Carboxylic acids examples

On treatment with the appropriate nucleophile an acyl chlonde may be converted to an acid anhydride an ester an amide or a carboxylic acid Examples are presented m Table 20 1... 

Aldehydes, therefore, can also be oxidised to carboxylic acids. Example... 

Oxidative cleavage of alkynes by a variety of reagents has been reviewed [35, 60, 70, 71]. In most cases the CC bond is broken, but in some cases a-diketones are formed instead of, or in addition to, carboxylic acids. Examples of both types of reaction are given in Tables 3.3 and 3.6. 

Isocyanates of the general structure shown in Figme 2.2 react vigorously with amines, alcohols, and carboxylic acids. Examples will be discussed later in this chapter. Table 2.1 presents the relative reaction rates of some of the molecules we will use to design our own polymers. 

Ruthenium tetroxide oxidizes an alcohol to furnish an aldehyde. However, the oxidation does not stop at this stage. As soon as the corresponding aldehyde hydrate has been formed from the aldehyde at equilibrium—which is ensured by the high water content in the reaction mixture—the oxidation continues to form the carboxylic acid (example Figure 17.12). Mecha-... 

Acidification of the reaction mixture produces a carboxylic acid. Examples are provided in the following equations ... 

Primary alcohols are oxidized to aldehydes or acids, and secondary alcohols are oxidized to ketones. Tertiary alcohols resist oxidation, unless they are dehydrated in acidic media to alkenes, which are subsequently oxidized. The conversion of alcohols into carbonyl compounds can be achieved by catalytic dehydrogenation or by chemical oxidation. Catalytic dehydrogenation is especially of advantage with primary alcohols, because it prevents overoxidation to carboxylic acids. Examples are tabulated in equations 223-227 and 265-268. 

Replacement of H in H3PO4 by a radical R gives substituted phosphoric acids 0P(0H)20R and OP(OH)(OR)2 and finally the phosphoric ester, OP(OR)3. The structure of dibenzylphosphoric acid, HP02(0CH2C6Hs)2, was described in Chapter 8 the molecules are linked in pairs by O-H-0 bonds as in dimers of carboxylic acids. Examples of mono- and di-substituted ions are the phenyl-phosphate ion, (h), studied in the K salt, and the diethylphosphate ion, (i), in the Ba salt, and of an ester, triphenylphosphate,... 

Carboxylic acids that contain a double bond in their structure are called unsaturated carboxylic acids. Examples of these acids are propenoic acid, 2-methylpropenoic acid, trans-2-butenoic acid, cis-2-butenoic acid. 

Carboxylic acids examples of mono-, di- and polybasic acids... 

Other mixtures of water and organic solvents have also been proposed to titrate some other poorly soluble carboxylic acids. Examples are water/DMF and water/acetone. The indicators used are bromothymol blue and phenolphthalein. 

The reagent will selectively protect the amino group in the presence of alcohols and phenols as well as carboxylic acids. Examples include the Boc protection of a kanamycin A derivative (eq 4) and of the glycopeptide antibiotic A41030A (eq 5). ... 

A selection of important anionic surfactants is displayed in table C2.3.1. Carboxylic acid salts or tire soaps are tire best known anionic surfactants. These materials were originally derived from animal fats by saponification. The ionized carboxyl group provides tire anionic charge. Examples witlr hydrocarbon chains of fewer tlran ten carbon atoms are too soluble and tliose witlr chains longer tlran 20 carbon atoms are too insoluble to be useful in aqueous applications. They may be prepared witlr cations otlrer tlran sodium. 

A pletliora of different SA systems have been reported in tire literature. Examples include organosilanes on hydroxylated surfaces, alkanetliiols on gold, silver, copper and platinum, dialkyl disulphides on gold, alcohols and amines on platinum and carboxyl acids on aluminium oxide and silver. Some examples and references can be found in [123]. More recently also phosphonic and phosphoric esters on aluminium oxides have been reported [124, 125]. Only a small selection out of tliis number of SA systems can be presented here and properties such as kinetics, tliennal, chemical and mechanical stability are briefly presented for alkanetliiols on gold as an example. 

As an example, the empirical formula of phenylalanine may be split into a more extended form that shows the presence of a phenyl ring, as well as an amino and a carboxylic acid group (the condensed form in Figure 2-4). 

This reaction applies to many i,2 diketones, and is termed the Benzilic Acid Rearrangement. It provides a ready method for the preparation of disubstituted a4iydroxy-carboxylic acids. When applied to a cyclic 1,2-diketone, the ring system is necessarily reduced by one carbon atom for example, cyclohexan-i,2 ... 

