Reactions of Bases

The OH ions are responsible for the characteristic reactions of bases. The following reactions are in an aqueous medium  

Reaction with Acids Bases react with acids to produce a salt and water. See reaction of acids with bases in Section 15.2. 

Amphoteric Hydroxides Hydroxides of certain metals, such as zinc, aluminum, and chromium, are amphoteric that is, they are capable of reacting as either an acid or a base. When treated with a strong acid, they behave like bases when reacted with a strong base, they behave like acids  

Reaction of NaOH and KOH with Certain Metais Some amphoteric metals react directly with the strong bases sodium hydroxide and potassium hydroxide to produce hydrogen  

Write the formulas and names of the acid and base from which these salts are formed. 

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The complex greases are obtained by the reaction of bases with mixtures of organic and/or inorganic acids. The three groups of complex greases are ... 

A base is any material that produces hydroxide ions when it is dissolved in water. The words alkaline, basic, and caustic are often used synonymously. Common bases include sodium hydroxide (lye), potassium hydroxide (potash lye), and calcium hydroxide (slaked lime). The concepts of strong versus weak bases, and concentrated versus dilute bases are exactly analogous to those for acids. Strong bases such as sodium hydroxide dissociate completely while weak bases such as the amines dissociate only partially. As with acids, bases can be either inorganic or organic. Typical reactions of bases include neutralization of acids, reaction with metals, and reaction with salts ... 

To summarize under favorable conditions the acidity of a-hydrogens facilitates the generation of a-sulfoxy and a-sulfonyl carbanions in thiirane and thiirene oxides and dioxides as in acyclic sulfoxides and sulfones. However, the particular structural constraints of three-membered ring systems may lead not only to different chemical consequences following the formation of the carbanions, but may also provide alternative pathways not available in the case of the acyclic counterparts for hydrogen abstraction in the reaction of bases. 

Table 5 Reactions of bases with carbonyl compounds, a selection.

Yatsimirskii (1970) attempted to quantify HSAB theory and produced hardness indices for adds and bases. These indices were obtained by plotting the logarithms of the equilibrium constants for the reactions of bases with the proton (the hardest add) against similar values for the reactions with CHjHg (one of the softest adds). For adds, the hydroxyl ion (the hardest base) and the chloride ion (a soft base) were chosen. 

Analogously for the two-step reaction of base B with solvent HS ... 

Scheme 15. Reaction of base-stabilized monomers with transition metal complexes.

This reaction was easily performed with malonic ester derivatives using approaches described above for nitro carbanions. It should be noted that the anion of malonic ester can be prepared not only by the reactions of bases with malonates but also by desilylation of silyl ketene acetal (449) with fluoride anion. 

The major entry into Os5 cluster chemistry comes from the reaction of base with Os6(CO)18 (203). This gives the [Os5(CO)15p anion in high yield ( 80%). The general chemistry of these species is summarized in... 

Perlmutter-Hayman and Shinar (15, 16) have studied by temperature-jump the reactions of bases with different acid-base indicators having intramolecular hydrogen bonds. With Tropaeolin 0, direct attack of the base on the hydrogen bridge predominates according to their interpretation, whereas, for Alizarin Yellow G, the observed relaxation is ascribed chiefly to diffusion controlled reaction between the base and that part of the indicator present in the open form. Thus, data exist that lead one to doubt the generality of statement number 5. 

An esterifying substituent of value in prodrug design is the (2-oxo-l,3-dioxol-4-yl)methyl group (8.62 in Fig. 8.4). The interest in this moiety was first documented with prodrugs of antibiotics, as discussed below. To the best of our knowledge, no detailed or systematic studies on the mechanism of activation of (oxodioxolyl)methyl derivatives have been published. The available evidence supports a clean reaction of base-catalyzed hydrolysis as shown in Fig. 8.4, although the actual mechanism may be more complex and/or condition-dependent [74][75]. Briefly, hydrolysis liberates the pro-... 

Although both the Beckmann and Neber reactions can use oxime derivatives as starting materials, O-unsubstituted oximes cannot undergo the Neber rearrangement. The latter occurs only in strongly alkaline reaction conditions while the former can also proceed in both acid and basic media. As a consequence, the Neber rearrangement will only be a possible side reaction of base-induced Beckmann rearrangements. 

Sodium nitroprusside was first prepared and investigated in the middle of the nineteenth century, and a comprehensive summary of the earlier chemical investigations has been published (17). Up to 1910-1930, the addition reactions of bases to NP were explored, involving the characterization of colored intermediates (e.g., with SH-, SR-, and SO3 ), useful for analytical purposes. The hypotensive action of NP was first demonstrated in 1929, and a considerable research effort has attempted to establish the mode of action of NP and its metabolic fate. Questions still arise on the mechanism of NO release from NP in the biological fluids, and we refer to them below. New accounts dealing with modern structural and reactivity issues associated with the coordination of nitrosyl in NP and other complexes have appeared (18-20). From the bioinorganic and environmental viewpoint, nitrosyl iron complexes have been studied with... 

Ionic polymerisation is a well-known technique for the preparation of graft copolymers but the fate of these reactions is determined by the reaction conditions. Since the discovery of living polymerisation , (anionic polymerisation) [67] it has become an excellent method for the synthesis of block and graft copolymers. In anionic polymerisation the graft copolymerisation is initiated by the anion generated by the reaction of bases with acidic protons in the polymer chain as shown in Scheme 2. 

Scheme 17. Mechanism for the formation of ammonia in the reactions of base with frarcs-[M(NH)X(dppe)2]+ (M = Mo or W X = halide).

Complete each of the following equations for the reaction of bases with OH in the for-... 

In those cases in which positions I and 11 of the aporphine are connected by a bridge, the arguments put forward are not operative, and the elimination of an ammonium group leads exclusively to a phenanthrene alkaloid. Thus, thaliglu-cine (174) is the only product isolated on reaction of base with a thalphenine salt (175) (57,60). In this case the substituents at C-1 and C-11 obviously greatly favor the planar phenanthrene 174. 

The reaction of bases with most silicate glasses produces dissolution rates when tested in 5% NaOH solution at 95°C. The mechanism also involves a complete dissolution process as that described for acid. Weaker alkaline solutions may both leach and dissolve and sometimes show greater dependence on glass composition. And, in the case of strong alkali solutions, the rate of attack doubles for each 10 K increase in temperature or each increase in pH unit. Usually higher alkali durability glasses are used for laboratory wares. 

The reactions of bases with borylstannylalkanes generally lead to cleavage of the tin moietyand lithium thiophenoxide is especially specific. It is of interest that the reaction of fluoride anion with di-mesitylboryl(trimethylsilyl)alkanes also gives a-boryl carbanions, thus obviating the need to use organo-metallics. ... 

Bordwell and his co-workers discovered that the formation of the pseudo-base from nitromethane in hydroxide ion solutions (Equation 21) has a Pf of 1.28 and a p q of 0.83 giving rise to an a/ of 1.54. Similarly the ttf values for reaction of bases with other nitroalkanes are greater than unity also violating the Leffler assumption. 

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