Anilinium salts

A naphthalene sulfonation product that is rich in the 2,6-isomer and low in sulfuric acid is formed by the reaction of naphthalene with excess sulfuric acid at 125°C and by passing the resultant solution through a continuous wiped-film evaporator at 245°C at 400 Pa (3 mm Hg) (26). The separation in high yield of 99% pure 2,6-naphthalenedisulfonate, as its anilinium salt from a cmde sulfonation product, has been claimed (27). A process has been patented for the separation of 2,6-naphthalenedisulfonic acid from its isomers by treatment with phenylenediarnine (28). 

Even though they aie weaker bases, aiylamines, like alkylanines, can be completely protonated by strong acids. Aniline is extracted from an ether solution into 1 M hydrochloric acid by being completely converted to a water-soluble anilinium salt under these conditions. 

The Brpnsted acidic anilinium salt [PhNH3+][ B(C6F5)4] has been developed as a catalyst for the hydroamination and hydroarylation of alkenes, such as styrenes, nor-bomene, cyclic alkenes, and cyclohexadiene, with anilines. The weakly coordinating... 

Trichloroacetic acid decomposes in water, alcohol and aniline and other basic solvents but it does not decompose in non-basic solvents such as benzene, carbon tetrachloride, sulfuric and acetic acid. Furthermore, the ethyl ester of trichloroacetic acid dissolves in alcohol but it does not decompose. It is known that this ester does not ionize in alcohol. Trichloroacetic acid, the sodium salt, the barium salt, and the anilinium salt all decompose in water at the same rate and all give beautiful first order constants throughout the whole course of the reaction. It is known that all these salts... 

At 70° the specific decomposition rates for the barium salt and the anilinium salt are both 1.754 X10 5, practically the same as for the sodium salt. 

In alcohol, the sodium salt gives a first order constant throughout the whole range, and the results are reproducible as before. The barium salt, however, decomposes more slowly and a first order constant is not obtainable. The anilinium salt dissolved in alcohol, gives an apparent first order constant toward the end of the reaction. An increase in ionic strength through the addition of electrolytes gives an increase in the decomposition rate. 

In aniline, the anilinium salt decomposed faster towards the end of the reaction, and here also a concentration effect was noticed, the dilute solution giving a higher specific decomposition rate. 

Quaternary ammonium salts with asymmetric nitrogen atoms. Inversion of configuration is not possible because there is no lone pair to undergo nitrogen inversion. For example, the methyl ethyl isopropyl anilinium salts can be resolved into enantiomers. 

If the negative charge on the anion can actually be delocalized round the ring, as with substituted phenols, we should expect the size of p to increase. Both the phenol and the anion are delocalized but it is more important for the anion. The effect is larger for the ionization of anilinium salts as the acid (ArNH ) does not have a delocalized lone pair but the conjugate base (ArNH2) does. 

Quaternary anilinium salts (240), obtained from reaction of (pyrrol-l-yl)methanol and the appropriate aniline with trioctylphosphine, react in polar solvents via the azonia-fulvene ion (241) with enamines through a Mannich-type reaction followed by cyclization to give pyrrolizidines 242 and 243124. The ratio between the pyrrolizidines formed varies considerably with ring size of the enamine employed (equation 50). Pyrrolizines have also been obtained by reaction of pyrrole with two equivalents of enamine125 or condensation of some ketones with L-sodium or L-ethyl prolinate126. 

Phosphorylation of alkyl bromides. Alkyl bromides react with 1 in refluxing DME to form an alkyl di-f-butyl phosphate, which is converted by TFA in benzene to a monoalkyl phosphate, usually isolated as the anilinium salt. ... 

Although protonation of the amine leads to the anilinium salt which is a deactivating substituent, nitration of aniline in nitric acid sulfuric acid yields 60% para and 34% meta substitution, whilst nitration of acetanilide gives 79% para and 19% ortho nitroacetanilides. 

Polyaniline filaments have been synthesized in mordenite and zeolite Y. 3 Aniline was sorbed from hexane solution into the dehydrated zeolites containing different levels of hydroxyl groups (an alternate route is the exchange of anilinium salt into the host, see ref. 93b). Oxidative polymerization was achieved by immersion of the loaded zeolites into an aqueous solution of peroxydisulfate, as demonstrated by spectroscopic identification and recovery of the encapsulated polymer (Figure 10). 

A useful preparation is the Emmert cleavage. This is a reductive ring opening of anilinium salts in which one of the A-alkyl groups is simultaneously attached to the 2-position of the benzene ring (XVIII). The products are of the type XIV [169-170]. 

This mesomeric (or M) effect is seen when aniline is placed in a solution of pH 8-14, i.e. when the basic aniline is unionised. When aniline is placed in a solution of pH < 7, the A,max returns to virtually the value obtained for benzene (203 nm). What is happening is that aniline in acidic solution reacts to form the anilinium salt. The lone pair of electrons on the nitrogen is now involved in bond formation to an H+ ion and can no longer function as an auxochrome. The structure of aniline hydrochloride is shown in Figure 7.8. 

It forms acidic anilinium salts (phenyl ammonium) upon reaction with acids. C6H5NH2 + HCI C6H5NH3+Cf... 

Anilinium salts can be converted back to aniline by NaOH. 

Phenacylammonium Salts Phenacyl anilinium salts have light absorption 300-350 nm that make them preferable for photoinduced cationic polymerization. Upon irradiation, these salts undergo either a heterolytic cleavage or a homolytic cleavage followed by an electron transfer to yield a cation intermediate that in turn can initiate polymerization of appropriate monomers [16]. Scheme 11.14 shows the mechanism in detail. As can clearly be seen, the photolysis of phenacylammonium salts are irreversible and different than their sulfonium analogs [43]. 

F. Kasapoglu, et al., Photoinitiated cationic polymerization using a novel phenacyl anilinium salt. Polymer 2002, 43(8), 2575-2579. 

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