J»-Nitroaniline

Figure 1.1 CVs of /j-nitroaniline in 0.1M NBiuPFg/DMF in the presence of different amounts of 1,3-diphenylurea (a) OmM urea, (b) 0.5 mM urea, ( ) 1 mM urea, and (d) 10 mM urea. 500mV/s scan rate.10...

A stock solution was prepared consisting of a 1 1 (v/v) mixture of Ac-Phe-Gly-p-nitroaniline (Ac-Phe-Gly-PNA, 0.3 mg/mL) in DMF and 50 mM phosphate buffer pH 6.8. To 1 mL of substrate stock solution, 50 pL of papain (Stock 160mg/mL protein) was added and the absorbance was measured spectrophotometrically using a Shimadzu UV-1601 at 405 nm for 100 second. Enzyme activity per minute was calculated from the initial linear portion of the absorbance vs. time curve. Activity units are the amount of enzyme activity which catalyzes the transformation of 1 micromole of the /j-nitroaniline per minute in phosphate buffer (pH 6.8) at 25 C using 8 mg/mL protein catalyst. 

Solid /j-nitroaniline (690 mg, 5.00 mmol) and Viehe salt 2 (815 mg, 5.00 mmol) were ball-milled at -20 °C for 1 li. Most of the HCl escaped tlirough the Teflon gasket that was tightened against a torque of 50 Nm. Residual HCl was pumped off at room temperature. The yield of pure salt 3 was 1.321 g (100%). 

The mixture may be warmed if necessary to dissolve the /j-nitroaniline hydrochloride. 

Dibr omo- 5 - nitrobenzene [prepared from j -nitroaniline as in part (c)]... 

With very basic amines, the catalytic effect of perchloric acid is much stronger than that for j -nitroaniline. For example,... 

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