Diazonium salts analysis

The arenediazocyanides have been known since 1879. They played an important role in the Hantzsch-Bamberger debate on the (Z)/( ,)-isomerism of diazo compounds (see Sec. 7.1). When an aqueous solution of a diazonium salt is added to a solution of sodium or potassium cyanide, both in relatively high concentration, at a temperature below 0°C, a yellow to red (Z)-arenediazocyanide starts to crystallize. Hantzsch and Schulze (1895 a) found that these compounds rearrange into the (ii)-isomers, which have a bathochromically shifted visible absorption (see Sec. 7.1). Under strongly alkaline conditions a 1 2 adduct is formed, to which Stephenson and Waters (1939) assigned the structure 6.36. It was never corroborated, however, by modern instrumental analysis. 

The first diazonium-salt-crown-ether adduct was isolated and identified as a 1 1 complex by Haymore et al. (1975). Unfortunately Haymore never published the X-ray structural analysis of benzenediazonium hexafluorophosphate with 18-crown-6 which he performed in 1980. ORTEP drawings with measured bond angles and lengths from Haymore s investigation can be found in a review chapter by Bartsch (1983, p. 893). A few data from Haymore s work (e.g., R = 0.064) were also mentioned by Cram and Doxsee (1986, footnote 7). Groth (1981) published the results of his X-ray investigation of 4-methoxybenzenediazonium tetrafluoroborate and 21-crown-7 (R = 0.042) and Xu et al. (1986) those of 4-methoxybenzenediazonium tetrafluoroborate and dibenzo-24-crown-8 (R = 0.086). 

This type of titration is quite simple to carry out and is very useful for the analysis of sulphonamide antibiotics and aminobenzoic acid-derived local anaesthetics. Titration is carried out with acidified sodium nitrite causing the primary aromatic amine function to be converted to a diazonium salt shown in Figure 3.15 for sulphacetamide. 

The only published method available for the determination of personal exposure to benzidine-based dyes utilized the analysis of urine for benzidine and benzidine metabolites (JO, J 1 ). This method does not allow for quantitation of a daily exposure, since benzidine and its metabolites have been found in the urine of hamsters fed a benzidine-based dye up to 168 hours after a single dosing (J 2). A method for the determination of personal exposure to azo dyes and diazonium salts has been developed (J 3), but it is not specific enough to determine an exposure to a benzidine-based dye. 

This method has been used to analyze both symmetrical (C.I. Direct Red 28 and C.I. Direct Blue 6) and unsymmetrical (C.I. Direct Black 38 and C.I. Direct Brown 95) benzidine-based dyes. Based on this work, the application of the method to other benzidine-based dyes should be straightforward. When field samples are submitted for benzidine-based dye analysis, bulk samples of the dyes present in the sample also should be submitted. With these bulk samples, the analyst should be able to determine if this method is applicable to the various dyes submitted and if any interferences are present. The method presently has not been tested on field samples. An existing sampling method (J 3) for azo dyes and diazonium salts should be directly applicable to this method with a change from a cellulose ester to a Teflon filter. This change is necessary to insure quantitative recovery of the sample from the filter. 

Dehydroalanine 116 desmosine 48, 49 diazo compounds 157 aryl diazonium salts, reactive properties 157 synthesis 160 diazoacetates, analysis of products 165 reactive properties 162 synthesis 164 diazoketones, analysis of products 162 conversion to haloketones 139 reactive properties 165 synthesis 140 diazomethane preparation 141 reactive properties 162 diazonium salts 89 diazonium-IH-tetrazole 90, 95 3,4-dihydroxyproline 52, 53 diimidoesters 69 diisopropylfluorophosphate 130 2,3-dimethylmaleic anhydride 83 dinitrophenylation 79 disulfide bond reduction 103... 

Phenols in trace concentrations were derivatized by coupling with a 4-sulfobenzene-diazonium salt at pH 10.5. The azo dyes were combined with tetradecyldimethylbenzy-lammonium ions at pH 5.0 and, after SPE on a PTFE membrane filter, the end analysis was carried out by RP-HPLC with UVD at 352 nm. LOD was between 40 ppt (phenol) and 2 ppb (2,5-xylenol) for eight phenols tested. The method was used for determination of phenols in river water ... 

