Conventional Synthetic Routes

A microwave-assisted method to prepare novel 8-mercapto-3-methyl-7-alkyl xanthines 68 has been reported. Compared to conventional synthetic routes, the new method has significantly shortened synthetic steps and reaction time <06TL775>. 

This chapter surveys different process options to convert terpenes, plant oils, carbohydrates and lignocellulosic materials into valuable chemicals and polymers. Three different strategies of conversion processes integrated in a biorefinery scheme are proposed from biomass to bioproducts via degraded molecules , from platform molecules to bioproducts , and from biomass to bioproducts via new synthesis routes . Selected examples representative of the three options are given. Attention is focused on conversions based on one-pot reactions involving one or several catalytic steps that could be used to replace conventional synthetic routes developed for hydrocarbons. 

All known M(COD)2 complexes can now be synthesized on a millimolar scale by the metal atom technique, although both Ni(COD)2 and Pt(COD)2 are more conveniently prepared by conventional synthetic routes (35, 99). The use of palladium vapor to afford Pd(l,5-COD)2 is a straightforward, high-yield (>50% in situ), one-step synthesis, offering advantages over the conventional method if isolation of a... 

Benzenesulfonates carrying alkyl- substituents in ortho position to the sulfonato-group are intermediates in the synthesis of a new class [3] of potent herbicides. More conventional synthetic routes as, e.g. Friedel-Crafts alkylation fad to yield these products at economically acceptable costs. 

Interesting results have been obtained in the synthesis of biologically active compounds such as insect pheromones. Conventional synthetic routes to these pheromones are often multistep sequences, which make many pheromones too expensive for widespread use [23]. Metathesis offers a shorter, alternative route to pheromone synthesis, generating these compounds in a few steps only. The use of insect sex pheromones is an environmentally friendly, effective, and selective method of pest control. Kiipper and Streck [24] synthesized insect sex pheromones by cross-metathesis reactions between linear olefins. In the presence of the catalyst Re207/Al203, 9-tricosene was synthesized by cross-metathesis of the readily available aUcenes 2-hexadecene and 9-octadecene (Eq. 8). 

Direct processes are the most common synthetic routes available for the preparation of sUyl esters. A brief survey of the literature indicates that the conventional synthetic routes available for silaesterification reactions require harsh reaction conditions and most often are accompanied by side reactions. " For example, triethylacetoxysilane was prepared by the cleavage of acetic anhydride and triethylethoxysUane (Scheme 3.1). The reaction involves nucleophilic attack of anhydride groups on the silicon center, resulting in the elimination of triethylacetoxysilane. 

Gas-phase studies using laser vaporization techniques have provided evidence for Ni-benzene compounds displaying so-called rice-ball structures in which one or more Ni center is completely surrounded by benzene molecules. On the other hand, 77 -interactions predominate in (Tr-arene)-Ni compounds, which are often prepared by metal-vapor techniques or in liquid nitrogen matrices. In a few cases, more conventional synthetic routes have been used for the preparation of (Tr-arene)-Ni compounds. For instance, the reaction of Ni(ii) salts with various sources of aryl ligands 05X5 (X = F zor Cl) in the presence of arene sources (usually an aromatic solvent) gives Ni(G6X5)2(r7 -arene). ... 

Utilization of Organic Carbonates and Conventional Synthetic Routes... 

In this chapter, various photochemical reactions involving CPs and MOFs have been described. These include structural transformations, post-synthetic modification of surfaces to create reactive sites, radicals which are not possible by convention synthetic routes, polymerization on the surfaces, and cis-trans isomerization of the guest molecules in the cavities using the dynamic behavior of the structures. Further, [2+2] cycloaddition reaction has been used as a tool... 

It was recently reported that PAn-CNT composite can also be made from enzymatic synthesis [84]. This is a non-conventional synthetic route (although essentially stiU a chemical synthetic route) for the making of such composites. However, as an enzymatic process, it has the merit of being environmentally friendly. Also., the PAn-CNT composites made from this method had comparable stmcture and morphology to those made of the conventional chemical oxidation method. The specific capacitance of this composite was 440 F g [84]. 

Sulphenamides and Related Compounds.—Conventional synthetic routes to sulphenamides are represented with new systems in the recent literature. A sulphenyl chloride reacts with a hydrazone to give the sulphenamide ArCR= NNHSAr, and with an acid hydrazide to give the analogous product. Salts are formed between an arenesulphenyl chloride or a thiolsulphonate and a tertiary amine e.g. ArSCl + NEtg -> ArSNEt, Cl ). ... 

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