1129-27-7

Upstream product

• 3555-18-8 4-sec-butyl-2-nitrophenol 
• 120-80-9 benzene-1,2-diol 
• 78-92-2 iso-butanol 
• 99-71-8 4-(1-methylpropyl)phenol 

Relevant academic research and scientific papers

Comparison of Substituted 2-Nitrophenol Degradation by Enzyme Extracts and Intact Cells

The first catabolic pathway enzyme, nitrophenol oxygenase, transforms o-nitrophenol (ONP) to catechol. Thirteen of 16 substituted nitrophenols tested were actively transformed by both enzyme preparations and intact cells yielding a wide range of Km (Ks) and Vmax. Individual chemicals in binary mixtures demonstrated competitive inhibition. Chemical and physical characteristics (electron withdrawal, size, and position of substitution on the 2-nitrophenol ring) affected degradation kinetics. The strongest correlation were between Km or Vmax values and electron withdrawal, though there was also evidence for effects relating to position and size of substitution on the aromatic ring. Kinetic parameters determined for enzyme preparations did not correlate to those determined for intact cells. Though enzyme reactivity ultimately determined whether a given chemical would be transformed, the transformation by intact cells was apparently affected by factors other than those directly impacting the initial catabolic enzyme.

Carbon nanotubes as activating tyrosinase supports for the selective synthesis of catechols

A series of redox catalysts based on the immobilization of tyrosinase on multiwalled carbon nanotubes has been prepared by applying the layer-by-layer principle. The oxidized nanotubes (ox-MWCNTs) were treated with poly(diallyl dimethylammonium chloride) (PDDA) and tyrosinase to yield ox-MWCNTs/PDDA/ tyrosinase I. Catalysts II and III have been prepared by increasing the number of layers of PDDA and enzyme, while IV was obtained by co-immobilization of tyrosinase with bovine serum albumin (ox-MWCNTs/PDDA/BSA-tyrosinase). Attempts to covalently bind tyrosinase provided weakly active systems. The coating of the enzyme based on the simple layer-by-layer principle has afforded catalysts I-III, with a range of activity from 21 units/mg (multilayer, II) to 66 units/mg (monolayer, I), the best system being catalyst IV (80 units/mg). The novel catalysts were fully characterized by scanning electron microscopy and atomic force microscopy, showing increased activity with respect to that of the native enzyme. These catalysts were used in the selective synthesis of catechols by oxidation of meta- and para-substituted phenols in an organic solvent (CH 2Cl2) as the reaction medium. It is worth noting that immobilized tyrosinase was able to catalyze the oxidation of very hindered phenol derivatives that are slightly reactive with the native enzyme. The increased reactivity can be ascribed to a stabilization of the immobilized tyrosinase. The novel catalysts I and IV retained their activity for five subsequent reactions, showing a higher stability in organic solvent than under traditional buffer conditions.

Layer-by-Layer coated tyrosinase: An efficient and selective synthesis of catechols

Agaricus bisporous tyrosinase was immobilized on commercial available epoxy-resin EupergitC250L and then coated by the Layer-by-Layer method (LbL). The two novel heterogeneous biocatalysts were characterized for their morphology, pH and storage stability, kinetic properties (Km, V max, Vmax/Km) and reusability. These biocatalysts were used for the efficient and selective synthesis of bioactive catechols under mild and environmental friendly experimental conditions. Ascorbic acid was added in the reaction medium to inhibit the formation of ortho-quinones, thus avoiding the known enzyme suicide inactivation process. Catechols were obtained mostly in quantitative yields and conversion of substrate. Tyrosinase immobilized on EupergitC250L and coated by the LbL method showed better catalytic activities, higher pH and storage stability, and reusability with respect to immobilized uncoated tyrosinase. Since chemical procedures to synthesize catechols are often expensive and with high environmental impact, the use of immobilized tyrosinase represents an efficient alternative for the preparation of this family of bioactive compounds.

Structure-activity relationship in the domain of odorants having marine notes

We synthesized or re-synthesized a large series of 2H-1,5-benzodioxepin- 3(4H)-ones 9 (Scheme 1), 4,5-dihydro-1-benzoxepin-3(2H)-ones 10 (Schemes 3 and 4) and 5,6,8,9-tetrahydro-7H-benzocyclohepten-7-ones 11 (Schemes 5 and 6), since the lead compound for the olfactory note of perfumes based on marine accords is a well-known benzodioxepinone named Calone 1951 (9b). We meticulously described the odor profile of each synthesized compound and discussed relevant structure-odor relationships (Tables 1-3). In particular, we revealed a correlation between the conformation of the seven-membered ring and the activities of these compounds (Table 4 and Fig. 3). We also clarified the effect of the position and the size of the alkyl substituent at the aromatic ring.

Hair dyeing composition containing an aryldiamine and a substituted catechol

A composition for use in the dyeing of keratinous fibre such as hair includes an aqueous anaerobic solution of an aryldiamine and a substituted catechol. Optionally, an aromatic coupling agent can also be incorporated in the composition to modify the shade of color produced. Anaerobic storage conditions can, for example, be maintained by packing the composition in an aerosol container with a halocarbon propellant.