Benzamide, hydrolysis

Bacillus macerans, starch degradation by 194 Bacillus sublilis protease [enzyme] 82 bacterial polysaccharides 220-1, 255 benzamide, hydrolysis of 204... 

Hydrolysis of Benzamide. When acid amides are hydrolysed, the corresponding acid and ammonia are formed. Consequently the hydrolysis, which is extremely slow with water alone, is hastened con-... 

Benzamide from Benzonitrile. (A) Although benzonitrile when boiled with 70% sulphuric acid undergoes ready hydrolysis to benzoic acid (see above), treatment with hot 90% sulphuric acid gives the intermediate benzamide. This difference arises partly from the difference in temperature employed, but also... 

The hydrolysis by alkali is illustrated by the following experimental details for benzamido. Place 3 g. of benzamide and 50 ml. of 10 per cent, sodium hydroxide solution in a 150 ml. conical or round-bottomed flask equipped with a reflux condenser. Boil the mixture gently for 30 minutes ammonia is freely evolved. Detach the condenser and continue the boiling in the open flask for 3-4 minutes to expel the residual ammonia. Cool the solution in ice, and add concentrated hydrochloric acid until the mixture is strongly acidic benzoic acid separates immediately. Leave the mixture in ice until cold, filter at the pump, wash with a little cold water and drain well. RecrystaUise the benzoic acid from hot water. Determine the m.p., and confirm its identity by a mixed m.p. test. 

The nucleophiles used are OH (32) [the 2-hydroxythiazole can also be obtained by acidic hydrolysis with strong mineral acids (33)], OR" (5, 8, 30, 34), SR" (8, 9, 12), ArSH (35), and amines (4, 7, 14, 33). Benzamide also reacts with 2-bromothiazole, yielding 2-benzamidothiazole (36). Sulfonamide also reacts with 2-halogenothiazoles in presence of a base and copper powder, yielding 2-sulfonamidothiazoles (37, 38). 

Reaction 12, the acid-catalyzed hydrolysis of substituted benzamides, has p = — 0.22, so the reaction is modestly facilitated by electron-donating groups. This suggests that protonation of the amide is kinetically important ... 

Acetoxymetbyl)benzamide (AMB). Cleavage is initiated by ester hydrolysis. 

Acid anhydride-diol reaction, 65 Acid anhydride-epoxy reaction, 85 Acid binders, 155, 157 Acid catalysis, of PET, 548-549 Acid-catalyzed hydrolysis of nylon-6, 567-568 of nylon-6,6, 568 Acid chloride, poly(p-benzamide) synthesis from, 188-189 Acid chloride-alcohol reaction, 75-77 Acid chloride-alkali metal diphenol salt interfacial reactions, 77 Acid chloride polymerization, of polyamides, 155-157 Acid chloride-terminated polyesters, reaction with hydroxy-terminated polyethers, 89 Acid-etch tests, 245 Acid number, 94 Acidolysis, 74 of nylon-6,6, 568... 

These reactions involve a diazonium ion (see 12-47) and are much faster than ordinary hydrolysis for benzamide the nitrous acid reaction took place 2.5 x lo times faster than ordinary hydrolysis. Another procedure for difficult cases involves treatment with aqueous sodium peroxide. In still another method, the amide is treated with water and f-BuOK at room temperature. " The strong base removes the proton from 107, thus preventing the reaction marked k j. A kinetic study has been done on the alkaline hydrolyses of A-trifluoroacetyl aniline derivatives. Amide hydrolysis can also be catalyzed by nucleophiles (see p. 427). 

Amides can also be deacylated by partial reduction. If the reduction proceeds only to the carbinolamine stage, hydrolysis can liberate the deprotected amine. Trichloroac-etamides are readily cleaved by sodium borohydride in alcohols by this mechanism.237 Benzamides, and probably other simple amides, can be removed by careful partial reduction with diisobutylaluminum hydride (see Section 5.3.1.1).238... 

