Anilinium hydroxide

On-column methylation of barbiturates, hydan-toins, and some carboxylic acids can be achieved by injecting the sample mixed with 0.2M trimethyl-anilinium hydroxide in methanol. For carboxylic acids, the sample can be dissolved in 14% boron trifluoride in methanol and heated at 60 to 100° for 30 minutes. After evaporation of the bulk of the methanol, the mixture is diluted with a few millilitres of water and the methyl derivative extracted with a small volume of hexane. 

In the case where liquid chromatography is not available, acidic herbicides need to be derivatized because they can dissociate in water and are not usually volatile to be analyzed by gas chromatography. The basic methods used for chlorophenoxy acid herbicides are esterification, silylation, and alkylation, as described in a recent exhaustive review.The derivatization step is performed after preconcentration and cleanup. The step consists of the formation of esters and ethers from the carboxyl and phenol groups of the acidic herbicides. A lot of reagents and chemical mechanisms can be used to perform derivatization reactions. The most employed derivatization reagents are diazomethane, methyliodide, trimethylsulfonium (or anilinium) hydroxide, bis (trimethylsilyl) trifluoroacetamide (BSTFA), pentafluorobenzyl bromide, and anhydride acetate. It should be noted that explosive and hazardous diazomethane was replaced by safer agents. Authors also underline that surface water generally contains humic substances, which can interfere with the derivatization reaction. ... 

The presence of the /3-hydroxypropionic ester unit in deacetylpicraline is established by oxidation with chromic acid in acetone, which yields an aldehyde base, picralinal, C21H22N2O4 the latter is readily deform yla ted by short treatment with methanolic potassium hydroxide, which affords picrinine in quantitative yield. Reduction of picralinal with sodium borohydride regenerates deacetylpicraline. Vigorous treatment of deacetylpicraline with sodium borohydride gives a noncrystalline indoline base, which exhibits the UV-absorption of an anilinium ion in concentrated perchloric acid hence, the Na-carbinol-amine ether function must have suffered reduction. Since acetylation of the noncrystalline base gives a product which exhibits acylaniline UV-absorption, picraline and its derivatives must contain an NaH group (53, 54). 

An extensive study of the decomposition of the N,N-dimethylbenzyl-anilinium ion 22 was recently carried out by Lepley and coworkers 93.99) As expected, displacement reactions occur exclusively with hydroxide and alkoxide, an orf/io-rearrangement occurs with amide, and a variety of products are formed with various organolithium reagents. The products found when butyllithium was employed are listed below. 

Why is aqueous sodium acetate preferred to aqueous sodium hydroxide for the conversion of anilinium hydrochloride (14) to aniline ... 

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