2,4-xylidine

The mixture of xylidines has been used as a first component of azo-dyes. The chief constituent of the mixture is m-xylidine (4-amino-1,3-xylene). It can be separated by crystallization from glacial ethanoic acid. It is also used for the preparation of azo-dyes. 

Complex linear polyamines are best designated by replacement nomenclature. These trivial names are retained aniline, benzidene, phenetidine, toluidine, and xylidine. 

Xstrata AG, 205 m-Xylene-diamine, 138 Xylenes, 137 3,5-Xylenol, 138 Xylidines, 138... 

Reaction of 2,4-xylidine with methylamine and ethyl orthoformate leads to the amidine 119 condensation of that product with a second mole each of orthoformate and 2,4-xylidine gives the scabicide amitraz (120) [29]. 

X-Strahlen, m.pl. X-rays, Rdntgen rays, Xylldinrot, n. xylidine red. 

Bromobutyric acid 2,6-Xylidine n-Propylamine Hydrogen chloride... 

The starting material is prepared by reacting 2-bromobutyric acid with sulfonyl chloride to give the acid chloride. It is then reacted with 2,6-xylidine, then with potassium iodide followed by n-propylamine. 

One mol of 2,6-xylidine is dissolved in 800 ml glacial acetic acid. The mixture is cooled to 10°C, after which 1.1 mol chloracetyl chloride is added at one time. The mixture is stirred vigorously during a few moments after which 1,000 ml half-saturated sodium acetate solution, or other buffering or alkalizing substance, is added at one time. The reaction mixture is shaken during half an hour. The precipitate formed which consists of cj-chloro-2,6-di-methyl-acetanilide is filtered off, washed with water and dried. The product is sufficiently pure for further treatment. The yield amounts to 70 to 80% of the theoretical amount. 

Alternatively, in this and all subsequent titrations with 0.025M potassium iodate, a 250 mL conical flask may be used and the carbon tetrachloride or chloroform indicator replaced by 0.5 mL amaranth or xylidine ponceau indicator, which is added after most of the iodine colour has disappeared from the reaction mixture (see Section 10.125). 

The presence of free bromine, and consequently the end-point, can be detected by its yellow colour, but it is better to use indicators such as methyl orange, methyl red, naphthalene black 12B, xylidine ponceau, and fuchsine. These indicators have their usual colour in acid solution, but are destroyed by the first excess of bromine. With all irreversible oxidation indicators the destruction of the indicator is often premature to a slight extent a little additional indicator is usually required near the end point. The quantity of bromate solution consumed by the indicator is exceedingly small, and the blank can be neglected for 0.02M solutions. Direct titrations with bromate solution in the presence of irreversible dyestuff indicators are usually made in hydrochloric acid solution, the concentration of which should be at least 1.5-2M. At the end of the titration some chlorine may appear by virtue of the reaction ... 

The titrations should be carried out slowly so that the indicator change, which is a time reaction, may be readily detected. If the determinations are to be executed rapidly, the volume of the bromate solution to be used must be known approximately, since ordinarily with irreversible dyestuff indicators there is no simple way of ascertaining when the end point is close at hand. With the highly coloured indicators (xylidine ponceau, fuchsine, or naphthalene black 12B), the colour fades as the end point is approached (owing to local excess of bromate) and another drop of indicator can be added. At the end point the indicator is irreversibly destroyed and the solution becomes colourless or almost so. If the fading of the indicator is confused with the equivalence point, another drop of the indicator may be added. If the indicator has faded, the additional drop will colour the solution if the end point has been reached, the additional drop of indicator will be destroyed by the slight excess of bromate present in the solution. 

To determine the purity of a sample of arsenic(III) oxide follow the general procedure outlined in Section 10.127 but when the 25 mL sample of solution is being prepared for titration, add 25 mL water, 15 mL of concentrated hydrochloric acid and then two drops of indicator solution (xylidine ponceau or naphthalene black 12B see Section 10.125). Titrate slowly with the standard 0.02M potassium bromate with constant swirling of the solution. As the end point approaches, add the bromate solution dropwise with intervals of 2-3 seconds between the drops until the solution is colourless or very pale yellow. If the colour of the indicator fades, add another drop of indicator solution. (The immediate discharge of the colour indicates that the equivalence point has been passed and the titration is of little value.)... 

X-ray methods 9 X-rays 9, 647 Xylene cyanol FF 268 Xylenol orange 319 Xylidine ponceau 405... 

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