Acid- base reactions salts from

This is an acid-base reaction with from HNO3 combining with OH from AgOH to produce water. The other product is the salt, AgNOs, which is soluble (nitrate salts are soluble, see Table 4.2 of the text). 

Amides are sometimes prepared directly from carboxylic acids and amines by a two step process The first step is an acid-base reaction m which the acid and the amine combine to form an ammonium carboxylate salt On heating the ammonium carboxy late salt loses water to form an amide... 

Whenever possible, the chemical reactions involved in the fonnation of diastereomers and their- conversion to separate enantiomers are simple acid-base reactions. For example, naturally occurring (5)-(—)-malic acid is often used to resolve fflnines. One such amine that has been resolved in this way is 1-phenylethylarnine. Amines are bases, and malic acid is an acid. Proton transfer from (5)-(—)-malic acid to a racemic mixture of (/ )- and (5)-1-phenylethylarnine gives a mixture of diastereorneric salts. 

Seven chemical reactions were identified from the chemistry syllabus. These chemical reactions were selected because they were frequently encountered during the 2-year chemistiy course and based on their importance in understanding concepts associated with three topics, namely, acids, bases and salts, metal reactivity series and inorganic chemistry qualitative analysis. The seven types of chemical reactions were combustion of reactive metals in air, chemical reactions between dilute acids and reactive metals, neutralisation reactions between strong acids and strong alkalis, neutralisation reactions between dilute acids and metal oxides, chemical reactions between dilute acids and metal carbonates, ionic precipitation reactions and metal ion displacement reactions. Although two of the chemical reactions involved oxidation and reduction, it was decided not to include the concept of redox in this study as students had only recently been introduced to ion-electron... 

Two matrices are formed a metal polyacrylate salt and a polymer. There is a lack of water in the system because some of it has been replaced by HEM A, and lack of water in glass polyalkenoate cements is known to slow down the ionomer add-base reaction (Hornsby, 1977). Thus, the initial set of these materials results from the polymerization of HEMA and not the characteristic acid-base reaction of glass-ionomer cements. The later reaction serves only to harden and strengthen the already formed matrix. 

Under the aforementioned circumstances, the two-step reaction 4.53 and the associated eqns. 4.54-4.62 are equally valid on the understanding that HS represents Hcres, etc. further, it must be realized that during titration various amounts of HX and B are simultaneously present. Therefore, from previous measurement of the conductivities (k) of dilution series of the separate acids, bases and salts in m-cresol, the overall constants KHX, KB and KBH+X were calculated by the Fuoss and Kraus method66,67 (with the use of e = 12.5 and viscosity = 0.208 P for m-cresol). For C6H6S03H and HC1 it was necessary to calculate the equivalent conductivity at zero concentration from the equation... 

The resultant solution at the equivalence point of any acid-base reaction contains only salt and water. The pH is determined from the concentration of the salt. 

When a salt is dissolved in water, the metal ions, especially transition metal ions, form a complex ion with water molecules and/or other species. A complex ion is composed of a metal ion bonded to two or more molecules or ions called ligands. These are Lewis acid-base reactions. For example, suppose Cr(N03)3 is dissolved in water. The Cr3+ cation attracts water molecules to form the complex ion Cr(H20)63+. In this complex ion, water acts as the ligand. If ammonia is added to this solution, the ammonia can displace the water molecules from the complex ... 

The acidic or basic property of an aqueous solution of a salt results from reactions between water and the dissociated ions of the salt. Some ions do not react with water. They are neutral in solution. Ions that do react with water produce a solution with an excess of HsO iaq) or OH (aq). The extent of the reaction determines the pH of the solution. As you will see, the reaction between an ion and water is really just another acid-base reaction. 

