B-acid

B) ACID ANHYDRIDES. Acetic anhydride, succinic anhydride phthalic anhydride (and substituted derivatives). 

Fig. 23. Representative protecting groups for phenolic and carboxylic acid-based systems, (a) The polymer-based protecting groups are fisted in order of increasing activation energy for acid-catalyzed deprotection, (b) Acid-labile monomeric dissolution inhibitors, a bifunctional system based on protected bisphenol A. (c) Another system that combines the function of dissolution inhibitor and PAG in a single unit.

Fig. 36. Representative bilayer resist systems. Both CA and non-CA approaches are illustrated (116—119). (a) Cross-linking E-beam resist, 193-nm thin-film imaging resist (b) acid-cataly2ed negative-tone cross-linking system (c) positive-tone CA resist designed for 193-nm appHcations and (d) positive-tone...

Bases of low polarizabiUty such as fluoride and the oxygen donors are termed hard bases. The corresponding class a cations are called hard acids the class b acids and the polarizable bases are termed soft acids and soft bases, respectively. The general rule that hard prefers hard and soft prefers soft prevails. A classification is given in Table 3. Whereas the divisions are arbitrary, the trends are important. Attempts to provide quantitative gradations of "hardness and softness" have appeared (14). Another generaUty is the usual increase in stabiUty constants for divalent 3t5 ions that occurs across the row of the Periodic Table through copper and then decreases for zinc (15). 

Fig. 3. Examples of nuclei occurring in important cyanine dyes, (a) = basic terminal groups for cyanines and merocyanines (b) = acidic terminal groups...

Anthraquinone Blue B (Acid Blue 45, l,5-diamino-4,8-dihydroxy-9,10-anthraquinone-3,7-disulfonic acid di-Na salt) [2861-02-1] M 474.3, m >300°, Cl 63010, X.max 595nm, pKesi(1) <0, pKEst(2) 2, pKEst(3) 9. Purified by salting out three times with sodium acetate, followed by repeated extraction with EtOH [McGrew and Schneider 7 Am Chem Soc 72 2547 1950]. 

Figure 4.1-11 The EXAFS data and pseudo-radial distribution functions of Co(ll) in (a) basic and (b) acidic chloroaluminate ionic liquid. Reproduced from reference 46 with permission.

Appendix A Nomenclature of Polyfunctional Organic Compounds A-1 Appendix B Acidity Constants for Some Organic Compounds A-8 Appendix C Glossary A-10 Appendix D Answers to In-Text Problems A-30... 

Two important sources of error in titrations involving iodine are (a) loss of iodine owing to its appreciable volatility and (b) acid solutions of iodide are oxidised by oxygen from the air ... 

Self-Test 10.7B Use Tables 10.1 and 10.2 to decide which species in each of the following pairs is the stronger acid or base (a) base C,H,N or NH2NH2 (b) acid C5H5NHy or NH2NH,+ (c) acid HIO, or HCI02 (d) base C102 or HSO . ... 

Marmorek, D.R. Thornton, K.W. Baker, J.P. Bernard, D.P. Jones, M.L. Reuber,B. Acidic Episodes in Surface Waters The State of ence. Final Rept., US/EPA, Corvallis, OR, 1987. 

Figure 2. Tangent A plotted against temperature for hydrophobic humic strong (a) and weak (b) acids. The arrow marks the curve maximum.

Figure 3. Excitation-emission spectra for hydrophobic humic weak (a) and strong (b) acids.

Figure 4. Phase-resolved plots of the six humic fractions superimposed on the normal emission scan for each fraction. The emission spectrum of the first fluorophore was suppressed and a scan was made of the second fluorophore then the second fluorophore was suppressed and an emission scan was made of the first fluorophore. Fractions hydrophobic humic weak (a) and strong (b) acids.

Figure 2. Analysis of free (A) and total (B) acids in wild type (open bars) and transgenic (closed bars) plants. Fig. 2C shows the ratio of free to total acids (in %). The bars represent the mean +/- S.E. of 4-11 independent determinations.

Spectroscopy. In the methods discussed so far, the information obtained is essentially limited to the analysis of mass balances. In that re.spect they are blind methods, since they only yield macroscopic averaged information. It is also possible to study the spectrum of a suitable probe molecule adsorbed on a catalyst surface and to derive information on the type and nature of the surface sites from it. A good illustration is that of pyridine adsorbed on a zeolite containing both Lewis (L) and Brbnsted (B) acid sites. Figure 3.53 shows a typical IR ab.sorption spectrum of adsorbed pyridine. The spectrum exhibits four bands that can be assigned to adsorbed pyridine and pyridinium ions. Pyridine adsorbed on a Bronsted site forms a (protonated) pyridium ion whereas adsorption on a Lewis site only leads to the formation of a co-ordination complex. 

Figure 1.47. REE patterns of the fresh volcanic rocks in the Kuroko mine area. Data source Dudis et al. (1983). (a) basalt (b) acidic rocks (Shikazono, 1999a).

Ahrland et al. (1958) classified a number of Lewis acids as of (a) or (b) type based on the relative affinities for various ions of the ligand atoms. The sequence of stability of complexes is different for classes (a) and (b). With acceptor metal ions of class (a), the affinities of the halide ions lie in the sequence F > Cl > Br > I , whereas with class (b), the sequence is F < Cl" < Br < I . Pearson (1963, 1968) classified acids and bases as hard (class (a)), soft (class (b)) and borderline (Table 1.23). Class (a) acids prefer to link with hard bases, whereas class (b) acids prefer soft bases. Yamada and Tanaka (1975) proposed a softness parameter of metal ions, on the basis of the parameters En (electron donor constant) and H (basicity constant) given by Edwards (1954) (Table 1.24). The softness parameter a is given by a/ a - - P), where a and p are constants characteristic of metal ions. 

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