Basicity comparing

Which nitrogen in each molecule is more basic Compare energies of the alternative conjugate acids (Nprotonated imidazole, NH protonated imidazole, N protonated pyrazole and NH protonated pyrazole). Which compound, imidazole or pyrazole, is more basic Compare the energies of protonation (leading to the favored conjugate acid in each case). Rationalize your result. 

In cases where a lot of proplnt has successfully passed the one-year exposure to methyl violet paper, only a 3% inspection of the exposed test strips need to be made thereafter until such inspection indicates progressive deterioration of the proplnt or other nonstandard condition, at which time 100% inspection and test of the lot under suspicion will be resumed It is considered desirable that succeeding annual inspections include at least 1/3 of the containers included in the original 3% inspection as outlined above. In this manner, such containers may be considered as a basic comparative control with reference to the balance of the lot under test... 

This result has been further substantiated by the work of Koppel et al. <2001PCA9575>. They conducted a theoretical study of the basicity of phosphorus imines and ylides. Verkade bases 6-8 were included. They showed basicities comparable to commercially used organic superbases (/-BUP4 phosphazene imine), with compound 8 in particular giving calculated basicities similar to Li3P and Li20. 

The term proton sponges indicates a series of compounds with unusually high basicity, compared to the basicity of isomers. A recent review106 collects and discusses crystallographic results of the literature on this subject. 

Complex 1 1 is considered the only complex present, but the hydrogen bond may be either two (76) or three center (77). Nitroenamines are more prone to complex with 4-fluorophenol than the nitroanilines and they form the strongest hydrogen bond presently known for nitro-bases. In particular, l-piperidino-2-nitroethylene (78) and 1-dimethylamino-2-nitroethylene (79) (both in E form) present a hydrogen bond basicity comparable to that of tributylamine. 

As with the methylbenzenes the methyl derivatives of condensed aromatic substances show an increase in basicity compared to the unsubstituted compound. Thus, the methyl groups exert a very profound influence on the electron distribution. The extension of these considerations by theoretical methods will be discussed in Section V. 

Purine [93] is analogously protonated on N-1 (Cobum et al., 1965). With a pT a Value of 2 30, it has an enhanced basicity compared with that of pyrimidine (pA a " T23). In the nmr spectrum in trifluoroacetic acid, the resonance of the captured proton is not observable owing to exchange, but it can be observed in... 

For other drugs, priority was given to annual prevalence data found by means of household surveys. A number of countries, however, did not report annual prevalence data, but lifetime or current use of drug consumption, or they provided annual prevalence data but for a different age group. In order to arrive at basically comparable results, it was thus necessary to extrapolate from reported current use or lifetime prevalence data to annual prevalence rates and/or to adjust results for differences in age groups. 

Using water as reference, an amphiprotic solvent having an acidity and a basicity comparable to those of water is called a neutral solvent, one with a stronger acidity and a weaker basicity than water is called a protogenic solvent, and one with a weaker acidity and a stronger basicity than water is called a protophilic solvent. The solvent with relatively strong acidity usually has in its molecule a hydrogen atom... 

These social standards are basic compared to the more comprehensive standards of other... 

The blue-shift results from the chemical environment inside the pores of MCM-41, which is dominated by residual silanol and, especially, non reacted amino groups, and thus more basic compared to that in solution. The interaction of the dye molecules with the host is further confirmed by a broadening of the absorption bands of anchored dyes (e.g. rhodamine B sulfonylchloride, Figure 4) in comparison to the main bands of the free chromophores in solution. 

High temperature and supercritical H2O have greatly enhanced acidity (and basicity) compared to room-temperature water because the dissociation constant increases as water is heated towards the critical point [25,27], At the same time, there is a marked drop in the dielectric constant which reduces the solubility of polar compounds but increases the solubility of non-polar compounds, and of organic compounds in particular. 

The oxygen and sulfur bases are weaker than the nitrogen bases, and accurate solution basicities are not available. Arnett s heat of protonation studies indicate that the order of decreasing basicity is ROR > ROH > HaO,98 a result that is in agreement with gas-phase measurements.99 Hydrogen sulfide in the gas phase has basicity comparable to that of water (Table 3.18), and substitution of H by alkyl produces stronger gas-phase bases just as does similar substitution on oxygen. 

