Reduction of 4-nitrophenol

Prepared by reduction of 4-nitrophenol or 4-nitrosophenoi. Can be diazotized and used as a first component in azo-dyes. Chief outlet is for sulphur dyes in which it is fused with sodium polysulphides. L/sed as a photographic developer. 

Similar observation was recorded for the GME and FGME catalyzed reduction of 4-nitrophenol (4NP) [46]. The GME and FGME nanoparticles are prepared in the... 

Brezova, V., Blazkova, A., Surina, I., and Havlmova, B. (1997) Solvent effect on the photocatalytic reduction of 4-nitrophenol in titanium dioxide suspensions. Journal of Photochemistry and Photobiology A Chemistry, 107 (1-3), 233-237. 

The kinetics of 4-nitrophenol reduction in presence of microgel-metal nanocomposite particles was studied by UV/Vis spectroscopy. Figure 9 shows the UV spectra for the reduction of 4-nitrophenol measured at different times. For a typical measurement, successive decrease of peak intensity at 400 nm with time can be utilized to obtain the rate constant [59, 72, 73]. This peak is attributed due to the presence of 4-nitrophenate ions in the system. The formation of 4-nitrophenate ions... 

Figure 15 shows the influence of temperature on the catalytic activity in an Arrhenius plot of the TOFs. These data can be compared to data obtained for the reduction of 4-nitrophenol with an excess of NaBkLt in presence of the metal nanocomposite particles. From Fig. 15, a nonlinear relationship between In (TOF) and T l can be seen. The TOF increase more than exponentially with increased temperature. Only in the immediate vicinity a significantly smaller TOF is monitored. 

Esumi K, Isono R, Yoshimura T (2004) Preparation of PAMAM- and PPI-metal (silver, platinum, and palladium) nanocomposites and their catalytic activities for reduction of 4-nitrophenol. Langmuir 20 237-243... 

The other dendrimer stabilizing strategy carried out by Esumi involves coordination of the NPs by surface amino groups of PAMAM and PPI dendrimers [19c-e], and these catalysts were used for various catalytic reactions including the reduction of 4-nitrophenol. In this case, one may visualize PdNPs surrounded by a number... 

Generally, the conditions leading to a CRP system were found to yield a well-defined polymer shell. In some examples, the latter was a classical hydrophobic polymer such as polyMMA [158,160], polyMA [158], polystyrene [163], poly(tert-butyl acrylate) [163], or polyBMA [163]. In one example, the grafted polymer was polyDMAEMA, which showed pH- and temperature-responsive behavior when the particles were further transferred to water [159]. The polyDMAEMA domains were used as nanoreactors to generate gold nanoparticles at the particle surface, the catalytic activity of which was effective in the reduction of 4-nitrophenol by NaBILj... 

The catalytic reduction of 4-nitrophenol to 4-aminophenol has been used for the analysis of the catalytic activity of the Pt NPs. The Pt NCs exhibit a high catalytic activity and turnover numbers as high as 1580 50, which is among the highest turnover numbers measured for this reaction. Hence, the composite particles consisting of the SPBs and the Pt NCs present a system with high colloidal stability that may be used for catalysis in an aqueous environment. 

The catalytic activity of microgel-based metal nanoparticles was investigated by monitoring photometrically the reduction of 4-nitrophenol by an excess of NaBH4. We assumed that reduction rates were independent of the concentration of NaBH4 because it was in excess compared to 4-nitrophenol. Moreover, the apparent rate constant, feapp, was found to be proportional to the surface S of the metal nanoparticles present in the system ... 

According to Praharaj et al., ° the resin-bound gold nanoparticles (R-Au) have been used successfully as a solid-phase catalyst for the reduction of 4-nitrophenol by... 

To study the catalytic activity of the resin-bound gold nanoparticles, the reduction of 4-nitrophenol with sodium borohydride was chosen as a model reaction. An aqueous solution of 4-nitrophenol shows a distinct spectral profile with an absorption maximum at 317 nm. Now addition of sodium borohydride solution results in the shifting of the peak position to 403 nm (Figure 2.6). This peak was due to the formation of 4-nitrophenolate ions in alkaline conditions caused by the addition of NaBELj. The BH4 under the experimental conditions (devoid of catalyst) is incapable of reducing 4-nitrophenol to the corresponding amino compoimd. Hence, the resin-bound gold entity has been employed as a catalyst for the effective reduction to occur. 

One of the most common reactions to test the catalytic activity of metal nanopartides is the catalytic reduction of 4-nitrophenol by an excess of NaBH4. Pradhan et were the first to identify this as an excellent model reartion for testing the catalytic activity of free or immobilized nanopartides. The kinetics of this reaction can be easily monitored by UV-vis spectroscopy as shown in Figure 21. After the addition of metal nanocomposite partides, the peak at 400 nm, which is due to the 4-nitrophenate ions, decreases gradually with time and a new peak appears at 290 nm. This peak results from the product, 4-aminophenol. The concentration of sodiirm borohydride was adjusted to exceed the concentration of 4-nitrophenol. Under these conditions, first-order rate kinetics with regard to the 4-nitrophenoI concentrations could be used to evaluate the catalytic rate. These conditions are widely used in the literature and fadlitate comparison and evaluation of the... 

