Experimental conditions for synthesis

TABLE 2. Experimental conditions for synthesis and properties of platinum-containing nanoparticle alloys... 

As you become familiar with the metal ion with which you are working, designing and manipulating experimental conditions for synthesis and further application will become more straightforward. 

Empirical kinetics are useful if they allow us to develop chemical models of interfacial reactions from which we can design experimental conditions of synthesis to obtain thick films of conducting polymers having properties tailored for specific applications. Even when those properties are electrochemical, the coated electrode has to be extracted from the solution of synthesis, rinsed, and then immersed in a new solution in which the electrochemical properties are studied. So only the polymer attached to the electrode after it is rinsed is useful for applications. Only this polymer has to be considered as the final product of the electrochemical reaction of synthesis from the point of view of polymeric applications. 

In preparation for scale-up of the strigol synthesis described by Sih (8), efforts were made to improve the yield of some of the seven steps involved in the scheme. Of these steps, nine are satisfactory from the standpoint of yield and experimental conditions. For three of the steps, we have improved the yield and/or experimental conditions such that the yield of (+ )-strigol would be raised to 2.85% overall from citral rather than 1.53% based on Sih s procedure and reported yields. Improvements were developed preparation of a-cyclocitral (III), the oxidation of the hydroxyaldehyde (V) to the ketoacid (VII), and for the preparation of the hydroxybutenolide (XVII). For the remaining five steps, our attempts to change experimental conditions have failed to improve, and in most cases to even obtain, the yields reported in the literature (8). We have considered the preparation of strigol analogs and determined the conditions and limitations for the preparation of a series of alkoxybutenolides (XVI) and a butenolide dimer (XVIII). Modification of the literature procedure (11) to eliminate the use of the mesylate (XX) and the use of polar aprotic solvents gave better yields of the 2-RAS (XXI). 

Table I. Experimental Conditions for the Synthesis of PDMAAm-l-PIB Amphiphilic Networks...

Figure 9.2-3. Design of continuous experimental apparatus for synthesis under supercritical conditions S, substrates 1, molecular sieves 2, saturation column 3, packed-bed enzymatic reactor 4,5, separators P, high-pressure pump PI, pressure indicator TI, temperature indicator H, heat exchanger [17].

The experimental conditions for this method are demonstrated in Scheme 16 for the synthesis of the Boc-D-Phe-Cys-OMe related thiazole derivative 52.[92] Starting with the N-protected amino acid Boc-D-Phe-OH (47), methyl ester 48 was obtained by alkylation with Mel and KHCO3 in DMF. The methyl ester 48 was then reduced to the amino alcohol 49 with NaBH4/LiCl, followed by oxidization to the amino aldehyde 50 (without appreciable... 

Based on that methodology, Oppolzer [551] and Nicolaou [552] devised procedures for the total synthesis of aromatic steroids as (+)-estradiol and ( )-estra-l,3,5(10)-triene-17-one. In this latter case, experimental conditions for the pyrolytic step are given. 

The synthesis of benzo[6]thiophenes by the PPA-promoted cyclization of (arylthio)acetaldehyde dimethyl or diethyl acetals [Eq. (4)] was introduced by Tilak287, 288 in 1950 and improved in 1951.289 The acetals are readily prepared from aryl mercaptans and bromo-acetaldehyde dimethyl (or diethyl) acetal in the presence of sodium ethoxide, or by reaction of an aryllithium compound with [(MeO)2CHCH2S]2.290 Diethyl acetal as starting material sometimes gives better yields of product than the corresponding dimethyl acetal.291 Optimum yields of benzo[6]thiophenes are obtained when cyclization of the acetals is carried out under reduced pressure so that the lower boiling benzo[6]thiophenes distill as soon as they are formed. Experimental conditions for obtaining optimum yields vary from case... 

Synthesis of carbide and nitride films by reactive sputtering. Table 14.3 presents a summary of the experimental conditions for the formation of carbides and nitrides. The phases formed are different from those in Table 14.2. As sputtering is a non-equilibrium technique, it was possible to synthesize the 6-MoC and the fi-WCi x carbides and the... 

Since the experimental conditions for the traditional Biginelli reaction are quite straightforward, small libraries of DHPMs are readily accessible by parallel synthesis. Along these lines the generation of a 140-member single compound DHPM library by combination of 25 aldehydes, 6 ureas/thioureas, and 7 acetoacetates or acetoamides under standard reaction conditions has been reported [123, 124]. More rapid approaches make use of microwave-enhanced solution-phase protocols [88, 89, 125]. Apart from these conventional solution-phase methods, it is also possible to employ polymer-supported reagents to aid in the purification and workup protocol. Polymer-assisted solution-phase chemistry using polymer-supported... 

The regulation of the synthesis of the polypeptides of PS II appears to be particularly complex, with evidence for regulation at transcriptional, translational and post-translational levels. The synthesis of the individual polypeptides does not appear to be tightly coordinated, with certain polypeptides accumulating in the absence of other PS II polypeptides under a variety of experimental conditions. The synthesis of a functional PS II complex is strongly dependent on light, both for its effect on the transcription of PS II genes and for its absolute requirement for Chi synthesis. 

The mechanism and experimental conditions for these reactions have been discussed in two reviews of all methods for the synthesis of benzoins and acyloins. ... 

How should suitable model substrates be selected to make it possible to develop the experimental conditions for key steps in the synthesis of complex natural products so that precious material is not wasted by inefficient transformations ... 

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