Hydrolysis mixture

The bottoms from the stripper (40—60 wt % acid) are sent to an acid reconcentration unit for upgrading to the proper acid strength and recycling to the reactor. Because of the associated high energy requirements, reconcentration of the diluted sulfuric acid is a cosdy operation. However, a propylene gas stripping process, which utilizes only a small amount of added water for hydrolysis, has been described (63). In this modification, the equiUbrium quantity of isopropyl alcohol is stripped so that acid is recycled without reconcentration. Kquilibrium is attained rapidly at 50°C and isopropyl alcohol is removed from the hydrolysis mixture. Similarly, the weak sulfuric acid process minimizes the reconcentration of the acid and its associated corrosion and pollution problems. 

The absorbate containing the mixed ethyl sulfates is hydroly2ed with enough water to give an approximately 50—60% aqueous sulfuric acid solution. The hydrolysis mixture is separated in a stripping column to give dilute sulfuric acid bottoms and a gaseous alcohol—ether—water mixture overhead. The overhead mixture is washed with water or dilute sodium hydroxide and then purified by distillation (63,65,66,68,69). 

The submitters did not stir the hydrolysis mixture. The checkers found that, if stirring was omitted, bumping occurred during the reflux period. 

Figure 4. Infrared spectrum of methyl-transrpyrethrate Prepared from pyrethric acid isolated from hydrolysis mixture of pyrethrum concentrate. Pure ester isolated by gas chromatography...

The columns labeled PI reflect the total of pyrethrin I and cinerin I just as in the AO AC procedure. The gas chromatographic results are in terms of the total amount of the mixture but were analyzed as the methyl ester of chrysanthemic acid. The present state of the determination of PII (pyrethrin II plus cinerin II) is not complete because of the erratic extractability of the dicarboxylic acids from the hydrolysis mixture. The gas chromatographic pattern is distinct and straightforward. As the extraction procedure for PII is improved, the gas chromatographic method will be more applicable. The present recovery of PII is in the range of 80 to 90%. The average of the values shown in Table II for PI is 98.0%. 

Note 5) is equipped with a powerful mechanical stirrer and a thermometer and is immersed to a depth of 20 cm. in an ice bath. A mixture of 11. of thiophene-free benzene and 2 1. of 6 A hydrochloric acid is placed in the copper vessel. The above reaction mixture is added to the vigorously stirred contents of the copper can at such a rate that the temperature does not rise above 25° (about two hours is required). When the addition is. complete, the reaction flask is rinsed with a little ice water, and the rinsings are added to the hydrolysis mixture. Stirring is continued for ten minutes longer. The benzene layer is decanted, and the aqueous layer is diluted with 1 1. of ice water. The aqueous layer is extracted with 500 cc. of benzene and is discarded. The combined benzene solutions are washed with 250 cc. of ice-cold hydrochloric acid and are dried for two hours in a stoppered flask over 250 g. of anhydrous calcium chloride. 

Process Hydrolysis mixture Total iron Absorbable iron ... 

The slowing down of enzyme reactions has often been attributed to reaction with, or equilibrium between, the enzyme and its substrate or between the enzyme and the products of its action. In order to determine the influence of the products of the action of pancreatic amylase on the extent of the hydrolysis of starch, portions of its hydrolysis mixtures were subjected to efficient dialysis during hydrolysis and the results compared with aliquots of the reaction mixture which had been treated in the same way except for dialysis.41 The results of such experiments... 

Similarly, the addition of substrate to hydrolysis mixtures that had reached stages of very slow rates of change with dialysis resulted in extensive hydrolysis of the added substrate. Comparisons showed that the new substrate was hydrolyzed to practically the same extent in the same time as the original substrate.41 These findings show not only that active amylase was present but that no appreciable inactivation of the amylase had taken place in the dialyzing hydrolysis mixtures when the... 

Oxidants are occasionally added to the hydrolysis mixture to favor the removal of lignin. For instance, the co-feed of 02 or air appeared beneficial to the deligni-fication efficiency of a lime-catalyzed hydrolysis step [57]. Similar improvements are also reported for the co-feed of H202 to formic or acetic acid hydrolysis [58],... 

Refluxing is a technique that allows substances to be heated for a prolonged period of time without the volatile reactants and/or products escaping into the atmosphere. The hydrolysis mixture is placed in a round-bottomed flask, along with some anti-bumping granules. 

The Smith analysis discussed at the beginning of this Section gives little information on the presence or absence of (1 — 6)-linkages. If, however, the polyalcohol is methylated before hydrolysis, mixtures of mono- and di-methylglycerols and erythritols (or threitols) may be obtained.807,830,631 This method was clearly explained by Bahl and... 