Now that steric parameters have been introduced in this way, the treatment can be extended to include the reactions of o-substituted benzene derivatives as well. Thus for the acid-catalysed hydrolysis of o-substituted benzamides (43), the value of 8 is found to be 0-81 so this reaction is apparently slightly less susceptible to the steric... 

Scheme 1.1 Hydrolysis of benzamide. The first published example (1986) of microwave-assisted organic synthesis.

Capon et al., 1978. No reference bimolecular reaction is available, but o-cyanobenzoic acid is hydrolysed over 10 times faster than phthalamic acid (A.3.9), although benzonitrile is less reactive than benzamide towards acid hydrolysis. [Rate constants for hydrolysis are (1-2) x 10 s for benzonitrile in 1 M acid (Hyland and O Connor, 1973) and 3.5 x 10-4 dm3 mol-1 s 1 for benzamide (Bender et al., 1958), both measured at 100°]... 

That benzamide itself (4.61) undergoes hydrolysis was shown many years ago. Indeed, it is converted in rabbits to benzoic acid, which is then excret-... 

In contrast to the aforementioned monosubstitutions, much less is known about the effect of disubstitution. It appears that such benzamides are resistant to hydrolysis. The metabolic fate of nitromide (3,5-dinitrobenzamide, 4.63), a chicken-feed additive for the prevention of coccidosis, was investigated in rats. The metabolite 3-amino-5-nitrobenzoic acid (4.64), formed by ni-tro reduction and hydrolysis, was excreted in only trace amounts. Nitromide was metabolized mainly via nitro reduction [36], Similarly, no hydrolysis was... 

The simplest structures in this series are A-methyl- and A-ethylbenz-amide (4.73 and 4.74, respectively). When administered intraperitoneally in rats, these amides yielded methylamine and ethylamine, respectively, plus benzoic acid, which was detected in the urine as hippuric acid [47]. An alternative metabolic pathway is possible, involving A-dealkylation to the primary amide followed by hydrolysis its contribution, if any, must be minor, since benzamide levels in urine were negligible. 

Other examples of secondary benzamides include the therapeutic class of orthopramides, which are, again, markedly resistant to hydrolysis. Thus, hydrolysis of the amide bond is a minor metabolic pathway in humans for the antiemetic drug metoclopramide (4.76) [49]. Clebopride (4.77), an anti-dopaminergic agent, was found to be hydrolyzed to a limited extent in rabbit liver homogenates and in dogs to 4-amino-5-chloro-2-methoxybenzoic acid (4.78) and to the amine 4.79 [48] [50], Attempts to detect in vivo formation of this metabolite in rats, rabbits, or humans were not successful [50],... 

Tertiary benzamides whose N-atom is part of a cyclic system can also be hydrolyzed metabolically as shown in the following examples. The hydrolysis of the amide group in 6-[4-(3,4-dimethoxybenzoyl)piperazin-l-yl]-3,4-di-hydro-1 //-quinolin-2-one (OPC-8212, 4.85), an inotropic agent, occurred in rats, mice, dogs, monkeys, and humans [54], After oral administration to rats, both products of hydrolysis, namely 3,4-dimethoxybenzoic acid (veratric acid, 4.86) and piperazine-l//-quinolin-2-one (4.87) were detected in the plasma, urine, and feces. 

Having discussed amides that carry an aromatic group on either the nitrogen or the carboxy side of the amide bond (i.e., anilides or benzamides, respectively), we continue our presentation with compounds in which the amide bond links two aromatic systems. The simplest structure in this class is A-phenylbenzamide (4.154). The influence of the nature and position of substitution on the rate of hydrolysis of a series of A-phenylbenzamides was investigated in mouse and sheep liver homogenates, with the goal of elucidating the metabolism of the anthelminthic niclosamide (4.158) [102],... 

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