Hydrolysis, acid, carbohydrates esters

Carbohydrate lactones have been used as the carbonyl reagent in the Reformatsky reaction. Thus, 2,3 5,6-di-O-cyclohexylidene-D-mannono-1,4-lactone [44, obtained by oxidation of the mannofuranose derivative (49)] reacted with ethyl bromoacetate and zinc to give the protected 2-deoxy-3-octulosonic acid ethyl ester (45a) in 69% yield (50). Ketonic hydrolysis with potassium hydroxide in aqueous methanol, followed by acidification and heating, afforded the 1-deoxyheptulose derivative 45b. Similarly, starting from compound 44, the 1-C-substituted allyl and propar-gyl lactols were prepared on reaction with allyl or propaigyl bromides in the presence of zinc (51). 

The related reaction foro-nttrobenzyl esters results in hydrolysis of the ester, and this has been developed for use in the protection of alcohols, carboxylic acids and amines. For example, the C-1 hydroxyl group in carbohydrates can be protected as its o-njtrobenzyl ester, and the ester group removed under the very mild conditions of irradiation in neutral solution (5.51). Similarly, the carboxylic acid... 

A third wax subfraction (soluble in both ether and alcohol) was shown to be a mixture of glycerides, carbohydrate esters of fatty acids, and true waxes. Alkaline hydrolysis gave glycerol and the carbohydrate as the water-soluble constituents. The carbohydrate yielded only inositol and D-mannose on hydrolysis with dilute mineral acid. 

For the partial synthesis, a regio- and stereoselective reaction is required, in which a bond with defined stereochemistry is formed exclusively between the carboxylic acid and the carbohydrate at the anomeric carbon atom. Due to the polyene system and the ease of the hydrolysis of the ester bond at the anomeric carbon atom, the application of protecting groups on the carbohydrate is restricted. Therefore a method using unprotected carbohydrates has been developed. Crocetin-di(P-D-glucosyl) ester (543) was synthesized in 70% yield by the reaction of crocetin-diimidazolide (4) or crocetin-di(l,2,4-triazolide) (5) and unprotected p-D-glucose in pyridine in the presence of a base [5]. The esterification takes place exclusively at the anomeric carbon atom and produces only the p-anomer [6]. The method was also applied to 8 -apo-P-caroten-8 -oic acid (486) and to other carbohydrates [7]. 

Catalyze the hydrolysis of carbohydrates, Upids, proteins, or phosphoric acids esters by breaking single bond and add water across bond... 

It is industrially produced by the acid-catalysed hydrolysis of carbohydrates such as cellulose or starch. The global production of levulinic aid is very small (<3,000 t/a), the acid is used as a solvent in the ethyl ester form and in small niche markets [16]. 

Various investigations have supplied ample experimental justification for the analogy drawn by Brown and Todd between simple hydroxylated dialkyl phosphoric esters and polynucleotides. With the object of applying classical methods of carbohydrate chemistry, yeast ribonucleic acid was methylated, and the carbohydrates obtained after hydrolysis were examined.200- 201 D-Ribose and mono-O-methyl- and di-O-methyl-D-riboses were... 

Hydrolysis can detoxify a wide range of aliphatic and aromatic organics such as esters, ethers, carbohydrates, sulfonic acids, halogen compounds, phosphates, and nitriles. It can be conducted in simple equipment (in batches in open tanks) or in more complicated equipment (continuous flow in large towers). However, a potential disadvantage is the possibility of forming undesirable reaction products. This possibility must be evaluated in bench- and pilot-scale tests before hydrolysis is implemented. 

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