Carboxylic acids hydrolysis

Carboxylic acid derivative (Section 20 1) Compound that yields a carboxylic acid on hydrolysis Carboxylic acid de nvatives include acyl chlondes acid anhydndes esters and amides... 

KEY TERMS amide hydrolysis carboxylic acid amine... 

Synthesis of 210 was started from preparation of chiral diamine 211 (Scheme 50) [172], In particular, D-serine methyl ester was converted to iV-benzyl derivative 212, which was transformed into carboxylic acid 212 using reaction with chloroacetyl chloride and subsequent hydrolysis. Carboxylic acid 212 was subjected to coupling with benzyl amine, reduction, reaction with ethyl oxalyl chloride and reductive cyclization to give bicyclic compound 213. Finally, 211 Two-step reduction of 213 led to the formation of diamine 211, which was isolated as dihydrochloride. Reaction of 211 with dichloro derivative 215 and then - hydrazine hydrate gave the product 216, which was coupled with carboxylic acid 217 and subjected to catalytic hydrogenation to give 210. 

Figure 3-5. The search for a) oxidations of primary alcohols to carboxylic acids will obtain reaction b) as a hit, although this reaction is in reality a hydrolysis of an ester, c) The correct specification of the query to obtain reactions invoivingthe oxidation of aicohols to carboxyiic acids.

Hydrolysis of Acetonitrile. Nitriles, like acid amides, undergo hydrolysis to give the corresponding carboxylic acid and ammonia. Consequently... 

The action of esterases consists essentially in the hydrolysis (or synthesis) of carboxylic acid esters according to the equation ... 

A further improvement is embodied in the Klndler variation of the Willgerodt reaction this consists in heating the ketone with approximately equal amounts of sulphur and a dry amine instead of aqueous ammonium polysulphide. The principal product is a thioamide, and hydrolysis with acid or alkali affords the carboxylic acid, usually in good yield. 

Inspired by the many hydrolytically-active metallo enzymes encountered in nature, extensive studies have been performed on so-called metallo micelles. These investigations usually focus on mixed micelles of a common surfactant together with a special chelating surfactant that exhibits a high affinity for transition-metal ions. These aggregates can have remarkable catalytic effects on the hydrolysis of activated carboxylic acid esters, phosphate esters and amides. In these reactions the exact role of the metal ion is not clear and may vary from one system to another. However, there are strong indications that the major function of the metal ion is the coordination of hydroxide anion in the Stem region of the micelle where it is in the proximity of the micelle-bound substrate. The first report of catalysis of a hydrolysis reaction by me tall omi cell es stems from 1978. In the years that... 

The first was proposed by Iraoto and Otsuji (511) and Otsuji et al (512) and concerned the pK of substituted 2-, 4-, and 5-carboxylic acids and the alkaline hydrolysis rate k of their respective ethyl esters (259, 260, and 261, where Y = Et). When Hammett cr , values were used for... 

The most widely used method for the preparation of carboxylic acids is ester hydrolysis. The esters are generally prepared by heterocyclization (cf. Chapter II), the most useful and versatile of which is the Hantzsch s synthesis, that is the condensation of an halogenated a- or /3 keto ester with a thioamide (1-20). For example ethyl 4-thiazole carboxylate (3) was prepared by Jones et al. from ethyl a-bromoacetoacetate (1) and thioformamide (2) (1). Hydrolysis of the ester with potassium hydroxide gave the corresponding acid (4) after acidification (Scheme 1). 

Hydrolysis of ethyl 4-methyl-2,5-thiazole dicarboxylate (9) or dicar-boxylic acid dichloride gives an excellent yield of 4-methyl-5 thiazole carboxylic acid (10) instead of the dicarboxylic acid (Scheme 6). This lability is a general Property of 2-thiazolecarboxylic acids. 

Aldehydes are easily oxidized to carboxylic acids under conditions of ozonide hydroly SIS When one wishes to isolate the aldehyde itself a reducing agent such as zinc is included during the hydrolysis step Zinc reduces the ozonide and reacts with any oxi dants present (excess ozone and hydrogen peroxide) to prevent them from oxidizing any aldehyde formed An alternative more modem technique follows ozone treatment of the alkene m methanol with reduction by dimethyl sulfide (CH3SCH3)... 

Converting aldehydes and ketones to cyanohydrins is of synthetic value for two reasons (1) a new carbon-carbon bond is formed and (2) the cyano group in the prod uct can be converted to a carboxylic acid function (CO2H) by hydrolysis (to be discussed in Section 19 12) or to an amine of the type CH2NH2 by reduction (to be discussed m Section 22 9)... 

SYNTHESIS OF CARBOXYLIC ACIDS BY THE PREPARATION AND HYDROLYSIS OF NITRILES... 

Primary and secondary alkyl halides may be converted to the next higher carboxylic acid by a two step synthetic sequence involving the preparation and hydrolysis of nitriles Nitnles also known as alkyl cyanides are prepared by nucleophilic substitution... 

Nitrile groups m cyanohydrins are hydrolyzed under conditions similar to those of alkyl cyanides Cyanohydrin formation followed by hydrolysis provides a route to the preparation of a hydroxy carboxylic acids... 

This chapter differs from preceding ones in that it deals with several related classes of compounds rather than just one Although the compounds may encompass sev eral functional group types they share the common feature of yielding carboxylic acids on hydrolysis and for this reason are called carboxylic acid derivatives... 

Hydrolysis (Section 20 4) Acyl chlorides react with water to yield carboxylic acids In base the acid is converted to its carbox ylate salt The reaction has little prepara tive value because the acyl chloride is nearly always prepared from the carboxyl ic acid rather than vice versa... 

Hydrolysis (Section 20 6) Acid anhydrides react with water to yield two carboxylic acid func tions Cyclic anhydrides yield di carboxylic acids... 

FIGURE 20 3 An acid cat alyzes the hydrolysis of a carboxylic acid anhydride by increasing the rate of the first stage of the mecha nism The faster the tetra hedral intermediate is formed the faster the rate of hydrolysis... 

Fats and oils are naturally occurring mixtures of glycerol tnesters Fats are mixtures that are solids at room temperature oils are liquids The long chain carboxylic acids obtained from fats and oils by hydrolysis are known as fatty acids... 

Once formed the tetrahedral intermediate can revert to starting materials by merely reversing the reactions that formed it or it can continue onward to products In the sec ond stage of ester hydrolysis the tetrahedral intermediate dissociates to an alcohol and a carboxylic acid In step 4 of Figure 20 4 protonation of the tetrahedral intermediate at Its alkoxy oxygen gives a new oxonium ion which loses a molecule of alcohol m step 5 Along with the alcohol the protonated form of the carboxylic acid arises by dissocia tion of the tetrahedral intermediate Its deprotonation m step 6 completes the process... 

To isolate the carboxylic acid a separate acidification step following hydrolysis is nec essary Acidification converts the carboxylate salt to the free acid... 

Ester hydrolysis in base is called saponification, which means soap making Over 2000 years ago the Phoenicians made soap by heating animal fat with wood ashes Animal fat is rich m glycerol triesters and wood ashes are a source of potassium car bonate Basic hydrolysis of the fats produced a mixture of long chain carboxylic acids as their potassium salts... 

Mechanistically amide hydrolysis is similar to the hydrolysis of other carboxylic acid derivatives The mechanism of the hydrolysis m acid is presented m Figure 20 7 It proceeds m two stages a tetrahedral intermediate is formed m the first stage and disso ciates m the second... 

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