Analog Studies

A target that has interesting or commercially attractive properties may exhibit deleterious side effects, or be unstable to storage and handling. Subsequent studies often show that structural modification to the basic skeleton gives a molecule with different characteristics and the new molecule becomes the synthetic target. 

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Analogous studies on dienophiles 5.1c and 5.1g in SDS and Zn(DS)2 lead to essentially the same conclusions. Figure 5.9 shows the relaxation data for 5.1g in Zn(DS)2 solutions. The corresponding data for 5.1c could not be measured due to solubility problems. Analogously, Figure 5.10 shows the relaxation data of 5.1c and 5.1g in SDS solutions. 

The enhanced activity from acylation of the 3- and 4 -hydroxyl groups of leucomycin prompted analogous studies of tylosin. Bioconversion of tylosin by S. thermotokrans yielded 3- and/or 4 -0-acyl derivatives possessing increased activity against certain resistant microorganisms and higher... 

For smaller, high-speed compressors the piping sizing rules of thumb discussed above, in conjunction with pulsation bottles sized from Figure 11 -24, should be sufficient for individual field compressors. These niles of thumb can also be used for preliminary sizing of piping and bottles in preparation for an analog study. 

In an analogous study by Meske, the impact of various oxazaborolidinone catalysts for the 1,3-dipolar cycloaddition reactions between acyclic nitrones and vinyl ethers was studied [31]. Both the diastereo- and the enantioselectivities obtained in this work were low. The highest enantioselectivity was obtained by the application of 100 mol% of the tert-butyl-substituted oxazaborolidinone catalyst 3d [27, 32] in the 1,3-dipolar cycloaddition reaction between nitrone la and ethyl vinyl ether 8a giving endo-9a and exo-9a in 42% and 27% isolated yield, respectively, with up to 20% ee for endo-9a as the best result (Scheme 6.10). 

An analogous study concerned with the synthesis of prostaglandin analogs was also highly diastereoselective. The initial anionic adducts were quenched with various aldehydes, however, the diastereoselectivity at the carbinol stereocenter was not reported21. 

In the analogous studies of the photolysis of sulfolane (31), the work of Honda and coworkers66 was carried out in the gas phase at 70-130 °C and established the formation of S02, ethylene, cyclobutane and acetylene as the major products, on mercury-sensitized photolysis. In considerable contrast, photolysis of sulfolane at 185 nm in the liquid phase67 produced ethylene( = 0.22), the sultine (32) (parallel experiments on aqueous solutions of sulfolane, a sulfinic acid is also believed to be formed. The authors believe that both four-membered (33) and six-membered (32) sultines may be formed during these photolyses. Further work in this area would appear to be necessary to unravel the full mechanistic details. 

An analogous study of the oxidation of benzyl alcohol by permanganate in aqueous perchloric acid yielded a rate law... 

An entirely analogous study using Hg(OAc)2 showed that for this reagent reaction ceases at the organometallic compound unless the temperature is increased to 135 °C k ec = 8.6X 10 sec ). 

An analogous study has been reported of the oxidation of 2-methyl-but-3-yn-ol by Cu(II) chloride in aqueous ammonia to give 2,7-dimethylocta-3,5-diene-2,7-diol. Simple, second-order kinetics were obtained, but a very sharp increase in rate occurred when the pH was increased from 8 to 10. Addition of ammonium ions retarded reaction but Cu(I) was without effect. The reaction mechanism put forward is similar to that given above. 

An analogous study of benzyl hydroperoxide indicates a rate law at 25 °C of... 

In this contribution, we present new results of a cychc voltanunetiy study of the influence of (CeHglads on Hypo and on anion adsorption at the Pt(l 11) electrode in aqueous HCIO4 and H2SO4, and relate them to analogous studies at Pt(110) and Pt(lOO) electrodes in aqueous H2SO4. Perchlorate anions are known to be less strongly adsorbed on Pt than bisulfate or sulfate anions thus, the cychc voltanunetiy behavior in the two electrolytes is expected to reveal important differences. 

Analogous studies of the chemisorption of 14C-labeled benzene on copper powder and on platinum powder showed no chemisorption on the former, and the establishment of a low surface coverage over a range of temperature on the latter (Fig. 1). Again the surface coverage of hydrogen on platinum appeared to be about three times that achieved by benzene. 

In an analogous study similar arguments were used to show that a tetraoxa[7.7.1]-... 

Analogous studies on 1-monoxides and 1,1-dioxides support the nonaromaticity of these derivatives. The. /(C—C) spin-spin coupling between 13C nuclei has been determined for 1,2,5-thiadiazole (48.1 Hz) and correlated to bond length and tentatively to aromaticity <1994MRC62>. Based on this, a low aromaticity was assigned to 1,2,5-thiadiazole similar to furan and isoxazole while a high aromaticity assignment was made for 1,2,3-thiadiazole, contrary to that reported by Bird. 

Computational results were also obtained, in a different study for the possibility that the chloride rather than the ammonia in cis-(NH3)2PtCl2 was substituted by methane (148). In the same contribution, an analogous study examined the reactivity of the (bipyrimidine)PtCl2 complex (Fig. 4). 

In another study, thermodiffractometry was used to study phase transformations in mannitol and paracetamol, as well as the desolvation of lactose monohydrate and the dioxane solvatomorph of paracetamol [56]. The authors noted that in order to obtain the best data, the heating cycle must be sufficiently slow to permit the thermally induced reactions to reach completion. At the same time, the use of overly long cycle times can yield sample decomposition. In addition, the sample conditions are bound to differ relative to the conditions used for a differential scanning calorimetry analysis, so one should expect some differences in thermal profiles when comparing data from analogous studies. 

In its mirror image form, for unpaired and paired anions, this equation has been used to good effect to determine the kp and in a large number of anionic polymerisations. In the field of cationic polymerisation, analogous studies have so far only been reported for thietans [2b] for which the kp and do not differ very much this seems to be a characteristic feature of heterocyclic systems which will be discussed below.b... 

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