A further example is given below illustrating the use of a dibasic anhydride (succinic anhydride) the succinoylation reaction is a valuable one since it leads to aroyl carboxylic acids and ultimately to polynuclear hydrocarbons. This general scheme of synthesis of substituted hydrocarbons through the use of succinic anhydride is sometimes called the Haworth reaction. Thus a-tetralone (see below) may be reduced by the Clemmensen method to tetralin (tetrahydronaphthalene) and the latter converted into naphthalene either catal3d.ically or by means of sulphur or selenium (compare Section, VI,33). 

The melting points of some typical substituted aromatic amides are collected in Table IV,192. Other examples will be found in the appropriate columns of Tables IV,100A and B Primary and Secondary Aromatic Amines) and of Table IV,175 (Aromatic Carboxylic Acids). 

This is an example of the Doebner synthesis of quinoline-4-carboxylic acids (cinchoninic acids) the reaction consists in the condensation of an aromatic amine with pyruvic acid and an aldehj de. The mechanism is probably similar to that given for the Doebner-Miller sj nthesis of quinaldiiie (Section V,2), involving the intermediate formation of a dihydroquinoline derivative, which is subsequently dehydrogenated by the Schiff s base derived from the aromatic amine and aldehyde. 

The presence of certain substituents e.g., the amino group) may markedly affect the solubibty and other properties of the sulphonic acid or carboxylic acid. Thus such sulphonic acids as the aminobenzenesul-phonic acids, pyridine- and quinoline-sulphonic acids exist in the form of inner salts or zwitter-ions that result from the interaction of the basic amino group and the acidic sulphonic acid. Sulphanilic acid, for example, is more accurately represented by formula (I) than by formula (II) ... 

The reaction of trivalent carbocations with carbon monoxide giving acyl cations is the key step in the well-known and industrially used Koch-Haaf reaction of preparing branched carboxylic acids from al-kenes or alcohols. For example, in this way, isobutylene or tert-hutyi alcohol is converted into pivalic acid. In contrast, based on the superacidic activation of electrophiles leading the superelectrophiles (see Chapter 12), we found it possible to formylate isoalkanes to aldehydes, which subsequently rearrange to their corresponding branched ketones. 

In order for the transferability of parameters to be a good description of the molecule, force fields use atom types. This means that a sp carbon will be described by different parameters than a. sp - carbon, and so on. Usually, atoms in aromatic rings are treated differently from sp atoms. Some force fields even parameterize atoms for specific functional groups. For example, the carbonyl oxygen in a carboxylic acid may be described by different parameters than the carbonyl oxygen in a ketone. 

A classical way to achieve regioselectivity in an (a -i- d -reaction is to start with a-carbanions of carboxylic acid derivatives and electrophilic ketones. Most successful are condensations with 1,3-dicarbonyl carbanions, e.g. with malonic acid derivatives, since they can be produced at low pH, where ketones do not enolize. Succinic acid derivatives can also be de-protonated and added to ketones (Stobbe condensation). In the first example given below a Dieckmann condensation on a nitrile follows a Stobbe condensation, and selectivity is dictated by the tricyclic educt neither the nitrile group nor the ketone is enolizable (W.S. Johnson, 1945, 1947). 

Silylation of alcohols, amines and carboxylic acids with hydrosilanes is catalyzed by Pd catalysts[l 19], Based on this reaction, silyl protection of alcohols, amines, and carboxylic acids can be carried out with /-butyldimethylsilane using Pd on carbon as a catalyst. This method is simpler and more convenient than the silylation with /-butyldimethylsilyl chloride, which is used commonly for the protection. Protection of P-hydroxymethyl-(3-lactam (125) is an example 120]. 

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). 

Decarboxylation of 2-thiazolecarboxyIic acids occurs readily (49). 5-carboxylic acids can also be decarboxylated without difficulty (50). but 4-thiazolecarboxylic acids are relatively stable (7. 38). For example,... 

Two aldehydes two ketones or one aldehyde and one ketone may be formed Let s recall the classes of carbonyl compounds from Table 4 1 Aldehydes have at least one hydrogen on the carbonyl group ketones have two carbon substituents—alkyl groups for example—on the carbonyl Carboxylic acids have a hydroxyl substituent attached to the carbonyl group... 

Carboxylic acids are exceedingly difficult to reduce Acetic acid for example is often used as a solvent in catalytic hydrogenations because it is inert under the reaction con ditions A very powerful reducing agent is required to convert a carboxylic acid to a pri mary alcohol Lithium aluminum hydride is that reducing agent... 

Fischer esterification is reversible and the position of equilibrium lies slightly to the side of products when the reactants are simple alcohols and carboxylic acids When the Fis cher esterification is used for preparative purposes the position of equilibrium can be made more favorable by using either the alcohol or the carboxylic acid m excess In the following example m which an excess of the alcohol was employed the yield indicated IS based on the carboxylic acid as the limiting reactant... 

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