Fig. 15.1 (a) Schematic illustration for the functionalization of SWCNTs in various ILs by mechanically grinding them with diazonium salts at room temperature for minutes and (b) AFM analysis by height of SWCNTs functionalized with 4-chlorobenzenediazonium tetrafluoroborate in OmimBF,. The vertical distances measured (shown as numbers, in nm, on the micrograph) are predominantly <1.4 nm, therefore indicating individual SWCNTs (Reproduced from Ref. [58] with kind permission of the American Chemical Society)... 

To probe this, model compounds were prepared and subjected to the reaction. Firstly, formation of the ABE ring system was modeled [14]. Diazotization of the amine 35 and reaction of the resulting diazonium salt afforded the spirocyclic product 36 in an acceptable 57% yield from the amine. This marked the first example where the radical-polar crossover reaction was terminated in an intramolecular manner. Modeling the ABCE tetracycle also worked well in preparing products 40 42. Importantly, the relative stereochemistry of 42, and by implication that of the other tetracycles, was verified by X-ray crystal structure analysis... 

Products. The product analyses for the reaction of nitronium hexafluorophosphate with aromatic amines were carried out by n. m. r. A solution of the nitronium salt and trinitrobenzene (as a standard material for n. m. r. analysis) in nitro-methane was added dropwise, with shaking, to a solution of an amine in the same solvent. After fifteen minutes the reaction mixture was poured into ether (50 ml), and any precipitate filtered off using a glass filter. The precipitate was dissolved in a small amount of acetone and analysed for the diazonium salt by n. m. r. The ether solution was washed with water, dried on magnesium sulphate and filtered using a filter paper. After evaporation of the solvent under reduced pressure, the products were dissolved in acetone or deuterated chloroform and analysed by n. m. r. 

Several synthesis on the basis of stilbenes as starting materials were reported. The paper [113] presented experimental data regarding some azo dyes synthesized by coupling of the diazonium salt of 4,4 -diarnino-stUbene-2,2 -disulfonic add with different acetoacetarylides. Reaction products were purified and characterized by means of elemental analysis by UV-VIS, IR, H-NMR, and C-NMR spectroscopy. A series of stilbene and fluorene compounds were prepared [114]. Compounds of... 

In analysis of the primary cannabinoids (A9-tetrahydrocannabinol, cannabidiol, and cannabinol) in marijuana samples Cannabis saliva L.), diverse eluent systems have been described in the literature for use in chromatographic runs, such as ethyl acetate methanol water concentrated ammonium (12 5 0.5 1), toluene chloroform (7 3), and n-hexane diethyl ether (80 20) [1]. The detection of cannabinoids can be accomplished using diverse diazonium salts, such as Fast Blue B, or with Duquenois-Levine reagent (Table 16.1) [2], The limit of detection (LQD) varies from 2 to 10 ng mL (Figure 16.1). 

The second problem prepares ethoxybenzene (21 phenetole) from benzene, and the retrosynthetic analysis is 21 19 => 42 benzene. Because 21 is an ether, the most likely precursor is phenol (19), which is prepared from aniline (23) via the diazonium salt. Aniline is derived from nitrobenzene (42), which is prepared directly from benzene. Therefore, the synthesis is that shown in the following illustration. 

The standard method for the determination of nitrite in seawater is based on the reaction of nitrite with an aromatic amine leading to the formation of a diazonium compound which couples with a second aromatic amine. The product is an azo dye which is quantified by spectrophotometry. Early methods were modifications of the Griess-Ilosvay procedure where the nitrite diazotized with sulphamic acid. The diazonium salt then coupled with 1-naphthylamine. The method described below is generally accepted for seawater analysis and is based on the method proposed by Shinn (1941) and adapted for seawater by Bendschnei-der and Robinson (1952). This method is very sensitive and is unaffected by the presence of other constituents normally occurring in seawater. Sulphanilamide hydrochloride is used as the amino compound, which after diazotization is coupled with N-(l-naphthyl)-ethylene-diamine dihydrochloride. 

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