2.5- Dichloroaniline diazotization

Spengler and Jumar [90] used a spectrophotometric method and thin layer chromatography to determine carbamate and urea herbicide residues in sediments. The sample is extracted with acetone, the extract is evaporated in vacuo at 40°C and the residue is hydrolysed with sulphuric acid. The solution is made alkaline with 15% aqueous sodium hydroxide and the liberated aniline (or substituted aniline) is steam distilled and collected in hydrochloric acid. The amine is diazotized and coupled with thymol, the solution is cleaned up on a column of MN 2100 cellulose power and the azo-dye is determined spectrophotometrically at 440nm (465nm for the dye derived from 3-chloro- or 3.4-dichloroaniline) with correction for the extinction of a reagent blank. 

It is obtained by coupling two equivalents of diazotized 2,4-dichloroaniline onto bisacetoacetylated 3,3-dimethylbenzidine, also known as Naphtol AS-G. 

Dinitro-3,4-dichlorobenzene, ndls (from petr eth), mp 97° can be prepd by diazotizing with NaN02 2-nitro-5,6-dichloroaniline (Ref 1) lt2-Diniiro-3, wdichlurobenzen , crysts (from ale +benz), mp 95 98° obtd by nitrating with mixed acids l-nitro-3,5-dichlorobenzene (Ref 2)... 

Pigment Red 2 [6041-94-7] 12310 NaphtholAS (Naphthol Red) coupling diazotized 2,5-dichloroaniline with 2-hydroxy-3-naphthanilide... 

Another common laboratory reaction of amines is diazotization to provide unstable and highly reactive diazonium salts. Plimmer et al (14) have isolated an aromatic triazene (XV) from soil containing 3,4-dichloroaniline (XIV) and presented evidence that it is formed by "natural diazotization of the aniline followed by coupling with a second amine molecule (Fig. 5). If this is true— that the natural nitrite commonly found in soil and water can bring about diazotization—a new dimension must be added to both the natural mechanisms of herbicide degradation and the generation of new series of potentially dangerous transformation products. 

JA2587> both couple with diazotized 2,4-dichloroaniline and several other arylamines to produce the 8-arylazo derivative, and 2,6-diaminopurine also furnishes the 8-arylazopurine (154) with diazotized 2,4-dichloroaniline. 

Dinitro 3,4 dichlorobenzene, ndls (from petr eth), mp 97° can be prepd by diazotizing with NaN02 2-nitro-5,6-dichloroaniline (Ref 1)... 

Dinitro-2,6 -dichlorobenzene, ndls or prisms-(from ale), mp 114° was prepd by diazotizing 4-nitro-2,6-dichloroaniline with NaN02 soln... 

As well as diazotized sulphanilic acid, other diazo reagents have been tried, e.g. 2,4-dichloroaniline. 

A reagent stick manufactured by Ames for the detection of bilirubin in urine. It is based on the reaction of bilirubin with diazotized 2,4-dichloroaniline. 

---