Order of strength

Many of the inorganic oxoacids are strong (i.e. have negative PX3 values) in aqueous solution. But, as we have seen, use of a solvent with a lower proton affinity than water (for example pure ethanoic (acetic) acid makes it possible to differentiate between the strengths of these acids and measure pX values. The order of strength of some typical oxoacids is then found to be (for H X -> H , X- + H") ... 

Polar acceptors include, in roughly descending order of strength, amines, ethers, ketones, aldehydes and esters (with aromatic materials usually being more powerful than aliphatics). 

The enantioselectivity of the macrocyclic CSPs are different in each of the operating modes, probably because of different separation mechanisms functioning in the different solvent modes. The possible chiral recognition mechanisms for three mobile phase compositions on glycopeptide phases are listed in Table 2-3 in descending order of strength. 

Rank the following acids in order of strength CICH2COOH, Cl,CCOOH, CH.COOH, and CH.CHXXKIH. Justify your answer. 

TABLE 9.1 Some Groups with +Af and in Order of Strength of Effect... 

The qualitative proportion between some model parameters should be as that known from existing knowledge e.g. the relative adsorption strength of various sjjecies on different metals is quite well known and a totally different order of strength found by regression can be considered as an indication that the model should be rejected. 

In reversed-phase thin-layer chromatography (RP-TLC), the choice of solvents for the mobile phase is carried out in a reversed order of strength, comparing with the classical TLC, which determines a reversed order of values of compounds. The reversed order of separation assumes that water is the main component of the mobile phase. Aqueous mixmres of some organic solvents (diethyl ether, methanol, acetone, acetonitrile, dioxane, i-propanol, etc.) are used with good results. 

Pairwise magnetic interactions in bioEPR spectroscopy (interactions given in typical decreasing order of strength at X-band frequencies)... 

The solid acidity of these atom-planted silicalites was examined by ammonia TPD measurement. The ammonia TPD profiles of all these metallosilicates showed one peak at a higher temperature than 453 K. Figure 4 shows the relationship between peak temperatures of ammonia TPD and wavenumber of IR absorption bands due to the acidic SiOH groups of atom-planted silicalites. A straight line was obtained. From these results, the order of strength of acid sites would be as follows ... 

TABLE 9.1 Some groups with + M and - M effects, not listed in order of strength of effect... 

These criteria are in descending order of strength. If criteria 1 and 2 hold, the rest will follow, in most—but not all—cases. Note that in the serine proteases, tertiary structure is more conserved than primary structure. Sometimes structure has been conserved through evolution, but function has changed that is, criteria 3 and 4 do not hold. For example, the binding protein haptoglobin appears to have diverged from the serine proteases. 

FIGURE 10.15 The sum of the pKa of an acid (pink) and the pfCb of its conjugate base (blue) is constant, and equal to pKw, which is 14.00 at 25°C. The values of the constants allow us to arrange all acids and bases in order of strength on a single chart. 

DBCP on a 1% w/w catalyst, on a mass basis, it appears that sulfite has a stronger effect than nitrate or sulfate, which in turn has a stronger effect than chloride. Similarly, for the reaction of PCE on a 1% w/w Pd/PAC catalyst, the effect of solutes in decreasing order of strength are bisulfide, nitrite, nitrate, sulfate, and chloride. From these results, it is clear that solutes present in the water can affect the reaction kinetics the Schiith results indicate that catalysts can be tailored to minimize the negative effects of solutes on the reaction process. 

Interactions Give the relative order of strength of interactions (weak, medium, strong) in the following series of pairs in low-polar solvent, dielectric constant e<10 (a) solvent + additive, (b) Calcium benzenesulfonates reverse micelles formation, (c) strong acid (HS) + N-base, (d) weak acid (HA) + N-base, (e) soot particle + reverse micelle, and (f) mechanically activated surface processes and molecular decomposition. 

The principal modes of vibration of the anthracene molecule, active in absorption and in fluorescence, have been given in ref. 58. This subsection is intended to provide a consistent analysis of the whole structure of the crystal absorption (reflectivity) and to discuss its shape in terms of vibron-two-particle states and collective couplings and of the spectral and dynamical (relaxation) effects to which they give rise. These active vibration modes are here summarized in decreased order of strength ... 

To summarize, the state of a substance depends on the forces between the particles of that substance. If the forces are very strong, that substance is likely to exist as a solid. If the forces are weaker, that substance will exist as a liquid, or as a gas. The state of a non-polar substance also depends on the size of the molecule. Smaller non-polar molecules are more likely to be gases. Larger non-polar molecules will probably exist as liquids or even solids. Table 11.1 shows the forces discussed in this section ranked in order of strength. 

The thickening ability of hydrophilic fumed silica in a highly polar liquid is also rather low. In a polar medium the hydrophilic silica surface will be effectively wetted, the particles are shielded from each other and their interaction is prevented. Hydrogen-bonds and other polar interactions within the liquid, between surface and liquid molecules or between particle surfaces are of the same order of strength - no energy results from hydrophilic particles that interact in a polar medium and consequently no thickening is reached. 

TABLE 9.1. Some Groups with +M and —M Effects, Not Listed in Order of Strength of Effect"... 

Similar gelation tests were also used with m-xylylene diisocyanate and with hexamethylene diisocyanate [146]. In these tests the order of strength of the catalysts was found to be different from when tolylene diisocyanate was used. Table 12 lists the results of some catalyst screening tests with the three different diisocyanates. 

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