Water reaction with base

Cation derived from a strong base Reaction with water neither ion Solution neutral Examples NaCl, K2SO4, Ca(N03)2 Reaction with water only the anion Solution basic Examples NaCHsCOO, KF, Mg(HS04)2... 

Cation derived from a weak base Reaction with water only the cation Solution acidic Examples NH4CI, NH4NO3, NH4CIO4 Reaction with water both ions Solution neutral if ka = kb, acidic if ka> kb, basic if kb > ka Examples NH4CN (basic), (NH4)2S (basic), NH4NO2 (acidic)... 

Amino acids contain a carboxyl group and can therefore serve as acids. They also contain an NH2 group, characteristic of amines (Section 16.7), and thus they can also act as bases. Amino acids, therefore, are amphiprotic. For glycine, we might expect the acid and base reactions with water to be... 

Just as the carbocation formed in the first step is a reaction intermediate, the protonated alcohol formed in the second step is also an intermediate. Only after this second intermediate is deprotonated by an acid-base reaction with water is the final product formed. 

The reaction begins with an attack on a hydrogen of the electrophile, HaO", by the electrons of the nucleophilic tt bond. Two electrons from the 7T bond form a new a bond between the entering hydrogen and an alkene carbon, as shown by the curved arrow at the top of Figure 7.6. The carbocation intermediate that results is itself an electrophile, which can accept an electron pair from nucleophilic H2O to form a C-0 bond and yield a protonated alcohol addition product. Removal of H" " by acid-base reaction with water then gives the alcohol product and regenerates the acid catalyst. 

Wnte an equation for the Brpnsted acid-base reaction that occurs when each of the fol lowing bases reacts with water Show all unshared electron pairs and formal charges and use curved arrows to track electron movement... 

Other methods for safely cleaning apparatus containing sodium residues or disposing of waste sodium are based on treatment with bismuth or lead (103), inert organic Hquids (104—106), or by reaction with water vapor carried in an inert gas stream (107). 

The steric effects in isocyanates are best demonstrated by the formation of flexible foams from TDI. In the 2,4-isomer (4), the initial reaction occurs at the nonhindered isocyanate group in the 4-position. The unsymmetrically substituted ureas formed in the subsequent reaction with water are more soluble in the developing polymer matrix. Low density flexible foams are not readily produced from MDI or PMDI enrichment of PMDI with the 2,4 -isomer of MDI (5) affords a steric environment similar to the one in TDI, which allows the production of low density flexible foams that have good physical properties. The use of high performance polyols based on a copolymer polyol allows production of high resiHency (HR) slabstock foam from either TDI or MDI (2). 

The hydrolysis process, ie, reaction with water, for lime is called slaking and produces hydrated lime, Ca(OH)2. Calcium hydroxide is a strong base but has limited aqueous solubiHty, 0.219 g Ca(OH)2/100 g H2O, and is therefore often used as a suspension. As an alkaH it finds widespread iadustrial appHcatioa because it is cheaper than sodium hydroxide. 

The catalytic effect of protons has been noted on many occasions (cf. Section II,D,2,c) and autocatalysis frequently occurs when the nucleophile is not a strong base. Acid catalysis of reactions with water, alcohols, mercaptans, amines, or halide ions has been observed for halogeno derivatives of pyridine, pyrimidine (92), s-triazine (93), quinoline, and phthalazine as well as for many other ring systems and leaving groups. An interesting displacement is that of a 4-oxo group in the reaction of quinolines with thiophenols, which is made possible by the acid catalysis. 

Molecules. As pointed out in Chapter 4, there are many molecular weak bases, including the organic compounds known as amines. The simplest weak base is ammonia, whose reversible Bronsted-Lowry reaction with water is represented by the equation... 

Equilibrium constants of weak bases can be measured in the laboratory by procedures very much like those used for weak acids. In practice, though, it is simpler to take advantage of a simple mathematical relationship between Kb for a weak base and Ka for its conjugate acid. This relationship can be derived by adding together the equations for the ionization of the weak acid HB and the reaction of the weak base B- with water ... 

Investigation of the reactions of other compounds that have the properties of a base shows that each compound can produce hydroxide ions in water. The OH (aq) ions may be produced directly (as when solid NaOH dissolves in water) or through reaction with water (as when Na2COj and NHj dissolve in water) ... 

Base catalysis was shown not to be significant on two grounds. Firstly, the second-order rate coefficients for the two sets of acetate buffer data are the same within experimental error, and secondly, the addition of base of concentrations 0.05 and 0.2 M to the reaction with water caused a negligible change in the rate coefficient. 

Phenol was originally recovered during the coking of coal, essentially being a by-product. Eventually, commercial routes were developed based on benzene (from coal or petroleum) for example, sulfonation of benzene to ben-zenesulfonic acid followed by reaction with water to phenol plus regenerated sulfuric acid. Phenol is used to make plastics (phenol-formaldehyde and epoxy resins) and textile fibers (nylon). Phenol is also used in solution as a general disinfectant for cleaning toilets, stables, floors, drains, etc. and is used both internally and externally as a disinfectant for animals. 

Any acid that undergoes quantitative reaction with water to produce hydronium ions and the appropriate anion is called a strong acid. Table gives the structures and formulas of six common strong acids, all of which are supplied commercially as concentrated aqueous solutions. These solutions are corrosive and normally are diluted for routine use in acid-base chemistry. At the concentrations normally used in the laboratory, a solution of any strong acid in water contains H3 O and anions that result from the loss of a proton. Example shows a molecular view of the proton transfer reaction of a strong acid. 

Any anion of a weak acid, including the anions of polyprotic acids, is a weak base. The acid-base properties of monoanions of polyprotic acids are complicated, however, because the monoanion is simultaneously the conjugate base of the parent acid and an acid in its own right. For example, hydrogen carbonate anions undergo two proton-transfer reactions with water ... 

Base strength refers to the relative tendency to produce OH- ions in aqueous solution by (1) the dissociation of soluble metal hydroxides or (2) by ionization reactions with water using Arrhenius theory. A more general definition, applying Bronsted-Lowry theory, is that base strength is a measure of the relative tendency to accept a proton from any acid. 

Based on the results of these studies it is quite evident that the reaction with ionic liquid as immobilization phase requires a chloride-free catalyst phase in order to achieve any advantage over the reaction with water as the immobilizing phase. 

Numerous types of chemical reactions pose potential hazards. Literature and incident data highlight the hazards of common industrial reactions, such as polymerization, decomposition, acid-base, oxidation-reduction (redox), and reactions with water. Polymerization and decomposition can be classified as self-reactions because they often involve just one chemical substance. However, other... 

We can ignore ions such as Sr2+, which come from strong acids or strong bases in this type of problem. Ions, such as C2H3O2", from a weak acid or a base, weak acid in this case, will undergo hydrolysis, a reaction with water. The acetate ion is the conjugate base of acetic acid (Ka = 1.74 x 10 5). Since acetate is a weak base, this will be a Kb problem, and OH will form. The equilibrium is ... 

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