Acid hydrolysis products phase

The third aspect of improvement may mean an entirely different process for making an old substance. For many decades soap has been manufactured by caustic soda saponification of fats in the batch process. In recent years plants have been installed for the high pressure, high temperature rapid hydrolysis of fats in the countercurrent liquid mixed phase using water and a catalyst. In this case the sodium fatty acid or the soap may be prepared by neutralizing the free fatty acid hydrolysis product with caustic soda or soda ash depending upon convenience and the market. Naturally the unit consumption factors changed when the improved process was used. 

Figure 2. Direct analysis by capillary GC of the acid hydrolysis products of a dlmethyloctyl lOum silica phase, using C5 dimer as an Internal standard. The smaller unidentified peaks were from the Internal standard and from slight Impurities in the hexane extractant. Instrumental and reaction conditions are described In the experimental section.

Hydroxides. The hydrolysis of uranium has been recendy reviewed (154,165,166), yet as noted in these compilations, studies are ongoing to continue identifying all of the numerous solution species and soHd phases. The very hard uranium(IV) ion hydrolyzes even in fairly strong acid (- 0.1 Af) and the hydrolysis is compHcated by the precipitation of insoluble hydroxides or oxides. There is reasonably good experimental evidence for the formation of the initial hydrolysis product, U(OH) " however, there is no direct evidence for other hydrolysis products such as U(OH) " 2> U(OH)" 2> U(OH)4 (or UO2 2H20). There are substantial amounts of data, particulady from solubiUty experiments, which are consistent with the neutral species U(OH)4 (154,167). It is unknown whether this species is monomeric or polymeric. A new study under reducing conditions in NaCl solution confirms its importance and reports that it is monomeric (168). 8olubihty studies indicate that the anionic species U(OH) , if it exists, is only of minor importance (169). There is limited evidence for polymeric species such as Ug(OH) " 25 (1 4). 

It has been found that the tris(tert-butyloxycarbonyl) protected hydantoin of 4-piperidone 2, selectively hydrolyses in alkali to yield the N-tert-butyloxycarbonylated piperidine amino acid 3. The hydrolysis, which is performed in a biphasic mixture of THF and 2.0M KOH at room temperature, cleanly partitions the deprotonated 4-amino-N -(tert-butyloxycarbonyl)piperidine-4-carboxylic acid into the aqueous phase of the reaction with minimal contamination of the hydrolysis product, di-tert-butyl iminodicarboxylate, which partitions into the THF layer. Upon neutralization of the aqueous phase with aqueous hydrochloric acid, the zwitterion of the amino acid is isolated. The Bolin procedure to introduce the 9-fluorenylmethyloxycarbonyl protecting group efficiently produces 4.8 This synthesis is a significant improvement over the previously described method9 where the final protection step was complicated by contamination of the hydrolysis side-product, di-tert-butyl iminodicarboxylate, which is very difficult to separate from 4, even by chromatographic means. 

Chromatographic characterisation of hydrolysis products Hydrolysis products from sodium polypectate were analysed by thin-layer chromatography on silica gel G-60, using ethyl acetate / acetic acid / formic acid / water (9 3 1 4, by volume) as the mobile phase system. Sugars were detected with 0,2% orcinol in sulphuric add-methanol (10 90ml) [14]. 

The superiority of extractive hydrolysis over acid hydrolysis with respect to its productivity, yield, raw materials, and waste streams, for the transformation of drug intermediates (e.g. for Primaxin) in formate ester form to the corresponding alcohol, has been effectively demonstrated by King et al. (1985). They carried out the hydrolysis of the relevant formate ester with simultaneous extraction of the desired product from the undesired impurities by two-phase reaction/extraction with a base. 

The concept of extractive reaction, which was conceived over 40 years ago, has connections with acid hydrolysis of pentosans in an aqueous medium to give furfural, which readily polymerizes in the presence of an acid. The use of a water-immiscible solvent, such as tetralin allows the labile furfural to be extracted and thus prevents polymerization, increases the yield, and improves the recovery procedures. In the recent past an interesting and useful method has been suggested by Rivalier et al. (1995) for acid-catalysed dehydration of hexoses to 5-hydroxy methyl furfural. Here, a new solid-liquid-liquid extractor reactor has been suggested with zeolites in protonic form like H-Y-faujasite, H-mordenite, H-beta, and H-ZSM-5, in suspension in the aqueous phase and with simultaneous extraction of the intermediate product with a solvent, like methyl Aobutyl ketone, circulating countercurrently. 