In a related application, polyelectrolyte microgels based on crosslinked cationic poly(allyl amine) and anionic polyfmethacrylic acid-co-epoxypropyl methacrylate) were studied by potentiometry, conductometry and turbidimetry [349]. In their neutralized (salt) form, the microgels fully complexed with linear polyelectrolytes (poly(acrylic acid), poly(acrylic acid-co-acrylamide), and polystyrene sulfonate)) as if the gels were themselves linear. However, if an acid/base reaction occurs between the linear polymers and the gels, it appears that only the surfaces of the gels form complexes. Previous work has addressed the fundamental characteristics of these complexes [350, 351] and has shown preferential complexation of cationic polyelectrolytes with crosslinked car-boxymethyl cellulose versus linear CMC [350], The departure from the 1 1 stoichiometry with the non-neutralized microgels may be due to the collapsed nature of these networks which prevents penetration of water soluble polyelectrolyte. 

All these electrolytes are neutral in Bronsted acid-base properties. Although rather exceptional, an acid, a base, or a pH buffer may be added to the supporting electrolyte of neutral salts. The acid-base system to be selected depends on the purpose of the measurement. We often use trifluoromethanesulfonic acid (CF3S03F1) as a strong acid acetic acid, benzoic acid, or phenol as a weak acid an amine or pyridine as a weak base and tetraalkylammonium hydroxide (ILtNOH) as a strong base. Examples of buffer systems are the mixtures of picric acid and its R4N-salt and amines and their PlCl04-salts. Here, we should note that the acid-base reactions in aprotic solvents considerably differ from those in water, as discussed in Chapter 3. 

We can use the ionic equation to write the molecular equation of the same reaction, keeping in mind that every ion of the original substances was obtained from some acid, base, or salt, and that every ion in the products must be shown as the salt, base, or acid that would be obtained if the solution were evaporated to dryness. 

Related ammonium salts derived from amines, such as [CH3NH3]C1, [(CH3)2NH2]C1, and [(CH3)3NH]C1, also give acidic solutions because they too have cations with at least one dissociable proton. The pH of a solution that contains an acidic cation can be calculated by the standard procedure outlined in Figure 15.7. For a 0.10 M NH4C1 solution, the pH is 5.12. Although the reaction of a cation or anion of a salt with water to produce H30+ or OH - ions is sometimes called a salt hydrolysis reaction, there is no fundamental difference between a salt hydrolysis reaction and any other Bronsted-Lowry acid-base reaction. 

Quaternary ammonium salts of dantrolene and clodanolene have been prepared, and the effect of the organic cation on the aqueous solubility has been reported (Ellis et al., 1980). It was reasoned that since the hydantoin moiety in each drug is weakly acidic, a strong base should be found for salt formation. The 13 different quaternary ammonium compounds were therefore used in the hydroxide salt form. The acid-base reaction proceeded rapidly, and the salt products were stable during recrystallization steps. Of the four salts for clodanolene, the aqueous solubilities ranged from 2- to 100-fold that of clodanolene sodium, on a mass basis. Of the 11 salts for dantrolene, the benzyl-trimethyl ammonium salt exhibited comparable solubility to that of dantrolene sodium. Among the other 10 salts were several examples that yielded enhanced solubilities of up to 1000-fold that of the sodium salt. Twelve of the Lfteen salts successfully demonstrated muscle relaxant activity when administered orally. 

These acid-base reactions allow a simple way distinguishing between most carboxylic acids, phenols, and alcohols. Since the salts formed from the acid-base reaction are water soluble, compounds containing these functional groups can be distinguished by testing their solubilities in sodium hydrogen carbonate and sodium hydroxide solutions. This solubility test is not valid for low molecular weight structures like methanol or ethanol since these are water soluble and dissolve in basic solution because of their water solubility rather than their ability to form salts. 

The synthesis of amides directly from carboxylic acids is not easy because the reaction of an amine with a carboxylic acid is a typical acid-base reaction resulting in the formation of a salt (Following fig.). Some salts can be converted to an amide by heating strongly to expel water. 

