Tribasic carboxylic acids

Many molecules act as ciosslinking iniliatots. Crosshnkages are formed by epichlorohydtin (70), vinyl sulfone (71), dibasic and tribasic carboxylic acids (72), cyanuric chloride (73), tripolyphosphates (74) and trimetaphosphates (75) to name only a few. Aldehydes, such as formaldehyde (76) and acetaldehyde (77), also have been used to connect starch polymers. These crosslinking reactions usually are conducted on an alkaline starch slurry at moderate temperatures (20° to 50°C). 

Cross-linkages - phosphate esters, crosslinkages using epichlorohydrin, vinyl sulfone, dibasic and tribasic carboxylic acids, cyanuric chloride, tripolyphosphates, formaldehyde, and acetaldehyde... 

Esters of aliphatic di- and tribasic carboxylic acids occur frequently as aroma components in alcoholic beverages. Because these compounds are mildly odored, they are apparently not very significant aroma factors. In addition to aliphatic fatty acid esters, several hydroxyl- and oxo-acid esters have been determined by GC/MS. Unlike the fatty acid esters, the esters of hydroxyl and oxo acids are slightly volatile compounds. However, they do not play an important role in the formation of the odor. 

Carboxylic acids with one acid group are known as monobasic acids while those with two acid groups are dibasic acids. All acids with more than one acid group are in the class of polybasic acids. The simplest organic acid, formic acid, is responsible for the irritation of bee and ant stings. Vinegar is a 5% solution of acetic acid in water. The acetic acid is responsible for the characteristic sour taste. Citric acid, found in citrus fruits and used in soft drinks, is a tribasic acid with three carboxylic acid groups. The dibasic acid, adipic acid, is a major component of nylon. 

Typical simple carboxylic acids are the monobasic ethanoic acid, CH3COOH, and benzoic acid, CeHsCOOH. Succinic acid is an example of a dibasic acid, and citric acid a tribasic acid. 

Kraft, A., Reichert, A., Kleppinger, R. (2000), Supramolecular liquid crystals with columnar mesophases through self-assembly of carboxylic acids aroimd a tribasic core. Chemical Communications, 12,1015-16. 

Maleic acid and fumaric acid can also be, and are often, incorporated in alkyd resins in the form of the Diels-Alder adduct of rosin. The adducts are tribasic acids which provide pendent carboxyl groups in the resin molecules, which can be saponified to give ionic, and, in turn, water-soluble characteristics to the resin. However, the resultant alkyds often have poorer color retention, toughness, gloss retention, and exterior durabiUty. 

IR and NMR spectra of basic lead carboxylates used as heat stabilisers for halogenated polymers, e.g. PVC, indicated that these salts were not complexes, or double compounds of lead oxide, as suggested in most textbooks, but unique compounds of interesting structure. Stabilisers studied included monobasic lead phthalate, tribasic lead maleate, tetrabasic lead fumarate, dibasic lead phthalate and dibasic lead stearate. Lead stabilisers probably functioned in these polymers by converting hydrogen chloride to water, interfering with acid catalysis of the elimination reaction. 6 refs. 

Kolbe s formula is closely related to the modern formula shown, proposed by Salet/ who said the acid is tetratomic but tribasic , the hydroxyl hydrogen being more difficult to replace than the carboxyl hydrogen. 

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