Nitration of phenols with tertiary butyl nitrite (TBN) obeyed second-order kinetics with a first-order dependence on [TBN] and [phenol] under acid-free conditions. Reaction rates were significantly altered by a change in the dielectric constant and other physical properties of solvent. The rate of nitration increased with an increase in temperature (303-323 K) in different solvent media (acetonitrile, dichloroethane, CCl 4 , dimethyl formamide (DMF), and toluene). The rates of nitration (log k) could not fit into either Amis or Kirkwood plots [log k' vs. (1/D) or [(D -1)/(2D + 1)], but the trends were better explained by the basic form of multivariate linear solvent energy relationships (MLSER) suggested by the Koppel and Palm approach on the one hand and the Kamlet and Taft approach on the other hand. These observations probably substantiate that cumulative contributions of basic solvent parameters (equilibrium as well as frictional solvent effects) and solvent-solute interactions for solvation of transition state during nitration of phenols. Reaction rates accelerated with the introduction of electrondonating groups and retarded with electron-withdrawing groups. Accordingly, the reactivity of structurally different phenols was found to follow the following sequence:

Die Ketone (I), (III) und (IV) geben in Eisessig in Anwesenheit katalytischer Mengen konzentrierter Schwefelsäure mit Natriumazid die Lactame (II), (V) und (VI).

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Ti6Al4V sheet metal has found significant applications in the aerospace, defence and biomedical sectors due to its high strength-to-weight ratio and excellent corrosion resistance. The texture plays an important role in tailoring the mechanical properties which can be modified via thermo-mechanical processing. Constrained groove pressing (CGP) is a well-known sheet metal severe plastic deformation (SPD) technique for grain refinement and enhancement of mechanical properties. In this work, high temperature CGP has been performed successfully on Ti6Al4V alloy at 550°C followed by heat treatment at 500°C. CGP and heat treatment led to grain refinement and formation of submicron size grains. The inverse pole figure (IPF) reveals the decrease in texture intensity of basal planes from 5.9 to 4.5 in CGPed Ti6Al4V. Heat treatment further reduced the IPF texture intensity to 3.5. Enhancement in mechanical properties such as YS, UTS and microhardness is also observed. Although slight enhancement is observed in yield strength, ultimate tensile strength has been improved by 21% after CGP and heat treatment. Up to 20% improvements in microhardness have also been observed in processed samples. CGP and heat treatment together can serve as an efficient technique for tailoring microtexture and mechanical properties of Ti6Al4V and other HCP alloys.

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