the reductive alkylation of alcohols and amines with aldehydes leading to the green synthesis of ethers and amines. These reactions are generally catalyzed by palladium [35]. This reaction can replace the classical Williamson s synthesis of ethers which requires an alcohol and an alkyl halide together with a base, and always results in the concomitant production of salt. The choice of Pd/C as catalyst is due to the low efficiency of this metal for the competitive carbonyl reduction. Analysis of the... 

Ionic liquids (imidazolium salts) were utilized as green solvents in the Friedlander synthesis. Reactions of o-amino-substituted aromatic carbonyls with a variety of ketones (cyclic, acyclic, aromatic) result in the desired quinolines in uniformly high yield. Conditions are mild and no hazardous acids or bases are used <03JOC9371>. 

Most of the recent literature in this field is concerned with synthetic organic reactions, supramolecular chemistry and crystal engineering. However, solvent free approaches can also be used in the extraction of natural products, although less information is available in the mainstream literature. Juice extractors can be used to afford aqueous solutions of biologically active compounds from undried plant material. An extract of Capsicum annum L. was recently prepared in this way, and then used in the green synthesis of silver nanoparticles. The actual synthesis of the nanoparticles was conducted in the aqueous phase and therefore this work will not be discussed further here. However, this solvent free approach to extraction is probably worthy of greater representation in the green chemistry literature. 

Sinha, J., Layek, S., Mandal, G. C., Bhattacharjee, M. A green Hunsdiecker reaction synthesis of P-bromostyrenes from the reaction of a,p-unsaturated aromatic carboxylic acids with KBr and H2O2 catalyzed by Na2Mo04.2H20 in aqueous medium. Chem. Common. 2001, 1916-1917. 

More recently, a protocol was elucidated by Malezcka and Smith to produce aryl borate esters directly without first producing aryl halides.144 The reaction involves an Ir-catalyzed C-H activation (Section 7-2-1) to yield the aryl borate, which can then be used directly in Suzuki cross-coupling (equation 12.71). This new development adds another green aspect to Suzuki cross-coupling, which is already a relatively green synthesis tool. 

The formation of arylalkanes, alkenes and alkynes as well of more functionalized derivatives and some bi(hetero)aryls is exemplified in some schemes below, in order to illustrate the contribution of this reaction to green synthesis (Scheme ISa-c). ... 

Especially, the eco-friendly ionic liquids have obtained extensive attention in organic synthesis with the merits provided as above. The ionic liquids as the unusual green solvents are applied extensively in various organic synthesis reactions, such as Friedel-Crafts reactions, oxidation reactions, reduction reactions, addition reactions, C-C formation reactions, nucleophilic substitution reactions, esterifications, rearrangements, hydroformylations, and nitration reactions [7-14]. Besides, the ionic liquids also have applications in the extraction separation, the electrochemistry, and preparation of nanostructured materials, the production of clean fuel, environmental science, and biocatalysis. This chapter would present in detail the application of the ionic liquids as the unusual green solvents (also as dual green solvent and catalyst) for the alkylation and acylation. 

M. K. Patil, M. Keller, B. M. Reddy, P. Pale, J. Sommer, Copper-zeolites as green catalysts for multicomponent reactions an efficient and green synthesis of propargyl amines, Eur. J. Org. Chem., 2008, 26, 4440 445. 

A.G. Livingston, L. Peeva, S. Han, D.A. Nair, S.S. Luthra, L.S. White, L.M. Freitas dos Santos, Membrane separation in green chemical processing - solvent nanofiltration in liquid phase organic synthesis reactions, Ann. N.Y. Acad. Sci., 984 (2003) 123-141. 

Greenes synthesis starts from (S)-phenylglycine. [331 ] The corresponding amino-alcohol is reacted with benzoyl chloride. After Swern oxidation and a Grig-nard reaction, an aUyl alcohol is obtained. After protection of the alcohol function, the desired product results from periodate cleavage. 

The original synthesis of the pain reliever ibuprofen required six reactions that together sent 23 H atoms, 7 C atoms, 8 O atoms, and 1 Cl, 1 Na, and 1 N atoms into waste products. A new green synthesis using the same starting materials requires only three steps and creates waste products containing only 4 H atoms, 2 C atoms, and 2 O atoms. 

The monomer-loaded zeolite samples display dramatic color changes from white to different hues of blue and green when (a) aniline in different acidic zeolite forms is treated with the oxidant, or when (b) pyrrole or thiophene monomers are admitted into Cu(II)/Fe(III)-containing zeolites Y or MOR from the vapor phase or from hexane (or other hydrocarbon) solutions (Table 1). These color changes correspond to those observed in bulk synthesis reactions.H l No reaction is observed with the zeolite sodium forms, indicating that the polymerizations proceed only in the presence of intfazeolite protons and/or appropriate oxidants. No polymer formation is detected in zeolite Cu(II)A (pore size 0.4 nm, smaller than pyrrole or thiophene). This is... 

Table 8.2 Components of a synthesis reaction captured by the mass metrics of a battery suitable to assess its material greenness."...

Figure 8.4 Battery of metrics for assessment of the material greenness of synthesis reactions. Left The assessment (and optimization) involves two dimensions that require different metrics. Right Scope and hierarchy of the metrics.

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