Acids, dibasic

They are formed by heating dibasic acids or their anhydrides with ammonia. The hydrogen atom of the NH group is acidic and can be replaced by a metal. Mild hydrolysis breaks the ring to give the half amide of the acid. See succinimide and phthalimide. 

H0S(0)200S(0)20H. Dibasic acid formed as salts by electrolysis of sulphates at low temperatures and high current density. The acid and persulphates are strong oxidizing agents ( "[S20a] to S04 -t-2 01 volts in acid) but the reactions are often slow. Compare permonosulphuric acid. 

Phosphorous acid, H3PO3, HP(0)(0H)2-A dibasic acid (PCI3 plus cold water), strong reducing agent. 

It is a dibasic acid, and forms stable metallic salts. Distillation with soda lime gives benzene. Readily dehydrated to phthalic anhydride. Its reactions are similar to phthalic anhydride in which form it is almost invariably used. 

The solution obtained when sulphur dioxide dissolves in water has long been thought to contain unionised sulphurous acid, H2SO3, but more probably contains hydrated sulphur dioxide (cf. NHj solution, p. 217). The solution behaves as a dibasic acid, i.e. 

Concentrated sulphuric acid displaces more volatile acids from their salts, for example hydrogen chloride from chlorides (see above) and nitric acid from nitrates. The dilute acid is a good conductor of electricity. It behaves as a strong dibasic acid ... 

Although some dibasic acids, e.g, succinic acid and phthalic acid, readily lose water on heating with the formation of cyclic anhydrides, most monobasic... 

Ammonium salt of any acid Acid amides Acid nitriles Imides of dibasic acids... 

This is an example of the reduction of an ester of a dibasic acid to the corre spending glycol (Bouveault-Blanc reduction) ... 

By pyrolysis of dibasic acids or their salts to yield cyclic ketones. The slow distillation of adipic acid with about. 5 per cent, of baryta affords cyclo-pentanone in good yield ... 

By hydrolysis of substituted malonic esters with 50 per cent, potassium hydroxide, followed by decarboxylation of the resulting malonic add by heating above the m.p. or, better, by rendering the aqueous solution of the potassium salt of the dibasic acid strongly acid and refluxing the mixture, for example ... 

Place 1 0 g. of the monobasic acid and 2 g. of aniline or p-toluidine in a dry test-tube, attach a short air condenser and heat the mixture in an oil bath at 140-160° for 2 hours do not reflux too vigorously an acid that boils below this temperature range and only allow steam to escape from the top of the condenser. For a sodium salt, use the proportions of 1 g. of salt to 1 5 g. of the base. If the acid is dibasic, employ double the quantity of amine and a reaction temperature of 180-200° incidentally, the procedure is recommended for dibasic acids since the latter frequently give anhydrides with thionyl chloride. Powder the cold reaction mixture, triturate it with 20-30 ml. of 10 per cent, hydrochloric acid, and recrystallise from dilute alcohol. 

Certain dibasic acids, of which the sodiuna or potassiuna salts are sparingly osluble in dilute alcohol, cause difficulty these should be neutralised with ethylamine solution. 

Anhydrides of dibasic acids (succinic or glutaric acid type) may be prepared ... 

Sometimes a large proportion of sulphuric acid is employed (see below under esters of dibasic acids). The good yields thus obtained are partially due to the removal of water by the acid as well as to the catalytic effect. 

This procedure is speedy, economical, and employs materials which are readily available. It is not satisfactory for esters of dibasic acids. 

The catalyst, which may be regarded as complementary to Raney nickel (Section VI,5) is largely used for the hydrogenation of esters (esters of monobasic and of dibasic acids to alcohols and glycols respectively) ... 

This preparation illustrates the use of the copper-chromium oxide catalyst in the r uotion of esters of dibasic acids to glycols ... 

Polyfunctional molecules (glycols, dibasic acids, hydroxy acids, diamides, etc.). 

Polyamides from diamines and dibasic acids. The polyamides formed from abphatic diamines (ethylene- to decamethylene-diamine) and abphatic dibasic acids (oxabc to sebacic acid) possess the unusual property of forming strong fibres. By suitable treatment, the fibres may be obtained quite elastic and tough, and retain a high wet strength. These prpperties render them important from the commercial point of view polyamides of this type are cabed nylons The Nylon of commerce (a 66 Nylon, named after number of carbon atoms in the two components) is prepared by heating adipic acid and hexamethylenediamine in an autoclave ... 

Division III. Heterocyclic compounds (Heterocyclic stem nuclei). The carbon atoms are joined in closed rings which include one or more other kinds of atoms as ring components. Anhydrides and imides of dibasic acids, as well as lactones, lactams, etc. are thus included in this division... 

In contrast, equilibrium properties have been successfully discussed in terms of the field effect. Notable instances are those of the ionisation constants of saturated dibasic acids, - and of carboxyl groups held in... 

Unsaturated Polyesters. Unsaturated polyesters are produced by reaction between two types of dibasic acids, one of which is unsaturated, and an alcohol to produce an ester. Double bonds in the body of the unsaturated dibasic acid are obtained by using maleic anhydride or fumaric acid. 

Acetamide has been used experimentally as a source of nonprotein nitrogen for sheep and dairy cattie (13). It does not appear to be toxic in amounts of about 2—3% of ration. Buffering the diet with dibasic acids serves to allow higher levels of intake because the ammonia Hberated in the digestive process is then scavenged. 

Crystallization and Purification Solvent. Dimethylacetamide is useful ia the purification by crystallization of aromatic dicarboxyHc acids such as terephthahc acid [100-21-0] and/vcarboxyphenylacetic acid [501-89-3]. These acids are not soluble ia the more common solvents. DMAC and dibasic acids form crystalline complexes containing two moles of the solvent for each mole of acid (16). Microcrystalline hydrocortisone acetate [50-03-3] having low settling rate is prepared by crystallization from an aqueous DMAC solution (17). 

The hydroxyl groups can be esterified normally the interesting diacrylate monomer (80) and the biologicaky active haloacetates (81) have been prepared in this manner. Reactions with dibasic acids have given polymers capable of being cross-linked (82) or suitable for use as soft segments in polyurethanes (83). Polycarbamic esters are obtained by treatment with a diisocyanate (84) or via the bischloroformate (85). 

Other by-products formed are relatively easy to separate, including esters of higher unsaturated monobasic acids (alkyl 3-pentenoate and 3,5-heptadienoate) (5) and esters of multiply-unsaturated dibasic acids, eg, suberates. 

Other constituents may be added to assist in the formation of uniform beads or to influence the use properties of the polymers through plasticization or cross-linking. These include lubricants, such as lauryl or cetyl alcohol and stearic acid, and cross-linking monomers such as di- or trivinylbenzene, diaHyl esters of dibasic acids, and glycol dimethacrylates. 

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