Amides can be synthesized directly from carboxylic acids, using heat to drive off water and force the reaction to completion. The initial acid-base reaction of a carboxylic acid with an amine gives an ammonium carboxylate salt. The carboxylate ion is a poor electrophile, and the ammonium ion is not nucleophilic, so the reaction stops at this point. Heating this salt to well above 100 °C drives off steam and forms an amide. This direct synthesis is an important industrial process, and it often works well in the laboratory. 

The mutarotation constant, ki + ko is the sum of the constants for the two opposing reactions, and k lki is the equilibrium constant. Lowry and Hudson pointed out and showed that the same value is obtained for ki + kj from the mutarotation of the a and /8 anomers, a situation which has been experimentally confirmed by many others. Hudson found the reaction constant to be independent of the concentration of sugar over a wide range, and dependent on catalysis by both acids and bases, as had also been shown less precisely by Urech and by Levy. The effect of acids, bases, and salts will be considered in more detail in Part II of this review. 

A hydroxide nucleophile is needed to synthesize an alcohol, and salts such as NaOH and KOH are inexpensive and commercially available. An alkoxide salt is needed to make an ether. Simple alkoxides such as sodium methoxide (NaOCH3) can be purchased, but others are prepared from alcohols by a Brpnsted-Lowry acid-base reaction. For example, sodium ethoxide (NaOCH2CH3) is prepared by treating ethanol with NaH. 

Thus, the water-soluble salt, C6H5COO Na (derived from CgHsCOOH by an acid-base reaction) can be separated from water-insoluble cyclohexanol by an extraction procedure. 

Because removal of a proton from a carbon bonded to phosphoms generates a resonance-stabilized carbanion (the ylide). this proton is somewhat more acidic than other protons on an alkyl group in the phosphonium salt. Very. strong bases are still needed, though, to favor the products of this acid—base reaction. Common bases used for this reaction are the organoUthium reagents such as butyllithium, CH3CH2CH2CH2Li, abbreviated as BuLi. 

An amine can be separated from other organic compounds by converting it to a water-soluble ammonium salt by an acid-base reaction. 

Both enantiomers of A -acetyl alanine have a free carboxy group that can react with an amine in an acid-base reaction. If a chiral amine is used, such as (/ )-a-methyibenzyiamine, the two salts formed are diastereomers, not enantiomers. Diastereomers can be physically separated from each other, so the compound that converts enantiomers into diastereomers is called a resolving agent. Either enantiomer of the resolving agent can be used. 

However, the case in which the solubility of a solid can be calculated from the known analytical concentration of added components and from the solubility product alone is very seldom encountered. Ions that have dissolved from a crystalline lattice frequently undergo chemical reactions in solution, and therefore other equilibria in addition to the solubility product have to be considered. The reaction of the salt cation or anion with water to undergo acid-base reactions is very common. Furthermore, complex formation of salt cation and salt anion with each other and with one of the constituents of the solution has to be considered. For example, the solubility of FeS(s) in a sulfide-containing aqueous solution depends on, in addition to the solubility equilibrium, acid-base equilibria of the cation (e.g., Fe + H2O = FeOH + H ) and of the anion (e.g., S + HjO = HS + OH, and HS" + H2O = H2S + OH ), as well as on equilibria describing complex formation (e.g., formation of FeHS" or FeSi ). 

The choice of techique for the measurement of rates of protonation must also be carefully considered. In CV, DCV, and LSV measurement, complications due to reduction of reactants other than the probase are relatively easily detected. In contrast, processes taking place just after the PB reduction may affect the results obtained by methods such as DPSC, which involves stepping beyond the probase reduction peak. An example comes from a study of the reaction between 9-fluorenylidene dianions and phosphonium salts. The product of the acid-base reaction is the ylid, which turns out to be reducible in the region to which the potential is stepped in DPSC experiments [81]. For reaction in DMSO between the dianion of 9-fluorenylidene derivative (7b, Scheme 23) and [Ph3PCH2Ph]" " the rate constant determined [81] by DPSC appears to be 4.5 x 10 M s . In contrast, DCV gives [43] a rate constant of only 12.31 M s . The DPSC method works well for... 

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