Alkaline saponification

Example 4.3. The p value for alkaline saponification of methyl esters of substituted benzoic acids is 2.38, and the rate constant for saponification of methyl benzoate under the conditions of interest is 2 x 10 s . Calculate the rate constant for the hydrolysis... 

Generally, alkaline saponification in hydroalcoholic KOH is the most widespread approach [11 13]. This allows us to cleave ester bonds and, if necessary, to separate the saponifiable fraction (acids) and unsaponificable fraction (alcohols, sterols, and hydrocarbons). Generally, 3 h of saponification in 10% KOH in water/methanol (3 1) at 60 °C achieves a quantitative yield for triglycerides. Wax esters are less prone to hydrolysis and generally need stronger conditions. Quantitative hydrolysis of beeswax long chain esters has been obtained using 10% KOH in ethanol assisted by microwaves, for 60 min at 80 °C and at 200 W [21],... 

JA Maclaren. Amino acids and peptides. V. The alkaline saponification of A-benzy-loxycarbonyl peptide esters. Aust J Chem 11, 360, 1958. 

This procedure illustrates a general method for the selective splitting of a carbomethoxy group in the presence of easily hydrolyzed esters of other alcohols, such as the easily hydrolyzed equatorial acetoxy group. The specificity of the reaction is not affected by steric hindrance, and a highly hindered methyl ester can be split in the presence of other less hindered esters of secondary alcohols. Normal alkaline saponification goes in exactly the opposite way. 

After alkaline saponification, each reaction mixture was divided into three portions %bich were treated as follows 1) Absorbent polymer was methanol-precipitated as is with no adumiium chloride treatment. These products served as controls and provided absorbency vadues that could be conpared with absorbencies presented in earlier tables. 2) Absorbent polymer was methanol-precipitated aifter addition of either 15, 12.5, or 10 g of AlCls 6H20 to the saponiflcate. 3) Polymer was methanol precipitated after adding aduminum chloride followed by an amount of s um hydroxide solution equivalent to that needed to convert alumirum chloride to aduminum hydroxide. Wicking as well as absorbency was then determined both as is and aifter treatment with HCl in methanol to neutralize excess alkali. 

Anionic polymerization proceeds by acyl-oxygen cleavage for almost all lactones, consistent with the mechanism for alkaline saponification of esters [Duda and Penczek, 2001 Hofman et al., 1985 Kricheldorf et al., 1988], For example, initiation by methoxide ion proceeds as... 

C3 H, 04 mw 104.06. One of the products of the alkaline saponification of NC and nitro-oxycellulose (Ref 1). Berl and Smith (Ref 3) obtained it, calling it oxypyruvic acid, by the alkaline hydrolysis, not only of NC, but also of nitrates of glucose and levulose... 

Table IV gives the Rf values determined under these conditions. Figure 3 shows the chromatograms of the reaction products of the re-esterification of a number of plasticizers. It is obvious that the method is suitable for identifying the alcohol components of all frequently used ester types. Difficulties have been met with phenolic components although they are present primarily in phosphoric acid esters. To identify these, evaporate to dryness a few drops of the reaction mixture of an alkaline saponification and mix this with a bit of the precipitated alkali salt. Add this residue to 10 to 20 drops of chloroform and gradually evaporate it repeat...

Table IV. Alkaline Saponifications. Properties of Saponified Dispersions...

Alkaline Saponifications in Water. A suspension of 1.0 g of starch-g-PAN or starch-PAN physical mixture in 9 ml of 0.711 sodium hydroxide (in a 25 ml Erlenmeyer flask) was heated on a steam bath for 5-10 min until the mixture thickened sufficiently to preclude settling. Reactions with either starch or PAN... 

Alkaline Saponifications in Aqueous Ethanol. A solution of 2 g of 50% sodium hydroxide in 4.44 ml of water and 4.44 ml of 95% ethanol was prepared, and 1 g of either starch-g-PAN or starch-PAN physical mixture was added. Reactions with starch or PAN homopolymer were run with 0.5 g of polymer. The mixture was heated under reflux for 3 hr, and the resulting reaction mass was dispersed in water, dialyzed, and analyzed as described for saponifications in water. Saponifications run at higher ethanol water ratios were carried out in a similar manner. 

The influence of sample pretreatment by alkaline saponification and oxidation by K2Cr207 in acetic acid, and the influence of the solvent and addition of haloacetic acids (e.g., trichloroacetic acid required for... 

One trf the most popular methods of synthesizing anhydro derivative of monosaccharide containing a-oxide rings is the alkaline saponification sugar tosylates (5). We have studied the possibility of... 

Another type of cellulose anhydro derivative, a mixed polysaccharide containing glucose and 3,6-anhydroglucose units, has been synthesized by the alkaline saponification of cellulose tosylate (V) tl,12) and 6-0-tosyl-2,3-di-0-acetylcellulose (VI) 13) ... 

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