Carboxylate salts amides, hydrolysis

As with hydrolysis of carboxylic esters, amide hydrolysis requires the presence of a strong acid or base, and the nature of the final products depends on which of these reactants is used. Notice in the following examples that under acidic conditions, the salt of the amine is produced along with the carboxylic acid, and under basic conditions, the salt of the carboxylic acid is formed along with the amine. Also, notice that heat is required for the hydrolysis of amides. 

As we have indicated in Section 23-12, amide hydrolysis can be an important route to amines. Hydrolysis under acidic conditions requires strong acids such as sulfuric or hydrochloric, and temperatures of about 100° for several hours. The mechanism involves protonation of the amide on oxygen followed by attack of water on the carbonyl carbon. The tetrahedral intermediate formed dissociates ultimately to the carboxylic acid and the ammonium salt ... 

Saponification is the base-mediated hydrolysis of an ester, yielding its component carboxylate salt and alcohol. Ammonolysis of esters gives amides. Esters react with Grignard reagents to give tertiary alcohols. With lithium aluminum hydride, on the other hand, they are reduced to primary alcohols. 

The mechanism for basic hydrolysis begins with attack by hydroxide on the electrophilic carbon of the cyano group. Protonation gives the unstable enol tautomer of an amide. Removal of a proton from oxygen and reprotonation on nitrogen gives the amide. Further hydrolysis of the amide to the carboxylate salt involves the same base-promoted mechanism as that already discussed. 

Ring-Opening Polymerization. Polyamides can be formed by ringopening reactions as in the polymerization of caprolactam. The polymerization may be carried out at high temperature with water, amino acid, or amine carboxylate salt as Initiator. The predominate ring-opening mechanism with these initiators is carboxyl-catalyzed aminolysls. In the case of water initiation, hydrolysis occurs (Reaction 10) to form small amounts of the amino acid. The amino acid then reacts with lactam amide groups (Reaction 11). 

Hydrolysis of amides in base requires similarly vigorous conditions. Hot solutions of hydroxide are sufficiently powerful nucleophiles to attack an amide carbonyl group, although even when the tetrahedral intermediate has formed NH2 (pfC of the ammonium ion 35) has only a slight chance of leaving when HO j)K of water 15) is an alternative. Nonetheless, at high temperatures amides are slowly hydrolysed hy concentrated base since one product is the carboxylate salt and this does not react with nucleophiles. The base for the irreversible step might be hydroxide or NH. ... 

Amides undergo hydrolysis in acidic conditions to yield a carboxylic acid and an amine salt Hydrolysis under basic conditions produces a carboxylate salt and an amine. 

In aqueous base, the products of amide hydrolysis are a carboxylic acid and ammonia or an amine. Base-catalyzed hydrolysis is driven to completion by the acid-base reaction between the carboxylic acid and base to form a salt. One mole of base is required per mole of amide ... 

The protecting acetyl group is removed by acid-catalyzed hydrolysis to generate the hydrochloride salt of the product, sulfanilamide. Note that of the two amide linkages present, only the carboxylic acid amide (acetamido group) was cleaved, not the sulfonic acid amide (sulfonamide). The salt of the sulfa drug is converted to sulfanilamide when the base, sodium bicarbonate, is added. 

The acid-catalyzed hydrolysis of butanamide proceeds as expected to give butanoic acid, 7. An example is the acid-catalyzed hydrolysis of the tertiary amide iV,iV-diethyl-3-phenylpentanamide (34) to give 3-phenylpentanoic acid (35). The initial product is iV,AT-diethylamine, but under the acid-catalyzed conditions, the basic amine reacts to form the observed product, ammonium salt, 36. Secondary and primary amides react in an identical manner the leaving group is an amine for the secondary amide, but it is ammonia for the primary amide. Acid hydrolysis of pentanamide, for example, gives pentanoic acid and ammonia (NHg) and, under acid conditions, the ammonia is converted to the ammonium ion (NH4+). When amides are heated with aqueous hydroxide, the products are the salt of the carboxylic acid and the amine. Acid hydrolysis of the carboxylate salt generates the acid, as with saponification. 

In base, the nucleophilic hydroxide ion adds to the carbon-nitrogen triple bond (Fig. 18.46). Protonation on nitrogen and deprotonation from oxygen leads to the amidate anion, which is protonated to give an intermediate amide. Basic hydrolysis of the intermediate amide leads to the carboxylate salt. 

Information in the literature does not indicate how closely the experimental times and. temperatures have approached the minimal values. There is reason to believe that, once the reaction to form the amide is complete, continued heating of the mkture produces little further change except for the slow hydrolysis of the amide to ammonium carboxylate salt. In the absence of specific information about optimum conditions with individual compounds, it is probably safest to err on the side of an overly long reaction period. 

Amides undergo hydrolysis when water is added to the amide bond to split the molecule. When an acid is used, the hydrolysis products of an amide are the carboxylic acid and the ammonium salt. In base hydrolysis, the amide produces the carboxylate salt and ammonia or an amine. 

In the hydrolysis of the amide, the amide bond is broken between the carboxyl carbon atom and the nitrogen atom. When a base such as NaOH is used, the products are the carboxylate salt and an amine. 

Hydrolysis of an amide by a base produces the carboxylate salt and an amine. 

When a carbonyl group is bonded to a substituent group that can potentially depart as a Lewis base, addition of a nucleophile to the carbonyl carbon leads to elimination and the regeneration of a carbon-oxygen double bond. Esters undergo hydrolysis with alkali hydroxides to form alkali metal salts of carboxylic acids and alcohols. Amides undergo hydrolysis with mineral acids to form carboxylic acids and amine salts. Carbamates undergo alkaline hydrolysis to form amines, carbon dioxide, and alcohols. 

Hydrolysis of amide groups to carboxylate is a major cause of instability in acrylamide-based polymers, especially at alkaline pH and high temperatures. The performance of oil-recovery polymers may be adversely affected by excessive hydrolysis, which can promote precipitation from sea water solution. This work has studied the effects of the sodium salts of acrylic acid and AMPS, 2-acrylamido-2-methylpropanesulfonic acid, as comonomers, on the rate of hydrolysis of polyacrylamides in alkaline solution at high temperatures. Copolymers were prepared containing from 0-53 mole % of the anionic comonomers, and hydrolyzed in aqueous solution at pH 8.5 at 90°C, 108°C and 120°C. The extent of hydrolysis was measured by a conductometric method, analyzing for the total carboxylate content. 

Additional work was carried out by the GE group on optimization of the reaction yield and to eliminate unwanted linear oligomers [14], Three side reactions which interfere with synthesis of cyclics were identified reaction of the amine with acid chloride to form an acyl ammonium salt, followed by decomposition to an amide (Equation (3.2)) reaction with CH2CI2 to form a salt (Equation (3.3)) hydrolysis of the acid chloride, forming carboxylate via catalysis... 

A) The acid hydrolysis of an amide produces a carboxylic acid and an amine. (B) The basic hydrolysis of an ester produces the salt of a carboxylic acid and an alcohol. 

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