After the mild-hydrolysis step at 70°, the sialic acids liberated are removed from the sample by dialysis or ultrafiltration at 2°, and the macromolecular material is rehydrolyzed, using, however, the stronger acidic conditions of 0.1 M acid. The dialysis time ranges between 6 and 24 h, depending on the volume and viscosity of the hydrolysis mixture. Therefore, the optimum dialysis time should be evaluated by determinations of sialic acid in the eluate, or by addition of a trace of radioactive Nen5Ac. The dialyzates, or filtrates, are combined, and processed as will be described. By using this procedure, the overall yield of purified sialic acids is 70-80%, and the loss of O-acetyl groups107 is 40%. 

The hydrolysis mixture is transferred to a 1-1. round-bottomed flask fitted with a reflux condenser, and 500 ml. of concentrated hydrochloric acid is added (Note 5). The mixture is heated on a steam bath for 1.5-2 hours. The flask is cooled in an ice bath the crystals are collected on a sintered-glass funnel and washed with 200 ml. of ice-cold concentrated hydrochloric acid and then with 200 ml. of ice-cold dry ether. The crude product weighs 50-56 g. The product is dissolved in a mixture of 50 ml. of water and 150 ml. of concentrated hydrochloric acid by boiling under reflux. The tetraphenylarsonium chloride hydrochloride separates when the solution is cooled in an ice bath. The white needles are collected on a sintered-glass funnel and washed with 50 ml. of ice-cold concentrated hydrochloric acid and then with 200 ml. of ice-cold dry ether. The yield of tetraphenylarsonium chloride hydrochloride melting at 204-208° with decomposition is 42-45 g. (74r-80%). 

Hydrolysis of mt/o-inositol l(3),2-cyclic phosphate under acidic or alkaline conditions affords a mixture of myo-inositol l(3)-phosphate and myo-inositol 2-phosphate, with the former preponderating.275 As the cyclic phosphate may be prepared275 from the 2-phosphate, which is itself readily obtained from myo-inositol hexaphosphate by enzymic cleavage,268,276 and as the l(3)-phosphate may be isolated277 from the hydrolysis mixture, the reaction sequence provides a convenient way... 

A small proportion of O-D-glucosylribitol was produced directly by hydrolysis of the teichoic acid with alkali ( see Fig. 16) this product is identical with that obtained by dephosphorylation of the hydrolysis mixture. The major products of such a hydrolysis with alkali were the isomeric monophosphates (58) and (59), in which R = 0-D-glucopyranosyl, both of which gave the O-D-glucosylribitol on enzymic dephosphorylation. The isomer (58) reduced 3 molar proportions of periodate, and the ribitol residue was oxidized, whereas the isomer (59) reduced 2 molar proportions of periodate, the ribitol residue being resistant to oxidation. Small proportions of the diphosphates (56) and (57) were also produced. Oxidation of the diphosphate (57) with periodate, followed by treatment with alkali to remove the aldehydic residues, gave a ribitol diphosphate. 

Formation of hydroxo-bridged complexes by hydrolysis in aqueous solution is, not surprisingly, the most common preparative method. As a rule, such reactions give quite complex product mixtures containing species with different nuclearities, each of which may be present in many isomeric forms. The fact that most of the preparative procedures employed lead to the isolation of one single and pure isomer probably more often reflects favorable solubility properties rather than stereospecificity. In some cases ion-exchange chromatography has been used to isolate the polynuclear species, but systematic analysis of hydrolysis mixtures by this technique has been reported for only a few systems. 

By acidifying the hydrolysis mixture with sulfuric acid and by fractionating the product, Curtius procured anhydrous hydrazoic as a colorless liquid which boils at 37°. Hydrazoic acid is intensely poisonous and bad smelling. It is easily exploded by flame, by a brisant explosive, or by contact with metallic mercury. The anhydrous substance is extremely dangerous to handle, but dilute solutions have been distilled without accident. 

The equilibrium reactions for alkoxysilane hydrolysis mixtures are given in equations (l)-(3). Data on equilibrium constants for these reactions have not been reported. 

A series of studies were conducted to define parameters related to reactivity, solubility, and stability of alkoxysilane hydrolysis mixtures for the purpose of generating model compounds stable in water solution and maintaining coupling agent activity. 

Glidine, a commercial diabetic food which is prepared from wheat flour and contains over go per cent of protein, may be used as a satisfactory source of glutamic acid. If this is used, it is not necessary to wash in order to remove the starch. From 1130 g. of this material, by hydrolyzing with 2500 cc. of concentrated hydrochloric acid and working up as before, 275-285 g. of glutamic acid hydrochloride may be obtained. Usually, the product from glidine is more difficult to decolorize. It has been found that an ether extraction of the hydrolysis mixture, after removal of the melanin, improves the color of the final product. 

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