Judicial activism and overreach in India

Article by R. Shunmugasundaram (Senior Advocate, Member of Parliament, Rajyasabha) published in Amicus Curiae - Journal of the Society for Advanced Legal Studies. The Journal is produced by the Society for Advanced Legal Studies at the Institute of Advanced Legal Studies, University of London

Structure-reactivity correlations in the reactions of phenacyl bromide and ethyl bromoacetat with ortho-substituted cinnamate ions

707-708The second order rate constants in the title reactions in 90% acetone-10% water (v/v) mixture at three different temperatures indicate that electron-releasing substituents accelerate the rate while electron-withdrawing substituents retard the rate. A good Hammett correlation with σp constants is obtained for ortho-substituted cinnamate ions. The rate data have also been analysed using the method of Charton

Kinetics of reaction of 2,4-dinitrophenyl acetate with 3- and 4-substituted Pyridines and 4’-susbstituted 4-styrylpyridines

852-855Second order rate constants have been de ermined for the reaction of 2,4-dinitrophenyl acetate with 3- and 4-substituted pyridines and 4'-substituted 4’-styrylpyridines in acetonitrile-water (50%, v/v) mixture at 25°, 30°, 35° and 40°C. Activation parameters have been evaluated. Electron-releasing substituents increase the rate while electron-withdraw in substituents retard it. In both the reaction series linear free energy relationship is found to exist between the logarithms of rate constants and σ constants with ρ = -3.39 ± 0.38 (r = 0.989; s = 0.163;  n= 12 for 3- and 4-substituted pyridines and ρ = -0.390 ± 0.080 (r = 0.984; s = 0.028; n = 8) for 4'-substituted 4-styrylpyridines at 30°C. The ratio of effectiveness of transmission of substituent effect in styryl system relative to pyridine system in this reaction is 0.115. The Bronsted plot obtained is linear and βN is found to be 0.692 ± 0.056 (r = 0.990; s= 0.146; n = 16) indicating the extensive bond formation between pyridine and the reaction centre in the transition state

Structure-reactivity correlations in the reaction of substituted N-methyl- 2-styrylpyridinium iodides with alkaline hydrogen peroxide

666-669The kinetics of reaction between N-methyl-2-styrylpyridinium iodides and alkaline hydrogen peroxide have been studied spectrophotometrically in 1:1 (v/v) water-methanol mixture. The reaction is first order in [substrate], [H2O2] and [OH-]. Structure-reactivity study with various 2'- and 4'-substituted N-methyl-2-styrylpyridinium iodides shows that the reaction is accelerated by electron-withdrawing substituents and retarded by electron-releasing substituents. A Hammett ρ-value of +0.916 ± 0.064 (r = 0.988; s = 0.063) is obtained. A suitable mechanism involving the attack of hydroperoxide ion on the β-carbon atom of the substrate to form epoxide in a slow step followed by cleavage of epoxide is proposed. Analysis of ortha-effects using multiparameter extensions of the Hammett equation in the reaction of 2'-substituted-N-methyl-2-styrylpyridinium iodides with alkaline hydrogen peroxide shows that both localised and delocalised effects are important and the steric effect is insignificant

Kinetics of reaction of <i>para</i>-substituted β-nitrostyrenes and β -methyl- β-nitrostyrenes with <i>n</i>-butylamine

609-613The kinetics of addition of n-butylamine to β nitrostyrene and β -methyl- β-nitrostyrene and their para- substitutedderivatives in acetonitrile at four different temperatures have been followed spectrophotometrically. The order in [substrate] is unity and in [n-butylarnine] it is non-integral. On the basis of the observed kinetic data, a stepwise mechanism involving the formation of zwitterionic addition complex in an equilibrium step followed by conversion into the reaction product via proton transfer in catalytic route by the amine has been proposed. The study of effect of substituents in these reactions shows that the electron-withdrawing substituents accelerate the reaction and electron releasing substituents retard it. Good Hammett correlations have been observed in both the reaction series

Kinetic study of charge transfer interaction of substituted pyridines and substituted 4-styrylpyridines with <em>p-</em>bromanil

402-405Kinetics of charge transfer interaction of various 3- and 4-substituted pyridines and 4' –substituted 4-styrylpyridines with p-bromanil has been studied spectrophotometrically in carbon tetrachloride at three different temperatures and thermodynamic parameters have been evaluated. The reaction between pyridine and p-bromanil follows second order kinetics, first order in each reactant. Electron-releasing substituents in pyridine ring increase the rate of the charge-transfer interaction while electron- withdrawing substituents retard it. Good Hammett correlations have been observed in both the reaction series. The ratio of effectiveness of transmission of substitutent effect in styrylpyridine system relative to pyridine system in this reaction is computed to be 0.167

High Capacity Li-Rich Positive Electrode Materials with Reduced First-Cycle Irreversible Capacity Loss

