Acidities of the Functional Groups

Now that you know all about the important functional groups, it is a good idea to know their acidities. From weakest to strongest acids, they are as follows  

A student added Nad to ethanol in the polar aprotic solvent DMF. and no reaction took place. To die same solution, he then added HC1. A react ion took place resulting in chioroethane. Which of the following best explains the student s results  

The addition of HCl increased the chloride ion concentration which increased the rate of the reaction and pushed the equilibrium to the right. 

The chloride ion in a better nucleophile in a polar pnotic solvent and the HCl protonated the solvent, 

The HCl protonated die hydroxyl group on the alcohol making it a better leaving group. 

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Benzoic acids, in particular, can be used to evaluate the selectivity of the ligand to variations in the electron density at the active site by determining the amount complexed from solution as electron withdrawing/ donating substituents on the aromatic ring increase or decrease the acidity of the functional group. The interaction may be summarized by equation 3. 

Section 27 5 Ammo acids undergo reactions characteristic of the ammo group (e g amide formation) and the carboxyl group (e g esterification) Ammo acid side chains undergo reactions characteristic of the functional groups they contain... 

Titanium chelates are formed from tetraalkyl titanates or haUdes and bi- or polydentate ligands. One of the functional groups is usually alcohoHc or enoHc hydroxyl, which interchanges with an alkoxy group, RO, on titanium to Hberate ROH. If the second function is hydroxyl or carboxyl, it may react similarly. Diols and polyols, a-hydroxycarboxyflc acids and oxaUc acid are all examples of this type. P-Keto esters, P-diketones, and alkanolamines are also excellent chelating ligands for titanium. 

Display electrostatic potential maps for the conjugate bases of the acids above (hydroxide, ethoxide, formate and propionate anions), and examine the value of the electrostatic potential at the most electron-rich site. What causes a larger change in electrostatic potential, switching the alkyl group for H, or changing the structure of the functional group ... 

We see from reactions (75) and (79) that oxidation of an aldehyde gives an organic acid. All of these acids contain the functional group —COOH, the carboxyl group. The bonding in this group is as follows ... 

Step-growth polymerization processes must be carefully designed in order to avoid reaction conditions that promote deleterious side reactions that may result in the loss of monomer functionality or the volatilization of monomers. For example, initial transesterification between DMT and EG is conducted in the presence of Lewis acid catalysts at temperatures (200°C) that do not result in the premature volatilization of EG (neat EG boiling point 197°C). In addition, polyurethane formation requires the absence of protic impurities such as water to avoid the premature formation of carbamic acids followed by decarboxylation and formation of the reactive amine.50 Thus, reaction conditions must be carefully chosen to avoid undesirable consumption of the functional groups, and 1 1 stoichiometry must be maintained throughout the polymerization process. 

In molecules with both an acidic and a basic function, there is in principle the possibility of an intramolecular proton transfer leading to betaines (see above). Due to the values of the functional groups, pyridine and carboxylic acid, in [66] no intramolecular proton transfer takes place and no betaine is formed. 

The strength of ion binding is enhanced when the arrangements of the functional groups permit chelate formation (Begala Strauss, 1972). Thus, magnesium is more firmly bound to poly(vinyl methyl ether-maleic acid) than to either poly(acrylic acid) or poly(ethylene maleic add). 

The transformation of carboxylic acids with CDI into imidazolides has a wide range of applicability. CDI reacts with aliphatic, aromatic, and heterocyclic carboxylic acids under very mild conditions, and these reactions are not affected by the presence of functional groups unless the latter are strongly nucleophilic and themselves react with CDI in such cases a reversible protection of the functional groups is necessary. The reaction of CDI also works in such specific cases as trifluoro- and trichloroacetic acids, leading to the very reactive Af-trifluoro- and N-trichloroacetylimidazoles. 1 111... 

Biosorption is a rather complex process affected by several factors that include different binding mechanisms (Figure 10.4). Most of the functional groups responsible for metal binding are found in cell walls and include carboxyl, hydroxyl, sulfate, sulfhydryl, phosphate, amino, amide, imine, and imidazol moieties.4 90 The cell wall of plant biomass has proteins, lipids, carbohydrate polymers (cellulose, xylane, mannan, etc.), and inorganic ions of Ca(II), Mg(II), and so on. The carboxylic and phosphate groups in the cell wall are the main acidic functional groups that affect directly the adsorption capacity of the biomass.101... 

The binaphthol 13 is different from 1 and 7 owing to the lower acidity of its functional groups. Therefore, crystalline complexes of 13 with amines (see Table 3) are not expected to have a salt character. The 13 imidazole 1 2 complex (Fig. 22)81) was studied in the light of the general interest in this guest partner and its relation to alcohol functions in biological ensembles. The host molecule adopts ideal twofold... 

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