Fig. 2 Nonlinearity of IEs on trimethylamine basicities, comparing (CH D3 )3 ( = 3,2,1) to (CH D3 )3 (w = 2,1,0), displayed as ApAa per D-0.021.3 Reprinted with permission from J Am Chem Soc 2008 130 11143-8. Copyright 2008 American Chemical Society.

Alkyl substituents, which increase the basicity compared with RO substituents, make the proton less labile. 

Elimination is the major product when secondary halides react with anions as basic as or more basic than hydroxide ion. Alkoxide ions have a basicity comparable with hydroxide ion and react with... 

N methylation changes secondary amines into tertiary amines. While inductive effects might mean an increase in the amine gas phase basicity, the low solvation of tertiary amines generally means that methylation reduces solution basicity (compare entries 1 and 7). In addition to solvation effects, it is thought that steric effects may favour the out con former. In the case of tetramethylcyclam (entry 8)... 

Today the requirements are basically comparable for distributors, with the expectation that laws and regulations imposed on environmental protection and safety in general will become even more stringent. 

The reactions presented in scheme (10) also account for effects exerted by the addition of Lewis bases or acids (as well as other electron donors and acceptors) to the polymerisation system on the microstructure of the polymers formed. As shown in Tables 5.4 and 5.5, some catalysts that are highly stereospecific for the formation of cis- 1,4-polybutadiene yield trans- 1,4-poly butadiene (or eb-m-1,At trans-1,4-polybutadiene) after the addition of a Lewis base or other electron donor to the catalyst system. A plausible explanation of the observed phenomena is that the added component occupies a coordination site at the transition metal, thus forcing the incoming monomer molecule to coordinate as an s-trans-rf ligand. When the additional catalyst component has a basicity comparable with that of the monomer, a competitive monomer/ Lewis base (electron donor) coordination takes place, as shown below [7] ... 

The following are the major conclusions (i) The MgCr204 surface properties are dominated by the reactivity of Cr3+ centers, (ii) the Mg2+ ions do not play a detectable role in the CO/spinel chemistry within the investigated pressure range, and (iii) the surface oxygen ions do not have a basicity comparable to that of oxygen ions on MgO and La203. 

The trithione -methides (3-methylene-1,2-dithioles) are iso-77-electronic with the heptafulvenes,71 and possess a basicity comparable to that of the latter. Some true 3-alkylatSd 1,2-dithiolium salts can be obtained by protonation of compounds 52. This method of preparation is rather narrowly limited, however, by the fact that the simple derivatives of 52 (as in the hydrocarbon series) are evidently very unstable and have not as yet been described. These dithiafulvenes become stable, easily handled compounds only when they contain aryl or typical acceptor residues (R and/or R = CN, C02R) in the 6-position.53, 72 This substitution, however, again as in the hydrocarbon series,73 lowers the basicity to such an extent that the dinitrile (52) (Rj = R2 = H, R = R = CN), for example, is not appreciably protonated even in pure trifluoroacetic acid.52... 

This method of preparing cyanine-like dyes is more versatile than the basically comparable methods previously known. Both the carbonyl components and the bases can be varied within wide limits. 

Metal basicity may be probed by protonation. While neutral species such as Fe(CO)s are only weak bases, metal carbonyl anions are readily protonated to give metal hydrides. The basicity is increased by the presence of ligands such as Cp, and Cp2ReH for example has a basicity comparable to that of ammonia. Examples are ... 

The pK, of the protonated (CONH2)4 radical is 2.0, with a shift from 425 nm to 400 nm on deprotonarion. The change in the absorption maxima for both 3- and 4-carbamidopyridinyl radicals implies protonation on the amide group rather than the ring (Eq. 26). Thus, the pyridinyl radicals are more basic than benzamide derivatives, but very weakly basic compared to dihydropyridines (pK, ca. 7) or typical tertiary amin (pK, ca. 10-11). 

As such, this first chapter represents what you normally expect from a textbook or other science resource, which is a set of straightforward explanations. If you do own Chemistry Basics, comparing this chapter to that book will provide a clear example of what it s like to learn science concepts with and without use of the Learning Cycle. 

---