Carboxyl groups acidity

THE NITRO AND CARBOXYL GROUPS ACID AND BASE STRENGTHS... 

Suppose that the end group is a carboxyl group acidic enough to be titrated with NaOH. If Ns moles of NaOH is needed to titrate the i-molecules, then the total moles of NaOH required to titrate the mixture will be... 

The discovery of lithium aluminum hydride and similar compounds has made possible the direct reduction of the carboxyl group. Acid chlorides, esters, and anhydrides are similarly reduced to primary alcohols. Lactones are converted to diols." The reaction takes place readily at room temperature. The compound to be reduced is added to an ethereal solution of the reagent, and the resulting alcoholate is hydrolyzed by acid. 

Depending upon the number of carboxyl groups, acids can be classified as monocarboxylic acids or polycarboxylic acids. 

Some of the physical and chemical properties of carboxylic acids are dependent upon the polarity of the carboxyl group. Acid molecules can form strong hydrogen bonds with each other and as a result carboxylic acid molecules can form dimers. 

The basic mechanisms are well known.The nucleophilic species undergoes addition at the carbonyl group, followed by elimination of the halide or carboxylate group. Acid halides and anhydrides are reactive acylating reagents because of a... 

In this chapter, we study five classes of organic compounds, each related to the carboxyl group acid halides, acid anhydrides, esters, amides, and nitriles. 

Humic constituents of alluvia and soils are very effective trapping material and remove uranium from natural waters. Their structure is only broadly known. They are insoluble at acid pH and soluble in alkaline medium. Their molecule consist of a polyaromatic skeleton that carries phenolic hydroxyl and carboxyl groups. Acidic hydrogen of the carboxyl group is exchanged with the uranyl ion this process is so effective that very high enrichment factors may be obtained. 

These compounds are named by lUPAC rules like those for the aldehydes, except that the ending on the stem name is -oic followed by the word acid. Many carboxylic acids have been known for a long time and are usually referred to by common names (see Table 24.8). The carboxylic acids are weak acids because of the acidity of the H atom on the carboxyl group. Acid-ionization constants are about 10 . ... 

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. 

The aliphatic acids are all soluble in cold water. The aromatic acids are very sparingly soluble in cold water, but readily soluble in boiling water. Phthalic acid, having two carboxyl groups, is more soluble than the other aromatic acids in cold water. 

Heating the acids or their salts with soda lime eliminates the carboxyl group, volatile products being often detectable. 

Physical Properties. Glycine is a colourless crystalline solid soluble in water. Owing to the almost equal opposing effects of the amino and the carboxylic groups. its aqueous solution is almost neutral (actually, slightly acidic to phenolphthalein) and glycine is therefore known as a neutral ampholyte. f It exhibits both acidic and basic properties. 

Vigorous oxidation of a monosaccharide (e.g., with dUute nitric acid) produces carboxyl groups at both ends of the chain. Thus galactose gives the sparingly soluble mucic acid glucose affords the soluble saccharic acid, which is best isolated as the sparingly soluble acid potassium salt. 

There are complications in applying the Hinsberg test to certain amines containing hydroxyl, nitro and carboxyl groups, e.g., p-N-methylamiiiobenzoic acid CHjNHC.HjCOOH (I 4) may behave in this test as a primary amine (soluble in alkali) so that it is essential to consider the properties of the original compound in conjunction with the results of the test. 

Salicylic acid. The preparation of salicylic acid by passing carbon dioxide into dry sodium phenoxide at 170-190° is the classical example of the Kolbe-Schmltt reaction. The latter is a method for introducing a carboxyl group directly into a phenol nucleus. 

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