The reduction of 4-nitrophenol by an excess of NaBH4 in the presence of microgels functionalized by metal NPs was often used as a model reaction to evaluate the catalytic activity of different systems. The reduction of 4-nitrophenol to 4-aminophenol is of industrial importance as 4-aminophenol is a commercially important intermediate for the manufacturing of analgesic and antipyretic dmgs. Additionally, 4-nitrophenol is one of the most refractory pollutants that can occur in industrial wastewaters. The reduction of 4-nitrophenol can be monitored by successive decrease of peak intensity at 400 nm (attributed to the presence of 4-nitrophenate ions) with time to obtain the rate... 

K. Hayakawa, T. Yoshimura, K. Esumi, Preparation of Gold-Dendrimer Nanocomposites by Laser Irradiation and Their Catalytic Reduction of 4-Nitrophenol, Langmuir 19, 5517, 2003. 

Figure 4.10 UV-visible absorption spectra of the catalytic reduction of 4-nitrophenol to 4-aminophenol. [Reproduced with permission from Ref [32], Copyright 2013, RSC Publication, CrystEngComm, 2013, Vol. 15, pp. 6819-6828.]...

Xiao S, Xu W, Ma H, Fang X (2012) Size-tunable Ag nanoparticles immobilized in electrospim nanofibers synthesis, characterization, and application for catalytic reduction of 4-nitrophenol. RSC Adv 2 319-327... 

Fig. 35 Catalytic reduction of 4-nitrophenol by NaBHa in the presence of (a) dried Pt-NC5 gel powder (3.5 mg), and (b) dried Pt NPs (1 mg) in the surrounding solution. The strong UV absorption peak at 400 nm corresponds to the nitrophenolate ion. Reprinted from Haraguchi and Varade [149], Copyright 2014, with permission of Elsevier...

Gazi, S., Ananthakrishnan, R. (2011). Metal-free-photocatalytic reduction of 4-nitrophenol by resin-supported dye under the visible irradiation. Applied Catalysis B Environmental, 105, 317—325. http //dx.doi.Org/10.1016/j.apcath.2011.04.025. 

Chronocoulometry (CCM) of coupled chemical reactions The possibilities of CCM can be illustrated in the study of electrochemical reduction of 4-nitrophenol and 4-nitrosophenol [92]. The sequence of reactions (ECi E mechanism) is very close for both compounds as has been discussed above, in paragraph 4.2.3. The normalized chronoam-perometric working curves are constructed using the following dependence (cf [93]) ... 

For the evaluation of kinetic parameters in the EC ev mechanism potential-time shifts are recommended [108]. The effect exerted by the sphericity of the electrode surface on the E-t curves and on the transition times observed at MDE has been estimated in [111]. This correction was applied to the reduction of 4-nitrophenol (model process) governed by the ECE mechanism. 

The authors reported the catalytic performance of this dendrimer-stabilized nanoparticle in C-C CTOsscoupUng reactions, including the Suzuki-Miyaura, Sonogashira and Heck, and reduction of 4-nitrophenol. 

The catalytic activity of this catalyst for reduction of 4-nitrophenol was exceptional. The amoimt of Pd was quite low (down to 0.02 mol%) and the TOFs were very high. 

Deraedt C, Salmon L, Astruc D. Click dendrimer-stabilized palladium nanoparticles as a green catalyst down to parts per million for efficient C-C cross-coupling reactions and reduction of 4-nitrophenol. Adv Synth Catal 2014 356 2525-38. 

The catalytic performance of microporous vanadosilicates with octahedral and tetrahedral S104 nanofibres (AM-6) is enhanced in the reduction of 4-nitrophenol by NaBH4 by the exposed proportion of V-O terminals in AM-6 which, with different morphologies, is hydrothermally synthesized by controlling the Na/K molar ratio of... 

A single Au nanoparticle inside the pNIPAM shell catalytic system, a so-called hybrid yolk-shell nanostructure, was synthesised as shown in Fig. 13.9 (Wu et al, 2012). This system showed catalytic activity in the reduction of 4-nitrophenol and nitrobenzene with NaBH, in which the selectivity of hydrogenation depended on temperature. The reduction of 4-nitrophenol was much faster at lower temperature, whereas nitrobenzene reacted faster at higher temperature. Both compounds are of similar size thus the changes in pNIPAM core conformation from a swollen to a shrunken state could not affect the diffusion of the reactants through the pNIPAM core. However, 4-nitrophenol is more hydrophilic than nitrobenzene. The interaction of the reactants with pNIPAM in its hydrophilic and hydrophobic state could be a reason for the temperature dependence of the selectivity of catalysis. 

---