Moderately acidic

Fortunately, under moderately acidic conditions, in the presence of acetone and paraformaldehyde, 4.54 undergoes an elimination reaction similar to that described in Scheme 4.13, producing oc,(3-... 

Butyl esters are stable to mild basic hydrolysis, hydrazine, and ammonia they are cleaved by moderately acidic hydrolysis. 

This derivative is prepared from an A-protected amino acid and the anthrylmethyl alcohol in the presence of DCC/hydroxybenzotriazole. It can also be prepared from 2-(bromomethyl)-9,10-anthraquinone (Cs2C03). It is stable to moderately acidic conditions (e.g., CF3COOH, 20°, 1 h HBr/HOAc, / 2 = 65 h HCl/ CH2CI2, 20°, 1 h). Cleavage is effected by reduction of the quinone to the hy-droquinone i in the latter, electron release from the —OH group of the hydroqui-none results in facile cleavage of the methylene-carboxylate bond. The related 2-phenyl-2-(9,10-dioxo)anthrylmethyl ester has also been prepared, but is cleaved by electrolysis (—0.9 V, DMF, 0.1 M LiC104, 80% yield). ... 

Axial alcohols e.g. 60) are formed predominantly when platinum is used in moderately acidic media. The use of acetic acid alone as solvent affords the equatorial alcohol as the main product from both and 7-keto compounds. Addition of 2-10% of a strong acid e.g. hydrochloric acid) to this solvent leads to the axial alcohol as the primary, if not the exclusive, product. Primary and secondary alcohols may be converted in part to the corresponding acetates under these conditions. 

The coordination chemistry of the large, electropositive Ln ions is complicated, especially in solution, by ill-defined stereochemistries and uncertain coordination numbers. This is well illustrated by the aquo ions themselves.These are known for all the lanthanides, providing the solutions are moderately acidic to prevent hydrolysis, with hydration numbers probably about 8 or 9 but with reported values depending on the methods used to measure them. It is likely that the primary hydration number decreases as the cationic radius falls across the series. However, confusion arises because the polarization of the H2O molecules attached directly to the cation facilitates hydrogen bonding to other H2O molecules. As this tendency will be the greater, the smaller the cation, it is quite reasonable that the secondary hydration number increases across the series. 

Potassium iodate is a powerful oxidising agent, but the course of the reaction is governed by the conditions under which it is employed. The reaction between potassium iodate and reducing agents such as iodide ion or arsenic(III) oxide in solutions of moderate acidity (0.1-2.0M hydrochloric acid) stops at the stage when the iodate is reduced to iodine ... 

At fairly high nitrous acid concentrations (0.1 m) and at moderate acidities (4 m) the blue color of N203 (Amax = 625 nm) is easily detected by eye. The overall equilibrium of Scheme 3-10 has been determined. A relatively recent determination of the equilibrium constant gave the value K = 3.0 x 10"3 m (Markovits et al., 1981). Accurate determinations of this constant are difficult, as N203 decomposes easily into NO and N02. Pure N203 is stable only as a pale blue solid or as an intensely blue liquid just above its freezing point (-100°C). The liquid starts to boil with decomposition above -40°C. 

The well know isomerisation (ref. 11) at the position 8 in ergolene nucleus is usually easy and is difficult to be totally avoided. The moderate acidic media, lowering of temperature and non-polar solvents can successfully suppress this reaction. At any case, the iso compound 2-bromo-a-ergocryptinine 2a can readily be transformed back into bromocriptine 2, also in industrial scale. 

Phenolics Clear soluble fluids Black/white Slight Moderate/ Acid pH Protect skin and eyes Very irritant Adsorbed by rubber/plastic Greatly reduced by... 

In aqueous solutions of moderate acidity (< 1 M) the rate expression is ° ... 

This oxidation state is stable only when complexed by anions, e.g. PO4 , or in moderately acidic solutions. Perchloric acid solutions of Mn(IIl) perchlorate have been prepared these are fairly stable, although the omnipresent equilibrium... 

Nitrite concentration The kinetics of N-nitrosamine formation in vitro has been studied at length (, ) and, in moderately acidic media, the reaction rate is directly proportional to the concentration of the free amine (non-protonated) and to the square of the concentration of the undissociated nitrous acid. Therefore, it is not surprising that the amount of nitrite permitted in bacon has received considerable attention. Although, there have been suggestions that it is the initial and not the residual nitrite that influences N-nitrosamine formation in bacon (41), recent evidence seems to indicate that the lowest residual nitrite gives the least probability of N-nitrosamines... 

Low (1-1.5) A,X Relatively low stability of framework. Low stability in acids. High stability in bases. High concentration of acid groups with moderate acid strength. Hydrophilic. 

