Solution based synthesis

Trentler T J ef a/1999 Synthesis of Ti02 nanoorystals by nonhydrolytio solution-based reaotions J. Am. Chem. Soc. 121 1613... 

Combinatorial. Combinatorial methods express the synthesis problem as a traditional optimization problem which can only be solved using powerful techniques that have been known for some time. These may use total network cost direcdy as an objective function but do not exploit the special characteristics of heat-exchange networks in obtaining a solution. Much of the early work in heat-exchange network synthesis was based on exhaustive search or combinatorial development of networks. This work has not proven useful because for only a typical ten-process-stream example problem the alternative sets of feasible matches are cal.55 x 10 without stream spHtting. 

Heuristic. The heuristic approach is another early synthesis technique based on the appHcation of sets of rules to lead to a specific objective such as network cost. Unfortunately, heuristics caimot guarantee that the objective will be reached although they generally offer quick solutions. 

Potassium-containing tantalum and niobium fluoride compounds can be precipitated from HF solutions as described previously (see Fig. 3 and 4). Ritchie and Mitra [59] described the synthesis of K.2TaF7 in an HF solution, based on the following interaction (5), using TaCl5 as a precursor ... 

Materials. Ketene was synthesized as described by Andreades and Carlson ( ) from diketene. Diazomethane was synthesized from N-methyl-N-nitroso-pi-toluenesulfonamide as outlined by Hudlicky (10). A typical synthesis of cyclopropanone involved the slow addition of 400 mL of a 1.0 M diethyl ether solution diazomethane to a 2-3-fold molar excess of ketene at -78°C. This synthesis was based on the... 

Xia, Q. and S. Macchietto. Design and Synthesis of Batch Plants—MINLP Solution Based on a Stochastic Method. Comput Chem Eng 21 S697-702 (1997). 

Solution-Liquid-Solid (SLS) growth of semiconductor nanowires by Wang etal. (2006). The synthesis proceeds by a solution-based catalysed growth mechanism in which nanometer-scale metallic droplets catalyse the decomposition of metallo-organic precursors and crystalline nanowire growth. 

The key effect of oxide supports on the catalytic activities of metal particles is exerted through the interface between oxides and metal particles. The key objective of this study is to develop synthesis methodologies for tailoring this interface. Here, an SSG approach was introduced to modify the surface of mesoporous silica materials with ultrathin films of titanium oxide so that the uniform deposition of gold precursors on ordered mesoporous silica materials by DP could be achieved without the constraint of the low lEP of silica. The surface sol-gel process was originally developed by Kunitake and coworkers.This novel technology enables molecular-scale control of film thickness over a large 2-D substrate area and can be viewed as a solution-based... 

These macromolecule-based purification methods isolate polymer-bound products from soluble impurities, but do not generally purify the product from other polymer-bound byproducts. Such byproducts arise from incomplete reactions or side reactions and in classical solution chemistry, similar byproducts are removed during product purification at each step of a multi-step synthesis. Support-based methodologies, while removing the multiple, laborious purification steps of a classical synthesis, generally do not provide a method for the purification of intermediates. Instead, these methodologies demand that reaction conditions be optimized such that reactions are driven to completion to avoid a complicated final mixture of products. However, some developed liquid-phase methods achieve high purity of products without quantitative reaction yields [21-26]. 

Reductive carbonylation in alkaline methanol solution of Na2[PtCl6] 6H20 gives the series of dianions [Pt3(CO)6]2 (n = 3-10) the value of n depends on the alkaline reagent and the experimental conditions.1 The lowest term of this series of inorganic oligomers, which has been isolated in the solid state, is the [Pt6(CO)12]2- dianion. Its reported synthesis is based on the reduction with lithium metal in tetrahydrofuran (THF) of Pt(CO)2Cl2, or of preformed [Pt3(CO)6]2 (n > 3).1,2... 

Our synthesis is based on the hydrolysis of a silicon alkoxide (TEOS Si(OCH2CH3)4) in a diluted solution of nonionic polyethylene oxide-based surfactants. The hydrolysis is then induced by the addition of a small amount of sodium fluoride [5], Depending on the initial mixing conditions, the size of the solubilized objects leads to either a colorless or milky emulsion. Small particles ( 300 nm) with a 3D worm-hole porous structure or small hollow spheres with mesoporous walls, are usually obtained [6]. The synthesis we report herein after exhibits an apparently slight but actually drastic change in the preparation conditions. The main feature of this approach is an intermediate step that utilizes a mild acidity (pH 2 - 4), in which, prior to the reaction, a stable colorless microemulsion containing all reactants is... 

A flexible means of access to functionalized supports for solid-phase synthesis is based on metallated, cross-linked polystyrene, which reacts smoothly with a wide range of electrophiles. Cross-linked polystyrene can be lithiated directly by treatment with n-butyllithium and TMEDA in cyclohexane at 60-70 °C [1-3] to yield a product containing mainly meta- and para-Iithiated phenyl groups [4], Metallation of noncross-linked polystyrene with potassium ferf-amylate/3-(lithiomethyl)heptane has also been reported [5], The latter type of base can, unlike butyllithium/TMEDA [6], also lead to benzylic metallation [7]. The C-Iithiation of more acidic arenes or heteroar-enes, such as imidazoles [8], thiophenes [9], and furans [9], has also been performed on insoluble supports (Figure 4.1). These reactions proceed, like those in solution, with high regioselectivity. 

Generally, solution-based approaches for the generation of inorganic split and pool libraries have substantial advantages over approaches where solid phases are introduced as chemical sources during the different synthetic steps. Solution chemistry offers, potentially, a wide range of synthetic opportunities that can be exploited not only for the purpose of parallel synthesis but also for synthetic steps for Split Pool library creation. 

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