Nitrobenzenediazonium Tetrafluoroborate

These salts can be made easily since tetrafluoroboric acid (HBF4) and hexa-fluorophosphoric acid (HPF6) are commercially available. However, the main advantage of the diazonium salts with the anions of these acids is their stability, which is significantly higher than that of probably all other diazonium salts. 4-Nitrobenzenediazonium tetrafluoroborate is nowadays even a commercial product. Preparative diazotization methods with these two acids can be found in Organic Syntheses (tetrafluoroborate Starkey, 1943 hexafluorophosphate Rutherford and Redmont, 1973). 

The hydro-de-diazoniation of 4-nitrobenzenediazonium tetrafluoroborate with tri-phenylphosphine in methanol (Yasui et al., 1991) is hardly interesting for synthetic purposes, as the yield of nitrobenzene passes through a narrow maximum (95 %) if 0.5 equivalent of triphenylphosphine is used. 

Dipping solution II Dissolve 25-50 mg 4-nitrobenzenediazonium tetrafluoroborate in 10 ml diethylene glycol and make up to 100 ml with water [20] or acetone [15]. 

Sodium hydroxide, pellets 4-Nitrobenzenediazonium tetrafluoroborate Diethylene glycol Ethanol Methanol Acetone... 

Organic synthesis 38 [OS 38] Formation of an azobenzene derivative from N,N-dimethylaniline with 4-nitrobenzenediazonium tetrafluoroborate... 

The synthesis of N,N-dimethylaniline with 4-nitrobenzenediazonium tetrafluoroborate yielded the corresponding azobenzene derivative [107] (see also [14]). 

OS 38] [reactor and protocol given in [107]] By reaction of N,N-dimethylaniline with 4-nitrobenzenediazonium tetrafluoroborate, the corresponding azobenzene derivative is obtained at a conversion of 37% using methanol (protic solvent) or acetonitrile (aprotic solvent) under electroosmotic flow conditions [107] (see also [14]). 

Arenediazonium tetrafluoroborates were unreactive towards tellurium3 under conditions that had produced diaryl tellurium dichlorides from arenediazonium chlorides. However, addition of lithium chloride to a mixture of tellurium and 4-nitrobenzenediazonium tetrafluoroborate led to the formation of bis[4-nitrophenyl] tellurium dichloride in 33% yield2. 

As an example of a solvent-dependent electrophilic substitution reaction, the azo coupling (SsAr) reaction of 4-nitrobenzenediazonium tetrafluoroborate with N,N-dimethylaniline is given in Eq. (5-27) [504]. According to the two-step arenium ion mechanism, the activation process of the rate-limiting first step is connected with the dispersion of the positive charge. This should lead to a decrease in rate with increasing solvent polarity. 

For example, 4-nitrobenzenediazonium tetrafluoroborate (60) was coupled to 4,4 -dinitrobiphenyl (61) in 82% yield [100], respectively. Scheme 27. The yield of azoarene side-product 62 is minimized to less than 5% by using Cu(II) salts as an additive. 

In 1997, Harrison and coworkers reported on the synthesis of an azobenzene compound in microfluidic channels [37] for the purpose of combinatorial synthesis. The azo coupling of N,N-dimethylaniline and 4-nitrobenzene diazonium tetrafluor-oborate (Scheme 4.17) was carried out in a Pyrex microreactor driven by electro-osmotic flow. A few years later, Hisamoto et al. described a phase transfer diazo coupling reaction carried out in a microfluidic chip [38]. By providing a huge liquid-liquid interface between a solution of 5-methylresorcinol dissolved in ethyl acetate and an aqueous solution of 4-nitrobenzenediazonium tetrafluoroborate (Scheme 4.18), 100% conversion within a 2.3 s residence time was achieved. In contrast to macroscale experiments, the reaction could be accelerated and the formation of unwanted precipitates and bisazo side products was successfully suppressed. 

There is a wealth of hterature on graphene which reports that the edge of graphene is particularly more reactive than its side (basal plane). For example, using Raman spectroscopy Strano and co-workers [22] report the reactivity of graphene, that being single-, double-, few- and multi-layer towards electron transfer chemistries with 4-nitrobenzenediazonium tetrafluoroborate. Strano et al. [22]... 

Improved stability of tyrosinase-based BDD biosensor was reported by Zhi s group.They combined chemical and electrochemical modifications of BDD film with 4-nitrobenzenediazonium tetrafluoroborate to produce aminophenyl-modified BDD, followed by immobilizing tyrosinase covalently at the BDD surface via carbodiimide coupling. They used this sensor for detection of phenol, p-cresol, and 4-CP and reported 90 % of its original activity after intermittent use for 5 weeks. In all mentioned studies on tyrosinase-based BDD aminosensor no applications on analysis of model or real matrices are presented. 

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