The Effect of Structure on Acid-Base Properties

Cation is from strong base anion is KCI, KNO3, Neither acts as an Neutrai 

Cation is conjugate acid of weak base NH4CI, Cation acts as an acid Acidic 

Cation is highly charged metal Ion AI(N03)3. Hydrated cation acts as Acidic 

Since ATt for CN is much larger than for NH4, CN is a much stronger base than NH, is an acid. This solution will be basic. 

This solution will be acidic, since for A1(H20)6 is much greater than ATb for S04 -. 

The acid-base properties of aqueous solutions of various salts are summarized in 

IBLG See questions from The Effect of Structure on Acid-Base Properties  

Further aspects of acid strengths are discussed in Section 20.13. 

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This chapter sets the stage for all of the others by reminding us that the relationship between structure and properties is what chemistry is all about It begins with a review of Lewis structures moves to a discussion of the Arrhenius Brpnsted-Lowry and Lewis pictures of acids and bases and the effects of structure on acidity and basicity... 

Because acid—base reactions play such a prominent role in organic chemistry, we will now focus upon the effect of structure on acidity and basicity. We will consider four properties of the acid and its conjugate base. 

Several other natural products systems have been studied, some quite extensively, by NMR methodology, however space constraints prohibt detailed discussion of these systems therefore only important leading references will be given. Extensive NMR studies on amino acids and small peptides have been performed by Lauterwein and coworkers [116-119], by Fiat and coworkers [120-123] and others [124]. Several studies have used l O-enriched dioxygen and carbon monoxide to study by NMR techniques the interactions of these biochemically important small molecules with various proteins [125-128]. A number of investigators have explored the properties and interactions of nucleic acid bases [129,130], nucleosides [131,132], nucleotides [133-138] and one report has appeared in which NMR spectroscopy approaches were applied to the study of small molecule-DNA interactions [139]. A recent report describes the careful analysis of the effect of structure on NMR chemical shifts of over forty hydroxyterpenoids [140]. A study of the 1 0 NMR spectroscopy of over thirty steroid ketones, acids, esters and alcohols enriched with has recently appeared [141]. 

We have discussed the effect of structure on the acidity of alcohols and on the basicity of amines. The acid-base properties of their aromatic cousins, phenols and anilines, are affected by the aromatic ring. Both the pif values of phenols and the values of anilines illustrate this effect. 

The amino-acids that make up the primary structure of proteins will change their charge when the pH of the solution is altered due to their acid-base properties (Section 5.3 and Appendix 5.1). The effects of pH on enzyme-catalysed reactions can be complex since both Km and may be affected. Here, only the effects on Kmax are considered, as this usually reflects a single constant rather than several that may be associated within the constant Km (see Section 5.4.4.). It is assumed that pH does not change the limiting step in a multi-step process and that the substrate is saturating at all times. 

The presence of acidic functional groups, mostly carboxyl and phenolic OH groups, in the molecular structure of soil HS renders them major players in the acid-base buffering capacity of soils and in the fate, bioavailability, and physico-chemical behavior of macro- and micronutrients, toxic metal ions, and several xenobiotic organic compounds in soil (Ritchie and Perdue, 2003 Senesi and Loffredo, 2005). Consequently, the effects of amendment on the acid-base properties of soil HAs and FAs is a subject of considerable interest. 

When a substance is dissolved in water, it may behave as an acid, behave as a base, or exhibit no acid—base properties. How does the chemical structure of a substance determine which of these behaviors is exhibited by the substance For example, why do some substances that contain OH groups behave as bases, releasing OH ions into solution, whereas others behave as acids, ionizing to release H ions In this section we discuss briefly the effects of chemical structure on acid—base behavior. 

In each of the chapters of this text, we will explore the use of different models to explain and predict the structures and reactions of organic compounds. For example, we will consider alternative explanations for the hybridization of orbitals, the c,7c description of the carbon-carbon double bond, the effect of branching on the stability of alkanes, the electronic nature of substitution reactions, the acid-base properties of organic compounds, and the nature of concerted reactions. The complementary models presented in these discussions will give new perspectives on the structures and reactions of organic compounds. 

Likewise, Park et al. [123,124] have studied the effect of ceria on the structure and catalytic activity of V205/Ti02-Zr02 catalyst for the CO2-ODE reaction. In their previous research, the authors had found that titania-zirconia mixed oxides exhibited excellent catalytic activity and selectivity for the CO2-ODE to styrene because of the high specific surface area, good acid-base and redox properties. 

Why is NaOH a strong base, HNO3 a strong acid, and CH3 OH neither Each of these compounds contains O-H bonds, yet their proton transfer properties are strikingly different. In this section we examine the effect of molecular structure on acid strength. 

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