Reactivity, neutralized, strong-acid

The reactivity of the neutralized, strong-acid monomers [e.g., sodium styrenesulfonate (32) and 2-sulfoethyl methacrylate (30)] with nonionic monomers also is dependent on the changes in polarity of the system (i.e., dielectric constant, solvation, and hydration) and with solution pH (Table IV for the sodium styrenesulfonate studies). The effect also is evident (39) in the copolymerization of two ionogenic monomers, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, with different pK values. For acrylic acid, the reactivity ratio is 0.740 0.13 at pH 7 and 1.58 0.15 at pH 2-4. For 2-acrylamido-2-methylpropanesulfonic acid, the reactivity ratio was 0.187 0.09 at pH 7 and 0.111 0.03 at pH 2-4. These studies (39)... 

Alkaline Catalysts, Resoles. Resole-type phenoHc resins are produced with a molar ratio of formaldehyde to phenol of 1.2 1 to 3.0 1. For substituted phenols, the ratio is usually 1.2 1 to 1.8 1. Common alkaline catalysts are NaOH, Ca(OH)2, and Ba(OH)2. Whereas novolak resins and strong acid catalysis result in a limited number of stmctures and properties, resoles cover a much wider spectmm. Resoles may be soHds or Hquids, water-soluble or -insoluble, alkaline or neutral, slowly curing or highly reactive. In the first step, the phenolate anion is formed by delocali2ation of the negative charge to the ortho and para positions. 

Diorganotin esters of strong acids are relatively stable to hydrolysis under neutral conditions, but generally, diorganotin compounds ate more reactive chemically than the triorganotins. Diorganotin esters of weak acids are somewhat susceptible to hydrolysis, even under neutral conditions, but this reactivity is moderated somewhat by their hydrophobicity. 

The general discussion (Section 4.02.1.4.1) on reactivity and orientation in azoles should be consulted as some of the conclusions reported therein are germane to this discussion. Pyrazole is less reactive towards electrophiles than pyrrole. As a neutral molecule it reacts as readily as benzene and, as an anion, as readily as phenol (diazo coupling, nitrosation, etc.). Pyrazole cations, formed in strong acidic media, show a pronounced deactivation (nitration, sulfonation, Friedel-Crafts reactions, etc.). For the same reasons quaternary pyrazolium salts normally do not react with electrophiles. 

Chemical Reactivity -/Jcflctivify with Water No reaction Reactivity with Common Materials No data Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization May occur when the product is in contact with strong acids and bases Inhibitor of Polymerization No data. 

The first term of the rate law requires acid-catalyzed decomposition of the conjugated acid of the ester. This term predominates only under strongly acidic conditions. It has not been investigated in detail, but the major product of the acid catalyzed reaction is the corresponding hydroxylamine. The second term predominates under neutral to mildly acidic conditions. This term is consistent with uncatalyzed heterolysis of the N—O bond of the neutral ester to generate a heteroaryinitrenium ion. " The rate law is more complicated than that for reactive esters of carbocyclic hydroxylamines or hydroxamic acids that show pH-independent decomposition over a wide pH range. The kinetic behavior of the heterocyclic esters is caused by protonation of a pyridyl or imidazolyl N under mildly acidic conditions. The protonated substrates are not subject to spontaneous uncatalyzed decomposition, so decreases under acidic conditions until acid-catalyzed... 

Benzene reacted only slowly at ambient temperature with TBH in the presence of silica and less reactive substrates such as halogenobenzenes failed to react under such conditions. Thus, attention was turned to aluminosilicates as potential catalysts. These solids may be considered to have a silica-like lattice in which some of the Si atoms have been replaced by A1 atoms. This requires the A1 atoms to be tetracoordinate and consequently negatively charged. Electrical neutrality is achieved through the presence of accompanying cations (Fig. 4). The countercations may be protons and in this case the solids are much more strongly acidic than silica and might be more effective catalysts. 

Reactive dyes are well suited to dye blends of cellulose and PA fibers. Clear shades with very good fastness are obtained. Like with vat dyes, the depth of shade of reactive dyes depends relatively strongly on the type of PA and structural differences. Dyeing is carried out in a three-step process with appropriately selected products. First, the reactive dyes in a weakly acidic liquor are allowed to absorb on the PA component. Salt is then added to improve the yield on the cellulose component. Finally, the liquor is made alkaline for reaction with the cellulose fiber. Dyes (e.g., with MTC anchor) that dye PA from a neutral liquor in the presence of salt are applied in a two-step process, as in the case of cellulose. In the reversal of this dyeing process, the cellulose component is dyed first at alkaline pH, followed by neutralization with acid, and the PA component is then covered at elevated temperature. 

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