Acids salt formation

The interaction of Ca2+ with pectins is discussed. The role of carboxylic acid salt formation and the degree of polymerization are first considered in terms of electrostatic and/or cooperative specific interactions. Then the effect of the degree of esterification and that of the pattern of carboxylic group distribution are discussed pectin esterase forms blocks which behave as fully hydrolyzed polymers and favor aggregation. Finally, the role of the calcium addition on the degree of aggregation was established. All the data show the important role of molecular structure of the pectins on calcium interactions. 

Reactions of Carboxylic Acids 3.16.2.1 Acidity Salt Formation... 

In conclusion, weakly basic exchangers in the free base form are only usefully functional at low pH when the hydrogen ion concentration is sufficiently high to protonate the resin. Therefore although conceptually useful, it is somewhat fallacious to propose the initially ionized hydroxide form to explain the behaviour of weak base functional groups. Instead their reaction is better regarded as initially one of acid salt formation by a direct addition reaction and then where appropriate subsequent ion exchange, as depicted by equations 4.18-4.20. 

REACTIONS OF CARBOXYUC ACIDS 1. Acidity. Salt formation. Discussed in Secs. 18.4,18.10-18.14. 

Introduction. The object of this experiment is to illustrate a number of general reactions of carboxylic acids. Salt formation is a characteristic property of the carboxyl group. The salts of the alkali metals as a rule are soluble. The higher, sparingly soluble, fatty acids form salts which give colloidal dispersions. The soluble salts are prepared by neutralization of the acid with alkali, or by boiling with an excess of the metallic carbonate and evaporating the solution. 

In addition, final salt-forming steps can introduce genotoxic impurities. Some examples include formation of methyl chloride as a side reaction of hydrochloric acid in methanol, or esters of methanesulfonic acid as the by-product from the methanesulfonic acid salt formation step in alcoholic solvents. ... 

Complexation by the amino acids prior to polymerization alters the kinetics of chain propagation, which is consistent with the presumed catalytic role of the metal in these reactions (57), but amino acid salt formation has further implications from the standpoint of chemical evolution the polymerizations may be performed at temperatures that more closely resemble those found on the Earth s surface. Amino acids form salts with carboxylic acids (e.g. formic and acetic), and these salts tend to melt at lower temperatures than the corresponding amino acid. For example, a nrixtuie of the formate salts of glutamic acid and glycine (analogous to the first Harada-Fox melt, reference 27) fuses at 150°C, and the yield of polymer after foiu hours exceeds the typical yield obtained with the corresponding melt of amino acids. This trend towards lower melting points continues as one increases the number of amino acids in the mixture as a mixture of their formate salt, the Fox-Harada mixture of 16 amino acids (cf. reference 28) is a viscous paste at room temperature. The formation of peptides and ultimately precipitation of macromolecules from a concentrated aqueous solution of amino acid salts can be effected at 50°C. 

Dissolve ca. 0 2 g. of product (I) in cold ethanol, and add with shaking 1-2 drops of dilute sulphuric acid. A deep purple coloration appears at once. This shows that salt formation has occurred on the quinoline nitrogen atom to form the cation (Ha), which will form a resonance hybrid with the quinonoid form tils). [Note that the forms (IIa) and (11b) differ only in electron position, and they are not therefore tautomeric.] If, hoAvever, salt formation had occurred on the dimethylaniino group to give the cation (III), thrs charge separiition could not occur, and the deep colour would be absent. 

Now add more dilute sulphuric acid drop by drop the colour almost completely fades, as salt formation occurs on both nitrogen atoms with suppression of the resonance hybrid formation. 

Phenol condenses with phthahc anhydride in the presence of concentrated sulphuric acid or anhydrous zinc chloride to yield the colourless phenolphthalein as the main product. When dilute caustic alkah is added to an alcoholic solution of phenolphthalein, an intense red colouration is produced. The alkali opens the lactone ring in phenolphthalein and forms a salt at one phenolic group. The reaction may be represented in steps, with the formation of a h3q)othetical unstable Intermediate that changes to a coloured ion. The colour is probably due to resonance which places the negative charge on either of the two equivalent oxygen atoms. With excess of concentrated caustic alkali, the first red colour disappears this is due to the production of the carbinol and attendant salt formation, rendering resonance impossible. The various reactions may be represented as follows ... 

Processes rendered obsolete by the propylene ammoxidation process (51) include the ethylene cyanohydrin process (52—54) practiced commercially by American Cyanamid and Union Carbide in the United States and by I. G. Farben in Germany. The process involved the production of ethylene cyanohydrin by the base-cataly2ed addition of HCN to ethylene oxide in the liquid phase at about 60°C. A typical base catalyst used in this step was diethylamine. This was followed by liquid-phase or vapor-phase dehydration of the cyanohydrin. The Hquid-phase dehydration was performed at about 200°C using alkah metal or alkaline earth metal salts of organic acids, primarily formates and magnesium carbonate. Vapor-phase dehydration was accomphshed over alumina at about 250°C. 

Adipic acid undergoes the usual reactions of carboxyflc acids, including esterification, amidation, reduction, halogenation, salt formation, and dehydration. Because of its biflmctional nature, it also undergoes several industrially significant polymerization reactions. 

Salt Formation. Salt-forming reactions of adipic acid are those typical of carboxylic acids. Alkali metal salts and ammonium salts are water soluble alkaline earth metal salts have limited solubiUty (see Table 5). Salt formation with amines and diamines is discussed in the next section. 

The older methods have been replaced by methods which require less, if any, excess sulfuric acid. For example, sulfonation of naphthalene can be carried out in tetrachloroethane solution with the stoichiometric amount of sulfur trioxide at no greater than 30°C, followed by separation of the precipitated l-naphthalenesulfonic acid the filtrate can be reused as the solvent for the next batch (14). The purification of 1-naphthalenesulfonic acid by extraction or washing the cake with 2,6-dimethyl-4-heptanone (diisobutyl ketone) or a C-1—4 alcohol has been described (15,16). The selective insoluble salt formation of 1-naphthalenesulfonic acid in the sulfonation mixture with 2,3-dimethyl aniline has been patented (17). 

The reactions of oxaUc acid, including the formation of normal and acid salts and esters, are typical of the dicarboxyhc acids class. OxaUc acid, however, does not form an anhydride. 

Pigment Blue 24 [6548-12-5] 42090 1 triarylcarbonium Ba salt (Peacock Blue) condensation of ben2aldehyde-(9-sulfonic acid with /V-ethy1-/V-hen2y1 aniline, followed by sulfonation, oxidation, and salt formation... 

Pigment Red 52, calcium salt [17852-99-2] 15860 BONA (Ca salt) coupling of dia2oti2ed 2-amino-4-methyl-5-chloroben2enesulfonic acid with 3-hydroxy-2-naphthoic acid, foUowed by salt formation... 

Pigment Red 81 [12224-98-5] 45160 1 triarylcarbonium PTMA salt salt formation between Rhodamine 6G with phosphotungstomolybdic acid (PTALA)... 

Pigment Violet 1 [13264)3-0] 45170 2 triarylcarbonium PTMA salt salt formation between Rhodamine B and phosphotungstomolybdic acid... 

Salt formation with Brmnsted and Lewis acids and exhaustive alkylation to form quaternary ammonium cations are part of the rich derivati2ation chemistry of these amines. Carbamates and thiocarbamates are formed with CO2 and CS2, respectively the former precipitate from neat amine as carbamate salts but are highly water soluble. 

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