Solutions basic

Manganaies(Vf), (Mn04) . Deep green tetrahedral ion (Mn02 plus fused K.OH with KNO3, air, etc.). Only stable in basic solution. 

For chemical processes, some examples are the elimination of aromatics by sulfonation, the elimination of olefins by bromine addition on the double bond (bromine number), the elimination of conjugated diolefins as in the case of the maleic anhydride value (MAV), and the extraction of bases or acids by contact with aqueous acidic or basic solutions. 

In the strongly basic medium, the reactant is the phenoxide ion high nucleophilic activity at the ortho and para positions is provided through the electromeric shifts indicated. The above scheme indicates theorpara substitution is similar. The intermediate o-hydroxybenzal chloride anion (I) may react either with a hydroxide ion or with water to give the anion of salicyl-aldehyde (II), or with phenoxide ion or with phenol to give the anion of the diphenylacetal of salicylaldehyde (III). Both these anions are stable in basic solution. Upon acidification (III) is hydrolysed to salicylaldehyde and phenol this probably accounts for the recovery of much unreacted phenol from the reaction. 

This is my version, but may be better done. First one, evaporate methanol, better with vacuum. Then we have two layers similar in volume, we add 100 of solvent and 50 cc of basic solution (sodium carbonate, bicarbonate or 10 % NaOH ). We shake it and may be we will have little more precipitate or tar. Also may be we can t see separation, then w/e add a bit more solvent without shaking to see separation. We make two more extractions with 50 cc of solvent. Even if we can t see separation, we can add enough HCI and shake, this will forme some tar and layers will be distincts, so we can separate and make a basic wash. Sometimes I ve done first an acid wash, but I can t sure it s better. I m thinking now may be is better to do all extraction as Strike s top 3. Add acid solution, like 250 cc (less PdClz and no CuCI) 15% HCI, extract and make a basic wash. 

Alkylation of A-4-thiazoline-2-one may yield O-R or N-R derivatives according to experimental conditions. With diazomethane in ethanol O-raethylation takes place (29. 36. 214). N-Methylation is reported when a basic solution of A-4-thiazoline-2-one reacts with methyl iodide or dimethylsulfate (21, 29, 215, 216), Reaction of l-chloro-2-dimethyl-aminoethane with the sodium salt of 4 R-A-4-thiazoline-2-one (91) in alcohol, first claimed to yield the aminoalkylether (217, 218), was shown after infrared investigation to give the N-substituted derivative (92) (107), even when R Ph (Scheme 45). More probably the site of reaction in... 

The synthesis of sulfides (172) can be carried out by condensing 2-mercaptothiazoles and the required o-bromo compounds in basic solution at room temperature (488). 

Step 1 Hydrogen peroxide is converted to its anion in basic solution... 

Nucleophiles other than Gngnard reagents also open epoxide rings These reac tions are carried out in two different ways The first (Section 16 12) involves anionic nucleophiles in neutral or basic solution... 

Inversion of configuration is observed at the carbon that is attacked by the nucleophile irrespective of whether the reaction takes place m acidic or basic solution... 

Step 1 The aldehyde and its enolate are m equilibrium with each other m basic solution The enolate acts as a nucleophile and adds to the carbonyl group of the aldehyde ... 

Section 19 5 Although carboxylic acids dissociate to only a small extent in water they are deprotonated almost completely m basic solution... 

Section 20 11 Ester hydrolysis m basic solution is called saponification and proceeds through the same tetrahedral intermediate (Figure 20 5) as m acid catalyzed hydrolysis Unlike acid catalyzed hydrolysis saponification is irreversible because the carboxylic acid is deprotonated under the reac tion conditions... 

Section 20 19 The hydrolysis of nitriles to carboxylic acids is irreversible m both acidic and basic solution... 

It IS necessary to keep the acidity of phenols in mind when we discuss prepara tion and reactions Reactions that produce phenols when earned out in basic solution require an acidification step to convert the phenoxide ion to the neutral form of the phenol... 

An alternative approach is to increase the nucleophihcity of the phenol by con verting it to its phenoxide anion m basic solution... 

An OH group affects the UV VIS spectrum of benzene m a way similar to that of an NH2 group but to a smaller extent In basic solution m which OH is converted to 0 however the shift to longer wavelengths exceeds that of an NH2 group... 

Saponification (Section 20 11) Hydrolysis of esters in basic solution The products are an alcohol and a carboxylate salt The term means soap making and denves from the process whereby animal fats were converted to soap by heating with wood ashes... 

The pH of an acidic solution, therefore, must be less than 7.00. A basic solution, on the other hand, will have a pH greater than 7.00. Figure 6.3 shows the pH scale along with pH values for some representative solutions. 

Balance the following redox reactions, and calculate the standard-state potential and the equilibrium constant for each. Assume that the [H3O+] is 1 M for acidic solutions, and that the [OH ] is 1 M for basic solutions. 

Cyanide is frequently used as a masking agent for metal ions. The effectiveness of CN as a masking agent is generally better in more basic solutions. Explain the reason for this pH dependency. 

In reverse-phase chromatography, which is the more commonly encountered form of HPLC, the stationary phase is nonpolar and the mobile phase is polar. The most common nonpolar stationary phases use an organochlorosilane for which the R group is an -octyl (Cg) or -octyldecyl (Cig) hydrocarbon chain. Most reverse-phase separations are carried out using a buffered aqueous solution as a polar mobile phase. Because the silica substrate is subject to hydrolysis in basic solutions, the pH of the mobile phase must be less than 7.5. 

The concentration of nitromethane, CH3NO2, can be determined from the kinetics of its decomposition in basic solution. In the presence of excess base the reaction is pseudo-first-order in nitromethane. For a standard solution of 0.0100 M nitromethane, the concentration of nitromethane after 2.00 s was found to be 4.24 X 10 M. When a sample containing an unknown amount of nitromethane was analyzed, the concentration remaining after 2.00 s was found to be 5.35 X 10 M. What is the initial concentration of nitromethane in the sample ... 

For acidic solutions, balance the hydrogen in each half-reaction by adding H3O+ and H2O to opposite sides of the reaction for basic solutions, add OH and H2O to opposite sides of the reaction. 

When the surface conditions are acidic or the ambient humidity is low enough to affect the cure significantly, a surface accelerator may be used to promote the reaction. Available from most manufacturers, these basic solutions may be dip, wipe, or spray appHed. Recentiy, new additive chemistry has been developed that accelerates the cure under adverse conditions without the need for a separate accelerator. 

The AsF ion is very stable toward hydrolysis in aqueous solution. It is not hydroly2ed by boiling a strongly basic solution almost to dryness (26), although it is hydroly2ed in sulfuric acid (27) or in boiling perchloric acid (26). The hydrolysis of AsF in concentrated sulfuric acid (27) and in base (28) at 193—222°C is first order in AsF . The hydrolysis of AsF in alkaline solution is slower than either PF or SbF . ... 

The extent of the initial hydrolysis depends on temperature and how the water is added. Hydrolysis is reduced at slower addition rates and lower temperatures. The hydrolysis subsequent to the initial fast reaction is slow, presumably because part of the acid is converted to fluorosulfate ions which hydrolyze slowly even at elevated temperatures. The hydrolysis in basic solution has also been studied (17). Under controlled conditions, hydrates of HSO F containing one, two, and four molecules of water have been observed (18,19). 

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