Hydrolysis, acetal amide

Insight into the factors that govern breakdown of tetrahedral intermediates has also been gained by studying the hydrolysis of amide acetals. If the amine is expelled, an ester is formed, whereas elimination of an alcohol gives an amide ... 

The toxicity of the acaricide 2-fluoro-A-methyl-A-(naphth-l-yl)acet-amide (MNFA) (4.152) to mammals is related to its hydrolysis. In this case, however, toxicity was mainly due to the acid formed. Indeed, the 2-fluoro-acetic acid (4.153) liberated by hydrolysis was further metabolized to fluoro-citrate, which inhibits the tricarboxylic acid cycle [101]. 

Digestion is the breakdown of bulk food in the stomach and small intestine. Hydrolysis of amide, ester and acetal bonds yields amino acids, fatty acids, and simple sugars. 

Hydrolysis of amides may be carried out in acid or alkaline medium. For example, the former is used for a-phenylbutyric acid (90%) and the latter for 2- and 4-dibenzofurylacetic acids (87%). ° A mixture of hydrochloric and acetic acids is employed for insoluble amides. Amides obtained... 

Figure 8 The effect of mild acid hydrolysis on amides in HMW DOM. Two potentially important classes of biochemicals that likely contribute to HMW DOM are (poly)-N-acetyl amino sugars (top) and proteins (bottom). Mild acid hydrolysis of (poly)-iV-acetyl amino sugars will yield free acetic acid, but will not depolymerize the polysaccharide. The generation of acetic acid will be accompanied by a shift in the N-NMR from amide to amine. In contrast, mild acid hydrolysis of proteins does not yield acetic acid, but may depolymerize the protein macromolecular segments to yield free amino acids. Free amino acids can be quantified by chromatographic techniques and compared to the shift from amide (protein) to amine (free amino acid) in N-NMR.

Pd on polyvinyl alcohol, 244 Hydrogenolysis, 187, 241 Hydrolysis, acetal, 108 amide, 212... 

Amides are compounds derived from carboxylic acids and amines, involving elimination of water (similar to ester formation from acids and alcohol). Amide functional groups are quite resistant to hydrolysis, and amide linkages between amino acids and peptides are essential to the stability of proteins. Acetaminophen, a well-known anti-inflammatory drug, is a simple amide formed from 4-hydroxy-phenylamine and acetic acid. 

The hydrolysis of amides substituted by tert-alkyl occurs under the action of sulfuric acid with the abstraction of the tert-alkyl group and formation of nonsubstitut-ed amide and tertiary alcohol. N-tert-butylamides of formic and acetic acids are hydrolyzed in such a way. 

Most of the studies on the effects of metallomicelles on the rate of hydrolysis of esters involve so-called activated esters in which nucleophilic attack is the rate-determining step. The effects of copper-containing metallomicelles (formed from both copper(II)-hydrophobic ligand complex as well as from hydrophobic ligand [L = Af,Af,M-trimethyl-Ai -tetradecylethylenediamine] containing free ions) on the rate of hydrolysis of amides 19 and 20 as well as activated esters 21, 22, and 23 have been stndied at pH 7.0 and 31°C. The apparent rate enhancements (kj i) of Cn +(L) metallomicelles on the rate of hydrolysis of 19 to 23, 2-nitrophenyl acetate (2-NPA), and 4-nitrophenyl acetate (4-NPA) under various reaction conditions are summarized in Table 6.4." The actual rate enhancements due to metallomicelles, Cu +(L), under various reaction conditions are not possible to estimate because of the lack of pseudo-first-order rate constants (kobs) for hydrolysis of 19 to 23, 2-NPA, and 4-NPA in the presence of Cu -A7V,A 7V -tetramethylethylenediamine complex. However, the values of k,, for 19 and 20 are almost same at 0.002-M Cu +(L) and 0.002 M Cu +(L) + 0.001-M Triton. The presence of 0.001-Af CTABr comicelles has no effect on k, for 20 but decreases kj i from 46 to 29 for 19 (Table 6.4), which may be attributed to larger cationie mixed micellar affinity of anionic 19 than that of neutral 20. 

Hydrolysis may be effected with 10-20 per cent, sodium hydroxide solution (see p-Tolunitrile and Benzonitrile in Section IV,66) or with 10 per cent, methyl alcoholic sodium hydroxide. For diflScult cases, e.g., a.-Naphthoniirile (Section IV,163), a mixture of 50 per cent, sulphuric acid and glacial acetic acid may be used. In alkahne hydrolysis the boiling is continued until no more ammonia is evolved. In acid hydro-lysis 2-3 hours boiling is usually sufficient the reaction product is poured into water, and the organic acid is separated from any unchanged nitrile or from amide by means of sodium carbonate solution. The resulting acid is identified as detailed in Section IV,175. 

We should distinguish between the phrases nucleophilic attack and nucleophilic catalysis. Nucleophilic attack means the bond-forming approach by an electron pair of the nucleophile to an electron-deficient site on the substrate. In nucleophilic catalysis this results in an increase in the rate of reaction relative to the rate in the absence of the catalyst. However, nucleophilic attack may not result in catalysis. Thus, if methylamine is reacted with a phenyl acetate, the reaction observed is amide formation, not hydrolysis, because the product of the nucleophilic attack is more stable than is the ester to hydrolysis. 

Hydrolysis of the amide 720 gave the acid 721. Boiling 721 in acetic acid for a prolonged period gave the dihydrofuro[3,4-6]quinoline 722 whose possible mechanism of formation is shown in Scheme 125 (85JCS(P1)1897). 

A heterocyclic ring may be used in place of one of the benzene rings without loss of biologic activity. The first step in the synthesis of such an agent starts by Friedel-Crafts-like acylation rather than displacement. Thus, reaction of sulfenyl chloride, 222, with 2-aminothiazole (223) in the presence of acetic anhydride affords the sulfide, 224. The amine is then protected as the amide (225). Oxidation with hydrogen peroxide leads to the corresponding sulfone (226) hydrolysis followed by reduction of the nitro group then affords thiazosulfone (227). ... 

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