Salt formation

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. 

Oxonium salt formation. Shake up 0 5 ml. of ether with 1 ml. of cone. HCl and note that a clear solution is obtained owing to the formation of a water-soluble oxonium salt. Note that aromatic and aliphatic hydrocarbons do not behave in this way. In general diaryl ethers and alkyl aryl ethers are also insoluble in cone. HCl. 

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 ... 

Von Baeyer (Nobel Prize, 1905) should be credited for having recognized in 1902 the saltlike character of the compounds formed. He then suggested a correlation between the appearance of color and salt formation—the so-called halochromy. Gomberg (who had just shortly before discovered the related stable triphenylmethyl radical), as well as Walden, contributed to the evolving understanding of the structure of related cationic dyes such as malachite green. 

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. 

In module II (Fig. lb) a crystallization vessel, jacketed and coimected to cooling water, is added. Thus the salt formation step, which may require heating, is separated from the crystallization (qv), which is completed upon cooling. Using module II a substantially iacreased production capacity can be achieved at only a minor additional capital investment. 

Tertiary amines have been shown to react with isocyanates ia an analogous fashion to form ureas (41—43). Similarly, a2iridines (three-membered rings containing nitrogen) are found to react with isocyanates to yield cycHc ureas. Tertiary amines have also been shown to form labile dipolar 1 1 adducts with isocyanates reminiscent of salt formation. In contrast, formaldehyde acetal aminals form iasertion products with sulfonyl isocyanates (44,45). 

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). 

Ammonium chloride [12125-02-9], ammonium sulfate [7783-20-2], and diammonium phosphate [7708-28-0] have also been used for shale stabilization (102,103). Ammonium ions have essentially the same effect on shales as potassium ions but use of ammonium salts is often objectionable because of the alkaline nature of the mud. In the North Sea and northern Europe, where magnesium-bearing salt formations ate encountered, magnesium chloride [7786-30-3] is used, but in the United States it is used only on a small scale. 

Pigment Blue 1 [1325-87-7] 42595 2 triarylcarbonium PTMA salt (Victoria Blue B) condensation of 4,4 -bis-A/A/-dimethyl aminoben2ophenone with /V-ethyl-1-naphthylamine, followed by oxidation and salt formation... 

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... 

The second difficulty, degradation, required the development of a two-step polyamidation process following salt formation (157). During salt formation, tetramethylenediammonium adipate salt is formed in water solution at approximately 50% concentration or at a higher concentration in a suspension. As in nylon-6,6 manufacture, this salt solution, when diluted, permits easy adjustment of the stoichiometry of the reactants by means of pH measurement. 

In the presence of an anionic surfactant such as sodium dodecyl-benzenesulfonate [25155-30-0] any protonated amine salt present forms an insoluble salt (4). Salt formation results in an increase in the pH of the solution. 

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. 

Salt Formation. Amines react with inorganic and organic acids. 

Salt Formation and Metal Chelation, Most a-ainiao acids form salts in alkaline and acidic aqueous solutions (88). For example, a-amino acids form inner complex salts with copper. 

Salt Formation. As a weaMy basic pyrimidine and a thiazolium cation, thiamine forms both mono- and dipositive salts, eg, the two commercial... 

Reactions of the carboxyl group include salt and acid chloride formation, esterification, pyrolysis, reduction, and amide, nitrile, and amine formation. Salt formation occurs when the carboxyUc acid reacts with an alkaline substance (22)... 

Chemical Properties. Like neopentanoic acid, neodecanoic acid, C2QH2QO2, undergoes reactions typical of carboxyHc acids. For example, neodecanoic acid is used to prepare acid chlorides, amides (76), and esters (7,11,77,78), and, like neopentanoic acid, is reduced to give alcohols and alkanes (21,24). One area of reaction chemistry that is different from the acids is the preparation of metal salts. Both neopentanoic acid and neodecanoic acid, like all carboxyHc acids, can form metal salts. However, in commercial appHcations, metal salt formation is much more important for neodecanoic acid than it is for neopentanoic acid. 

Salt Formation. Citric acid forms mono-, di-, and tribasic salts with many cations such as alkahes, ammonia, and amines. Salts may be prepared by direct neutralization of a solution of citric acid in water using the appropriate base, or by double decomposition using a citrate salt and a soluble metal salt. 

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