DIAZOTIZATION TITRATION PDF

Reaction time it takes 10—15 min : the compounds react with nitrous acid at different rates based on the nature of the compound. Slow diazotizable groups: sulpha groups, carboxylic groups and nitrogen oxide group. Fast diazotizing groups: anilide, toluidine and aminophenol. They are as follows: Rate of titration: Addition of sodium nitrite to the sample solution takes time to react with the amino group present in the sample solution.

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Reaction time it takes 10—15 min : the compounds react with nitrous acid at different rates based on the nature of the compound. Slow diazotizable groups: sulpha groups, carboxylic groups and nitrogen oxide group. Fast diazotizing groups: anilide, toluidine and aminophenol. They are as follows: Rate of titration: Addition of sodium nitrite to the sample solution takes time to react with the amino group present in the sample solution.

Different amino compounds react with the nitrous acid at different rates. Based on this, the amino compounds are classified into two main groups. They are as follows: Slow diazotizable compounds Example: Sulphanilic acid and anthranilic acid Fast diazotizable compounds Example: Aniline, aminophenol, and toluidine The reaction rate is increased by the addition of the potassium bromide solution. Temperature: Maintenance of the temperature is the main condition for the diazotization titration.

The diazonium salts formed are not stable at elevated temperatures. Types of Diazotization Titrations There are mainly three types of methods based on the titration procedure. They are as follows: Direct method: The main principle involved in this method is to treat the amino group containing drug with the acid solution. Then this solution is titrated with the sodium nitrite solution. The end point is determined by the above-mentioned methods. Indirect method: The principle involved in this method is that the excess nitrous acid is added to the titration sample solution and it is back titrated with the other appropriate titrant.

This method is mainly used for the titration of insoluble diazonium salts. Other method: The main principle involved in this method is the formation of the diazo oxide which is more stable than the diazo compounds. For example, the aminophenol is readily oxidized by the nitrous acid and converted to the quinones in the presence of copper sulphate solution and forms the diazo oxide compounds.

This readily undergoes the coupling reaction with the nitrous acid.

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Diazonium compound

Hence, secondary and especially tertiary alkyldiazonium species are either unbound, nonexistent species or, at best, extremely fleeting intermediates. Methyldiazonium carboxylate is believed to be a fleeting intermediate in the methylation of carboxylic acids by diazomethane , and alkyldiazonium species generated via diazotization of amines have been studied in physical organic chemistry studies. In contrast, aryldiazonium salts are more stable, though still dangerously explosive under certain conditions, because SN2 is geometrically impossible and does not occur, while SN1 occurs with much greater difficulty compared to alkyldiazonium species due to difficulty in forming the high energy aryl cation and stronger C sp2 —N bond compared to the C sp3 —N bond in alkyldiazonium compounds. Aryldiazonium salts due undergo SN1 Ar dissociative unimolecular nucleophilic aromatic substitution in a few cases, while the majority of their reactions take place by SRN1 Ar dissociative radical nucleophilic aromatic substitution in which an initial electron transfer takes place, allowing for the formation of an aryl radical rather than cation. Aryldiazonium salts are exceptionally versatile reagents for chemical synthesis.

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