Sulfonation of PPDMA occurs readily to yield the water soluble PSPDM. PSPDM is stable at neutral and moderately acidic conditions, but is readily hydrolyzed to amic acid (V)in 0.1N NaOH at 90 C. The amide of the hydrolyzed imide, however, is extremely resistant to further hydrolysis under basic conditions. 

The pH of formation waters in the Frio formation varies widely from moderately acidic (5.7) to moderately alkaline (8.2), with nearly neutral averages (6.8). The pH of formation waters from other injection sites tends to be more alkaline, ranging from slightly alkaline (Belle Glade, Florida, pH 7.5) and moderately alkaline (Wilmington, North Carolina, pH 8.6), to very alkaline (Marshall, Illinois, pH 7.1 to 10.7). 

In moderately acidic solutions bromocriptine mesilate readily forms ion pairs with anionic dyes such as picric acid, bromothymol blue, methyl orange, which are extractable with an organic solvent. A procedure has been developed both for direct assay and for assay following chromatographic separation from the impurities. Therein bromocriptine mesilate is allowed to react with bromothymol blue at pH 2.5. The resulting ion pair is then extracted with benzene and its concentration determined at 410 nm (25). ... 

Studies in this laboratory (69) of the water soluble ferri-heme model Fem(TPPS) in aqueous solution have shown that this species also undergoes reductive nitrosylation in solutions that are moderately acidic (pH 4-6) (Eq. (32)). The rate of this reaction includes a buffer dependent term indicating that the reaction of the Fem(TPPS)(NO) complex with H20 is subject to general base catalysis. The reaction depicted in Eq. (33) is not observable at pH values < 3, since the half-cell reduction potential for the nitrite anion (Eq. (1)) is pH dependent, and Eq. (33) is no longer thermodynamically favorable. 

The fact that adsorbed rhodium complexes contain one CF ion at most is remarkable, if one realizes that the actual concentration of Rh complexes with one Cl in moderately acid solutions cannot be high. According to Fenoglio et al. [11], exchange reactions between Cl ions and hydroxyls of the support of the type... 

The weak acidity of the pure OMS materials is disadvantageous for petrochemical processes but for the synthesis of fine chemicals, solids with moderate acidity can be very active catalysts. Table 4.2 gives... 

Independently the Mn"5 pyrophosphate complexes were developed as efficient initiators at very low concentrations (1 to 3 mmole/1) for grafting of vinyl monomers to starch. High yields of polymer (over 90%) and very high grafting efficiencies (98-99%) were obtained by reactions for 1 to 3 h at room temperature ( 30°C) in moderately acidic aqueous media (pH = 1.5 to 2.0). Co rresponding grafting experiments have later been carried... 

PEN is a good candidate for labels where temperature tolerance is required, such as multi-layer labels for automobile bodies when being painted and dried at high temperatures. PEN is ideally suited for bar code labels where dimensional stability and registration are required at elevated temperatures. PEN labels have dimensional-excellence performance on printed circuit boards, in solvent- and aqueous-based painting operations, and in under-the-hood applications. PEN labels also provide substantially improved performance over PET or vinyl labels when the label must survive in harsh chemical environments. PEN performs extremely well in applications where the label must be in contact with organic solvents, such as acetone, ethers, toluene and phenol, as well as strong bases (30 % NaOH) and moderate acids. 

Yet at fairly high nitrous acid concentrations (0.1 M) and at moderate acidities (4 M) the blue color of N2O3 (kmax = 625 nm) is easily detected by eye. A relatively recent... 

Cephalosporins are mostly degraded via intramolecular aminolysis (see above, Fig. 5.8). However, high drug concentrations may also favor degradation via oligomer formation [119]. In the case of loracarbef (5.44, Fig. 5.16), which is not subject to intramolecular aminolysis, the formation of dimeric structures becomes predominant under moderately acidic conditions [120],... 

For example, one indicator, called methyl red, is red when the pH is below 4.2, and yellow when the pH is above 6.2. The point in a titration at which an indicator changes colour is called the end-point. The colour change occurs over a range of about 2 pH units, but the pH of a solution changes rapidly near the equivalence point. Often a single drop of base causes the shift from colour 1 to colour 2. For methyl red, the end-point occurs over the pH range 4.2 to 6.2. Therefore, this indicator is used when an acid-base titration results in a moderately acidic solution at equivalence. Figure 9.3 shows the colours and end-points of various indicators. 

Note MS analysis was carried out in negative ionization mode due to the moderate acidity of glucuroconjugates. The mobile phase ionic strength was adjusted to 5 mM ammonium acetate at pH 5.0 in order to facilitate in-liquid ionization under established... 

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