The first charge–discharge cycling behaviors of two sets of Li–Ni–Mn–Co type positive electrode materials were compared. The samples in each set have similar Ni–Mn–Co ratios but different Li-to-total metal ratio (Li/M). The samples that were Li-rich with a Li­[Li_<i>x</i>M_{(1–<i>x</i>)}]­O₂ structure showed a typical 4.5 V “oxygen loss” plateau and a typical irreversible capacity loss near 25%. Surprisingly, other samples with lower Li/M ratios that still exhibited a 4.5 V “oxygen loss” plateau exhibited an irreversible capacity loss as low as 4.0% of their first charge capacity. XRD analysis revealed that all samples were single-phase layered oxides. A separate and a detailed XRD analysis combined with d<i>Q</i>/d<i>V</i> analysis showed that the reduced irreversible capacity loss was not caused by the admixture of a spinel phase. ICP-OES results and the oxidation state versus atomic occupancy rules suggested the presence of metal site vacancies in the pristine materials with low IRC, which were confirmed by densities measured with a helium pycnometer. The results presented here show that the small irreversible capacity is a consequence of (a) metal site vacancies, leading to Li­[□_<i>q</i>M_{(1–<i>q</i>)}]­O₂ structures, where □ is a metal site vacancy, which leads to (b) no Li atoms in the transition metal layer. These materials still have Li/M > 1, so they are “Li-rich”, but they are “traditional layered materials” with no Li in the transition metal layer. This study identifies a new route for fabricating high capacity Li-rich positive electrode materials with small irreversible capacity loss

In Situ X‑ray Diffraction Study of Layered Li–Ni–Mn–Co Oxides: Effect of Particle Size and Structural Stability of Core–Shell Materials

Lithium-rich Li­[Li_<i>x</i>M_1–<i>x</i>]­O₂ (M = Ni, Mn, Co) materials have been claimed to be two phase by some researchers and to be one phase by others when all the available lithium is extracted electrochemically. To clear up this confusion, the Li-rich samples [Li­[Li_0.12(Ni_0.5Mn_0.5)_0.88]­O₂ and Li­[Li_0.23(Ni_0.2Mn_0.8)_0.77]­O₂ with different particle sizes were synthesized for in situ X-ray diffraction experiments. In situ X-ray diffraction measurements revealed two-phase behavior of 10 μm particles and one-phase behavior for samples with submicrometer particles. The phase separation in samples with large particles agrees with literature proposals of oxygen release from a surface layer and the observation of distinct surface and bulk phases. The small particle samples are so small that they are entirely composed of the surface phase found in the large particle samples. These results strongly suggest that the size of particles can significantly affect the structural evolution testing and electrochemical performance of the Li- and Mn-rich materials. It is proposed that the surface phase continuously grows during charge–discharge cycling, which leads to voltage fade in large particle samples. Meanwhile, in situ X-ray diffraction measurements were also performed for the layered Li–Ni–Mn–Co oxides with varying nickel contents, including NMC811 (LiNi_0.8Mn_0.1Co_0.1O₂), NMC442 (LiNi_0.42Mn_0.42Co_0.16O₂), [Li­[Li_0.12(Ni_0.5Mn_0.5)_0.88]­O₂, and Li­[Li_0.23(Ni_0.2Mn_0.8)_0.77]­O₂. Samples with higher nickel content showed much faster contraction of unit cell volume as a function of cell voltage, which suggests that the core–shell structures with a nickel-rich core (e.g., NMC811) and a Mn-rich shell (e.g., Li_1.23Ni_0.154Mn_0.616O₂) should not crack during charge–discharge cycling

Synthesis and Characterization of the Lithium-Rich Core–Shell Cathodes with Low Irreversible Capacity and Mitigated Voltage Fade

Lithium-rich layered Ni–Mn–Co oxide materials have been intensely studied in the past decade. Mn-rich materials have serious voltage fade issues, and the Ni-rich materials have poor thermal stability and readily oxidize the organic carbonate electrolyte. Core–shell (CS) strategies that use Ni-rich material as the core and Mn-rich materials as the shell can balance the pros and cons of these materials in a hybrid system. The lithium-rich CS materials introduced here show much improved overall electrochemical performance compared to the core-only and shell-only samples. Energy dispersive spectroscopy results show that there was diffusion of transition metals between the core and shell phases after sintering at 900 °C compared to the prepared hydroxide precursors. A Mn-rich shell was still maintained whereas the Co which was only in the shell in the precursor was approximately homogeneous throughout the particles. The CS samples with optimal lithium content showed low irreversible capacity (IRC), as well as high capacity and excellent capacity retention. Sample CS2-3 (the third sample in the 0.67Li_1+<i>x</i>(Ni_0.67Mn_0.33)_1–<i>x</i>O₂·0.33Li_1+<i>y</i>(Ni_0.4Mn_0.5Co_0.1)_1–<i>y</i>O₂ CS2 series) had a reversible capacity of ∼218 mAh/g with 12.3% (∼30 mAh/g) irreversible capacity (IRC) and 98% capacity retention after 40 cycles to 4.6 V at 30 °C at a rate of ∼C/20. Differential capacity versus potential (d<i>Q</i>/d<i>V</i> versus <i>V</i>) analysis confirmed that cells of the CS samples had stable impedance as well as a very stable average voltage. Apparently, the Mn-rich shell can effectively protect the Ni-rich core from reactions with the electrolyte while the Ni-rich core renders a high and stable average voltage