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Acids acid-base strengths

Because of their diverse stmctures, there are few common threads to vitamin chemical properties aside from their fat or water solubiUty. Of general concern ia all appHcations, however, is vitamin stabiUty. Table 5 provides generic iaformation regarding stabiUty under several conditions. Levels of stabiUty vary greatly and are impacted by acid or base strength, light iatensity, etc. [Pg.6]

Adolph Baeyer is credited with the first recognition of the general nature of the reaction between phenols and aldehydes in 1872 ([2,5-7] [18], Table 5.1). He reported formation of colorless resins when acidic solutions of pyrogallic acid or resorcinol were mixed with oil of bitter almonds, which consists primarily benzaldehyde. Baeyer also saw resin formation with acidic and basic solutions of phenol and acetaldehyde or chloral. Michael and Comey furthered Baeyer s work with additional studies on the behavior of benzaldehyde and phenols [2,19]. They studied a variety of acidic and basic catalysts and noted that reaction vigor followed the acid or base strength of the catalyst. Michael et al. also reported rapid oxidation and darkening of phenolic resins when catalyzed by alkaline materials. [Pg.870]

The rate constant for a general acid- or general base-catalyzed reaction increases as the acid or base strength of the catalyst is increased. For many such systems... [Pg.344]

For discussions of field effects on acid and base strength and on reactivity, see Chapters 8 and 9, respectively. [Pg.18]

The properties of excited states are not easy to measure because of their generally short lifetimes and low concentrations, but enough work has been done for us to know that they often differ from the ground state in geometry, dipole moment, and acid or base strength. For example, acetylene, which is linear in the ground state, has a trans geometry... [Pg.311]

The structure of a molecule can affect its acidity or basicity in a number of ways. Unfortunately, in most molecules two or more of these effects (as well as solvent effects) are operating, and it is usually very difficult or impossible to say how much each effect contributes to the acid or base strength. Small differences in acidity or basicity between similar molecules are particularly difficult to interpret. It is well to be cautious when attributing them to any particular effect. [Pg.342]

Flood, H., Forland, T. Roald, B. (1947). The acidic and basic properties of oxides. III. Relative acid-base strengths of some polyacids. Acta Chemica Scandinavica, 1, 790-8. [Pg.27]

In summary, the effect of pH on the dissolution rate of a drug from an oral dosage form depends on (a) the pH of the GI fluids, a patient variable (b) the acid or base strength of the drug, a pharmaceutical variable as well as (c) the physicochemical properties of the dosage form, another pharmaceutical variable. Furthermore, by intentionally designing the dosage form such that it buffers the diffusion layer, we can control a patient variable by a pharmaceutical variable. [Pg.118]

OH-], so that A s,w = [H2S+][OH ]. This situation occurs for a mixture of hydrazine and water, where the equilibrium H20 + N2H4 OH" + N2H5+ is established. Other combinations of acid and base strengths can be discussed in similar terms. [Pg.61]

Acid-base strength in MejSO The chemistry of MejSO (general) Coordination compounds of sulfoxides The chemistry of MejSO (inorganic)... [Pg.125]

Using the multisite complexation model (MUSIC), ° the surface of palladium oxide has been modeled providing useful data on the nature, number, and the acid-base strength of the hydroxyl groups present on the different faces (111) and (10 0) of... [Pg.260]

The Bronsted relationship can be strictly accurate only over a certain range of acid and base strengths. When has diffusion-controlled values, which of course cannot be exceeded, the linear plot of log k/ y vs log must level off to a zero slope, that is a = 0. As well as being reported, although rarely, in simple metal complexes, the resultant curvature in the Bronsted plot is also shown by the zinc enzyme carbonic anhydrase (Chap. 8. Zn(II)). In... [Pg.102]

Relationships of acid-base strengths are in fact relationships between free energies of reaction in terms of the thermodynamic... [Pg.277]

One of the fundamental questions in considerations of acid-base strengths in solution of molecules involving mesomerism is the rela-... [Pg.278]

These expectations have been borne out. We have confirmed the anticipated correlations of experimental aqueous acid and base strengths with /s,min ° A base becomes stronger, and its p (b lower, as the /s,mm of the basic site decreases. An acid becomes stronger, and its pK lower, as the Is,mm of the conjugate base s basic site increases. To assess basicity and predict p Tb therefore, /s,mm should be computed for the basic site itself to assess acidity and predict pK, /s,mm must be obtained for the conjugate base, i.e. A for an acid HA. [Pg.22]

In this chapter, a brief summary of studies that made use of calorimetry to characterize compounds comprising group IIIA elements (zeolites, nitrides, and oxides catalysts) was presented. It was demonstrated that adsorption microcalorimetry can be used as an efficient technique to characterize the acid-base strength of different types of materials and to provide information consistent with the catalytic data. [Pg.248]


See other pages where Acids acid-base strengths is mentioned: [Pg.395]    [Pg.50]    [Pg.51]    [Pg.311]    [Pg.346]    [Pg.349]    [Pg.349]    [Pg.20]    [Pg.20]    [Pg.252]    [Pg.276]    [Pg.23]    [Pg.166]    [Pg.219]    [Pg.28]    [Pg.400]    [Pg.325]    [Pg.26]    [Pg.268]    [Pg.277]    [Pg.280]    [Pg.289]    [Pg.5]    [Pg.211]    [Pg.62]    [Pg.242]    [Pg.186]   
See also in sourсe #XX -- [ Pg.742 , Pg.743 , Pg.743 , Pg.744 , Pg.745 , Pg.746 , Pg.746 , Pg.747 , Pg.748 , Pg.770 , Pg.771 , Pg.772 , Pg.773 , Pg.774 , Pg.775 ]




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Acid strength

Acid-base buffer strength

Acid-base chemistry strength

Acid-base concepts strength

Acid-base dissociation equilibria. Strength of acids and bases

Acid-base equilibria relative strengths

Acid-base equilibria strength

Acid-base interactions measurement strength distribution

Acid-base strength

Acid-base strength

Acid-base strength and molecular structure

Acid-base strength distribution

Acid-base strength inductive effects

Acid-base strength inherent

Acid-base strength oxyacids

Acid-base strength proton affinity

Acid-base strength quantitative measures

Acid-base strength steric effects

Acid-base strength thermodynamic measurement

Acid-base strengths acids weak bases

Acidizing strength

Acids, acid strength

And acid-base strength

Base strength

Bases acid-base strengths

Bases acid-base strengths

Catalytic Activity and Acid-Base Strength

Classification of acids and bases according to strength

Conjugate acid/base pairs strength

Factors Affecting Strength of Acids and Bases

How Do We Measure the Strength of an Acid or Base

Lewis acid and base strength

Lewis acids/bases strengths

Nonaqueous solvents, acid-base strength

Quantitative determination of acid-base interaction strength

Relative Acid-Base Strength and the Net Direction of Reaction

Relative Strengths of Acids and Bases

Strength of acids bases

Strength of acids or bases

Strength, of acids and bases

Strengths of acids and bases acid-dissociation (or ionization) constant

Strengths of acids and bases in aqueous solution

Strengths of unsaturated fluoro-acids and -bases

Structure, acid-base strength

Structure, acid-base strength Lewis

Substituent Effects on Strengths of Bronsted Acids and Bases

The Strength of a Conjugate Acid or Base

The strengths of acids and bases

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