The electronic states of nitroanilines

A correlation of spectroscopic data with all-valence-electron, $\text{CNDO}\text{s-CI}$ results has been performed for a number of mono- and disubstituted benzenes containing nitro and/or amino groups. The lowest energy transitions of p-nitroaniline are predicted to be 1¹B₁ ← 1¹A₁, 2¹A₁ ← 1¹A₁, and 2¹B₁ ← 1¹A₁, in the order of increasing energy. These three transitions are assigned to (i.e., are encompassed within) the lowest energy absorption band envelope of p-nitroaniline. The lowest energy predicted transition of o- and m-nitroanilines is 2A′ ← 1A′ and is supposed to correspond to the totality of the lowest energy absorption feature in both of these systems. The orbital excitation nature of these transitions is discussed.     

Nonlinear second harmonic generation by light wave-plasma interaction in oscillating magnetic field

The nonlinear generation of second harmonic electromagnetic waves in a thin inhomogeneous (dense and rarefied) plasma layer (of lengthd) by obliquely and normally incident light waves is analyzed. We consider the effect of an external time-dependent magnetic field on the generation and amplification of waves. Two cases are considered, when the magnetic field oscillates at a frequency (i) equal to and (ii) double that of the incident wave. For normal incidence, waves are not radiated in case (i), while in case (ii) the second harmonics are radiated equally from the plasma boundaries atx=0 andx=d. For a rarefied plasma, the second harmonics are radiated with equal amplitudes in both cases.     

Study of the hydration products of the system CaO---Al2O3---SO3---SiO2 with varying CaO mole ratio

The hydrated phases of the system CaO---Al₂O₃---SO₃---SiO₂ were studied, and the effect of the presence of varying amounts of CaO on the hydrated phases was also investigated. These phases were assessed by the aid of differential thermal analysis (DTA) and X-ray diffractometry. They hydration kinetics of the pastes under study were followed by the determination of the chemically combined water.

Results revealed that 1 mole of CaO in excess reacts with the available SiO₂ and initiates the formation of sulphoaluminate hydrates. As the CaO is increased, the amount of such hydraulic phases is increased and, accordingly, the rate of hydration enhanced. The addition of 2 moles of CaO results in the formation of appreciable amounts of ettringite among the sulphoaluminate hydrates, but some anhydrous forms still exist. On the other hand, 4 moles give better formation of the hydraulic phases and some excess Ca(OH)₂ is also detected.     

An alternative Route to (±)-Warburganal Synthon

The transformation of the ketone (1) to the unsaturated diester (11) a potential intermediate for the warburganal (12) is described. The Wittig reaction of theketone (1) with methylenetriphenylphosphorane afforded the olefin (2) which reacts with Woodward's reagent (MeCOOAg, I₂ and MeCOOH and H₂O) to give the diol (13). This on heating with dimethylsulfoxide afforded the tetralin (14)     

Cathodic reduction of diazonium salts in aprotic medium

Cathodic reduction of diazonium salts in acetonitrile led to the formation of azobenzenes, in good to moderate yields, and diarylamines as minoritary products. The reactions were carried out at the second reduction potential of the diazonium salts, involving aryl anions in the formation of the products.     

Some aspects of the hydrothermal calcination of gypsum

Lump-size and powdered gypsum samples were calcined at 135, 150 and 180°C. The products were thoroughly investigated by differential thermal analysis and X-ray diffraction, and their chemically-combined water was determined thermogravimetrically. Results indicated that almost all the treated samples contained gypsum, hemihydrate and anhydrite in varying proportions. Gypsum and anhydrite increased, and the hemihydrate decreased as the heating temperature was increased and the grain size decreased. Such a variation in the phase constitution of the treated samples is discussed.The relative intensity of the main gypsum X-ray diffraction characteristic lines changes upon treatment. In the atmospheric calcination the relative intensities of the lines at 3.059, 2.867, 2.679, 2.59, 2.495, 2.45 and 2.40 Å show a pronounced decrease. Autoclaving, on the other hand, causes a detected decrease in the relative intensity of the line at 7.56 Å and an increase in the 4.27, 3.059, 2.59, 2.495 and 2.45 Å lines. These findings postulate that X-ray diffraction data could hardly be used for the quantitative assessment of the gypsum phase in the dehydration products of any calcined material.     

MINDO-Forces calculation of molecular geometries and reaction paths

A new method for the minimization of molecular energies is described, based on the Murtagh-Sargent procedure and the MINDO/2(3) semiempirical MO method. The derivative of energy is calculated according to the Pulay's Force method. This method was applied to the calculation of heats of formation and geometries of different organic molecules. The results agree well with the experimental and theoretical values known in the literature. The MINDO-Forces method was applied to the calculation of the internal rotation barrier of the benzyl carbonium ion. The calculated value 18.79 kcal/mol agrees well with the theoretical values known in the literature. The MINDO-Forces method was applied to the calculation of the internal rotation barrier of cyclopropyl carbinyl cation. The calculated rotation barrier, 21.28 kcal/mol is in agreement with the known theoretical values and with the expectation based on the NMR measurement of the barrier height in cyclopropyl dimethyl-carbinyl cation. Part of the Ph.D. thesis, S. M. Khalil, University of Baghdad 1976.     

Nonlinear Interaction of S-Polarized Incident Radiation and Surface Waves in Magnetoactive Plasma

The effect of an external magnetic field on the nonlinear interaction of S-polarized electromagnetic radiation incident on a S-polarized surface wave in a plasma layer was studied analytically. We have calculated the amplitudes of generated waves at combination frequencies. The generated waves are of P-polarization and can be either electromagnetic or surface waves, depending on the signal of the value=\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\chi '^2 = \frac{{k'^2 }}{{\varepsilon '}} - \frac{{\omega '^2 }}{{c^2 }} + k'\frac{\partial }{{\partial x}}\frac{{\varepsilon '_2 }}{{\varepsilon '\varepsilon '_1 }}} $\end{document}.     

Effects of thermal treatment on the surface properties of a wide pore silica gel

A mesoporous silica gel Davidson 59 was thermally treated in vacuo, in the temperature range 20–1000°C. Effects of thermal treatment on the water contents, nitrogen surface areas, pore structure and heats of immersion in water were investigated and discussed. The temperatures selected were 20, 110, 200, 290, 380, 480, 510 and 1000°C. These temperatures were found to cover all the various textural changes resulting from the heat effect.It could be shown that the heats of immersion in water depend primarily on the water content of the sample and are proportional, at least qualitatively to the number of hydroxyl groups on the surface and their availability for interaction with liquid water. The interesting result obtained is that a second factors is involved, namely the pore structure of the adsorbent. A qualitative parallelism exists between the normalized heat of immersion per unit area, and the average pore radius. Apparently the packing of water molecules in narrow pores leads to a decrease in the heat of immersion due to repulsion between the permanent dipoles of the molecules. In narrower pores, the heat of immersion in water is smaller than in wide pores.