Acetochlor and its metabolites are extracted from plant and animal materials with aqueous acetonitrile. After filtration and evaporation of the solvent, the extracted residue is hydrolyzed with base, and the hydrolysis products, EMA and HEMA (Figure 1), are steam distilled into dilute acid. The distillate is adjusted to a basic pH, and EMA and HEMA are extracted with dichloromethane. EMA and HEMA are partitioned into aqueous-methanolic HCl solution. Following separation from dichloromethane, additional methanol is added, and HEMA is converted to methylated HEMA (MEMA) over 12 h. The pH of the sample solution is adjusted to the range of the HPLC mobile phase, and EMA and MEMA are separated by reversed phase HPLC and quantitated using electrochemical detection. 

In order to elucidate the causes of the increased stability of the hydrolyzed cluster ions compared with the unhydrolyzed ions, further studies were made of the behaviour of [Te2X8]3 (where X = Cl,Br, or I) in solutions of hydrogen halides [43,52,80,87]. The studies were performed mainly in relation to the most stable and most readily synthesized [Tc2C18]3- ion (Fig. la) kinetic methods with optical recording were employed. The identity of the reaction products was in most cases confirmed by their isolation in the solid phase. The studies showed that the stability of the [Tc2X8]3 ions (where X = Cl, Br, or I) in aqueous solutions is determined by the sum of competing processes acid hydrolysis complex formation with subsequent disproportionation and dissociation of the M-M bonds, and oxidative addition of atmospheric oxygen to the Tc-Tc multiple bond. 

Deacylation [16], hydrolysis with 47% aqueous hydrofluoric acid (HF) and phase partition of the reaction products [1], and acetolysis [17] were performed as described in the literature. 

The hydrolysis half-life in three different natural waters was approximately 48 d at 25 °C (Macalady and Wolfe, 1985). At 25 °C, the hydrolysis half-lives were 120 d at pH 6.1 and 53 d at pH 7.4. At pH 7.4 and 37.5 °C, the hydrolysis half-life was 13 d (Freed et al, 1979). At 25 °C and a pH range of 1-7, the hydrolysis half-life was about 78 d (Macalady and Wolfe, 1983). However, the alkaline hydrolysis rate of chlorpyrifos in the sediment-sorbed phase were found to be considerably slower (Macalady and Wolfe, 1985). In the pH range of 9-13, 3,5,6-trichloro-2-pyridinol and 0,0-diethyl phosphorothioic acid formed as major hydrolysis products (Macalady and Wolfe, 1983). The hydrolysis half-lives of chlorpyrifos in a sterile 1% ethanoFwater solution at 25 °C and pH values of 4.5, 5.0, 6.0, 7.0, and 8.0 were 11, 11, 7.0, 4.2, and 2.7 wk, respectively (Chapman and Cole, 1982). 

Friedman, M., Levin, C. E. (1992). Reversed-phase high-performance liquid chromatographic separation of potato glycoalkaloids and hydrolysis products on acidic columns. J. Agric. Food Chem., 40, 2157-2163. 

For the cleavage reaction two methods have been described ozonolysis at —78 °C, which can be used to recycle the chiral information (137), or acid hydrolysis in a two-phase system. No racemization of the product ketone was observed under these conditions. 

Reactive crystallization, or precipitation, has been investigated by numerous research groups. Processes of industrial relevance include liquid-phase oxidation of para-xylene to terephthalic acid, the acidic hydrolysis of sodium salicylate to salicylic acid, and the absorption of ammonia in aqueous sulfuric acid to form ammonium sulfate (60). A very special type of reactive crystallization is diastereomeric crystallization, widely applied in the pharmaceutical industry for the resolution of enantiomers (61). Another fine example of reactive precipitation is the earlier-described production of nano-size particles of CaC03 in high-gravity fields (46). 

The effect of sulfuric acid is remarkable, since the absence of sulfuric acid results in a mixture of benzylic chlorides Ig (25%), Ih (20%), and the starting material la (34%) together with complex compounds (20%). Notably, the two-phase electrolysis procedure brings about no hydrolysis products on either the thiazoline or the beta-... 

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